Starting a new thread, I progressed (???) on the previous one and it was getting stale anyway. Here's where I am:
While trying get my system pressure right, the fuel pump started making whining and gurgling noises. I took this to mean that it was dead or dying, so I replaced it. Replaced fuel filter too, cause why not? Fuel flow seems fine and the return seems to be ok.
Now, when testing primary pressure, the pressure gradually rises to about 4 bar. But it rises quite slowly. My recollection is that it was originally pretty quick, maybe 10 seconds. Then there's a faint click and pressure drops to ~3 bar almost instantaneously and then climbs back to 4 in about a second or so. This repeats. It's like the pressure is trying to get where it should be, but then the regulator pops open. There's a pressure drop but then it climbs again and cycle repeats. I tried 3 different valve bodies, 2 different springs and 2 different cylinders. All with the same result. Is it possible that pressure needs to be set MUCH higher with more shuims? That is, more cylinder pressure is needed to get smooth regulator action? And on top of that the new fuel pump started making the same noises! The system pressure does hold up well though.
Does this suggest that the problem isn't the pressure regulator valve but something else? But what? Logic has failed me, I'm stumped and it's getting frustrating. Any suggestions would be very welcome at this point. Thanks and cheers,
It's quite common for fuel accumulators to fail. Only occasionally though I've seen them fail so badly that the leak back to the tank so fast that the pump can't keep up. Have you checked your accumulator
Are you sure it's the correct pump (nominal 6 bar, stall 8 bar) and not the unit intended for 124/126 twin pump setups (3 bar nominal, 4 bar stall)
Sorry for the split up messages, I'm typing from my mobile
Other thing to check is if the pump is getting adequate voltage AND current. Try giving it a good earth and a nice thick temporary power wire direct from the battery
As to the primary pressure regulator in the FD, I think it's highly unlikely that it would have suddenly go so far wrong.
BTW where are you measuring this pressure - at the line between fd and WUR? With your measurement valve closed ie system pressure?
Dave have you traced all the hard lines front to back? Probably a long shot but maybe a pin hole leak somewhere?
Thanks for the suggestions. I made big progress today, but still a ways to go. The fuel accumulator seems fine - it holds pressure for over 30 minutes. I can't find any other leaks anywhere. But I did discover a couple other things.
First, I replaced fuel pump whether it needed it or not (looks like maybe it did). New OE pump from Classic Center. Then, it turns out that I DID mix up the cylinders in the pressure regulator in the course of monkeying around. I read on a Porsche forum that they're mated to the FD, same as the metering cylinder. That was new to me. I stupidly fell into the traps of doing too much at the same time, no pictures and bad labeling of parts. ??? When I finally put in the original cylinder into the FD (trial and error) the pressure cycling stopped but system pressure was still low.
Second, I discovered that the regulator plug/spring assemblies are NOT all the same. I have several. The only one that works correctly right is the one that originally came with FD. The length is slightly different from the "same part" out of a parts car and another from eBay. Something else to be aware of.
Third: After the new pump, new filter and the right parts in the pressure regulator, the system pressure was still low, only 4.5 bar, and control pressure was the same. Looks like the WUR had suddenly gone crazy. (??) After swapping it for another WUR in my parts box, pressures were now pretty spot on:
- System pressure: 5.5 bar
- Cold control: ~1.8 bar (test done at 30C or so)
- Hot Control: ~4 bar (maybe on the high side, but not crazy)
Wunderbar! Now the car starts and is drivable again. But a problem remains. Under heavy throttle not much happens and the engine kind of bogs down. Going up a hill there was a kind of burp from the air flow sensor. Time to get seriously systematic. The CIS manual
Problem Diagnosis chart recommends as follows:
Symptom Test Stumble on acceleration: 3, 5, 9, 10, 11
Engine miss: 3, 5, 11, 12, 13
Lack of power: 1, 3, 7, 9, 10, 11, 13
High speed break up: 3, 4, 2
Here's the list of tests and what I seem to know at this point. I don't find the diagnosis chart very helpful since there's so much overlap. In the end you just need to do almost everything anyway. This is another case of systematically starting at the beginning step-by-step. Which I (and others) seem to ignore, again and again. ::) Anyway, results thus far:
Test Result 1 Check throttle linkage` OK, on inspection seems fine
2 pump delivery volume OK, excellent, well over spec
3 primary system pressure OK, 5.5 bar
4 static pressure test OK, tests accumulator
5 injection nozzle leak OK
6 cold start valve Didn't test, but no cold start problem
7 cold control pressure OK, 1.8 bar at 30C deg ambient.
8 auxiliary air valve Didn't test but no apparent problems here
9 warm control pressure OK? 4 bar. Spec is 3.4-3.8 bar, so a bit high.
But probably not so much to cause a profound lack of power.
I should correct spec for engine vacuum. I think mine is on
the low side (high altitude?) but not sure where to measure.
10 full load vacuum enrichment Looks like a problem! Taking vacuum off the
WUR drops control pressure from 4 bar down to 2.5 bar,
That's a whole 1.5 bar. Spec is dropping from 3.4-3.8 down
to 3.0-3.4 or just 0.4 bar! So, under heavy throttle I'm running
super-rich? I'm not sure what to make of this.
11 idle speed and CO adjustment I set mixture screw as best I could and adjusted idle accordingly.
Idle is actually very smooth and stable. It drops a little when A/C
is on. It didn't used to do this. Maybe suggests a small vacuum leak
someplace?
12 fuel injector test Didn't test but doesn't seem likely. (??)
13 test fuel distributor Didn't test but doesn't seem likely. (?)
What's next??? First, I'd greatly appreciate any comments on all this. I tried to go back and systematically describe it all by using the logic of the manual. At this point it all seems to point to a vacuum enrichment problem, so I'm going to follow that. But I'm really not sure how.
- Something faulty in the WUR or maybe wrong WUR? Maybe I ought to refurbish the original WUR. FWIW, it's a rare high altitude version.
- Some kind of wrong connection of WUR (I'm not sure how that's possible)
- Some other underlying vacuuum problem?
Finally, this is all rather long and tedious. Would it be better to start a new thread on vacuum enrichment?
As always, thanks for the ideas and continued support. Happy motoring and cheers,
Perhaps start considering sending the WUR and FD to CIS Flowtech for testing and calibration?
Quote from: rumb on 31 July 2022, 01:40 PMPerhaps start considering sending the WUR and FD to CIS Flowtech for testing and calibration?
LOL, ironically it IS a WUR that CIS rebuilt but never used. The reason was that I installed a high altitude WUR from that parts car. And it worked fine till now. I've got a box of WURs. I'm gonna test and tag them all.
While we're At it, do you know where to measure vacuum for purposes of setting control pressure? The vacuum that the WUR sees from its tubes seems lower thanthereal enginevacuim. The manual isn't clear on whether real manifold vacuum or the vavuum that the WUR sees from its tubes. Hope I'm making sense....
Control pressure too high will cause a lean condition, which could cause stumbling. Get pressures spot on before you look at anything else.
It seems you are nearly there in terms of the correct values for everything except hot control pressure. You have to get that down. At 4000+ feet SLC has slightly less than the ave air pressure but at times it seems it is only by a gnat's whisker. Frankly, I feel as tho it is a red herring.
There's a million cars a year go to 6000 feet in the Victorian snow fields and no one is in crisis. Indeed my own 6.9 travelled from sea level up to the mountain top every day for 10 years with a standard WUR.
So forget Hi altitude WUR's .
You have to get the control pressure down to 3.6 then let's see.
Quote from: Randys01 on 01 August 2022, 03:57 AMIt seems you are nearly there in terms of the correct values for everything except hot control pressure. You have to get that down. At 4000+ feet SLC has slightly less than the ave air pressure but at times it seems it is only by a gnat's whisker. Frankly, I feel as tho it is a red herring.
There's a million cars a year go to 6000 feet in the Victorian snow fields and no one is in crisis. Indeed my own 6.9 travelled from sea level up to the mountain top every day for 10 years with a standard WUR.
So forget Hi altitude WUR's .
You have to get the control pressure down to 3.6 then let's see.
Thanks much!! Got some progress to report. First, the system pressure is now exactly 5.5 bar and stable. I played around with a few WURs and seemed to find a good one. Hot control pressure is 3.5 bar. Cold pressure is a bit low, ~0.9 bar at 30C ambient. Should be more like 1.8 bar at that temp, but never mind for the moment. The car starts instantly and idles very smoothly. It revs freely and is drivable, kind of.
So far so good. But problems remain. It still bogs down under heavy throttle. Basically, anything beyond about 1/3 throttle doesn't have any effect. There are a couple further issues:
- Static pressure - The system holds static pressure OK for a few minutes, but gradually creeps down. There don't seem to hot start problems, though I haven't tried a hot restart after sitting 10 minutes. So, there's a leak someplace. For the time being I'll assume it isn't the fuel pump non-return valve since it's new. Regardless, the leak doesn't seem severe enough to cause lack of power. Or is that a bad assumption?
- Fuel pump sucking air - there's a variable hissing noise emanating from the fuel delivery cluster. It sounds as if air is getting sucked in somehow. Can that mess things up? Probably it can, but the power loss was present from the start, so seems unlikely.
- Full load vac enrichment - Manual indicates that malfunction causes stumble on acceleration and/or lack of power. Disconnecting the vac hose drops control pressure from 3.5 down to 2.5 bar. The spec is a drop of only about 0.4 bar as I understand it. But I tested 2 WURs and both did the same thing. When the vac hose is disconnected at idle the engine speeds up.Maybe a candidate?
Next steps:
Check fuel accumulator for a leak
Check cold start valve for leak
Confirm air leak and eliminate
How to really check vac enrichment?
That's where I'm at. Any ideas or suggestions would be wonderful. This is killing me. Thanks again,
Dave,in any complex problem it pays to fix the known problems first before looking for more problems. I think you need to get that acceleration control pressure sorted first. I recondition warmup regulators and then set up the system on the car. In my experience you really want no less than 2.9 bar at acceleration. Warm control pressure with vac is a little bit more forgiving. All the good condition unmolested wurs I've seen seem to have been 3.5 bar from the factory, but anything up to 3.8 bar should be fine. As you point out the differential between readings with and without vac is crucial. Aim for 0.5 to 0.6 bar. Then set the exhaust gas CO correctly with vac applied. As I'm sure you realize, CO is set with vac applied, which means that if the differential between control pressures with and without vac is too great,you will be going too rich under acceleration.
Next try to confirm and resolve the air ingress at the fuel pump package. I've only seen this once before, and the culprit was the hose from the tank to the damper which had gone slightly porous. The result was pinging under acceleration due to being too lean.
As you then chase down your acceleration issues,you need to be sure the ignition system is good,and that timing is correct with proper advance characteristics.
You loss of static fuel pressure is highly unlikely to be the cause of your troubles, it's just not fast enough.
Quote from: s class on 06 August 2022, 02:06 PMDave,in any complex problem it pays to fix the known problems first before looking for more problems. I think you need to get that acceleration control pressure sorted first. I recondition warmup regulators and then set up the system on the car. In my experience you really want no less than 2.9 bar at acceleration. Warm control pressure with vac is a little bit more forgiving. All the good condition unmolested wurs I've seen seem to have been 3.5 bar from the factory, but anything up to 3.8 bar should be fine. As you point out the differential between readings with and without vac is crucial. Aim for 0.5 to 0.6 bar. Then set the exhaust gas CO correctly with vac applied. As I'm sure you realize, CO is set with vac applied, which means that if the differential between control pressures with and without vac is too great,you will be going too rich under acceleration.
Thanks muchly! Very helpful. It really does seem like the vac is having an extreme effect. But why? Unfortunately the manual isn't very helpful. All it says is "replace warm-up/full load enrichment compensator." It's not clear whether this means replacing the whole WUR or just the internal diaphragm or other parts? It's also suspect that 2 WURs seem to be doing the same thing. I'm going to recheck that. And nowhere have i found even a shred of info on adjusting the full-load control pressure. All I can imagine is a bad diaphragm (which would presumably not change control pressure at all) or the wrong spring pressure.
This all seems to relate to the whole WUR/vacuum interaction and the warm-up process. I can find almost nothing on either this or more specifics on the Full-load enrichment. On my car the Small WUR tube is not open to the atmosphere, it goes to the big tube
behind the aux air valve. The larger vac tube connects to the curved rubber hose
before the auxiliary air valve. It's worth noting that as the AAV closes during warm-up it effects where the WUR is drawing vacuum - before of after the AAV. Moreover, the respective vac ports on the WUR have opposite effect on control pressure. Maybe my tubes are switched? Yet I never changed them! And their size if different. None of the Bosch literature I've seem shows or describes this configuration though it seems to be very common.
Anyway, this is going on too long here, so I'll start another thread devoted to the WUR/vacuum/warm-up system. I've already made a few discoveries that I've never seen discussed and might be useful for others. My plan is methodically characterize what happens with vacuum during the warm-up process. That way I'll have a clearer idea what I'm talking about. In the meantime, if anybody knows how to alter the range of the full-load enrichment control pressure I'd love to hear it. Thanks again and cheers,
It sounds like your vac connections are correct. Is it the correct wur though what is the bosch end number... '056, '057 and '010 should all serve.
If the diaphragm was torn, then vac would have no influence. I'll reveal some of the dark secrets of kjet now. There are three adjustable posts on the wur. The fuel cell that the two fuel lines attach to can be driven up or down. Yours needs to come outwards about 0.3mm to warm reduce control pressure from 3.8 to 3.5. You can screw an m10x1 bolt into the inlet port and couple a slide hammer to it to pull the cell upwards. Use a vernier to monitor your progress
Once the warm control pressure is on 3.5 bar, you can adjust the enrichment pressure. This is set by the plug on the underside. You need to drive yours in deeper to raise the enrichment pressure to 3.0. DONT overdo it, or you will have to strip the unit ruining the diaphragm in the process to get the plug back out. Use a vernier and go 0.1mm at a time
One warm and enrichment control pressures are correct you an turn to the cold control pressure. That's the post next to the electrical connector. Deeper in (knocking it in) lowers the cold control pressure, higher up (drill and tap it for m6x1) raises it
Here is a doc I found online, may or may not help with your WUR shenanigans:
WUR Tips.pdf
And another:
WUR Tips II.pdf
Quote from: daantjie on 08 August 2022, 03:51 PMAnd another:
WUR Tips II.pdf
Daniel, THANK YOU, this is great! Exactly what I've been looking for. So much more specific than the other WUR rebuild stuff out there. Everybody should have this. Cheers,
Quote from: s class on 08 August 2022, 02:39 PMOnce the warm control pressure is on 3.5 bar, you can adjust the enrichment pressure. This is set by the plug on the underside. You need to drive yours in deeper to raise the enrichment pressure to 3.0. DONT overdo it, or you will have to strip the unit ruining the diaphragm in the process to get the plug back out. Use a vernier and go 0.1mm at a time
Thank you, thank you! I got the system pressure and cold/warm control pressures spot on with one WUR. It seems to just be the vac enrichment pressure (if I can call it that) that's off. So his is exactly what I've been missing. In reasoning through it all, it seems like there would have to be some way of adjusting the small spring pressure acting on the diaphragm. So this is it. I'm a bit puzzled though by why this piece of info seems to be so broadly overlooked. I've been looking at the various Porsche, Volvo and Audi sites and never came across it. Well, no matter, I'm going to get on it.
My next step is to methodically measure all the WURs in my small collection. It's still a bit puzzling why the vac enrichment pressure would change rather abruptly, if it even did. The car was running great for several years and I didn't change anything. Presumably it
couldn't run well with Vac enrichment pressure so far out. But then power kind of fell off a cliff all of a sudden and we find that the vac pressure is totally wrong. ??? ??. Anyway, I'll post my findings in due course. Cheers,
Quote from: s class on 08 August 2022, 02:39 PMOnce the warm control pressure is on 3.5 bar, you can adjust the enrichment pressure. This is set by the plug on the underside. You need to drive yours in deeper to raise the enrichment pressure to 3.0. DONT overdo it, or you will have to strip the unit ruining the diaphragm in the process to get the plug back out. Use a vernier and go 0.1mm at a time
"When the going gets weird, the weird turn Pro." -Hunter S. Thompson
Very wise. It seems I'm becoming VERY pro. All that said, some minor progress to report.
I went about very systematically checking 4 WURs in every way. There was something wrong with all of them, all different. One was sacrificed by experimentation on how hard to tap the adjustment elements. Well, not destroyed, but now maladjusted. I had never actually done that before. At the end I decided to focus on the unit with the excessive full load enrichment. FWIW, this was a unit rebuilt by CIS. I never used it when I got it several years ago. It didn't work right at the time, so I threw on a high altitude WUR that I had on hand. The latter worked perfectly and was on the car until my problems started.
So, to recap: the CIS WUR is perfectly to spec apart from full load enrichment pressure. System pressure is a perfect 5.5 bar. Hot control pressure is 3.5. Perhaps a tiny bit on the low side, but within spec, 3.4-3.8 bar (especially since I'm at 1200m elevation). The problem is vacuum controlled enrichment. Pressure drops to 2.5 bar, as noted elsewhere. Spec is 3.0-3.4 bar. The specified pressure drop is pretty damn small! Regardless, my pressure drop is easily 2X the spec. So that's a problem and I reproduced it again today.
First, it did turn out that I had an air leak before the fuel pump. I fixed that. Next, per S class' info above, I tried to adjust the vac enrichment post and tapped it in ~0.5mm That was the least I could manage (how anybody manages 0.1mm increments is beyond me). This had NO EFFECT. Maybe that's OK, cause it was so far out of range that much more is needed? I did note that the adjustment post was oringally farther out than those on all the other WURs. So, what to make of this? Just keep tapping? Or should this absolutely have had
some effect? Obviously I don't want to ruin the WUR by overshooting. It occured to me to take a test drive anyway, but I couldn't cause car is elevated. The idea behind that is to remove the vacuum enrichment and see how it drives. Sure, it wouldn't optimum. But if it's a significant improvement then it would point to excessive enrichment - maybe? ???
Again, comments, ideas and prayers welcome. Thanks and cheers,
The way the enrichment works is when you remove vacuum, the diaphragm drops down internally against the lower end stop in the base layer of the WUR. If the plug is way low, then the diaphragm is resting on the base layer itself, and not the lower plug. You may need to drive it up a bit more before it is internally standing proud of the aluminum of the base layer itself and actually effective.
On my test bench the WUR is mounted on a steel base, in which I've drilled and tapped for a bolt which I can turn from underneath to press the plug upward in an easily controlled manner
https://forum.w116.org/mechanicals/my-k-jet-test-bench/msg123147/#msg123147
Thread from years ago when I first started on my test bench
OK, thanks, maybe some progress to report. Or at least some things that are now known NOT to be the problem.
I rebuilt and set up an entirely different WUR. Good results:
1. system pressure 5.7 bar - OK
2. Hot pressure 3.5 bar - OK. Low end of range perhaps, but OK.
3. Enrichment vac pressure drop: 3.5 (control) => 3.0 bar. OK.
Other things that are also OK:
1. new fuel pump
2. new fuel filter
3. Checked ignition timing and function: OK
Control pressure could be hair higher but still within spec. Yet the original problem still exists: The car drives fine at low speed but bogs and stumbles under heavy throttle. The engine revs freely when parked (no load). Again, I'm at a loss. What else is there to check? I'm starting to panic a little. Cheers :'( ,
Whilst it doesn't solve your problems, I'll reassure you that 3.5bar is good. The published spec is 3.4 to 3.8, but all the unmolested units I've come across had been factory set to 3.5bar,so that's what I usually target.
Quote from: s class on 11 August 2022, 03:58 PMWhilst it doesn't solve your problems, I'll reassure you that 3.5bar is good. The published spec is 3.4 to 3.8, but all the unmolested units I've come across had been factory set to 3.5bar,so that's what I usually target.
Well that's
something anyway. But I wracking my brain on how it can all fall apart under load when all that stuff seems to be as OK as it can get. Inexplicable exhaust back-pressure? Simultaneous failure of all the injectors? Tachyon beam entanglement? What's left?
Does it feel rich or lean when it bogs? What do the spark plugs look like after a bog situation?
Weak spark?
TICKET CLOSED. ;D
What a horrible waste of time this was. The last problem turned out to be simple fuel starvation. At the beginning of this whole saga I discovered that the inline sieve-filter on the FD had collapsed on itself and was pretty clogged. I replaced it with one from another FD that had much freer flow. But maybe not free enough, or all the system disruption knocked loose a lot of particulate junk. All that lead to the fuel pump, filter and WUR mysteries. What seemed to happen during all that was that an extremely fine rust powder had severely occluded the fuel line FD filter. So I was kind of going in a circle, solving one problem but creating another.
Anyway, the car now seems to be better than ever. Thanks to all for ideas and support and tolerating my whining. Maybe somebody can learn something from all this. :o It's good to be back on the road. I was hoping to drive it to an MB club outing tomorrow and now it looks like I'll be able to. ;D Thanks again and cheers,
Quote from: rumb on 31 July 2022, 01:40 PMPerhaps start considering sending the WUR and FD to CIS Flowtech for testing and calibration?
i called them today in my darkest hour. They're 9-12 weeks out! wtf?
I know it's too late, sorry been disconnected for some time, but that's why I apply a small deviation to the std written procedure when measuring system delivery volume: I mesure it 2 times; at the FD outlet first and after at the inlet and compare both to rule out FD internal blockage. The CIS KJet guide is great but in my experience it requires interpretation/understanding in so many different chapters, this one being an example. The good thing here is that the experience described will serve to other forum members in the future, and that's the spirit.
Quote from: raueda1 on 11 August 2022, 08:40 PMQuote from: rumb on 31 July 2022, 01:40 PMPerhaps start considering sending the WUR and FD to CIS Flowtech for testing and calibration?
i called them today in my darkest hour. They're 9-12 weeks out! wtf?
They're that good. It's worth the wait. No one else in the U.S. can come close to how good they are at what they do.
Quote from: UTn_boy on 12 August 2022, 09:42 PMQuote from: raueda1 on 11 August 2022, 08:40 PMQuote from: rumb on 31 July 2022, 01:40 PMPerhaps start considering sending the WUR and FD to CIS Flowtech for testing and calibration?
i called them today in my darkest hour. They're 9-12 weeks out! wtf?
They're that good. It's worth the wait. No one else in the U.S. can come close to how good they are at what they do.
good perhaps but not perfect. I got a rebuilt WuR back from them about 3 years ago. It was all fine EXCEPT for fuel enrichment, which was about a 1.2 bar drop rather than 0.5 orso (coincidentally one of my recent problems). Basically it didn't work. By coincidence I had another working WUR.
Quote from: revilla on 12 August 2022, 12:01 AMI know it's too late, sorry been disconnected for some time, but that's why I apply a small deviation to the std written procedure when measuring system delivery volume: I mesure it 2 times; at the FD outlet first and after at the inlet and compare both to rule out FD internal blockage. The CIS KJet guide is great but in my experience it requires interpretation/understanding in so many different chapters, this one being an example. The good thing here is that the experience described will serve to other forum members in the future, and that's the spirit.
Would the fuel inlet volume be higher than the outlet figure?
Quote from: raueda1 on 13 August 2022, 10:47 AMQuote from: UTn_boy on 12 August 2022, 09:42 PMQuote from: raueda1 on 11 August 2022, 08:40 PMQuote from: rumb on 31 July 2022, 01:40 PMPerhaps start considering sending the WUR and FD to CIS Flowtech for testing and calibration?
i called them today in my darkest hour. They're 9-12 weeks out! wtf?
They're that good. It's worth the wait. No one else in the U.S. can come close to how good they are at what they do.
good perhaps but not perfect. I got a rebuilt WuR back from them about 3 years ago. It was all fine EXCEPT for fuel enrichment, which was about a 1.2 bar drop rather than 0.5 orso (coincidentally one of my recent problems). Basically it didn't work. By coincidence I had another working WUR.
We shouldn't let one mistake condemn them. No company is perfect.
Quote from: UTn_boy on 13 August 2022, 09:22 PMQuote from: raueda1 on 13 August 2022, 10:47 AMQuote from: UTn_boy on 12 August 2022, 09:42 PMQuote from: raueda1 on 11 August 2022, 08:40 PMQuote from: rumb on 31 July 2022, 01:40 PMPerhaps start considering sending the WUR and FD to CIS Flowtech for testing and calibration?
i called them today in my darkest hour. They're 9-12 weeks out! wtf?
They're that good. It's worth the wait. No one else in the U.S. can come close to how good they are at what they do.
good perhaps but not perfect. I got a rebuilt WuR back from them about 3 years ago. It was all fine EXCEPT for fuel enrichment, which was about a 1.2 bar drop rather than 0.5 orso (coincidentally one of my recent problems). Basically it didn't work. By coincidence I had another working WUR.
We shouldn't let one mistake condemn them. No company is perfect.
That's true, and I don't. Unfortunately my sample size is 1 and it was a dud. And as it is, I'm back in business with the car. So I'm gonna send it back and let them have at it again.
Quote from: SteveDuNord on 13 August 2022, 02:54 PMQuote from: revilla on 12 August 2022, 12:01 AMI know it's too late, sorry been disconnected for some time, but that's why I apply a small deviation to the std written procedure when measuring system delivery volume: I mesure it 2 times; at the FD outlet first and after at the inlet and compare both to rule out FD internal blockage. The CIS KJet guide is great but in my experience it requires interpretation/understanding in so many different chapters, this one being an example. The good thing here is that the experience described will serve to other forum members in the future, and that's the spirit.
Would the fuel inlet volume be higher than the outlet figure?
If I understand your question correctly - yes.
The fuel supply from the rear assembly, if disconnecting the supply line from the FD, delivers maybe twice the amount (order of magnitude) compared to the return flow from the FD to tank. All due to the pump-curve -- less resistance leads to more flow and vice versa.