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My new 79 280SEL

Started by ImBroke, 09 January 2022, 07:02 AM

ImBroke

Just picked this up. Non running, of course. Fuel tank had about 1/8 of fuel when it was parked. Now there is nothing but dust in there, the sender is probably destroyed, and this is the fuel pump situation. I have no idea how any of this gets hooked up, but am trying to figure it out. I have a new pump, will get a new filter, but the accumulator is crazy expensive. Hoping I won't need it, but have a feeling I will. I'm hoping to get some help from the forum, mainly on a fuel side.

ImBroke

Fuel pump situation

ptashek

You will need the accumulator, otherwise hot starts will be a nightmare.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

daantjie

Replace everything in the fuel delivery system.  No point in trying to piecemeal this job.  As well you will have to take a good look at the inside of the tank.  If it's crusty then you'll have to replace it or have it professionally cleaned.
Mercedessource on youtube.com has lots of vids on the fuel delivery package on KJET.  All parts are still readily available.
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

Also the strainer in the bottom of the gas tank. They often crud up.

After you have replaced all the components, inspected the tank and replaced the rubber fuel lines. Then connect the in and out lines of the Fuel distributor together and run the fuel pump for 20 minutes or so.

Only then attempt to start the engine.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

daantjie

Quote from: rumb on 09 January 2022, 01:42 PM
Also the strainer in the bottom of the gas tank. They often crud up.

After you have replaced all the components, inspected the tank and replaced the rubber fuel lines. Then connect the in and out lines of the Fuel distributor together and run the fuel pump for 20 minutes or so.

Only then attempt to start the engine.

Indeed great tips as well. Bottom line is you must ensure your fuel delivery is pristine otherwise it will never run right and will make you want to drop kick the thing ;D
Daniel
1977 450 SEL 6.9 - Astralsilber

ImBroke

Thanks for the support so far. I have a new filter also, that was in the box. Will get an accumulator, bite the bullet. Tank needs a good cleaning, for sure. I think the sender might be toast. There is about two inches of varnish crud on the bottom of it. The top was loose, like someone tried taking it apart the wrong way. I'm familiar with the tank screen, and I will need the hose that attaches to it as well.   I'm not new to Mercedes, but my main interests were W123 and W126 diesels. I sold my R107, so picked this up. I noticed there are two fuel lines coming out of the bottom of the tank, on the passenger side. Not sure where they go yet. I know the engine runs fine, we used a bit of ether, and it is smooth. If it runs like crap when I get the fuel system finished, I know where to look.

Jan S

You will find a lot of material regarding the fuel assembly on this forum.

I completely renewed it 12-15 months ago (see link https://forum.w116.org/mechanicals/k-jetronic-pressure-testing-troubleshooting/msg149100/#msg149100) and got a lot of help from this forum. However, I did not clean the tank. It's on my list ......

Hence, I added a pre-pump filter (see link above) between the strainer and pressure damper. It will remove rust particles, dirt, etc that passes through the strainer. Saves the pump.

And check the fuel hard lines by using compressed air, both supply and return to tank.

AND, I support what daantjie said - "Replace everything in the fuel delivery system" ..... hoses, banjo fittings, washers, .... everything .... start from the back and move forward  :)

Good luck!
1975-mod W116 450 SE with 6.9 engine

ImBroke

Jan S, your fuel parts look fantastic. Mine are slightly different. There is the wrong fuel pump in the box, so will  have to order the right one. I am afraid when I try to take the thing apart, all of those metal pre bent fuel lines are going to fall to pieces.
In my pic, please correct me if I'm wrong. On the right side of the fuel pump is the feed from the tank strainer? If so, I think I need this line for that.  https://www.rmeuropean.com/Products/1134760926-MFG20.aspx

Jan S

Not quite. The hose from the strainer goes to the damper cage. This hose is 14 mm in my car. See attached pic (the pic shows the system in my car, your car has a slightly different system it seems.). A short hose connects the damper cage and pump inlet. This hose is 14 mm in my car

I believe the system in your car depends on VIN number. It starts with 116.025.12.??????
1975-mod W116 450 SE with 6.9 engine

ImBroke

Looking at yours is clearing things up for me. Thank you so much. although, my Accumulator only has one fitting. I'm thinking it goes from the filter to the distributor? Perhaps? Take a look, and this is how I see it.

Jan S

You are almost there. I would recommend connecting the flange where it says "Tank" to pump inlet, and use the other flange (that has a 12 or 14 mm short hose end to it in you pic) to the hose from the tank. That will results in a better positioning of the damper cage relative to pump.

See my last pic.
1975-mod W116 450 SE with 6.9 engine