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Garage => Mechanicals => Topic started by: 1980450sel on 29 September 2009, 03:54 PM

Title: 1980 450 SEL Fuel issues UPDATE!
Post by: 1980450sel on 29 September 2009, 03:54 PM
Hi Everyone, I'm new to this forum as I just picked up the car on Sunday. It was my brother-in-law's old beast and had been sitting for some time, at least two years. Before I got it he had it towed to a garage where they told him it would be $1200 to fix the fuel delivery system. Does anyone have any good suggestions on where to start in diagnosing why gas isn't making to the injectors and how hard is it to remove the gas tank?
Thanks,
Scott in Canada
Title: Re: 1980 450 SEL Fuel issues
Post by: koan on 29 September 2009, 05:35 PM
Any idea how it ended up not running?

Just didn't go one day or a progressive deterioration?

Two areas to look at, fuel delivery to the injection system and the injection system itself.

First, have a look in the library for your model and look at the engine section 07.3, Mechanically controlled gasoline injection system (CIS). The relevant jobs are 130, 165, 275 and 280. Read them to familiarise yourself with the parts

Start with fuel delivery, obvious things are fuel pump, fuel pump relay, fuel filter and a blocked hose or line.

Job 130 checks quantity of fuel delivered by the pump after the filter and feed hose. If you carry out this job and get a satisfactory result the problem must be within the injection system itself.

Good luck.

koan
Title: Re: 1980 450 SEL Fuel issues
Post by: 1980450sel on 29 September 2009, 09:38 PM
Thanks koan,
This was not a progressive thing, the previous owner drove about 2 years ago around the block and then parked it outside. When he sold his house he had no place for it, he went to start it and it turned over fine but wouldn't fire. I'm wondering if due to the sitting with very little gas in it if this is more of a rust, sediment and gumming up issue? If I do get the fuel flowing do anyone know what the fuel pressure is supposed to be?
Thanks,
Scott
Title: Re: 1980 450 SEL Fuel issues
Post by: koan on 30 September 2009, 01:59 AM
Quote from: 1980450sel on 29 September 2009, 09:38 PM
I'm wondering if due to the sitting with very little gas in it if this is more of a rust, sediment and gumming up issue? If I do get the fuel flowing do anyone know what the fuel pressure is supposed to be?
Thanks,
Scott

A combination of moisture, sediment and rust can certainly clog up the filer or tank strainer. Fuel pressures are covered in engine section pointed out before.

A pressure check without any flow is not useful, the delivery volume with no back pressure is a better test for clogged up filters.

koan
Title: Re: 1980 450 SEL Fuel issues
Post by: Gitz on 01 October 2009, 01:28 PM
Hi,

is there no fuel getting to the injectors,  or no fuel coming out of the injectors?

It´s a common problem with K-jet, after standing for a while.  Modern lead-free fuels turn to resin when it dries and clogs up injectors and distributors.

  Not sure if this applies to your problem, but not very expensive and worth doing anyway.  Take out the injectors and distributor(worth having a look at the little cup filters in the distributor, 1 for every cylinder and one for the fuel line from the fuel pump) and take them somewhere with an ultrasonic bath (motorbike workshop, my dentist has one, lol) and get them cleaned, costs around 20€ over here. If you take the injectors out, it would be worth getting new seals and gaskets for them (cost nothing)

btw if you go somewhere else as a mechanic shop to get them cleaned, ask what solution they use, some solutions have acid in them and if you have a steel distributor, you will probably get a rusty one back, which then you can toss in the bin lol.

I know its not a very professional suggestion, was has worked wonders for me more than a few times!

GL Davy
Title: Re: 1980 450 SEL Fuel issues
Post by: TJ 450 on 01 October 2009, 09:25 PM
A most likely scenario is a seized fuel pump. They usually end up like this after sitting, or so I've heard. My 6.9 was sitting for some years when I got it and it ran with a replacement fuel pump.

You should also check the airflow meter to see if the mechanism moves freely.

I would keep it simple to begin with, but it would be worthwhile inspecting the inside of the tank for rust etc.

Tim
Title: Re: 1980 450 SEL Fuel issues
Post by: 1980450sel on 03 October 2009, 02:12 PM
Thanks guys for the help so far. The fuel pump is toast. Does anyone know of a replacement part # or a suitable substitute for the original because when I phone around for one no one has one or if they can get one its weeks away. I live in a rural area far from a Mercedes dealership. I guess what I want to know is, has some out there replaced their fuel pump with some sort of generic model that would work. Please help me if you can.

Scott
Title: Re: 1980 450 SEL Fuel issues
Post by: s class on 03 October 2009, 02:30 PM
If the year model is indeed 1980, then it is a K-jet system, and this is the pump you need :

Link (http://www.autohausaz.com/search/product.aspx?sid=vu3im1nm1xedxk2j111pjm45&makeid=800016@Mercedes&modelid=1194881@450SEL&year=1980&cid=22@Fuel%20%26%20Air%20System&gid=6256@Fuel%20Pump,%20Electric)

Autohaus is good, and ships fast.  

you should replace the filter at the same time. 

Bear in mind that the pump sits between the tank and the filter, so if your tank is full of rubbish, the new pump will take punishment.  Hence cleaning the tank is a good idea. 
Title: Re: 1980 450 SEL Fuel issues
Post by: 1980450sel on 06 October 2009, 11:40 AM
Thanks for the help s class. The fuel pump is on its way. I also removed the fuel tank to clean it. The strainer was very plugged off but intact. What is the best way to clean the strainer and get the rust out of the tank?
Title: Re: 1980 450 SEL Fuel issues UPDATE!
Post by: 1980450sel on 18 October 2009, 12:03 AM
UPDATE! It's Alive! The 450 is on the road again after a complete clean of the fuel system and of course a new pump. Lots of white smoke for a while out the exhaust as it has not run for years. That cleared up after it warmed up but now I realize my next project will be the valve cover gaskets, another source of smoke. Oh and did I mention the play in the steering, I guess that will be my next thread. Thanks for all the tips everyone.

Scooter