Getting a 1978 450sel running
 

I recently inherited a '78 450sel that had been sitting for a few years. Needless to say the gas was gummy and the car would barely start/run. It had a new Bosch fuel pump put in shortly before it was put away.

Step 1:
* gas tank was drained and put in new gas
* leaking fuel pressure regulator was replaced

That got the car running but it stalls out as I press the gas pedal. If I feather the gas pedal I can get some revs after a while. Pour a little gas into the ventura and it perks up. Once it warms up it idles a little better but but it's still undriveable.

Step 2:
* gas tank was removed and cleaned,
* fuel filter was replaced

Still not running much better - still same symptoms as above.

It has lots of fuel pressure coming out of the pump but it doesn't seem to be reaching the injectors.

Any ideas out there?????

Hankster

Remove the injectors, soak them in carb cleaner. They're probably extremely crudded up. Make sure to clean the filter screens well, if any are broken, rusted or excessively clogged, replace them.

check if the fuel distributor puts out the same pressure on all 8 injectors. Do this by removing the injectors and just checking the lines to eliminate that item.

Peter

You can also spray carb cleaner through the injectors using some compressed air. That will also help you see if the spray pattern is cone shaped or the injectors are bad. Also, I think this car has an idle air control valve and you would want to clean that too.

If you check the spray patterns of the injectors it doesn't mean they are bad. New injectors can have bad patterns. Just make sure they provide the correct volume. Sonic clean hem, but replace injectors as a last resort.

Assuming your injectors are the type they work with, you might check with this outfit regarding a professional clean and calibrate of your injectors.

http://www.cruzinperformance.com/

I believe their prices are competitive with DIY after considering your time and materials and the potential uncertainty of results. Injectors are a fairly high precision part. Small errors made or differences in how they are cleaned could greatly affect the running of your car.

Just a thought...

230/8

A 78 SEL has CIS so injector spray pattern is less critical than in an injector set to open as the intake valve opens. As Emmerich said, volume is more important on Continuous Injection.

A CIS car that has set up that long probably has corrosion in the fuel distributor and warm up regulator among other places.

Do this carefully and at least a day ahead: put a lot of penetraing oil on the fuel lines at the fuel distributor. If you get too frisky twisting a steel line connector in an aluminum fuel distributor, you have bigger troubles.

At the fuel distributor where the steel injection lines screw in, you can just crack open the connection. Don't need to unscrew the connection entirely. With the engine idling, what flows out may look like muddy fuel. It is rust and such. You can do this with all the lines in turn to get out "the big pieces". Use a rag to collect fuel.

The inlet from the gas tank on the fuel distributor has a mesh screen in the fitting (depending on FD model) and these can collect lots of trash. The screen can be removed and blown out.

There is also a screen in the warm up regulator that is prone to collecting gunk.

The passages in the FD and WUR and particularly the piston in the FD that moves and allows for greater fuel flow on opening the throttle (your trouble) are pretty small and not too much crap will clog them.

CIS is all about flow and pressure. Clogged passages affects both.

I would start out with an expectation that a thorough cleaning might bring the system back completely, but that it probably won't happen overnight. The alternative that too many take is to start throwing parts at it. Fuel distributor and warm up regulators are really expensive.

Nobody can diagnose CIS on the internet. If your thorough cleaning can't bring it back, you'll have to get a fuel pressure gauge and procedures for how to measure flow and pressure. these are in the manuals. Also an excellent book is by Charles Probst and is the "bible" for Bosch K-jet and other CIS systems.

Have you got a new fuel filter? This is going to have to be done now and after you get the clean up done. Most of the fuel in your system is not burnt, but is cycled back to the gas tank, pump and filter over and over.

Because your car starts and only begins to act up when the throttle is opened I would guess that at a minimum your fuel distributor piston is gummed up. But it could be other stuff as well. It's all interrelated and one dirty part affects performance of all the others

it's like your servo and climate control, when one piece acts up, the whole thing can act haywire.

Techron is good cleaner. You can use more and more concentrated cleaners like toluene, but there are issues with toluene that you should be aware of. Try m-100.cc and search on toluene for some more information.

Sorry this is long, but I have spent a long time sorting out the fuel system on my 6.9 and a few tweaks here and there, particularly in the Warm Up Regulator and a good cleaning have really improved the performance of the car.

1978 450 sel fuel distributor tribulations
 

Thanks for all the information and suggestions so far folks. I'm still striking out in trying to get the '78 450sel up and running.

The fuel tank needed to be relined - done. New fuel pump and fuel filter and it's pumping nice clean gas but it just doesn't seem to be getting to the cylinders. Cleaned all the injectors and lines. Actually not bad looking at all and good spray patterns.

Took off the fuel distributor and the piston seemed to be moving okay. I think my bro-in-law and I may have done a bad thing in starting to unscrew the two pieces of the distributor. We thought the better of it and didn't get it apart but when we put the distributor back on it was leaking gas. Any comments or suggestions?

Also, I'm looking for some advice on a fuel distributor in case I need a new/used one - mine has a Bosch part number of 0438 120 062 whereas the Bosch website has a part number of 0438 100 089 which seems to be more commonly available. Any ideas on why the difference?

Thanks all!!

Hankster

I saw this guy on e-bay who rebuilds FDs for a reasonable price. I have no other information.