Lately, My '81 308 GTBi has been acting weird. If I try to restart the car shortly after shutting it down, I don't have a problem. If I let the car sit for 15 min. or more I have a problem restarting it. It seems like it's not getting fuel. I can hear the fuel pump working ( after the ignition buzzer stops it's infernal whine), but I detect a slight change in its sound, as if it is not picking up the fuel consistantly. Is the pump going bad, or is there an accumulator valve that's not working right? Thanks, Will
Will, you should search the archives...but ultimately you will need to take it to a service provider with the proper test equipment. They will be able to determine which part or parts need replacing. It could be any one or combination of the following: 1) Leaking injectors...not uncommon problem with the original steel Bosch injectors. Consider upgrading to the newer brass ones. A worthwhile improvement. 2) Fuel accumulator 3) Check valve 4) warm up regulator If you want to attempt a cheap DIY fix, start with the check valve, it is only $25 or $30. Next would be the fuel accumulator (around $100 I think)....but this starts getting expensive fast replacing parts. http://www.auto-solve.com/mech_inj.htm
It sounds like pressure leakdown. With the fuel pump running look at the accumulator and watch for fuel leaking from the small steel nipple on one end. No leak, OK. Run the fuel pump, shut it off and quickly remove the return line from the fuel distrbutor and time the drops of fuel leaking out. You don't want more than one drop every five seconds, average is 8 to 12 sec. If this is ok then the leakdown is probably the check valve in the fuel pump. Your fuel pump has an internal check valve and the replacment will have an external check valve. This means you will have to get Mercedes Benz parts to connect your new fuel pump to the car. You should be able to get this hardware at a salvage yard. If you talk to a old MB mechanic and tell him you are converting to the new fuel pump he should be familiar with what you will need. Also the test for the fuel pump delivery is run your return line into a container and run the fuel pump for 30 seconds and you should return min 1000 cc. Keep in mind your system pressure should be 5 to 5.2 Bar. I hope this helps you find your problem. If needed PM me with your phone number and I can talk you through other tests. Good luck Larry Fletcher
make sure the fuel pick up tube in the fuel tank if it is the OEM one and never change there is a fine screen on it if that is gone your fuel pump is piking up junck from the fuel tank that will destroy the fuel pump + check the fuel hose from the tank to the pump i did replase both on my 80 gtsi the screen was destroy on mine + the hose.
larry have you ever rebuilt any 308 fuel distrbutors ? i have no problems with mine yet i was thinking this winter to do the 25 year service on it or do thay last longer then that?
I do enough Ferrari fuel distributors that I stock some for exchange, 208/308/328/TR. My advice would be if you don't have a problem with your fuel distributor leave it alone. When you need one order it and swap it out. Even if you had something that is not in stock you would only be down a week to have yours done. If you keep clean fuel and don't use chemicals in the fuel that attack the rubber parts you should be in good shape. I have seen o-rings in these things from the early '70s that look good and have also seen o-rings from the early '90s that look bad, so I think conditions, use, and the fuel used have more of an effect on the life of the fuel distributor than anything. The o-ring mfg. tell me buna-n has a ten to fifteen year life but I have seen it last thirty years. So I guess that life span is probably something they had to have for certification and use in the aviation industry. Larry Fletcher
When I had a fuel line clog the fuel pump got loud. Point being, the noise is caused by fuel starvation from somewhere. Ken
larry thanks for the info. what do you charge to do a rebiult on a 308? + do you have a tel no just in case? + what chemicals will attack the rubber parts?
Sorry it took so long to answer, I have been very busy. You don't want to use any additive that will attack buna-n. Just take 2 common black o-rings from a local hardware and put one in the additive and compare it to the other one and that is what it will do to o-rings in your fuel system. Also the worst additives are the ones that mix water that is in the tank. For sales I work through distributors, you can call me and I can send you to one that best fits your needs on other parts too. Larry Fletcher 251-929-3771
The car has returned to normal. ( Go figure?) Took it out today without incident. My guess is the s#it in the gas tank must have clogged the line. Thanks for all of your responses. If the problem re-occures , I'll be sure to look up this thread Will
