I am continuing to have a problem accelerating. The problem is intermittent. I originally thought it got worse as the tank became less full, but that no longer seems to be the case. Yesterday I was driving on the interstate and was unable to get above 50mph. I am pressing on the gas pedal, but it feels as though not enough gas is getting where it needs to go. If I floor it, nothing changes. I have had the fuel filter and pump changed, but there is no improvement. After my trip to the airport yesterday, 20 minutes later I went for a 10 minute drive around town and it was seemingly fine. The tank is a tad more than 1/4 full. My idea was to use as much gas as possible then take it to the mechanic and have him clean the entire gas line, if that is even possible. At first I thought there was moisture in the gas tank, so I added a few bottles of HEET, but to no avail. It may be important to note that when I bought the car 4 years ago, it had been sitting for at least 11 years, and the gas tank had rusted on the interior. I had the tank replaced, as well as the filter and pump. I have a great mechanic, whom I trust, but he is stumped. Any ideas as to the root of this problem? Thanks!
Have you checked if it is a bad cap or tank vent? Try driving (carefully, just long enough to make sure you’re testing it) with the gas cap loose, it could be pulling a vacuum.
I’d also have the mechanic install a temporary fuel pressure gauge, see if it’s dropping off under the problem conditions. Left-over rust and contaminants could be plugging things up. Has he checked that all injectors are working properly?
And does your mechanic have experience on older German cars? With this injection setup (CIS, I think Correction, RK’s right, it’s the mechanical L-Jetronic system)?
Has the fuel pressure been tested as the problem was occurring? And is your mechanic familiar with the fuel system on your car. The Bosch Jetronic is most likely on the car and it is an early system that operates mechanically and meters fuel constantly into the intake ports. It has very little in common with later electronic fuel control systems. There were numerous Bosch manuals available on the system and hopefully your mechanic has a good one and can make sense of the system.
I so often seem to step on toes here, texases. Your post was not up when I opened my reply box. Please excuse me. We do, however, seem to share similar opinions of the problem.
Not a problem! I view several posts that agree as a way for the OP to judge which way to go.
p.s. - if your mechanic hasn’t already thought of all these ideas, you should find a mechanic more familliar with these cars.
This car should have CIS or a version thereof and while your mechanic may be great, if he does not have that special fuel pressure tester he’s dead in the water.
Whenever a performance problem exists with a car using this type of fuel system (VW, SAAB, Benz also) the first step is to connect the gauge and see what’s going on with the fuel pressures.
If your mechanic does not have this tester (a bit pricy) one could be made with some scrap fuel line fittings, F.I. hose, a gauge, and a shutoff valve while using a picture of the Bosch gauge as a reference for construction.
I guess “CIS” refers to all Bosch’s ‘Continuous Injection Systems’, with L-jetronic being one version of CIS.