Fuel pressure issues - ???

redcoupe86 · 08-01-2008, 11:40 AM

Here is the issue:

If I let the car sit for a week or so and then start is up it runs like its on 3 cylinders until it warms up, then it's fine. However, if I drive it until it's warmed up and then let it only sit for one day it starts up just fine.

What should I be looking for. . . ?

pope · pope's Garage

That doesn't sound like a fuel pressure issue. But the more knowledgeable people in here will help you pinpoint the problem.

ossiblue · 08-02-2008, 07:31 AM

Could be residual pressure issue--your system is not holding pressure when shut down. Possible check valve problem in fuel pump or maybe weak/failing fuel accumulator. Just guesses as I'm not an expert so hopefully the true wizards will reply soon, but your symptoms appear to be a fuel delivery problem.

pope · pope's Garage

But why does it work fine after 10-15mins? Fuel pressure should be up to normal either within the first minute of the pump's operation or never.

redcoupe86 · 08-02-2008, 08:41 AM

I thoght about this too. I thought maybe the check valve is slooooooowly not holding pressure so as not to show a problem unless the car has set for several days, but I don't know enought about the fuel system to really make a good guess.

Quote:

Originally Posted by ossiblue

Could be residual pressure issue--your system is not holding pressure when shut down. Possible check valve problem in fuel pump or maybe weak/failing fuel accumulator. Just guesses as I'm not an expert so hopefully the true wizards will reply soon, but your symptoms appear to be a fuel delivery problem.

redcoupe86 · 08-02-2008, 08:48 AM

I should clarify that even if the car has set for a week or so, it stops running likes it's on 3 cylinders after about 1 min. and runs more or less normally, but doesn't really smooth out until after the car has fully warmed up.

Quote:

Originally Posted by pope

But why does it work fine after 10-15mins? Fuel pressure should be up to normal either within the first minute of the pump's operation or never.

al lkosmal · 08-27-2008, 04:34 PM

Check your plugs. If they are dirty, clean them and fire up your car again. Running on all 6 now?
I was running rich and fowling plugs and the first symptom was starting up on 3 cylinders and as soon as I warmed up a bit the other cylinders would kick in. When I cleaned the plugs, it would start and run fine for a few days or a week, until the plugs would load up again. I chased my tail for a while, until I followed the complete Weber tuning adjust procedure to ensure balanced airflow and air/fuel mixture, etc. Also my fuel pressure was too high. But basically I was running way rich and fouling plugs. Try it...it's cheap and easy fix.

regards,

Al

BGCarrera32 · 08-27-2008, 06:42 PM

Nope- you have a sticky fuel injector. When the car is initially started and exhibits this behavior while driving pull over somewhere quick and pinch each injector carefully between your index finger and thumb and find the one that feels different or isn't ticking away the same. Give it a quick tap with a screwdriver and see how it drives then...

Run a container of 3M fuel injector cleaner into around 3/4 tank of gas and go for a good half hour spirited drive.

If you had a fuel pump check valve bad or either of the 2 pressure dampers on the back of each fuel rail the car would crank excessively long after just sitting for 20 minutes or so. I've been there done that...

Also, if its an '86 Carrera you don't have a fuel accumulator.

Of course a full tune up and valve adjustment helps...if you find a fouled plug you have to ask yourself "why" and when I had one it was an injector that was running rich (too much fuel).