Hopefully someone can help me understand my problem a little better. I have a '94 Z28 with automatic transmission. About a month ago or so, I was driving my car on the highway and I noticed it started to sputter until the car totally shut down and refused to start again. I had the car towed to get it looked at and the mechanic told me it was a bad fuel pump becuase it ws only putting out like 21psi. When I got the car back, the mechanic also told me that I was dripping motor oil on the distributor and that I should get it looked at later as soon as possible.

Here is the thing now. I drive the car around during the week and it seems like the car idles a little rough. I notice that the engine speed would drop from 700rpm down to like 500rpm and back up to 700rpm quickly. While it is doing this I also notice that battery voltage drops and goes back up again. The interesting part is if I don't drove the car during the weekend and leave it rested for a couple of days, the car won't start when I try to crank it a few times. But if I leave the car alone for a few hours, and try to start it again the car starts but it idles pretty rough again for a couple of mins and then it kinda settles down a bit and doesn't idle as rough as before.

I'm sorry for babbling but I tried to explain as best as possible the problem i'm experiencing. Any ideas or hints as to what is going on? I had the plugs and wires changes out sometime last year.

Thanks for your help.

 

Would oil leaking on the distributor cause a problem like this? Or does this sound like a fuel delivery problem?

 

You may have a hole in your fuel pressure regulator diaphragm. This leaks fuel into the vac line and richens up the mixture severely. Or you may have a leaking injector which drips fuel into the intake and puddles there. As the car sits it sort of dries out and starts easier. check the diaphragm by applying vacuum to the vac hook up on the regualtor. It should hold. If it turns out you do have a hole in it, replace the regulator and check your fuel pressure again.

If you haven't done so in a while, have your injectors proffesionally cleaned through the rail. This may unstick a sticky injector. It beats changing them out and my save you some money. If you check these things and still have low pressure, you're gona have to replace the pump.

The oil leak will have to be addressed but I don't think it's your problem at the moment.

good luck

 

A leaky injector could also be indicated by a drop off in fuel pressure after the car is turned off. The fuel pressure should hold for a long time after the car is turned off.

However this is not the only reason as a bad check valve in the fuel pump or a hole in the regulator could cause it as well. I'm with badass, leaky injector or a hole in the regulator diaphragm. But I'm puzzled if the car ran that crappy after the mechanic put the fuel pump in, why didn't he find it?