SoldGuy

OK so i've been having inconsistent running issues with my car for over a year that I have thought was vacuum leaks or air getting in my fuel lines. The problem has recently gotten worse. It feels like it's down a cylinder or 2.. rough low idle, when accelerating there is lots of resistance and the exhaust tone is Fop fop fop almost like propane. It used to come and go almost dependant on fuel level in my tank. When I would fill it it would act as if purging air bubbles until finally running strong again.. lately it hasn't recovered. I pulled the gas tank to fix a leak on the bottom this weekend but it didn't solve. Last night I pulled plugs on my driver's side first 2 closest to front.. I noticed a light white frosting on the plug arm. When checking the passenger side plugs I found BRIGHT white frosting on the plugs.. on at least 2 cylinders 2 & 3 front to back.

81 928 electronic injection. I have replaced most vacuum lines. I have removed the smog valve and capped the vacuum lines before/after the throttle blade. I replaced the plugs a year ago. Distributer cap and rotor maybe 6 months ago. I had a crack in the bottom of my fuel tank and the seal for the fuel line fitting on the tank. Both repaired this weekend and I'm getting a hiss when I take cap off now.

only other thing I haven't checked that I can think of is my timing belt. It's more than due I'm sure. I'm speculating maybe it lost a tooth?

Last note my fan pulley bearing is toast and I lost a belt recently for the fan/smog pump combo. I wouldn't think the smog pump not spinning would cause this condition but l thought I'd mention it as well.

Any ideas guys.?
Thanks, Erik.

Someone please tell me what's going on..

SoldGuy

maybe the fuel pressure regulator on the pass side is weak/open and bypassing tons of fuel back to my tank?

soontobered84

You should not get a hiss when you take off your gas cap. That would tell me that your fuel tank is not vented properly and your fuel pump is having to work to overcome that vacuum being created to supply fuel to the injectors.

When you replaced the vacuum lines did you re-route or change any of the vacuum line termination points? The fuel dampeners and the fuel regulator are very susceptible to changes in vacuum. If the vacuum is pulled from the wrong part of the throttle body, it will wreak havoc with your fueling.

Go back over the vacuum line diagram on the underside of your hood and make sure all the vacuum lines are connected as they should be.

Good Luck

SoldGuy

OK. Thanks. I broke the fitting on the tank going to the expansion tank when I was replacing hoses. I just melted it shut. Probably causing the tank pressure problem. I'll have to figure something out. Maybe just drill a hole in it. Nothing else I can do with this piece of **** tank