Cloud92

Ok folks I have a 85 c4 4+3 and it's giving me so many problems it's a nightmare.....it only runs decent about 25% of the time the rest of the time when it is running....it runs slugish and at times you can hear a loud pop from the intake like a small miss fire... exhaust smells like a propane bbq I ran the codes it gives me code 33 "maf" so I'm not sure if that's going to affect it... I have replaced the plugs fuel filters fuel relay

Ok for the fun....the car broke down after work one night...no fuel pressure no noises for the fuel pump....so I replaced the fuel pump....it fires right up after still running kinda crappy I go to work.....get out same thing no fuel pressure at the rails but I can get it to start on started fluid.....it's been a sad day

ctmccloskey

What is your fuel pressure doing all this time? I would check it and check your Fuel Pressure Regulator as well. Remove the vacuum line going to the FPR and see if it smells like gasoline, if it does you might need to replace the FPR or just install a new diaphragm in it. If you have to, put a fuel pressure gauge on the car and tape it where you can see it while driving.

While you are at it take a look at your EGR valve and make sure it is functioning like it is supposed to. There is a Vacuum solenoid that operates the EGR valve and they frequently fail or have vacuum leaks due to old vacuum lines. If your EGR is not working properly the car would run very poorly. The EGR's frequently fail when the passageways get plugged up, on mine there was a ton of carbon in the EGR passageway.

I had a blockage in my fuel supply line that restricted the flow of gas, my pump worked fine but there was little gas volume or pressure building in the fuel rails. I was forced to run a new line to supply fuel to the fuel filter. I have seen gas lines on C4's that were damaged by some bozo jacking the car up while crushing the fuel lines. I had a problem once where the previous owner had tried to crimp the wire supplying the fuel pump relay and made more trouble by making a high resistance connection that would not let the car start or run.

How old are the O2 sensors? Have you verified that your timing is set properly? If your car runs poorly and pops under the hood like you described be sure that your catalytic converters are all working properly. Catalytic converters do fail, I had one that would only run at a little above idle before it would start popping. You can remove the O2 sensor and see how much back pressure you have. If the catalytic is plugged it will blow a lot of exhaust out the O2 sensor hole.

When you replaced the pump did you reinstall the gadget that reduces the individual pulses that goes on the fuel line above the pump output? (I am sorry, I can't remember the name of that part.) I put a small section of fuel injection hose designed for being inside the gas tank. The other reason for your pressure dropping so fast is you might have an injector that is just leaking away. I had one that was really leaking and my pressure would drop in minutes to zero. I replaced the injectors and no more immediate pressure drop. My car will maintain pressure for many hours now and it runs great.

I hope that you can find the culprit and resolve it easily so you can get your Corvette back on the Road where it belongs!

billschroeder5842

Welcome to the forum. Why would you get a code for the MAF sensor, replace the plugs, not attend to the MAF and think that plugs would solve your issue?

Your engine problems are consistent with your MAF sensor being wonky. As long as you don't fix your code issue, you computer will continue to get wrong information and your car will not run right.

badduxx

I would say before doing anything else it would behoove you to test/replace the MAF.

Cloud92

I replaced the maf and cleaned up the connections went to a higher amp fuse for the fuel pump now it runs amazing!