HELP! Did some work on car now it barely runs. What's wrong?

Hi. I got an 89 camaro 350. I just did a full tune up and the car ran great. I changed air filters, oil filter, oil, cap and rotor, ignition wires, adjusted timing and the tps sensor. The car ran like a miracle. But none of the camaro lovers will just leave the car at that. One of the cheapest mods I found I could do was to change the “cap” on the Fuel Pressure Regulator to one that has a screw in it (Adjustable Fuel Pressure Regulator). If the pressure is raised to close to 50 psi the result will be more torgue and horse power. I changed it and the car stopped running. I changed it back to the original but the car would not run either. Originally, the regulator kept the pressure at around 32 psi (a little low according to the car manual but the car ran fine). With the new one I tried all different settings, from 30 psi to 50 and the car simply does not run. It will start and die right away. I can keep it running by constantly playing with the accelerator, but it’s hard to keep it running below 2000 rpm. When I changed the regulator I made sure that all vacuum hoses and electrical connectors were plugged back in so this is not an issue. I installed new plenum gaskets (plenum needs to come off in order to change the regulator) so there can’t be any air leaks into the plenum. I had to drive the car home (after having it sitting in my sister’s garage for 2 days). I could barely drive it, but I did since it’s not far but after about 2 minutes of driving I got a check engine light. According to it the mixture was lean. I am quite sure that the regulator is fine and that something with the electronics has to do with it, just probably bad luck that something happened to die at the same time. I did notice that my engine temperature gauge started going haywire the moment I crank the engine and the oil pressure gauge is also acting strange. Someone at another website told me that the ignition module probably went dead but someone else told me that if the module goes dead the car won’t start at all. Can someone point me in the right direction, what to check, in what order and how to check it? Oh, when I start it and tried to keep it running it also backfires real bad. Please HELP!!!

I suspect you have a leak in the air intake where you pulled the plenum. I know you thinking it can’t be with a new gasket, but maybe something got caught, or the gasket shifted. But, the problems your having are screaming vacuum leak to me. You may need to check around the entire air intake, plenum, throttle body, and air intake hoses to find the problem.

One ‘old-school’ trick to finding a vacuum leak is to run a rubber hose from a propane torch, and, with the engine running, crack the valve, and run the hose around the intake system. The engine will smooth out when your near the leak.

The worst thing you can do now is get panicky. You’ve gotta relax and take a systematic approach. You said that maybe something happened to go wrong at the same time, but it’s more likely if all of a sudden it’s running bad it was something you did. You’ve gotta re-check your work before you can try to solve this other something. Re-check easy stuff first and ASSUME NOTHING. Maybe first merely do an eyeball check only-

w/o taking anything apart- RELAX, go REAL SLOW and get nosey. You wouldn’t believe how often you find something right off the bat this way. After this you can start taking things apart. I used to double check all the wire harness connections I had disconnected but once I found one that was together but not snapped all the way into place. Made engine run like crap. Also, most connectors in a given area of the vehicle are

supposed to be “idiot proof” (no offense), but sometimes because of the way the electrical system’s designed, it may be possible for a plastic male connector, say, to fit nicely into the wrong female connector- or into the wrong component. This could cause the wierd gauge symptoms. You’ve gotta check this out. Maybe get a dentist’s mirror and eyeball the plenum and other gaskets you did. Sometimes it helps to get someone

else, maybe a friend who works on his own car, to help you. A lot of this is psychological- since he’s not enmeshed in this quagmire he may be able to spot something you’ve missed. You said you reinstalled all the vacuum hoses but are they attached to the right components? A lot of this stuff you finished before symptoms reared their heads, but remember: ASSUME NOTHING. If nothing turns up this way then maybe start

looking for that other something that might have died. Good luck, billybengal. P.S: for some crazy reason I keep thinking map sensor- vacuum and wire harness connected to it properly? You probably would’ve gotten a map sensor code but you never know. Assume nothing. Good luck and post back. Evenings I can get on alldata for wiring diagrams and stuff.

You might want to check the fuel pressure again.

When you were playing with the variable fuel pressure regulator, you may have adjusted the pressure too high for what you seem to indicate was an already marginal fuel pump. Doing this can cause the fuel pump to run hot. And if it was marginal to begin with, this could have done it in.

And by the way, if the fuel pressure is below spec, it means the fuel pump is worn out.