walrus108

I have a stock 89 GTA 350 that has me at my wits end. I'm going to tell you all everything even if it's prob not important just in case. The tranny wasn't down shifting so I readjusted the tv cable. While on the test drive i let it roll to about 10 and punched it. it downshifted and jumped like it's supposed to do finally. After coasting down though it seemed like it was going to want to stall. I pulled into a grocery lot and it died. I was able to restart it and it would run rough as long as I kept my foot into the gas. The minute I let off the gas it stalls. When it is running rough like that the tach is kind of jumpy or twitchy. It sort of jitters up and down. Now it's hard to start at all. If it sits in the hot carolina sun it will start and run very bad but stall if you let the gas go. I got no computer codes. I tried a new maf sensor from aotozone and cleared the ecm and it is the same. The fuel pump pressurizes the system and sounds good. After it stalls it pressurizes again when turned to run position. I need some help finding out what could be causing this. Could it be the fuel pump relay? Is there a way to bypass the relay to see if it's the culprit? Same for the MAF relays? Could it be the oil switch? Can I bypass the oil switch to eliminate this possibility? How would i do this. Could the ecm have gone bad? Anybody who could think of any possibilitys as to what could cause this would help me a lot.

walrus108

Just to clarify, I am able to keep it running if I keep my foot on the gas but it runs really rough and wants to stall. It seems to run smoother at some rpm's than others. I'm thinking egr. Anyone know how to diagnose or at least eliminate some of these possibilitys?

kevinc

Fuel pressure should be 43-48psi at idle w/ the vacuum disconnected and capped from the regulator, check it and report back.

Nixon1

Your problem sounds a bit too severe to be EGR....EGR usually causes a stumbling idle, but off idle it tends to clear up...

Have you checked actual fuel PRESSURE? And also I'd check spark with a tester, make sure your ign. coil isn't excessively weak. Do a vacuum test if you can too, maybe you have a bad vac leak. But you'd more than likely notice other issues such as brake fade, etc. if that were the case.

walrus108

Found it!!! I checked the fuel pressure and it was about 43 lbs and only dropped a 2 lbs when giving gas. i started to think timing chain. So I pulled the cap and rotor to do the static check to see how much slack is in the chain. It was all tight which is good but I noticed the star shaped thing underneath had pieces of metal hanging out of the bottom! This piece I guess is called the reluctor and it looks like it takes the place of the centrifugal and the vacuum advance in the older units. I picked up a rebuild distributor from autozone installed it set the timing and it runs better than ever. Just wanted to let you all know in case someone else down the line has the same problem. Thanks to everyone who offered some advice. I'm going for a drive

kevinc

Nice troubleshoot, great catch, congrats!