Hi everybody, this is my first post but Im definitly not new to the page. Im 18 years old and bought my buddies 1988 IROC 350 TPI with a 700 r4 that he had sitting in his driveway for 7 years after a tree fell on it. I've used this page to solve nearly every problem I've had but couldn't find a solution to this one yet. Last week the car was running great but still had a check engine light on. I originally thought it might've been a vacuum hose considering they were a little old. I took a look and sure enough the hose coming from the t near the fuel pressure regulator into the fire wall was unplugged so I plugged that back in and the car started for a second but then cut out. Ever since then it hasn't ran for more than 30 seconds. Earlier than day I also replaced the plugs and found oil on the threads of them in the process. They were pretty loose when I pulled them out so I dont know if that could've been the problem or if these two issue are related. I kept tinkering around and also found out that the car will only ignite when the TPS is reading .8 or more volts when the throttle is closed. I double checked the timing, its at 6 degrees advanced so I don't think that the problem. One more notable thing i discovered is that the car starts for the longest time in the morning after the car sits for a long time undisturbed. I really hope its not a ring problem. I know this is a lot of weird information but i figured the more I throw at you guys, the better chance of anyone knowing what could possibly be going on. Any info at all would be greatly appriciated. I am dead in the water of this project as of right now. Thankyou so much.

 

Does it run if you unplug the vacuum line? If so it's not getting sufficient idle air. You need to clean and inspect the IAC and also once it's working properly you need to go through the minimum idle air and TPS adjustments.

GD

 

i unplugged the vacuum hose and it still wont go. IAC looks good to me too. I put a little washer in between the idle screw and throttle and it will start for about 30 seconds but then cut out again

 

How does it run with the MAF unplugged?

GD

 

slightly better but still not strong

 

So when it does run, it runs poorly?

Make sure all your ignition wires are securely in place. You may have dislodged something when you were working on vacuum lines.

GD

 

correct and ok ill check first thing tomorrow. Im also going to get an obd1 reader. Hopefully that will give me some answers. thanks

 

Check the fuel pressure also, you mentioned in the original post that the vacuum line you reconnected was around the FPR. Maybe you are losing fuel pressure as the car runs which would cause it to run poorly and eventually die. Put a pressure gauge on the Schrader valve that is located on the passenger side fuel rail. When you key on the pump should pressure up to 35-45 psi. When running @ idle pressure should hold steady @ about 35 PSI. Observe the pressure gauge while running and see if it fluctuates when the car starts to die. You can Check the FPR function by pulling the vacuum line that goes to the FPR while the car is running and the pressure should jump up to max pressure of 43-45 PSI.

 

ok ill give it a look tomorrow, made some progress today. got it running consitnatly but tach is jumping all over the place. could be a fuel pressure thing thanks for the advice.

 

Tach jumping is a misfire. Check all your ignition components.

GD

 

ok thankyou for all the tips. really appriciate it you were a big help