having trouble repairing the kids car. 85 iroc tpi. Wont idle shooting codes 21 an d 22. Checked fuel pump. 42psi key on. Is it suppose to hold at 42 ? Ours drops off right away. I can keep the car running giving it gas but it stalls. The car ran great just prior. It says its the tps i replaced it but I cant seem to set the volts right. There way high. I was wondering if the fuel regulator is responsible for holding fuel pressure. ? Any help would be appreciated.
Need help.

 

follow up my volts from the middle blue tps wire is 3.3 to 4.75

 

Fuel pressure regulator is responsible for the pressure in the line. Should be 42-44 area. Fuel filter creating a block maybe.

 

When you say that it doesn't hold at 42, you mean without the engine on (i.e. it falls after priming) correct? If so then there are four things that would cause it to drop, which are the fuel pressure regulator, check valve in the pump, leaking rubber tube/pulsator in the tank, or fuel injectors leaking (which is usually a slower drop, as I understand it). You can figure out which one it is by clamping off various combinations of the feed and return lines, but as long as it is keeping proper PSI while it's running it shouldn't be causing the stalling. If, on the other hand the PSI is not holding at 35 or higher while running then there's a problem that needs fixed. 3.3 volts is very high for minimum on the TPS as well, if it is actually that high at idle position then something is wrong. It should be down around 0.5 to a max of 0.9 when the throttle is closed.

 

you might have a leaky injector. Try to run the engine then pull the plugs. If you have any wet cylinders then you have a leaky injector.


www.southbayfuelinjectors.com
516-442-4707

 

I will be renting a fuel tester this weekend and i will use the flow chart to diagnosis.
Thanks for the input.

 

I changed the tps and got a 3.9 volt. I removed it and checked it off the one i got off ebay was junk.
The fuel problem started out of the nowhere the car was running good. Now wont idle.
dont the fuel injectors go out over time ? not all of a sudden ? any way i will test this weekend.

 

Well i feel kinda dumb. My friend came over and helped me with the car. checked the fuel and we ended up realizing the base idle was low. adjusted it . and now the kid has been driving no problems. He said it must have backed out. Thanks for everyones input.

 

Just a side note. the base idle screw was apparently stripped or something i had to put a lock washer and nut on it so it stopped moving. It seems to have solved the problem. Maybe a new throttle body in the future. This one seems worn out.

 

Wanted to follow up on the rough idle story. The idle adjust was a temporary fix.
The fuel pump was bad the rubber plug in the pump was gone the mechanic said the fuel looked like seven up. lots of air bubbles. He also replace lots of other parts. but I dont think they were necessary. Bottom line FUEL PUMP. he also had to replace the burn off module I had to get one off ebay One year wonder part.