I have a 1991 Pontiac Firebird Formula That was wrecked and then swapped To a tbi L03 with the 700r4 with the DSS. It was done correctly back in the late 90's and the car had no issues until I received the car back in 2010. It all started after I Took it upon myself to use purple power and a low pressure spray nozzle to clean the engine, before I took the car out to the strip, which shouldn't have hurt anything but the car will no longer cold start...EVER, whether its -10 or 90 outside, until is has been hit with starter fluid, after that for the rest of the day the car will start. I have replaced my cold air charge sensor (cage looking doohicky in the air cleaner Because it was clearly non functional AKA broken off), My oil pressure sender switch by the oil filter housing(the only oil pressure sensor on my engine no nub by the dizzy on this one), the Fuel pump and filter, I replaced all Fuses inside the car, I also rebuilt the tbi unit and cleaned and did a flow test on the injectors they checked out. the pump comes on with the key and shuts off once it has reached the correct fuel pressure. I have noticed that It does not prime itself. All ignition components are new and functional.The car builds more than enough oil pressure to start (I think it needs something like 7 pounds it registers at nearly 30 cranking according to the gauge). So this one has me stumped I have access to a shop on the weekends to run about any test but after the oil pressure sender unit, the pump, the fuses, and tbi rebuild I'm unsure where to go. Not throwing codes or check engine light. I have plenty of mechanical experience but if this get's into technical electrical talk you'll have to dumb it down for me step by step. The car is my daily driver and has had this problem for Three years so I'm ready to figure this thing out(A can of starter fluid every other week adds up).

 

Swap your fan relay and fuel pump relay see if it primes sounds like a bad relay to me. (Maybe not reread your post and you say it the pump does prime)

 

Unfortunately the relay is fine. What I did figure out though is the circuit board on the back of the instrument panel had burnt up somehow and in the process either burnt the check engine bulb or broke it's connection to the power source. Upon doing an actual check for codes(not just the paper clip) I discovered a hefty list of codes15,21,22,23,54 Im going to reset the thing in the morning and see what codes come back

 

With the long list of codes check the ground(s) on the back of the head(s). Along with the battery cables and ground straps.

RBob.

 

That's a busy two sentences. Things would be easier to read if you'd use appropriate punctuation.

Does your service manual show one, or two oil pressure switches/sending units? My truck has two, with the second being a fuel pump relay bypass.

If it comes on with the key, and shuts off two seconds later, it's priming itself. What do you mean by "It does not prime itself"? What do you expect it to do?

It starts and runs when you supply supplemental fuel (starting fluid). I'd expect the problem to not be in the ignition system, but somewhere in the fuel system.

The only reason you need oil pressure to start is if the fuel pump relay circuit is somehow defective. If the fuel pump comes on when the key is turned on, and runs for two seconds, the relay and wiring is likely good. Having oil pressure would trigger the relay bypass switch, which supplies power to the fuel pump--bypassing the fuel pump relay.

Fix the dash light (SES, or Check Engine), clear the codes, see what symptoms remain, and what codes come back.

 

It builds fuel pressure I have tested this. What I mean by it doesn't prime(sorry for my wording) is no fuel comes out of the injectors upon trying to start the car. I'm assuming the only reason it starts after jumping it with fluid is because there is still fuel in the intake that has not yet evaporated so there's something to get it going. but if I go out in the morning and try to start it I can crank all day burn my starter up and the thing has no fuel coming out. This is of course only until something whether it be ether, gas, nitro, starter fluid, ect has been provided...I know my engine has just the one oil sensor switch because it is a 91'(according to the casting number) and it only comes with one. In my service manual it has one. I replaced the instrument panel circuit board and cleared the codes: every code came back so I'm in the process of checking my grounds. I just picked up a parts car so I'm gonna plug and play with sensors and resetting the computer to see if I can get some codes to resolve if I don't find a wiring issue. Apologies on not being timely with my reply I have been busy working on my wife's car. I think it could be my tps maybe making it not want to start? I'm not sure if that makes no sense. If I get the car running let it go through its idle changes and get to operating temp and then disconnect the tps and IAC the fuel mix goes rich but it will cold start. I do not plan to run my car like this I would rather have to use starter fluid then run my car rich.


Thanks for the replies I will keep posted with my progress but it will be slow, too many projects currently, I have to keep my car drivable day to day.

 

Interesting that you mentioned the TPS, yes, that can cause the car to not cold start. On a properly working vehicle holding the go-pedal to the floor while cranking is a clear flood mode. The injector PW is greatly reduced.

A TPS reporting high would trigger this clear flood mode in the ECM.

But as you mentioned every code came back. An open TPS ground would cause the TPS to report high, and put the ECM in clear flood mode.

RBob.

 

It was my tps and also a wire from my coolant temp sensor was smashed no more codes but not sure it's gonna start in the morning we'll see but I don't see any reason it shouldn't now.

Thanks for the help everyone! I appreciate the explanation of what a bad tps/tps ground does as far as communication with the ecm goes RBob,

-Formula-Finatic