L0tuS

iTrader: (3)

89 stock 305 tpi firebird. Out of ideas on this one,car ran fine moved it out of the garage let it sit for a day and now it won't start. Fuel pressure KOEO 45psi doesn't drop. cranking fluctuates around 37-45psi spray starter fluid in it nothing. Put noid light on the injectors flashes when cranking. Getting spark at the coil and plugs had a new coil and distributor laying around put both of those in and still nothing with the ECU timing wire connected and disconnected. Current prom in ECU has vats tuned out but tried a vats bypass box on it with tuned prom and stock prom still no luck. Haven't checked compression kinda hard to think it'll lose that over night and sounds the same when cranking. Replacing ECU as a next try??

Tuned Performance

iTrader: (92)

Might check compression and plug condition. Doesn’t sound like a bad ecm if it won’t sputter on starting fluid.

Eightyninef

it's not a compression problem.

Tuned Performance

iTrader: (92)

glad you checked, what was the compression?
The compression test will tell you whether the timing is on. If it is on, the compression will be normal. If it is lower than normal, that means that the cam is opening too soon or too late (not in synchronization with the piston) - and that the timing chain likely jumped.

A jumped timing chain - if it has only jumped one tooth - will easily act like it is about to start. You might even be able to get it to run in some cases. But it will never run well.

L0tuS

iTrader: (3)

Haha oh yea so I Pulled all the plugs and did compression check they were all around 165-175psi. Plugs didn't look bad a little black but not terrible I got a good spark on them but stuck some new one in and it fired up but still sounded a little off let it idle came back 20 mins later cars off again with the engine bay covered in oil. Pull the dip stick to find at least 2 gals of gas in the crank case now. But when I key on still holds 45psi of fuel at the rail. I drained everything out so I could drive it back in the garage and pull the 305 out and throw the injectors in the trash😂

Tuned Performance

iTrader: (92)

Wow, atleast it didn’t go unnoticed and destroy the bearings.

Airwolfe

iTrader: (1)

Does your 1989 LB9 TPI engine still have the original GM Rochester Products Multech fuel injectors?

If it does then the fuel injectors are bad, no matter if the car runs 100% flawlessly and the injectors test good on every single test known to mankind the GM RP Multec injectors are bad and should be replaced 1st thing.

There is no such thing as good 1989 to 1992 GM RP Multec fuel injectors. 1989 to 1992 LB9, L98, LT1, and LT5 engines came with them and every single one of them are BAD.

The very first thing a person should do when buying a 1989 to 1992 F body or Y Body is open the hood and check to see if it has RP Multec injectors. If it does then that is the first thing to be serviced. Install new injectors and throw the RP Multecs into the trash where every single one of them belong.