98 GTP will not start without fluid

[por935]

Recently bought a 98 GTP that was throwing 18 codes. I replaced the map, maf, plugs, wires, coils, ignition module, TPS, and cleaned air idle valve. Then I only had 4 codes: TPS performance, TPS low voltage (remember, TPS is NEW), misfire on 3, and maf. I checked the voltage values on TPS and it is good. Checked compression and spark on 3 and they are good. Checked injector 3 and 6, and 3 doesn't cause the engine to go down quite as much. Changed maf with a another running car. Checked fuel pressure and had 40 psi. It got 22 mpg on a trip over the weekend. Finally, I bought a ECM flashed to my car. No change. I still have to hit it with fluid to get it running. It also, idles up and down. Any ideas?

[Explicit_Spade]

Have you checked for a vac leak?

[por935]

yes, a few times

[BillBoost37]

Did you do an initial prime and bleed down test? Almost sounds like the pump or regulator aren't allowing enough pressure at key on for the prime to enter the cylinders.

[por935]

I have not tried that. How do I do it?

[BillBoost37]

Hook up the gauge, turn the key a few times and purge the air out. Then let it sit for say an hour or so.. Turn the key on and watch the pressure. GM says it should hold the pressure for 10 min. I have a feeling you'll find that when the key is initially turned..you aren't getting enough pressure.

[por935]

I tried it, and I had 50 psi everytime I hit the key. After a few seconds, it would drop to 40 after the pump turned off

[Frosty]

gotta let it sit for 10 mins before you test it after priming.

[por935]

With the key on or off? And, what am I looking for? I may have not understood you the first time. thanks