Hard starting when warm after engine rebuild

**Jrp79** · 01-21-2021

Just rebuilt the engine in my 02 gp gt. Have 300 miles on it plus about 5 hours idle time. First start of the day or when motors cold it starts fine. After i shut it off then try to restart itll crank for a few seconds start then immediately stall. I have to give it gas for a few seconds to keep it running but when its running it runs fine.. No pending engine codes. New plugs, wires. Fuel pressure is 55psi koeo, about 52psi running then jumps up to about 61 when vac line unplugged. Psi is about 58 when cranking.
Any one have any ideas

**Scottydoggs** · 01-21-2021

if your na it could be a bad fpr. pull and sniff the vac line for gas, if you pull the vac line running sometimes you get to see the fpr spitting gas out it.

**Jrp79** · 01-22-2021

Originally Posted by Scottydoggs

if your na it could be a bad fpr. pull and sniff the vac line for gas, if you pull the vac line running sometimes you get to see the fpr spitting gas out it.

Vac line is dry no sign of fuel leaking out of fpr... Psi goes up about 9psi when unplugged so i think its good. Someone told me either bad head or intake gasket. Leaning more towards intake plenum gasket as it was a ebay special

**Turbocharged400sbc** · 01-23-2021

pull the fluff from a q tip and use rubbig alcohol to gently scrub/wipe the thermisters clean.
clean the throttle blade of the black carbon coking, you may also want to pull the IAC and clean it off as the passage can get a carbon ridge pushed up and cause it to lose fine control of the airflow.

if your upstream (B1S1) O2 is a bosch unit or has close to 50k miles youll want to replace it with denso/NGK/AC delco. stay away from bosch, for some reason our pcm's do not like em.

id start there if you have good manifold vacuum

even if the so2 has only 30k on it it could be poisoned from coolant/oil from before the ovehaul

**Turbocharged400sbc** · 01-23-2021

and by thermisters i mean the tiny sensing fillaments inside the MAF sensor

i hate how i neverr see an edit button on my posts....

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