gas coming out of the exhaust pipe

[mpudgie282]

Hey guys im new here wonder if u guys can help me i just put in a 2000 motor into my 99 pontiac grand am when i start the car i have gas coming out of my exhaust pipe i try everything i put parts in i keep dumping money into this car and im getting no where and friend told me it mite be a vac leak some where on the manfold do u guys think that the problem im going to take a look tomorrow i dont know what to do people never herd of that problem gas coming out of my exhaust pipe i see it runing down the exhaust cause im on a hill can eany one help

[mpudgie282]

3400 sfi motor

[3100 MPFI]

not sure if it has anything to do with this, but did you use your stock fuel injectors, or the ones that came on the 2000 engine?

In 1999, they should have the fat injectors, but I have seen several 2000 engines that had the skinny injectors. If you have the skinny ones in there they are not calibrated to your older PCM, and probably throwing WAY too much fuel into the mix.

[Superdave]

not sure if it has anything to do with this, but did you use your stock fuel injectors, or the ones that came on the 2000 engine?

In 1999, they should have the fat injectors, but I have seen several 2000 engines that had the skinny injectors. If you have the skinny ones in there they are not calibrated to your older PCM, and probably throwing WAY too much fuel into the mix.

Swapping the FPR to the '99 one fixes that issue..

[geldartb]

he wouldnt even be able to run the engine the connector for the fuel injector harness is different from 99 to the 00+ car.

the 00+ cars got one big fat connector where as the 99 still had the separate connectors for the coolant sensor and injectors.

when i had the vac leak i had a fair amount of gas coming out the exhaust pipe. try using a propane torch without lighting it and sweep the top of the motor it will spike in rpm if theres a leak.

[mpudgie282]

yes i did switch over the fuel rail back to the 99 with the 99 injectors

[carbon]

Are you really certain it's gas and not stinky water that condensed in the exhaust that is getting blown out?

[torq455]

Are you really certain it's gas and not stinky water that condensed in the exhaust that is getting blown out?

--THANK YOU!!!

if you have raw gas coming out of the tail pipe, then the engine wouldn't be running. the plugs would be drenched with gas and wouldn't fire. if, by some miracle, the engine is running, it would be chugging horribly and puffing out huge amounts of black smoke. the fluid from the tail pipe only happens when the engine is cold right? if so, then it's condensation or compressed air, that hasn't gotten hot enough to evaporate...kinda like your air compressor.