93 jimmy no cold start unless primmed

12-14-2009, 04:34 PM
93 jimmy 4.3 cpi motor.63lbs fuel pressure running, 59lbs in run pos motor off. 3lbs drop in pressure in 25 minutes. runs great when warmed up and also starts fine. will only start cold with a shot of gas down throttle body.no leaks at spider.egr,tps,map,coil,wires,plugs,cap,dist coil,pump,filters all fine. new cold sensor. swapped pcm with what i think is a good one allthough there is a chance it may be bad along with maybe the original pcm? still no joy.does not need prime if running in last 5 minutes(-12 degrees c here!)tried alot of things now and getting nowhere. any ideas???

12-14-2009, 06:29 PM
When scanned what does the coolant temp sensor input to the ecu show?

12-23-2009, 11:35 AM
Its your fuel pump! Something like the backpressure er I dont know the fuel pump seems to be working right? Well I had a buddy with same prob for the last two winters in wisconsin changed tank and fuel pump couple a days ago and fixed it someone told him something about back pressure? IDK but trust me i bet it is your fuel pump let me know! Mitch

12-24-2009, 09:49 AM
Yes! it was the pump! made 62lbs at the rail but not at crank time. down to 40 or so so no go.thanks for the help guys! now i gotta fix that no 4x4 shifting problem. gotta love beaters.

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