northmansx

hello all, new to the forum and it looks like a great place to be.
i have a 96 chev with a vortec 5.7 130,000km for some time now it has been hard to start, like stalling after start up and running rough. it would also rev up to 1600 rpm and then fall off to about 1000 rpm. now that it is cold pit it will not start outside at all.i orginally suspected a fuel pump problem but when it warmed up it would start,but still run rough and rev up.

i took it to a chevy dealer explaining my problem.i also told them to change the fuel filter even if that was not the problem i picked up my truck and they said they did not do any work as it required more work that i knew about. they said they scanned the moter and it said 'FULL TUNE UP REQUIRED', well i know the scan tool does not say that. they also said cap, rotor, pvc valve brakes ball joints and a bunch of other crap.(i think they were just looking to make a bunch of money) i bought the cap and rotor and pvc valve because i wanted it fixed and i knew i could do that. installed a cap, rotor, pvc new plugs and cleaned the throttle body. i also scanned it and it had no error codes. it would start inside and i put it outside for 1 hour and it would not start. today we checked the relay and checked the pressure at the schrader valve, the relay was clicking, the fuse was alright, very little pressure at the schrader and the pump was coming on to prime the system.
How much pressure at the schrader valve?
Why only when cold does it act up?
Any advice or suggestions would be appreciated.we thought maybe it might be the oil pressure fuel pump relay but we jumped it and it did not help.thanks for reading such a long post, but i wanted to say everything about it and not leave anything out.

toivo

unplug the engine coolant temp sensor and see if it starts. if it does then you know what it is.

GMMerlin

That engine should have approximately 65 psi fuel pressure.
Many things could cause a cold start problem..schewed sensor, plugged injector poppets, low fuel pressure....
From your location, it sounds like you live in extreme cold...shame, Its 50 degrees here....
A schewed coolant sensor is a good possibility..if it is reading a good bit different than actual air temp, the PCM could change the fuel trim values...
Also, make sure the engine is spinning over fast enough to start...slow cranking speed will have an effect on the engines ability to start.

As far as the scanner saying "engine tune-up needed" ..I have to call bullshit on that one...don't go back to that dealer...sounds like a bunch of hacks.

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northmansx

i unplugged the coolant temp sensor while we scanned to make sure the scanner worked and it did not start, the scanner noticed the sensor was unplugged. i was going to test the fuel pressure but i can tell it has none. it barely wets my thumb nail when the valve is depressed. the engine spins over very well and the battery is at 13 volts. this dealer is a hack, but unfortunatly they are the closest dealer and they are 300 km away over a gravel winter road. i have tried to contact the dealer and they will not return my call. i talked once to the service manager and he said that his shop forman was away the day i took it in and he would talk to him and get back to me. maybe at this temp(-44 c this am) i should get a dog sled team to pull it to Thompson and push it through the show room window. i am stumpedand can't get any service from MCKAY CHEV OLDS IN THOMPSON, MANITOBA.

northmansx

well, got a new fuel pump to try and i installed it and the truck started up like a brand new truck. i left it outside overnight (-38 c) and it started right up. thanks to those who responded with ideas and no thanks to MCKAY CHEV OLDS!!!!!!!