I have a 98 GMC C1500, 5.0L, 4L60E. It turns over fine, but won't start. Fuel pressure is 60 while the fuel system is pressing up, then drops to 56 psi when the pump shuts off. It also has good spark. I scanned the computer, and have a P1870 DTC using an autoXray EZ-Read 2000. I can't find that code in any of the repair manuals I have. Any help would be greatly appreciated. Thanks
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Spray starting fluid into the air intake of the engine, if it starts and you have fuel pressure you have no injection or injector pulse as we call it. Check ECM fuse one and two for continuity if it starts with fluid..
The fuel pump only comes on for 2 seconds when the ignition switch is turned on until it starts.I would check the fuel pressure it should be 60-66 psi with key on engine off.Sounds like a weak fuel pump to me you'll know once you check the pressure.If its not within specs replace pump.
One easy thing is to tap on the bottom of the fuel tank while trying to start it.If it starts then you know it`s the fuel pump.The only other thing is to check the fuel pressure but you need a pressure tester.The other thing is to check and make sure you have power to the pump.This is the gray wire at the pump connector.Also make sure your ground is good.The specified pressure is 55-60 psi.Hope this helps.Good luck.
THOSE VEHICLES HAVE A HIGH PRESSURE FUEL PUMP THAT WILL ONLY START IF IT REACHES 60 PSI OR MORE.. BUT ONCE IT IS RUNNING REQUIRES LESS PRESSURE.... MAKE SURE THE FUEL PRESSURE WHEN STARTING EXCEEDS 60 PSI OR IT WILL NOT START...
the fuel pump could actually be malfunctioning. and the reason that you are able to restart and drive again is because when you turn the key on it is allowing the fuel pump to pressureize your system. but while the fuel pump is continuasly running it is loosing the fuel pressure. this is common on the cheap fuel pumps. i am not sure about were you got the fuel pump from but in all of my experiances with this problem i find that the fuel pumps have been boughten at a napa store.
i hope this helps you out.
and you could attach a fuel pressure gauge on to the fuel rail and start the car and watch the pressure to see if it is droping.