1995 Chevrolet C1500 TSB's, or known fixes for engine not starting till second try?
TSB's, or known fixes for engine not starting till second try?
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Two wheel drive with auto trans. throttle body injection, Mileage 150,000 - idles, and runs good, no odd sounds. Cap, rotor, and wires just cleaned and less than 10 k miles old, new coolant temp sensor due to thread leak, and one connector pin discolored black, new Denso oxygen sensor, replaced loose vacuum lines, cleaned PCV valve, cleaned IAC passage, Tested EGR valve by pulling vacuum on port with engine running and engine stumbles. The fuel pump and intake manifold gasket had been replaced a few years ago.
I am guessing the no start on first try is fuel system related, and has been affecting this C1500 since the truck was new according to my friend who owns the truck. Recently the truck doesn't readily start on the second try. I don't presently have a fuel pressure test set, or an OBD 1 code reader but the service engine light does come on, then go off momentarily at times. The data link connector looks like an upside down top hat. Before replacing the vacuum lines, the old oxygen sensor was black, and when replaced it was light grey.
Thank you in advance for any thoughts on cause and solution.
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Thank You for the quick response pushrod. I've already printed off the vehicle specific vehicle codes and will search for DLC pin layout for the jumper test.
Thank You also for the quick response Professor G! I have relayed the key cycling procedure to the owner, and will post the results when I get them. I am also going to replace the fuel pump relay, set base timing, and recommended a fuel filter replacement every 30 k miles to the owner.
I set the timing, changed the fuel filter, and disconnected the battery to clear any old saved codes. Started the engine after having the key on for five seconds, and it started in about three seconds. It didn't take long to reach a steady idle, but when I moved the throttle up or down slightly, the engine would stumble a little. The owner reported the key on cycling you suggested improved the idle after the engine had started earlier in the day. The throttle shaft has noticeable play also. I suggested a drive cycle after the engine cools down. I am thinking maybe low fuel pressure (ie defective fuel regulator), or throttle position sensor issue. Could this be associated with the PASSLOCK anti theft system? When the key is turned to KOEO the newly replaced fuel pump relay is getting slightly less than 12 volts from the control circuit. Any thought on what to check next? Thanks again for your help!
The passlock would not allow the car the start and continue to run. The 12volt issue bothers me. Is there good voltage from the fused side of the relay. The issue I feel is the fuel pump itself. By the cycling the key shows me the pump itself is bypassing and therefore the pump will not necessarily pump enough volume of fuel. Double check the voltage at the relay as well. Let me know.
I did more testing today. battery voltage = 11.98 vdc, fuel pump grey wire to ground wire terminal at frame = 8.5 ohms@ 200 ohm setting, grey wire from truck harness to frame ground - key on = 11.87 vdc, fuel pump pressure at new fuel filter = 6 psi. very low!
Fuel pressure spec is 9 - 14 psi, optimal would be 13 - 13.5 psi. While the truck was running with everything back together, pressure gauge still connected, I pinched off the return line and the pressure stayed at 6 psi which indicated the throttle body pressure regulator is ok.
From what I am seeing, the problem is at the pump end. The pump is bad, or there is a leak in the tank. I looked at a TSB #666309 warranty delay start dated 04/01/97 about no start, or hard starting that talked about a fuel pump pulsation damper replacement part # 25175836 with viton rubber. Apparently the factory installed damper leaks inside the tank and reduces pressure. The vin # is 1GCEC19KXSE187. Does this vehicle have the defective damper? What do you thing about the fuel pump health? Any thoughts would be much appreciated!
I just noticed that I wrote Denso pump, but was meaning to write Delphi pump. My brain must not be firing on all 8 cylinders tonight! LOL. Happy Trails to you also!
It doesn't have to be Delphi , saw the denso but everybody mistypes on here. I'm not sure who makes all the pumps now days but you'd be surprised. Just get a good warranty.
I purchased a Delphi fuel pump and strainer from RockAuto.com for around $40.00. Installed today and the engine runs smoothly now. This truck didn't have the pulsation damper. The original fuel pump must have still been pumping, just not to the specific pressure needed for the TBI setup. Thank You again for your wisdom!
Thank You for the quick response pushrod. I've already printed off the vehicle specific vehicle codes and will search for DLC pin layout for the jumper test.