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1990 chevy c1500 5.7L 2wd. i have replaced fuel pump, fuel filter, spark plugs and wires, cap and rotor, ingnition module and distributor, ignition coil, idle air control valve. it starts good and runs good, except when it reaches operating temp. when i get to a stop light and sit waiting or i let it idle it shuts off. its starts right up with no problem. i give it a little gas and that keeps it from shutting off. i suspect idle speed is slow but not sure. thanx.
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Hello Fabian,
I would connect a fuel pressure tester, and see if the pressure drops at the low idle, causing it to stall.
It may be that the relay isn't staying in, and the backup system, which is an oil pressure switch, opens when the oil pressure drops.
I wouldn't buy anything else till I narrowed down weather it is fuel or spark that is being lost.
Van
fuel pressure checks @ 11psi and does not change at all.i disconnected the fuel pump relay and it stayed running, i also disconnected the oil pressure switch and also had no effect on truck.
Answer -
Hello Fabian,
I assume, by the way you say it, that you disconnected the relay, and after reconnecting the relay, you disconnectd the oil pressure switch.
That indicates that both of those items are working, and the fuel pump is working.
I like 13 to 14 PSI, but 11 should be just fine, especially since it doesn't drop till after the engine dies.
The item I would suspect now is the TPS, which is the throttle position sensor.
I would sure want to test it before just replacing it.
What you want is a nice regular increase and decrease of continuity through the entire range of the TPS. Every time.
Van
i checked the tps and it checked ok.it didnt jump suddenly, it had a a regular increase and deccrease. also might i add that when it shuts off, it doesnt die suddenly. it slowly begins to drop RPM's till it dies. also i need to replace harmonic damper because the linning between the two pieces is falling apart, when installing a harmoonic damper, is there any special tools needed. i have the puller , but dont know exactly right way to install. thanks alot Van, reaaly appreciate it.
AnswerHi Fabian,
No special tools that I know of, but there may be a crankshaft position sensor mounted near the damper that sends a signal to the ECM to operate the injectors.
The damper may be your dying problem.
I'm not sure your sensor is there, but wouldn't that be a nice co-incidence.
Van
