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**Jason Banks** · 10-08-2023, 10:25 AM

This is a tough/crazy one.

My first thought was go through the wiring for the fuel pump and make sure it is all good.

Is the power supply to the fuel pump relay fused or circuit breaker? If it's a circuit breaker is it good? A friend of mine had a bad one that would cycle on and off randomly.
Swap the fuel pump relay.
Check signal from PCM to fuel pump relay.

The whole Tach moving with the gas pedal, got me started thinking bad TAC module... then wanted to check where the Tachometer got its signal. PIN 10 on the Green PCM connector, and right next to it PIN 9 on the Green PCM connector is 'fuel pump relay control'

Kind of rambling, but that's where I'd check first, make sure PIN 9 and PIN10 on the green PCM connector look good and the wires are not making contact anywhere or the wires are not making contact anywhere. Maybe replace the easiest wire to replace.

I'm thinking even though you hear the fuel pump run, maybe it's not and you don't really have fuel pressure, that's why the crank but no injector fire...

10-08-2023, 10:25 AM	#2
Jason Banks Senior Member Join Date: Dec 1999 Location: TX Posts: 1,529	Re: Intermittent No Start - 5.3 L59 swap - Injectors Not Firing This is a tough/crazy one. My first thought was go through the wiring for the fuel pump and make sure it is all good. Is the power supply to the fuel pump relay fused or circuit breaker? If it's a circuit breaker is it good? A friend of mine had a bad one that would cycle on and off randomly. Swap the fuel pump relay. Check signal from PCM to fuel pump relay. The whole Tach moving with the gas pedal, got me started thinking bad TAC module... then wanted to check where the Tachometer got its signal. PIN 10 on the Green PCM connector, and right next to it PIN 9 on the Green PCM connector is 'fuel pump relay control' Kind of rambling, but that's where I'd check first, make sure PIN 9 and PIN10 on the green PCM connector look good and the wires are not making contact anywhere or the wires are not making contact anywhere. Maybe replace the easiest wire to replace. I'm thinking even though you hear the fuel pump run, maybe it's not and you don't really have fuel pressure, that's why the crank but no injector fire...