Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Car will only start with starting fluid on cold startup, runs fine, and starts fine when warm

When you turn the key to on (engine not running) the fuel pump should run for around 2 seconds, then turn off. Does it? The pump will run continuously only if the ecm detects the engine is rotating. What happens to the fuel pressure when all this happens; i.e. you try to start the engine on a cold start but it won’t start? Ask a helper to crank the engine while you watch the fuel pressure gauge. Normal fuel pressure is around 50 psi. Do you have a scan tool that can command the fuel pump to run?

From what I see, the fuel pressure hold test specs are to turn on the pump until it measure 52 to 59 psi, then turn the pump off. Pressure shouldn’t drop more than 5 psi after one minute. So if it started at 55 psi, it should still be 50 psi or above after one minute. Then relieve the pressure to 10 psi. Starting there, pressure shouldn’t drop more than 2 psi (i.e. it should be 8 psi or higher) after five minutes.

I have a 1978 F150 with no sensers but this problem persists. How do I fix?