Fuel pump not turning on

[nvcook42]

When I key on my 87 ranger the fuel pump is not turning on, everything else sends fine. I have replaced the fuel pump, fuel relay, TFI module. I have checked the inertia switch. I am stuck in a parking lot and out of ideas.

Over the past few months the fuel pump turns off every once in a while and then if I let the truck cool down its running again in 10 minutes. This time its been a few days and still nothing. Any ideas would be helpful right now. Thanks.

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[turboeeyore]

a few questions. is the relay clicking? is the check engine light coming on(usually a sign the ecm is turning on). my first thought is the ecm relay is heating up and shutting down the ecm. but if you're getting spark the ecm is definitely coming on. another thing coming to mind is the ignition switch. late 80's had a lot of issues with the ignition switch falling apart. corrosion on wiring or a break in the wiring could cause a major headache. if all else fails toggle switch the pump until you can find the cause of the problem.

 

[nvcook42]

I am getting a spark. The relay is clicking. What do you mean by, toggle the switch pump? If it's the ignition switch would it die while it's running? Thanks

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[turboeeyore]

yes it would die while running. by toggle switch I mean run 12v power straight to the pump. before you do that check for ground and power at the pump harness. you may be getting power but the ground could be broken, no easy way to do this but run a long power wire from the battery attach the test light and see if the harness has ground. then reverse the test light and have someone cycle the key for the pump to come on. I just remembered the hall effect sensor in the distributor cap fires the fuel pump. so on a engine with dis the crank sensor would do the same operation. not sure if you have a distributor or not. I may not be explaining this right . what engine is in this truck?

 

[nvcook42]

Thanks, by tracing wires I discovered that the inertia switch is melted, by passing the switch works. Thanks for the tips.
Is it safe to run with it by passed for now?

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[Spott]

Yes. The purpose of the inertia switch is to turn off the fuel pump when an accident occurs, for safety, even if the engine is still running.

Sometimes it goes overboard, though, shutting off for little fender benders, rough roads and trails, or if the passenger thumps it with their foot.

It's good to replace it at your convenience, just in case, but bypassing it temporarily is perfectly functional.