Hey there ya’ll. I have a 1996 F150 with dual fuel tanks. The front pump always kicks on, but the tank has a leak so we don’t use it. The rear pump works awesome when it is dry, but when ever it rains, it doesn’t kick on. The funny thing is that if the truck is running while it is raining, it is fine, it’s not until it has been sitting overnight in the rain that it decides not to start until it is fully dry outside. For instance, this week here in Indiana has been very muggy and humid. The first part of the week, it rained off and on all day and night. The truck wouldn’t start. Last night the rain stopped completely, and while today was humid the sun was beating down all day. Early in the morning the truck wouldn’t start, the rear fuel pump doesn’t kick on. Same thing happens around noon and 5 pm, then, after 7 pm it starts right up and I am able to drive anywhere, shut it off and start right back up. This has been a cycle for a couple months now. I don’t want to go buy a new fuel pump because I don’t think that is the issue. My hubs and I have checked the relays, the fuses, wiring and all that fun stuff, but we are at a loss at this point. It’s driving us crazy since this is our daily driver, and my husband has been having to ride his motorcycle in the rain to and from work. The kicker of course is that this only happens when it is wet out.


any suggestions?

 

Welcome to the site!

Aaargh, intermittent issues are tough to trace, but you seem to have things narrowed down to specific causes.

Wondering about a crud, or given Indiana - any salt buildup on where the fuel pump connection are on top of the tank, effectively shorting things out when things are wet...???? At any rate, suggest you are correct in the thinking that it's not a pump proper problem, given your described conditions.

As far as correcting - wonder whether a hose can be canoodled to spray across the top of the tank to blow any crud off....?????

Good luck, and keep us posted.

 

Thanks for the advice. We will be working on it this weekend while we both have time off. Oddly enough, sometimes when this happens the ABS light comes on. My husband brought this to my attention today. Though the brakes work fine, nothing seems to be wrong with them. I’m wondering if there is a ground somewhere that is getting wet causing the issue. I have yet to track all of them down though.

 

Ah, additional information is always good!

Suggest to also take a look at the wiring going back - looking for pinched or otherwise damaged wiring where the insulation may have been compromised.