I have searched this site and all locations listed are not on my truck. I have a 1990 F-350 with a 460 and dual tanks. It was done over by Trail Wagons out of Yakama, Wa. I can't for the life of me find the relays! Not under the hood or any that I can see under the dash by the fuse panel. There are some questionalble wires/box by the radio area, but seem to be a VERY hard area to access. Any ideas???? Oh and the reason I suspect it is the relay and not the pump is that I came off the Interstate and it started to run funny and drove it 2 miles to work and when I got off work it wouldn't start using the front tank, but started from the fuel in the rear tank...... Thanks, Mark
If it ran on either tank it's not the relay since the same one powers both tanks, it could be your dash switch but that isn't common it's far more likely the pump is bad. The relay should be behind the airbox on the drivers side inner fender.
Thanks for the replys, but still can't find any fuel relays!!! If what was stated before about only 1 relay for both pumps, then I guess it has to be the front pump... Wow this really sucks as I live in a RV park and they don't allow working on vehicles here. Guess I'm gonna have to do it incognito here to do it.
The one with the green bottom is the fuel pump relay.
But we have already stated that there is nothing wrong with your fuel pump relay as the pump in the other tank will run OK. This is true if you have factory wiring and someone has not wired around the fuel pump relay.
Well, thanks for all the info guys. Guess I gotta start saving up for a new fuel pump! I didn't realize that they used 1 relay for both pumps. Anyone know how long it takes to change the front fuel pump? I do have an electric impact gun, so can remove bolts/nuts pretty fast. Thanks again, Mark
It will take about a half an hour to an hour once the bed is pull to the rear or removed to expose the top of the tank.
I just did one yesterday.
Getting the bed bolts out is the hard part.
You can drop the rear tank to change its FDM (pump) but getting to the front tanks strap bolts is very hard without removing the drive shaft for the nuts and getting hold of the head of the bolt on top side is also very hard.
It is a lot easier to just move the bed back or take it off.
Note your problem can still be the selector switch or the wiring to the pump and not the pump.
In the diagram below you have the bottom relay.
The top relay was to show how to convert to the newer stile relay if you have bad relay sockets or bad wiring under them.
Thanks for the info Bill. Crap, I have been using the truck as a rolling storage shed and have a bunch of stuff in the bed and also a bed liner. And a shell on it too. I will look at the wiring before I get a storage unit for my stuff. Hopefully it's the wiring!!
Also, I see that the switch is screwed onto the faceplate and I need to get the ***** for the light switch and wipers off and remove the faceplate. After that is it easy to test the switch? Thanks, Mark
Well, come to find out it was the pump. Ordered one from Rockauto.com and they didn't list it correctly and I got the wrong one. That place is screwed up! I will never do business with them again! Anyway got a used one and it works great..... Thanks to everyone for their help and advice!
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