duel fuel tank switch
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duel fuel tank switch
I've a '89 F-250 with the duel tanks. The rear tank is full and the truck will operate on that tank for only a short time (maybe 20 miles) and will then die. The guage will falsely read empty. filp the switch and all is well. Could that be the valve between the tanks or an electrical connection? Any info on how the mechanics of how the tanks are switched to feed the engine?
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Joined: Jul 2003
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From: TEXAS!!!!!!!!!!!!
mine does that too, only when i switch back to the other tank, it reads empty and still goes. Then after sitting awhile the gas from the rear tank goes to the front. Like wheni got home the other day from san antonio i had maybe 1/8th of a tank. then yesterday i had half a tank and today i have 4/3th of a tank all without stopping at a gas station. There was a recall on some trucks with dual tanks because of this problem. only i think it was becasue it was fillingup the tank and overflowing.
Posting Guru
Joined: Dec 2002
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From: Billings MT
If your '89 is like my '90(no pump on rail, only a filter), the electrical switch only switches power to the pump in the respective tank. I don't know when the switch was made from 3 to 2 pumps, I know that 88 has 3 pumps and my 90 has 2. I've been trying to figure out the same sort of problem. I've never seen an electric fuel pump give warning signs of going out, but yet, if it is designed like a hydraulic pump, failure is reasonable when the pump gets hot and begins to bypass internally. I'm think that my problem is vent related and am going to try switching the filler caps and see if the problem follows the caps.
As for the gauge, that is a either a wiring problem or a sending unit problem. It could also be a switch problem. When my switch went out, the gauge would read but no power to the pump. It could do the reverse, not show one side but still supply power.
As for the gauge, that is a either a wiring problem or a sending unit problem. It could also be a switch problem. When my switch went out, the gauge would read but no power to the pump. It could do the reverse, not show one side but still supply power.
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As for the gauge problem, it reads correctly when the rear tank is suppling fuel to the engine but when it starts to falter, the gauge also falters and drops to empty. If I try the rear tank periodically, it will sometimes start suppling again and then the gauge reads correctly again but alas, they both falter again in a short time. That is why my it is my suspicion the two problems are directly connected.
Fleet Mechanic
Joined: Nov 2003
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From: West Cornwall, CT
The two problems are almost certainly connected. The most obvious problem could be in the switch itself. Since you are not having problems with fuel moving from one tank to another, the fuel selector valve is probably OK.
Troubleshooting the switch seems like the easiest place to start.
Lou Braun
Troubleshooting the switch seems like the easiest place to start.
Lou Braun
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From: Billings MT
Ok, so they happen at the same time. I guess I didn't understand that part.
As Lou said, the switch will be the easiest place to start. My guess is, that when the switch gets warm(due to resistance on the terminals), it begins to faulter. The switch is a dealer item at like $15 if I remember correctly. You might want to also replace the plug part that goes into the switch, just incase the problem is there as well. When mine went, it almost melted the two pieces together.
Good luck.
As Lou said, the switch will be the easiest place to start. My guess is, that when the switch gets warm(due to resistance on the terminals), it begins to faulter. The switch is a dealer item at like $15 if I remember correctly. You might want to also replace the plug part that goes into the switch, just incase the problem is there as well. When mine went, it almost melted the two pieces together.
Good luck.
