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Does a 1987 F250 4x4 diesel have an inertia switch? I am asking because the fuel gauge for the front tank moves back and forth, particularly when in motion. The rear tank reading is stable. In the manual, it show them on gas models, but I was wondering if the diesels have them.
There is 12 volts at the jack for the feed for the rear tank before the transfer valve, but on the front feed, there is only 8 volts before the transfer valve.
If there is an inertia valve, when is it located, and what does it look like?
On gas models, it is only used on the front tank.
Any hints or help would be appreciated.
Thanks for you advice.
Del
I can't say whether your diesel has a fuel inertia switch or not. But if it has electric fuel pumps, it probably does for safety reasons.
The inertia switch would not cause your fuel guage problems. It is there to interrupt power to the fuel pump(s) in case of an accident. If it is activated, by an accident or some other abrupt manuever, then it has to be reset manually, it will not reset itself. You may have a sending unit that is wearing out causing your erratic readings.
Thanks guys for the help. You were both right on the money. The sending unit was bad. After speaking with the service tech at the dealership, I found out that the voltage isn't and shouldn't be constant going to the unit. That seemed odd to me, hence, the uncertainty of the problem.
While the tank was out, I cleaned and sealed it.
Anyway, all is well again.
Thanks again for the advice and help.
Happy travels......Del