Fuel and Ol Pressure gauge problem

[Helge71]

Happy New Year to all Fordification Forums users!

I am quite new to Ford Trucks (my other old cars are mid 60s Pontiacs) and have recently purchased a 1969 F250 in otherwise nice condition with the following problem:

When i switch on the ignition, the indicators of the fuel gauge (no matter in which position the tank selector switch is) and the oil pressure are immediately going to the right (maximum) limit. The water temperature gauge works normally and the Ampère meter does not work at all... When i pull the cables from the senders the indication of the gauges does not change at all. I tried to search the forum but i am either too stupid to search or this problem has not been dealt with so far... Before i randomly try to renew components i hope that someone on this forum can point me in the right direction where to look for the cause of the failure...

Thanks

Helge

[Thunderfoot]

You can look here for some trouble shooting tips for the Fuel Gauge. http://www.fordification.com/tech/fuel- ... -units.htm
But from the sounds of it you have a short to ground for those gauges somewhere, these gauges work by measuring the resistance to ground from the sending unit so the less resistance to ground the sending unit has the "higher" the gauge reads. It could be the gauges themselves are bad or the wiring at the gauges has a problem, I would start by pulling the instrument cluster out and checking out the wiring there to make sure something isn't shorted out there and work back from there. Also, when checking this out double check the wires on the connector and make sure the wire colors match up from one connector to the other as someone might have changed the instrument cluster from one with Idiot lights to one with gauges.
The Amp gauges do not work well on these old fords, when the do work the needle doesn't move much at all...

[Helge71]

Thanks for the quick answer!

I will start checking the cabling behind the instrument panel...

Helge

P.S.: I like your signature...and fully agree to it

[Helge71]

Well, pulling the instrument cluster was a good idea... afther some testing and cable following i found out that the fuel gauge connection was wrong. The correct gauge plug was hanging aroun loose behind the dash. Now at least the in cab tank reads correct. The under bed tank sender is faulty and gives full ground all the time. I will have to change or repair it sooner or later but for now i can live with the in cab tank.

Helge

[Thunderfoot]

Sounds like your getting it figured out, thanks for letting us know what you found out.

[two-bit]

For your oil pressure gauge problem...
When i transplanted my '63 T-bird block into my '69 F-100 i had a similar problem.
Turn the key on, and the gauge would read 100% oil pressure, start the engine and it would drop to zero.
Turned out the sender on the oil filter adapter from the car was set up for a warning light, not a gauge. So it only sent a signal when there was no oil pressure. (That was my best guess) I changed senders and problem solved.

Might be your problem, might not be. Just an idea.

Good luck with it.
Two-bit