I think this is my first post, but I'm not even sure since I'm a member of so many forums and I'm the admin at V6F150.com.

I bought the 1980 F100 a couple of weeks ago and only 2 of the gauges work all the time on the cluster. Thankfully one of those gauges is the speedometer and the other is the volt meter.

I'm pretty sure the gas gauge not working is either attributed to the float or something with the sending unit. I can deal with that later and I'll just replace the sending unit.

The problem I'm confused about is between the engine temperature gauge and the oil pressure gauge. I'll start the truck up and the oil pressure gauge will work and give what I feel like is a pretty accurate reading(as accurate as a 31 year old gauge can be). Randomly the oil pressure gauge will just drop to nothing, and the engine temperature gauge will start working. It also happens the other way aroumd(i.e temp gauge works, then goes to 0 and then the oil pressure gauge starts working).

What could be the cause of this problem? I've also read about the 1981-1986 gauge cluster going into the 1980, but I'm not really sure what the benefit of doing this swap would be? I have access to a free and working gauge cluster from a 1983 Bronco, but I'm not trying to dilly dally with anything unless I know it's either better or just a good replacement.

 

Find the sending units for the temp and oil pressure gauges on the engine, and with the key on, engine not running, take the sending unit wire off each one, and ground it to the block and then unground it. The gauge should swing back and forth when you do this.

 

Sounds like a good plan. I'll give it a try tomorrow. I suppose if I ground it and unground it and it swings, the sending unit for those is bad or dying?

 

Probably, or by fiddling with it, it may start working by itself(loose or corroded connection). Or you may find the wire in bad shape or rubbing against something.

 

Awesome. I'll screw around with it tomorrow. I've owned a carb'd vehicle before(actually 2), but I'm still not used to engines with problems that are so easy to fix.

If the pressure gauge didn't read on my F150, you would spend a while with a multimeter and a book trying to figure it out.

 

I got the oil pressure gauge to work every time the truck turns on, and I found that the coolant temp wire was a little bit stripped, so I wrapped that in electrical tape and grounded it out. The gauge went all the way up, and then down when I un-grounded it. Cleaned the connect on the temp unit and the connector, but I don't think it's doing it's job still, so I assume I should replace the coolant temp sensor.

Now for the gas gauge, when I jump the two connectors on the sending unit plug, the gauge goes all the way up, and I'm having the same problem I am with the temp sensor, except none of the wires are broken, cracked, or stripped on the fuel sending unit wire. I cleaned the connectors up and reconnected. I could either just be really low on gas or the sending unit needs to be replaced?

 

More than likely the sending unit is bad in the tank. A very common problem with these trucks.

 

I assume the temp sensor is probably bad too, correct?

I'm not crying about it either way. I paid $500 for the truck with a rebuilt C4 transmission, put a new battery in it, and it'll cost me $300 to fix all the problems and put new shocks on. Sometimes it's awesome to have friends who work at parts stores.