I acquired an 86 F-150 that had been parked for a couple of years and due to the ethanol gas, the tank and sending unit were rotted out. The truck was a factory 300 6cyl so it was not fuel injected. From a little research, it appears that they changed the sending unit hole in the tank in 85 to accommodate the fuel pump in the tank and since the non-fuel injected fuel sending was made for 1 year plus the 300 in 86, I could find no one that listed it. I ended up buying a tank and sending unit for an 84. Can anyone tell me if there is a resistance difference between the 84 and 85/86 non-fuel injected sending units? If there is a difference, is it as simple as getting a fuel gauge out of an 84 to make it read right? Currently with a full tank it is reading half but with all the other hack jobs that have been done on this truck I don't want to chase a problem that may not exist.

From what i know Ford has used one resistance for a long long time. Like all the way back into the 60s. And the same for GM they allways been the same,

No for the newer truck like after 2003 that might have change. But i think from 80 to 96 there all the same.

The resistance up to 87 was the same, so the small hole and large hoe senders up till then are the same, but with the new body they deemed it necessary apparently to change the resistance.

If you put the wrong resistance in, the gauge reads empty all the time. I have made that mistake, but was caught early. I found that when doing the Cummins conversion on the 92. I had scored a sender from an 85-6, went to hook it up and the gauge read empty all the time. It works fine in my 86 though...


Some other places that will help with this:
http://www.fordification.com/tech/fuel-sending-units.htm
http://www.classicinstruments.com/index.aspx?documentID=fuelgaugesandtank
http://summitracing3.custhelp.com/a...9/~/measuring-a-fuel-level-senders-resistance

Thanks for the links and info Fellro.