308 Fuel Gauge Level

For the first 200 miles of the tank, the gauge will go down to 1/2 a tank...slowly. When I fill it up at 1/2 tank, it takes 14 gallons, leaving only 4 gallons in the tank.

I am not sure what is causing it.

suggestions?

 

I just went through this with my ’83 308 GTSi QV. The fuel tank sending unit consists of a float on an arm, which in turn moves contacts inside the unit that send a signal to the fuel gauge. The motion of the arm is stopped by a plastic tab on the body of the unit. Due to poor design the arm can swing past the tab, thus putting the arm out of position and damaging the contacts. A replacement unit ($400) had the same design flaw. My mechanic bent the arm such that it would be less likely to swing past the stop.

 

John,

Did you get a factory part or aftermarket replacement?

Mine is a 83 too BTW

Thanks

 

The shop I deal with ordered it, so I'm not positive, but my understanding is that it was the factory part. I can double-check with them and get back to you tomorrow if you want.

 

No, it's ok. Was the one you took out repairable?

 

FWIW, when I switched my 80 GTSi over to VDO gauges, I had to get a universal sending unit for the tank. The universal unit, purchased through summit racing was maybe $25.

If memory serves I took the flange off the orginal ferrari sending unit and modified it to work with the new universal shaft, float, etc. I installed it and haven't had aproblem since.

You have to get a sending unit that is comatible with your guage. Something to do with the resistance or ohms that a gauge reads. I don't think the universal sender would work with a ferrai gauge.......... then why the hell did I even post this =(

 

Meister: You posted it to help me justify spending $400 for what should otherwise have been a $25 part. Thanks!

Matteo: The original unit in my car was not really repairable as the internal contacts were fairly well broken. The replacement unit also failed (due to flaw I mentioned) but was repairable. I suspect you don't know until you take it apart. If you get a new one and take it apart, be careful as they really aren't supposed to be disassembled. My mechanic called the parts supplier and basically said "this is defective, I'd like to try to fix it, will you take it back if I fail?" and they said "yes". Of course, he's probably dealt with them for 20 years.

 

Good info guys. Thanks!

I have a project for next week

 

Good luck; glad to be of help. If you dig into it and learn anything else that's of interest, let us know. I hope never to have to deal with it again but stuff happens.

 

I am going to take a DYI pic step by step of it and post it when I am done. I looked at the parts book and it seems like it would only be a few hours of work.

 

the fuel sending unit on my 'ol Ranger went out and because of the setup (unit on top of the tank, thnx ford), I have two choices: drop the tank or remove the bed. I plan on getting to it sometime....

 

This is probably obvious, but it’s a good idea to test the old and new (or repaired) sending units while they’re out of the tank. Move the float through its normal range of travel and see if the fuel gauge correspondingly moves between full and empty. It won’t be particularly accurate but will give you an idea what’s working and what’s not.