I've got a 1983 Scarab III, I bought it used and the fuel guage has never worked. So I decided to go ahead and track down the problem and fix it.

I've got the back seat out, and have access to the fuel level sending unit, it would be an absolute bear to remove. So I went down to the local auto parts store, picked up an auto fuel guage just so I could test if my existing guage was bad or not. So I hook it up, and the needle shoots to the F position. The old one would come up to the E position when the ignition was on. Now doing some research I've discovered that the sender units basically create resistance to send the proper level to the guage. I'm guessing a little on this.. So anyhow, my real questions are:

How can I test the guage?

How can I test the sender unit?

Thanks for the help!

Jim

The best way to test the sending unit is to pull it from the tank first. Back in 83 most were standard pos with probably 5 sheet metal screws holding the sender to the top of the tank. A float of some type will be riding on a lever that moves as the fuel level changes. This changes the elect resistance and is sent to the dash gauge as a reading. You mentioned that the different gauge you hooked up went to full, is your tank full? If so your tank sending unit is working ok and the problem lies in the wiring{probably} or the dash gauge. While you have the sending unit out and hooked to the gaage not in your dash move the float back and forth and see if the gauge changes. If it does the sending unit is ok. If not a universal sending unit at the boat retailer is 39.95 and easy to install. Good luck.

Bucky, its not full, I fill up before going out since I have no guage, So I've probably got 2 hours of fuel gone. When the needle goes to Full, it like shoots directly to the right, I've bypassed all the dash wiring to test, by hooking up a jumper wire from the sending unit to the new guage.. What would the correct resistance ranges be for a sending unit if you know?

Jim I had to replace the sender on my scarab. It all depends on your guage. what you need to do is pull the sender out and E-MAIL me and I will help you with the repair. Do you have VDO guages if so you probably have an ISSPRO sender. Just call them -they are on the web and they will send you a new one I think mine was less than $ 50

I ended up pulling it out this afternoon, went down to Boaters World, and bought a new one, It was one of the adjustable ones, just got it re-installed and it appears to be working splendidly!

Thanks for the offer of assistance!

Jim