Electrical guru needed - Fuel Gauge

Old Jul 30, 2015 | 05:36 PM
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Default Electrical guru needed - Fuel Gauge

I picked up a 1993 Turbo Wagon that runs great but the fuel gauge is stuck on empty. I read this old post over and over again and I'm totally confused.
https://volvoforums.com/forum/volvo-...-issues-82850/
Pierce, I hope you're seeing this. I pulled the cluster and at the C connector pin 3 is Gray and White and pin 4 is Brown. But at the sensor connector, below the antenna, both ends(towards the dash and towards the sensor) the Gray and White is 2 and the Brown is 3. I did bridge them at the sensor connector and checked for continuity at connector C and it did complete the circuit. So I knew I had the right wires even though they're mislabeled at the other end. And, by the way, it doesn't look like anyone did a hatchet job on the wiring so I'll blame the Swedes. I then bridged them with a 68 ohm resistor and got nothing, which means my fuel gauge is bad, right? Then I checked resistance across those 2 wires coming out of the sensor and got nothing, which means my sending unit is bad, right? How rare is that - to have the gauge and the sending unit bad? I did run across a youtube video and the guy said if the gauge is stuck on empty it's probably an open circuit. And is saw this wiring diagram and at the bottom it shows an inline fuse coming off the fuel gauge. http://www.volvowiringdiagrams.com/v...940%201992.pdf Could that be the problem? When I do turn the key on the low fuel light comes on and the needle takes a very quick little bump, doesn't move any but seems to jump when power's applied. Any and all suggestions would be appreciated. Thanks
 
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Old Jul 30, 2015 | 07:24 PM
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UPDATE: Now I do get a 1/4 tank showing on the gauge. Originally I bridged the wires with the resistor after I turned on the key and nothing. I just left the key off re-bridged it, turned on the key and it shows 1/4 tank. When I pull the resistor, with the key on, it goes back to empty but if I re-bridge it again, with the key on, it doesn't show the 1/4 tank. But turn the key off and then on and it does show. So I guess it needs to reset each time. Anyway, looks like my sending unit is shot, what I dreaded. But I'll read the tutorial on that over and over and give it a shot. Does anyone who's tried it have any updates that might make it easier. I did hear that reapplying the connecting ring is tough but I heard that if you soak it in warm water it will expand enough to make it easier to screw on. Thanks.
 
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Old Jul 31, 2015 | 05:29 PM
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The bung ring is not a problem--just put it back on while you are fiddling with the rest of the thing so it doesn't shrink. Apply vaseline to the treads when reinstalling it.

Have you taken it off yet?
 
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Old Jul 31, 2015 | 11:34 PM
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Originally Posted by lev
The bung ring is not a problem--just put it back on while you are fiddling with the rest of the thing so it doesn't shrink. Apply vaseline to the treads when reinstalling it.

Have you taken it off yet?


Actually, I just finished and it wasn't half as bad as I thought. I read the tutorial over and over and dove right in. I was lucky in that I didn't have any corrosion and all hoses we're a press on fit with a clamp. And my lock (bung) ring had a big worm clamp around it. I just tapped that gently and it unscrewed. It had to be turned in 2 different directions but it came right out. And then I ran across this story https://www.brickboard.com/RWD/volvo...fix_wacky.html
so I thought, what do I have to lose. I took apart the sender, which was also very easy and everything looked pretty good but it wasn't making an electrical connection. So I checked for conductivity up and down the wired rods and it worked, including the proper resistance. But when I checked the end of the rod there was none. I noticed the rods are covered in a clear plastic tube or hose and the ends of the coils are just tucked in between the hose and the rod. I narrowed it down to where I was losing it and just tucked the wire in a little farther and off to the side and Viola! total connection and resistance. What a cheap and lucky fix. I reassembled it and started to put the whole unit back in. And this is where I screwed up. I figured I could just repeat the steps I took to get it out and it would be easy. I should have done what the guy in the tutorial suggested. After a few frustrating tries I ran a string around the end of the pump and ran it to the front of the unit. I didn't compress it but kept it snug. With the pump facing 9 oclock and the bend 3 oclock I put it in as far as it would go then compressed it and turned it 90 degrees counter clockwise and it fell right in. Everything lined up and with a little Vaseline on the gasket it pushed in perfectly. It made sense afterwards that going in initially the sender had to be long(to clear the back wall of the baffle) then when it was time to turn it, it had to be short (to clear the front wall of the baffle). Screwing on the lock ring was easy too with that big worm clamp to keep it from distorting and skipping on the threads. All in all an easy repair. Took me about 3 hrs but a lot of that time was thinking time. If anybody's in a similar situation take the sender apart and see if it can be fixed before you toss it or buy another. I'm sure glad I did.
 
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