jgreg53 Posted July 31, 2022 Report Share Posted July 31, 2022 My fuel gauge was reading a fourth of a tank yesterday as I ran out of gas. Any ideas? Quote Link to comment Share on other sites More sharing options...
Jerry Roberts Posted July 31, 2022 Report Share Posted July 31, 2022 Pull the sender out of the tank and hook it to the dash gauge . Move the float up and down while watching the gauge . Be sure to ground the sender . That might help to get an idea of what is happening . Look for any frayed wires . Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted August 1, 2022 Author Report Share Posted August 1, 2022 Found the problem. Loose connection at the tank. At least I hope that's all it was. Quote Link to comment Share on other sites More sharing options...
motoMark Posted August 1, 2022 Report Share Posted August 1, 2022 Interesting. I think I just encountered a similar situation. My 51 Cambridge is very new to me (1 week) so I don't know the vehicle very well yet. On Saturday I was looking for a gas station near me that sells ethanol free gas because my fuel gage was just under 1/4 tank. Pulled up to the pump, shut it off and filled the tank. But then it wouldn't start, just cranked over. Checked for spark at the points by manually breaking the contact points - check. Took the top of the air cleaner off and checked for fuel. The road is pretty noisy in that location but I thought I heard a squirt when I moved the throttle. With no tools tools with me, I was ready to give up can call for a tow truck. But I thought I'd give it one more. It gave a little kick on the first crank so I pumped the gas before the second crank, and she fired. It's been running perfect ever since, and before too. It seems almost too coincidental the I ran out of gas at exactly the moment I pulled up to the pump, but I guess it's possible. Any ideas what this could have been? Quote Link to comment Share on other sites More sharing options...
Sniper Posted August 1, 2022 Report Share Posted August 1, 2022 I find these cars just need some loving every now and then 3 Quote Link to comment Share on other sites More sharing options...
motoMark Posted August 1, 2022 Report Share Posted August 1, 2022 21 hours ago, jgreg53 said: My fuel gauge was reading a fourth of a tank yesterday as I ran out of gas. Any ideas? Was the needle on your fuel gauge bouncing around a bit, or was it steady? Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted August 11, 2022 Author Report Share Posted August 11, 2022 Bouncing around. I took the sending unit out took it apart. First I tested the resistance. Moving the float made the reading erratic. I took it apart to see if anything was amiss. It's a very simple design. A pointer tab contacts a coil winding as the float level changes. My problem now is the gauge is at three fourth tank and other than fluctuating up and down the level is staying at 3 quarter. I know I'm not getting that much mileage. Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted August 11, 2022 Author Report Share Posted August 11, 2022 Should probably just keep the tank full. Quote Link to comment Share on other sites More sharing options...
SteveR Posted August 15, 2022 Report Share Posted August 15, 2022 Your float works like a dimmer switch that sends a current to the meter on the dash. If you remove the sender unit and with a meter set to ohms (resistance) move the float from one extreme to the other slowly. Digital meters do not react quickly. You should see a difference in the reading. Is there a spot where you get no reading? It might be possible you have a poor connection someplace. Quote Link to comment Share on other sites More sharing options...
busycoupe Posted August 15, 2022 Report Share Posted August 15, 2022 On 8/1/2022 at 10:22 AM, motoMark said: Interesting. I think I just encountered a similar situation. My 51 Cambridge is very new to me (1 week) so I don't know the vehicle very well yet. On Saturday I was looking for a gas station near me that sells ethanol free gas because my fuel gage was just under 1/4 tank. Pulled up to the pump, shut it off and filled the tank. But then it wouldn't start, just cranked over. Checked for spark at the points by manually breaking the contact points - check. Took the top of the air cleaner off and checked for fuel. The road is pretty noisy in that location but I thought I heard a squirt when I moved the throttle. With no tools tools with me, I was ready to give up can call for a tow truck. But I thought I'd give it one more. It gave a little kick on the first crank so I pumped the gas before the second crank, and she fired. It's been running perfect ever since, and before too. It seems almost too coincidental the I ran out of gas at exactly the moment I pulled up to the pump, but I guess it's possible. Any ideas what this could have been? The fuel pump could be weak. if the tank is more than a quarter full there is enough pressure from the tank to keep the fuel flowing to the pump, if less gas intank the pump cannot pull itthrough the line. Another thing that can cause this problem is a pin hole in the gas line. An old Mustang I had started very hard when I first got it. Once running it was fine. It never leaked gas either. Eventually I replaced the fuel line and discovered that the old line had a pinhole where it went up over the axle. When the car was stopped thefuel would drain out of the line back to the tank and the pump couldn't pull it back over the hump, but once started it would run fine. 1 Quote Link to comment Share on other sites More sharing options...
Veemoney Posted August 15, 2022 Report Share Posted August 15, 2022 (edited) On 7/31/2022 at 2:49 PM, Jerry Roberts said: Pull the sender out of the tank and hook it to the dash gauge . Move the float up and down while watching the gauge . Be sure to ground the sender . That might help to get an idea of what is happening It sounds like you pulled the sender and did a resistance check. Follow JRs above testing so you can determine if the gauge and sending unit are working with the sender out of the tank. I pulled my gauge when doing this test but you can get away with just pulling the sender. Set the sender flange up level on a something that allows you to position the sender float in different positions. Use some extra wire lengths to connect the sending unit wires to the gauge wires. Set the float in a few positions and turn the key on to view the gauge reading in the car. Give it 1-2 minutes to reach the full limit as it may keep creeping up. Check it with the float positioned at half tank, full and toward empty. Make sure the sender has a good ground connection. I found even testing out on the bench that I had to wire brush a spot on the sender to get a good ground before it worked. Stuff a rag in the sender unit whole to keep things out of the tank and any unwanted sparks from that opening. Picture below may not be identical to your gauge, but you should get the idea of makeshift positioning of sending unit flange and float for testing. Edited August 15, 2022 by Veemoney 1 Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted August 17, 2022 Author Report Share Posted August 17, 2022 I went ahead and ordered a new sending unit from AB just to eliminate that as the problem. It seems to me the bottom of the unit is constantly soaked in fuel. Couldn't be good for it. Quote Link to comment Share on other sites More sharing options...
Veemoney Posted August 17, 2022 Report Share Posted August 17, 2022 (edited) I believe mine is original to the truck. When I pulled the sender there was no cork float present so I fitted it with the wine bottle cork in the picture and just came back from a ride. So far been a week and still working as it should but will see how long it holds up. Don't throw your old one out till your sure the new one fixes the problem. Edited August 17, 2022 by Veemoney Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted August 24, 2022 Author Report Share Posted August 24, 2022 Is it at all possible to use a 12 volt fuel gauge in a 7 volt system? Quote Link to comment Share on other sites More sharing options...
Sniper Posted August 24, 2022 Report Share Posted August 24, 2022 16 minutes ago, jgreg53 said: Is it at all possible to use a 12 volt fuel gauge in a 7 volt system? Maybe, the later stock fuel gauges used in 12v Mopar systems don't actually use 12, they use roughly 5v. The is an Instrument voltage regulator that drops the q2v to work with the gauges, not sure how changing the ground polarity would affect teh needle swing though, probably make it backwards, lol. Now if you are talking about an aftermarket one, probably not because even with a buck boost setup the grounds are opposite. Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted August 25, 2022 Author Report Share Posted August 25, 2022 What if you hook it to a 12 volt battery. I have 2 12 volt lawn batteries to run my 12 volt radio. Quote Link to comment Share on other sites More sharing options...
Sniper Posted August 25, 2022 Report Share Posted August 25, 2022 I guess that might work, I was thinking of a more permanent solution though Quote Link to comment Share on other sites More sharing options...
lepic56 Posted August 26, 2022 Report Share Posted August 26, 2022 Talking about the fuel gauge, it is always moving when you are down from the full mark, it move with the motion for the car and bumps.etc.. If it is normal ? will this wear out he fuel gauge mecanism after a while,,?? any maintenance with light oil to the dash fuel gauge or something like that. or is it a problem with the fuel sender?? or finally '' live it alone '' lol Quote Link to comment Share on other sites More sharing options...
Sniper Posted August 26, 2022 Report Share Posted August 26, 2022 You are used to modern gauges that have a damper built in. That is designed to buffer the swings you are seeing in the older style gauges. IOW, what you are seeing is normal 1 Quote Link to comment Share on other sites More sharing options...
Veemoney Posted August 26, 2022 Report Share Posted August 26, 2022 1 hour ago, lepic56 said: any maintenance with light oil to the dash fuel gauge or something like that. or is it a problem with the fuel sender?? or finally '' live it alone '' lol Dash fuel gauge doesn't really have any need for oil or have parts that would wear out from the extra swinging. Oil would actually cause issues I believe. There is set of points that you clean on some gauges if they are not working but yours is working so leave it alone would be my recommendation. Most issues are with the sender but yours is working as it should and swings with the sloshing of the fuel some. 1 Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted September 1, 2022 Author Report Share Posted September 1, 2022 What is the round thing wired into the dash unit? And how do you test it? Quote Link to comment Share on other sites More sharing options...
Veemoney Posted September 1, 2022 Report Share Posted September 1, 2022 1 hour ago, jgreg53 said: What is the round thing wired into the dash unit? And how do you test it? I'm not sure if this question is directed to me for something I posted or someone else but please provide a bit more detail so we can help. Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted September 1, 2022 Author Report Share Posted September 1, 2022 (edited) It's either a resister, capacitor, or transistor. Round and red. Edited September 1, 2022 by jgreg53 Quote Link to comment Share on other sites More sharing options...
DakotaFrank Posted September 2, 2022 Report Share Posted September 2, 2022 It’s not a signal flasher, is it? The way it’s mounted to the other doohickey makes me doubt that. Quote Link to comment Share on other sites More sharing options...
jgreg53 Posted September 2, 2022 Author Report Share Posted September 2, 2022 Not a signal flasher. It's attached to the fuel gauge. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.