BigBrother-84 Posted August 14, 2023 Author Share Posted August 14, 2023 The way these gauges "work", I'd think it's from sloshing fuel, if the other gauges aren't affected as Gary said. Oh-oh… Maybe you’re touching something, Dane. You make me realize that maybe it’s not related to the engine rpm, but possibly to acceleration/deceleration/hilly road/turns/etc. This cluster is made of the best parts of 3 used ones plus NOS gauges. This fuel gauge is NOS. And this summer is the first time Big Bro is "really" on the road for long runs, if I can say, since mid 2019. And so for its "rebuilt" cluster. Maybe this NOS fuel gauge is much more sensitive than the old one I used to have? Before more digging the electrical question, I’ll pay attention to its behavior. If it varies only with truck’s movements, we’ll have found something. But one thing I can say is that the fluctuations proportion can be important, not just a little needle movement. Can the fuel sloshing influence so much a sending float, as Ralph described it? Link to comment Share on other sites More sharing options...
grumpin Posted August 14, 2023 Share Posted August 14, 2023 Oh-oh… Maybe you’re touching something, Dane. You make me realize that maybe it’s now related to the engine rpm, but possibly to acceleration/deceleration/hilly road/turns/etc. If it varies only with truck’s movements, we’ll have found something. But one thing I can say is that the fluctuations proportion can be important, not just a little needle movement. Can the fuel sloshing influence so much a sending float, as Ralph described it? I agree with Ralph that it happens but not radical, noticeable. I don't trust these fuel quantity systems. Never trusted my 1974 F250, 1986 F250 or 1988 F250 (7.3). My 1992 Bronco and 1994 F250 were and are the only ones I trusted. I never had enough faith or desire to try to fix them, went by mileage or oops better flip the switch. The best way I see to fix them is with the Meter Match that Gary is using. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted August 14, 2023 Author Share Posted August 14, 2023 Oh-oh… Maybe you’re touching something, Dane. You make me realize that maybe it’s now related to the engine rpm, but possibly to acceleration/deceleration/hilly road/turns/etc. If it varies only with truck’s movements, we’ll have found something. But one thing I can say is that the fluctuations proportion can be important, not just a little needle movement. Can the fuel sloshing influence so much a sending float, as Ralph described it? I agree with Ralph that it happens but not radical, noticeable. I don't trust these fuel quantity systems. Never trusted my 1974 F250, 1986 F250 or 1988 F250 (7.3). My 1992 Bronco and 1994 F250 were and are the only ones I trusted. I never had enough faith or desire to try to fix them, went by mileage or oops better flip the switch. The best way I see to fix them is with the Meter Match that Gary is using. Gentlemen, you were right, and THANK YOU for your advice: The fuel gauge behavior is strictly fuel sloshing related. I am dumbfounded that the fuel level can vary so much just because of the truck movements! I made a serious test on a hilly winding road near home (had fun driving Big Bro as if Montecarlo ), and the conclusion is clear. It is not linked to the engine rpm. The fluctuation can be as much as a quarter of tank(!), for a hairpin turn. The indicated level drops much more faster than it comes back to the “good” fuel level. But driving quietly on a flat highway is very stable, no matter how fast or idle the engine turns. I don’t understand why I’d never noticed this kind of fuel gauge behavior. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 14, 2023 Share Posted August 14, 2023 Gentlemen, you were right, and THANK YOU for your advice: The fuel gauge behavior is strictly fuel sloshing related. I am dumbfounded that the fuel level can vary so much just because of the truck movements! I made a serious test on a hilly winding road near home (had fun driving Big Bro as if Montecarlo ), and the conclusion is clear. It is not linked to the engine rpm. The fluctuation can be as much as a quarter of tank(!), for a hairpin turn. The indicated level drops much more faster than it comes back to the “good” fuel level. But driving quietly on a flat highway is very stable, no matter how fast or idle the engine turns. I don’t understand why I’d never noticed this kind of fuel gauge behavior. Glad you got it figured out and that there's no problem. You said the fuel gauge is NOS, so you haven't seen it work before. Apparently it is sensitive and small changes register more on it than the old gauge. Link to comment Share on other sites More sharing options...
Machspeed Posted August 16, 2023 Share Posted August 16, 2023 Glad you got it figured out and that there's no problem. You said the fuel gauge is NOS, so you haven't seen it work before. Apparently it is sensitive and small changes register more on it than the old gauge. Glad you got that figured out, Jeff! That would be a bit bothersome taking a long trip with a bad fuel gauge. Of course, if you know the MPG's on it, you could work the trip off the math. Do you have duel tanks or single? The only thing on my truck that does not work is the flipp'in fuel gauge. Strange thing is that once in a blue moon, I'll look down and see it working. That is rare moment though....LOL! I have got to look into this. Looking forward to meeting you at our show! Link to comment Share on other sites More sharing options...
81-F150-Explorer Posted August 16, 2023 Share Posted August 16, 2023 Glad you got that figured out, Jeff! That would be a bit bothersome taking a long trip with a bad fuel gauge. Of course, if you know the MPG's on it, you could work the trip off the math. Do you have duel tanks or single? The only thing on my truck that does not work is the flipp'in fuel gauge. Strange thing is that once in a blue moon, I'll look down and see it working. That is rare moment though....LOL! I have got to look into this. Looking forward to meeting you at our show! Glad to find out it was only fuel slosh. John- From your description, it sounds like the sending unit, or the electrical connector at the sending unit. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted August 17, 2023 Author Share Posted August 17, 2023 Glad you got that figured out, Jeff! That would be a bit bothersome taking a long trip with a bad fuel gauge. Of course, if you know the MPG's on it, you could work the trip off the math. Do you have duel tanks or single? The only thing on my truck that does not work is the flipp'in fuel gauge. Strange thing is that once in a blue moon, I'll look down and see it working. That is rare moment though....LOL! I have got to look into this. Looking forward to meeting you at our show! John, Big Bro is big, but has a little stomach… Single tank. So we’re going to often stop’n fuel, LOL! Excited about the trip, can’t wait to see y’all at the show! I will create a thread about this road trip, stay tuned! Link to comment Share on other sites More sharing options...
BigBrother-84 Posted May 9 Author Share Posted May 9 John, Big Bro is big, but has a little stomach… Single tank. So we’re going to often stop’n fuel, LOL! Excited about the trip, can’t wait to see y’all at the show! I will create a thread about this road trip, stay tuned! I finally fixed the issue. It was the fuel tank sending unit. We never had an accurate fuel gauge since we own Big Bro. So I didn’t really trusted this float, and I tested the gauge accuracy. Verdict: There no “reserve” or warning. When it shows “empty”… it is. I ran out of gas. Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 10 Share Posted May 10 I finally fixed the issue. It was the fuel tank sending unit. We never had an accurate fuel gauge since we own Big Bro. So I didn’t really trusted this float, and I tested the gauge accuracy. Verdict: There no “reserve” or warning. When it shows “empty”… it is. I ran out of gas. You fixed it by dropping the tank and replacing the sending unit? That's a lot of work if it was the rear, and still a fair amount if the front. Bummer about running out of gas. Been there, done that. My father loaned me his '72 Mustang, and forgot to tell me one important thing - when the needle touches E you just ran out of gas. I pulled into our driveway and turned it off, and the next morning it wouldn't start. He said "Oh, I forgot to tell you about that." Link to comment Share on other sites More sharing options...
BigBrother-84 Posted May 10 Author Share Posted May 10 You fixed it by dropping the tank and replacing the sending unit? That's a lot of work if it was the rear, and still a fair amount if the front. Nan, Big Bro has only the side tank. And I didn’t do it myself, I asked my garage if he had time do to it while the truck was up for the summer tires swap. He charged me half an hour for the job, everything went easy. When I left Big Brother at the garage, it was so empty that it ran out of gas just going out of the garage. Is it becoming a habit, Big Bro…? 🧐 Link to comment Share on other sites More sharing options...
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