Fuel Gauge Question

jpjeep26uk

jpjeep26uk

YJ Enthusiast
Joined
Nov 12, 2022
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273
Location
UK
Hi all. OK so I've just emptied my tank to desert dryness. Then refilled with 3 gallons or so. Gauge is hardly moving from the bump stop, as in just about touching the bottom of the red marker. Surely should be showing at least near rhe quarter way mark? Any suggestions?
 
Depending how old the float is inside the tank, it could be flooded with gas and not floating as high as it should. Mine did that and I tried draining and resealing but that didn't last.
 
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You but too much faith in the accuracy of a factory fuel gauge, lol. I can go till it's under the E mark and still only put in 16-17 gallons on a 20 gallon tank.

These are more like rough references and probably calibrated a bit to show lower than what's actually in the tank to help keep people from running out of fuel.
 
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DOWNS said:
You but too much faith in the accuracy of a factory fuel gauge, lol. I can go till it's under the E mark and still only put in 16-17 gallons on a 20 gallon tank.

These are more like rough references and probably calibrated a bit to show lower than what's actually in the tank to help keep people from running out of fuel.
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Haha, nice one, I was worried there, yet another 40 dollar part flown in for twice the price! I'll put my faith in what the gas station says I put in. Cheers.
 
DOWNS said:
You but too much faith in the accuracy of a factory fuel gauge, lol. I can go till it's under the E mark and still only put in 16-17 gallons on a 20 gallon tank.

These are more like rough references and probably calibrated a bit to show lower than what's actually in the tank to help keep people from running out of fuel.
Click to expand...

Word. All Jeep gauges for that matter IMO.
 
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Well, I threw new plugs in again and syphoned out the pool of gas in the throttle body, made a coffee and....

Progress! It fired up!

[ I have to syphon out the gas from the bottom of the throttle body/intake every time otherwise she won't even start to fire up...]

Ran like a dog for about 12 mins then seemed to settle down and run less raggedy. Billows of smoke!

Almost sounded normal and the smoke eased off a lot. Went from black to grey.
Ran smoother for about five mins, I played with the throttle and revved her up and down gently and she actually responded well.

At first I revved up and she just faltered and hesitated to respond then eventually climbed in revs but after about 20 mins she responded like she should when I revved up [ all via the throttle cable in the bay, not via the pedal]

Then she petered out, revved down and died. Plenty of fuel, just died off. All the while, say 20mins total running time, the heating didn't warm up and the radiator was stone cold.

But at least she ran. But that's the longest she's ran in over eight months and longer than all the other fire ups added together. Which is about 6.
 
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Gilaguy23 said:
Word. All Jeep gauges for that matter IMO.
Click to expand...

Well I can add my mark to that statement now chaps.

When gently pulling the gauge cluster away from the dash board to make sure the gauges were all still wired up OK, there was a puff of smoke behind the cluster, and the clock stopped and two of the bulbs behind the engine temp and fuel gauges have died!

No way any wires touched as there aren't any back there, just a big connector into the rear of the cluster.
Yet somehow the pcb has a scorch mark and a fried thin copper strip right near the clock.
Beats me!
One thing after another with this Jeep.
New PCB on the way from PA!
 
Every thought of running sea foam through your engine? My engine was a smoking terd until I cleaned it out. I also ran marvel mystery oil through it and then changed the oil. It is now running clean and great.
 
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DOWNS said:
You but too much faith in the accuracy of a factory fuel gauge, lol. I can go till it's under the E mark and still only put in 16-17 gallons on a 20 gallon tank.

These are more like rough references and probably calibrated a bit to show lower than what's actually in the tank to help keep people from running out of fuel.
Click to expand...

You have a fuel pump with a float that it designed to only read up to 15 gallons. The tank is 20 gallons. I am in this exact same situation and when my tank is filled with 15 gallons it shows 3/4 full. People can argue with me on this or do the math. Ha ha ha
 
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redbullet said:
Every thought of running sea foam through your engine? My engine was a smoking terd until I cleaned it out. I also ran marvel mystery oil through it and then changed the oil. It is now running clean and great.
Click to expand...

Hi, I recently drained a bit of oil, put some seafoam in and ran the engine for about 5 mins ,as that is all she'll do, and emptied the oil out and put 3.8 litres fresh oil back in with a new filter. Do I need to do it differently? I'll try anything right now haha!
 
My wife broke down one day on the highway and got a tow, guage showed just about a 1/4 tank left, tow truck driver wouldn't put gas in it for her, I thought the worst, she said it just shut off, I put gas in it and she fired right up. Since then I shortened the overflow tube so I could get 20 gallons instead of the origional 15 Gallons.
 
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shore5 said:
My wife broke down one day on the highway and got a tow, guage showed just about a 1/4 tank left, tow truck driver wouldn't put gas in it for her, I thought the worst, she said it just shut off, I put gas in it and she fired right up. Since then I shortened the overflow tube so I could get 20 gallons instead of the origional 15 Gallons.
Click to expand...

Is it easy to shorten the overflow tube?
 
I'll have to do something. I put another 3 gallons in today, makes it 6 gallons in the tank and the needle is still only just moving from the stop bar. Should be at least quarter of a tank showing.
 
jpjeep26uk said:
Is it easy to shorten the overflow tube?
Click to expand...

You can do it with the tank in the Jeep. Took me about 20 minutes even with the old stuck on fuel hoses. It's really the vent hose not really the "overflow" tube. On Jeeps with the "15" gallon tank they still actually had 20 gallon tanks but they put an extended vent tube into them to limit the pump cut off at about 15 gallons. If you pull that tube and trim it down to a few inches long or just out right remove it you get access to the full 20 gallons. It was a dirty underhanded way for Jeep to sell a 20 gallon "upgrade" to people.

FWIW the CJs in the past regularly had 15 gallon tanks (or even 10 gallons if you go old enough) so maybe they thought folks wouldn't notice? The internet makes information like this easily accessible to everyone, where as in the early 90s this info would have had to spread via off road magazines and word of mouth.
 
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redbullet said:
You have a fuel pump with a float that it designed to only read up to 15 gallons. The tank is 20 gallons. I am in this exact same situation and when my tank is filled with 15 gallons it shows 3/4 full. People can argue with me on this or do the math. Ha ha ha
Click to expand...

Again, we put too much faith in the gauges and senders. Even before I shortened my vent tube, it would read full at 15 gallons, now it just reads full longer lol.
 
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DOWNS said:
You can do it with the tank in the Jeep. Took me about 20 minutes even with the old stuck on fuel hoses. It's really the vent hose not really the "overflow" tube. On Jeeps with the "15" gallon tank they still actually had 20 gallon tanks but they put an extended vent tube into them to limit the pump cut off at about 15 gallons. If you pull that tube and trim it down to a few inches long or just out right remove it you get access to the full 20 gallons. It was a dirty underhanded way for Jeep to sell a 20 gallon "upgrade" to people.

FWIW the CJs in the past regularly had 15 gallon tanks (or even 10 gallons if you go old enough) so maybe they thought folks wouldn't notice? The internet makes information like this easily accessible to everyone, where as in the early 90s this info would have had to spread via off road magazines and word of mouth.
Click to expand...

Nice one. I'll give that a try. If it ever stops raining!
 
DOWNS said:
You can do it with the tank in the Jeep. Took me about 20 minutes even with the old stuck on fuel hoses. It's really the vent hose not really the "overflow" tube. On Jeeps with the "15" gallon tank they still actually had 20 gallon tanks but they put an extended vent tube into them to limit the pump cut off at about 15 gallons. If you pull that tube and trim it down to a few inches long or just out right remove it you get access to the full 20 gallons. It was a dirty underhanded way for Jeep to sell a 20 gallon "upgrade" to people.

FWIW the CJs in the past regularly had 15 gallon tanks (or even 10 gallons if you go old enough) so maybe they thought folks wouldn't notice? The internet makes information like this easily accessible to everyone, where as in the early 90s this info would have had to spread via off road magazines and word of mouth.
Click to expand...

Never knew that about Jeep. That's a clever con isn't it. Blimey. OK I'll give it a go this coming weekend. Thanks for the pointer.
 
Heres a dumb fuel question. Will the Jeep run if the fuel and return pipes are swapped? Only asking as according to Haynes/ Chiltern manual, the fuel supply is the pipe on the RIGHT of the Throttle body as you look from the front of the hood.

But when I disconnect them to remove the throttle body, or simply check the pump is working, the fuel comes out of the pipe on the LEFT?

Is that my lack of understanding of how the flow works, or has someone swapped them by accident (it's been to three mechanics in the past 5 months and still won't start or run properly)

Feel free to shoot me down as I'm having to teach myself all of this stuff single handedly. It's bloody hard.
 
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