Fuel level issue

[bowez]

My fuel gauge went from 1/2 to Full while driving Saturday. I know with how much I've drive it should be 1/4 to less, any input/ideas the most likely issue? Time to drop the tank?

After restarting I did watch the gauge go from 7/8 full to Full.

 

[LukesCougar]

My fuel gauge went from 1/2 to Full while driving Saturday. I know with how much I've drive it should be 1/4 to less, any input/ideas the most likely issue? Time to drop the tank?

After restarting I did watch the gauge go from 7/8 full to Full.

Float maybe getting stuck/ issues with fuel sending unit? Would be my first assumption but idk if these cars have a float or if its all electronic. Ive never even dropped a tank on one of these so take my opinion with a grain of salt.

 

[theterminator93]

Anti-slosh module is where I'd start. They're known to go wonky more often than the sending unit in the tank.

 

[bowez]

Anti-slosh module is where I'd start. They're known to go wonky more often than the sending unit in the tank.

Would it make it go that far out of spec?

What's the best/correct way to check it?

 

[theterminator93]

I've never personally had to futz with it, but I'd start by reflowing the solder joints. IIRC when it goes bad it opens up and goes full ground, which is a full tank on the gauge.

I'm sure I'm wrong or missing something important though, so wait until Matt or Greg or someone who is sure chimes in.

 

[KevinVarnes]

I can try to scan the factory fuel gauge troubleshooting flowchart, but most of it requires manipulating the float. I had an '89 SC in the shop recently that always read full. I swapped in a different cluster (with anti-slosh module) and got the same thing. Wound up having to replace the sending unit in the tank.

 

[AdamG]

Check the cluster as well. When I got mine forever ago the gauge was stuck on full. There is a chip on the right side of the cluster. If it slides out some and looses connection it will go to full. I slide it back in and never had an issue since. That was over 15 years ago.

 

[KevinVarnes]

Check the cluster as well. When I got mine forever ago the gauge was stuck on full. There is a chip on the right side of the cluster. If it slides out some and looses connection it will go to full. I slide it back in and never had an issue since. That was over 15 years ago.

Right. That is the anti-slosh module Terminator mentioned above. Hopefully that is it, because it is a lot easier than the fuel sending unit.

 

[Generalee0527]

Hmm. I need to investigate. My gauge is all over the place. Generally hangs between 3/4 and full until it gets low then it "may" drop to 1/4 or less momentarily and shoot back to full. I did run it out 6 months ago so now I watch my trip odometer and track my fuel qty. I've got years of consistent mileage of 22-24 mpg on my daily commute. What annoys me is pre-paying and guessing how much it will hold and it clicking fill $6.00 left. Most times it goes back on card but have to go in to be sure.

 

[Grog6]

Brandon nailed it. The anti-slosh module is on the back of the cluster. While you have it out, you can short the 20 ohm resistor, so you can use a real oil pressure sender. Ours is a switch, and the 20 ohm sets the reading.
After you short it a ps60 sender will make it read real pressure. It's huge compared to the switch; I used a npt 90 to make it fit.
If you want to check the tank sensor, You'll have to use the evtm to find the wire.

 

[bowez]

Well, thank looks like the week I'll pull the cluster. I already have a Autometer Oil Gauge in the A-pillar, and have all the EVTMs... Got to to the Radiator fan first though (decided to got with weather-pak connector 630).

 

[Grog6]

I'd find a connector you can get to, and ohm the tank sender, to see if it's grounded.

 

[bowez]

Well joy, have 160 ohms at the cluster. Looks like a bad sending unit or stuck...

FYI we use all the connectors on the Anti-Slosh module, so the videos out there aren't exactly helpful.

 

[Grog6]

160 is across the whole resistor, so if you're sure it's not full, it's the sliding contact worn or corroded off. That would mach your symptoms too.
Check the tank for crud; something may be stuck to the resistor, keeping the slider from touching. While you have it open, siphon some into a clear jar, and see what it looks like. It would suck to replace the sender, and have the same shit the next week. ( the resistor on the sender is a wire wound around a form, and the float arm has a contact that shorts part of it ,the wire to the gage is connected to the slider. Pressure gages are the same, with a spring opposing the pressure.

 

[bowez]

Well I have about 2hrs of driving on a full tank and 1 hr with half a tank. I'm assuming about 5 gals or less now.

Yippie get the joy of dealing with my fully welded exhaust again...

 

[Grog6]

The exhaust on lazarus is the same; I have a kit for the red car, and I bought flanges to make a front and rear half.
I put a trans in in '17, and dropping it as one piece sucks. I'm seriously considering making a fuel pump access hole and cover.
I'm having a hell of a time pumping out a full tank of 15 yo gas.

 

[Generalee0527]

The exhaust on lazarus is the same; I have a kit for the red car, and I bought flanges to make a front and rear half.
I put a trans in in '17, and dropping it as one piece sucks. I'm seriously considering making a fuel pump access hole and cover.
I'm having a hell of a time pumping out a full tank of 15 yo gas.

Harbor freight has a small drill powered pump that you just screw a garden hose on. Other end can be cut as needed. Assuming u have a hose to waste or have a couple fittings to make one. Warning, the pump has the same male end so you need 2 female hose ends unless you can let it dump out the housing. I think it cost me $7 or so plus the extra fitting for a hose.

 

[bowez]

Harbor freight has a small drill powered pump that you just screw a garden hose on. Other end can be cut as needed. Assuming u have a hose to waste or have a couple fittings to make one. Warning, the pump has the same male end so you need 2 female hose ends unless you can let it dump out the housing. I think it cost me $7 or so plus the extra fitting for a hose.

Used one of those once, they do work but don't have a good self life after gas has gone through them.

I'll use the fuel pump and refill my 5gal can, since I think that is about all that is in there, anything over 5 gals I can deal with.

 

[Grog6]

I bought 4 5gallon cans from wallyworld. I'm on can 4,lol.

 

[XR7-4.6]

I bought 4 5gallon cans from wallyworld. I'm on can 4,lol.

I’d just drop with what’s left in it, it doesn’t have to be completely empty. Y’all know my opinion on access holes lol

 

[Grog6]

I'm not running whats in there thru a new engine; it's the worst crap I'd seen, until I saw the gas out of the bike, parked the same year. Our tank is relatively sealed, bike tank, not so much.
I ended up washing it out with a hose and simple green. I put 2 stroke oil in it and coated the inside.
I've got to ditch 20 gallons of dead gas, and only loudon co. will dispose of it. I did ask about the barrel+match disposal method, and the fire chief was nice enough to tell me the jail time and fines involved.

 

[XR7-4.6]

I'm not running whats in there thru a new engine; it's the worst crap I'd seen, until I saw the gas out of the bike, parked the same year. Our tank is relatively sealed, bike tank, not so much.
I ended up washing it out with a hose and simple green. I put 2 stroke oil in it and coated the inside.
I've got to ditch 20 gallons of dead gas, and only loudon co. will dispose of it. I did ask about the barrel+match disposal method, and the fire chief was nice enough to tell me the jail time and fines involved.

Well your first mistake was asking a person of authority. This is like when @Wile E. Coyote told is insurance agent about drifting and mods! Stop it!!!!! lol

Modern gasoline blends evaporate fast and I literally just said just go ahead and drop the tank as you have at least 3/4 out now, not to run it. It’s not that heavy(slightly unwieldy perhaps but way way lighter than a transmission and won’t crush you) and you can just flip it over and dump what’s left in a big pan if you take it all the way out.

 

[Wile E. Coyote]

This is like when @Wile E. Coyote told his insurance agent about drifting and mods! Stop it!!!!! lol.

Hey the drifting mods for drifting were fine, the supercharger on my street car wasn't lol

 

[Grog6]

I know the guy; if if it burned, he'd know in a heartbeat who did it. I asked him how to responsibly dispose of it. He used to come to our lake party for the fourth. With a fire truck, if it wasn't raining. We always do big fireworks.
I did try to let it evaporate, but that part is already gone,lol. It's well on its way to varnish. I'll borrow a truck, and drive it to loudon's dump. Maybe i'll buy some $3.00 eggs, lol. Dropping the tank is problematic as it's sitting on a hill on ramps. Most of the guys saw it at the eclipse party in '17.
As soon as I get over my fall last week, I'll get the rest out. My balance still sux at times. I'm afraid my desire to ride is going to see me being road rash king, but what's a little risk, right?

 

[bowez]

I know the guy; if if it burned, he'd know in a heartbeat who did it. I asked him how to responsibly dispose of it. He used to come to our lake party for the fourth. With a fire truck, if it wasn't raining. We always do big fireworks.
I did try to let it evaporate, but that part is already gone,lol. It's well on its way to varnish. I'll borrow a truck, and drive it to loudon's dump. Maybe i'll buy some $3.00 eggs, lol. Dropping the tank is problematic as it's sitting on a hill on ramps. Most of the guys saw it at the eclipse party in '17.
As soon as I get over my fall last week, I'll get the rest out. My balance still sux at times. I'm afraid my desire to ride is going to see me being road rash king, but what's a little risk, right?

Just take up the road a piece they have much worse stuff to dispose of than bad gas.

 

[Generalee0527]

I thought GasX was for bad gas-well laying off the refried beans helps too!

 

[Grog6]

It actually makes decent napalm, I may keep one can. Sometimes you need something to burn wet wood.

 

[XR7-4.6]

I know the guy; if if it burned, he'd know in a heartbeat who did it. I asked him how to responsibly dispose of it. He used to come to our lake party for the fourth. With a fire truck, if it wasn't raining. We always do big fireworks.
I did try to let it evaporate, but that part is already gone,lol. It's well on its way to varnish. I'll borrow a truck, and drive it to loudon's dump. Maybe i'll buy some $3.00 eggs, lol. Dropping the tank is problematic as it's sitting on a hill on ramps. Most of the guys saw it at the eclipse party in '17.
As soon as I get over my fall last week, I'll get the rest out. My balance still sux at times. I'm afraid my desire to ride is going to see me being road rash king, but what's a little risk, right?

I was under the assumption that you were wanting to remove the tank anyway to get it really flushed out. How high are the ramps? Is it on a concrete slab or just soil? I know with your situation the already not fun task of tank removal is utter shit but it’s 4 bolts, the filler coupler, the crossover and 3 lines and it’s out and after you fully dump it and flush it out it’s super light to put back in totally empty.

If you’re trying to pump out the varnished gas in it now without removing the tank you’ll never get it and various grime all out anyway. I don’t necessarily think it matters all that much anyway; it’s not like there’s rust floating around in there, you can dilute 5 remaining gallons of bad gas with 13 gallons fresh gas adequately and it’ll be fine after a refuel or two

 

[Grog6]

I've dropped a tank before; In '05,When Lazarus got hit, it tore the filler out and caved in the whole pass qp, all the way to the door.
I dropped the tank to pound that area out, and put a new tube in. I did his fp while I had it out.
I had the frame straightened, replaced the lca,uca and knuckle, pounded the rest of the qp out, and put another 450k mi on it.
There doesn't seem to be crud, but my fp seems to be dying. I have a 190 walbro I bought from gunn, but dropping the tank would involve jacking the rear over the wheel chocks holding it on the hill. (2x 12" cast aluminum speakers I destroyed with the stereo.) Ramps in front are ~14" steel. I'll post a pic.

 

[Generalee0527]

I feel you. These cars are slung really low. I swapped my transmission out in the driveway(cardboard helps but not much) and I recall using extended jack stands on the front until I got ready to drop it and then while balanced on my trolley jack I ease it off to the ground to learn the bell housing wouldn't clear. Had to take a 4x4 about a foot long on the trolley jack to get front high enough to drag that sob out. No big deal UNTIL you realize you got to go that high again to get replacement in. Yeah nothing like being committed and having to do hairy stuff. Be careful.