Fuel Consumption Problem - Help!

natasha69

New member
I just drove 2 miles and the fuel gauge dropped from a full tank down to 3/4 of a tank. I drove the car from the mechanic back to my house - he was investigating this issue but found nothing.

He pressure checked the fuel lines and the tank, but found nothing. He also checked codes but found nothing.

What could cause that much fuel to be consumed over 2 miles? There is no gasoline smell when I drive it onto my driveway. I cannot see any stains/spills/etc anywhere.

This is a big mystery - would love any help any of you might be able to offer.

Seeking wisdom...

Car is a 96 Limited 4Runner - original owner. 280k miles on it.
 
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Sounds to me like a ground is loose for the fuel gauge sending unit or something. If you were actually using that much fuel it would be pouring smoke and probably be at risk of washing out the cylinders. I doubt it would run well if at all.
 
Only issue is that I had the same situation last week. I filled up the car. A day later I drove to work (10 miles away) and back home. The gauge dropped from full to nearly empty. I went to the gas station and filled up the car (15 gallons).

Car runs fine. Nothing abnormal.

That's why I suspected a mysterious leak.

Besides a bad gauge any other ideas? This is pretty frustrating.

Thanks.
 
It sure as shit isn't consuming it. If it leaked 15 gallons in 10 miles, the source of the leak should be blatantly obvious.
 
My guess is there's someone hiding under the car that comes out while your driving and syphons all your gas out.


But realistically, the situation you're describing just doesn't happen. If it is seriously that bad and you're thinking theres a leak somewhere, have someone follow behind you and watch for leaks. A tank of gas doesn't just disappear in 10 miles. Nor do cars burn enough gas under any circumstance for this to happen. If so, I wouldn't ever drive the thing again.
 
My guess is there's someone hiding under the car that comes out while your driving and syphons all your gas out.


But realistically, the situation you're describing just doesn't happen. If it is seriously that bad and you're thinking theres a leak somewhere, have someone follow behind you and watch for leaks. A tank of gas doesn't just disappear in 10 miles. Nor do cars burn enough gas under any circumstance for this to happen. If so, I wouldn't ever drive the thing again.

20 miles (10 there, 10 back), but same difference.

Agreed on all points - that is why this is frustrating. I thought someone might be syphoning my tank and the gauge was catching up on the drive there and back - which is probably the only rational explanation. Until I went to the mechanic. He found no leaks, however when I dropped it off it had a full tank. When I drove home, I watched the gauge drop by a 1/4 tank. Really a huge mystery here.

The next step will be to fill the tank, drive the two miles, fill it again and see the actual volume of the fuel that is disappearing over that distance.
 
Not likely a leak as that would be pretty obvious to see & smell.
Check to see if your hand brake or either front caliper is sticking. One side or both would cause a lot of drag.
 
Not likely a leak as that would be pretty obvious to see & smell.
Check to see if your hand brake or either front caliper is sticking. One side or both would cause a lot of drag.

Not a chance in hell this is the issue here. The OP is getting about 1 MPG.
 
Where do you part your truck? Is someone stealing your gas?

driveway. i have security cams up which i was going to check. however, the car was parked at the mechanics shop over the weekend - experienced same symptoms, so i think i can rule out syphoning.

i'm going to fill the tank up, then drive 5 miles, and fill up the tank again. that will give a very clear picture if the gasoline is disappearing during the drive or when its parked. Will report back once that test is done.
 
driveway. i have security cams up which i was going to check. however, the car was parked at the mechanics shop over the weekend - experienced same symptoms, so i think i can rule out syphoning.

i'm going to fill the tank up, then drive 5 miles, and fill up the tank again. that will give a very clear picture if the gasoline is disappearing during the drive or when its parked. Will report back once that test is done.

Going to sound silly but are you using Unleaded gas? I know some stations sell the ethanol heavy stuff which could decrease your gas mileage. Like someone else mentioned earlier, these gas gauges are pretty crappy.
 
Going to sound silly but are you using Unleaded gas? I know some stations sell the ethanol heavy stuff which could decrease your gas mileage. Like someone else mentioned earlier, these gas gauges are pretty crappy.

the entire tank is disappearing, so pretty sure thats not it. we fill up at chevron, so no ethanol. yes, for the 96, we are using regular unleaded. but highly doubtful that is the issue.
 
Well IF there is a leak, and it's not enough to just leak when it's sitting parked, then let the truck idle and massage the throttle while parked. If you are actually leaking somewhere while under load (perhaps from a hose) then it'll start pouring on the ground.

I assume you've already crawled under it yourself to see that there is no visible leaks from the tank or hoses forward of the tank, or over the front bash plate?
 
Well IF there is a leak, and it's not enough to just leak when it's sitting parked, then let the truck idle and massage the throttle while parked. If you are actually leaking somewhere while under load (perhaps from a hose) then it'll start pouring on the ground.

I assume you've already crawled under it yourself to see that there is no visible leaks from the tank or hoses forward of the tank, or over the front bash plate?

Yes, I went under there. I also had my mechanic look at it. They ran it up in the air and inspected it. I revved the engine in the driveway as well as drove around and around in circles in my cul de sac. No visual or smelly evidence anywhere.
 
Yes, I went under there. I also had my mechanic look at it. They ran it up in the air and inspected it. I revved the engine in the driveway as well as drove around and around in circles in my cul de sac. No visual or smelly evidence anywhere.

Although I have never seen anything as severe as what you are describing that is not an obvious external leak I figured I'd share this quick test as I've seen it cause ungodly fuel consumption before but usually it is combined with running issues.

With the vehicle running pull the vacuum hose off of the fuel pressure regulator. If fuel is squirting out of the regulator it is bad and will need replaced. This will not be an external leak.

Something really quick and easy to at least rule out.

the vacuum hose is the small one for the nipple on top. The hose is not shown in the picture but hopefully this is easy enough to understand.
let me know if anything is coming out.

 

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