The Stovebolt Site Forums The Shop Area General Truck Talk quick way to check fuel in gas tank

Ok guys I need to clarify my situation before I ask a question for the simple reason that its gonna sound really stupid... so here goes...

With the key on... the fuel guage says there's 2/3 of a tank of gas in gas tank... however, the only way I can get fuel to the carb is to bypass the fuel tank by disconnecting the fuel line into the fuel pump and connecting fuel line that runs to 2 1/2 gallon gas can below the truck. Here's my question, how do I "confirm" that the fuel guage is correct? It will start and run just fine once I use the bypass fuel supply... but not at all when NOT the bypass method...

I have tried sticking a long wire into the gas tank (hoping to get similar results as one would with a dipstick for oil) but I only get about 8 inches down the filler neck before it snags... tried this 4 different times and farthest I got was approx. 8 inches.

is my only other option to drop the gas tank and check it that way? or what do you guys suggest? I already know that I could just simply pour in 5 or 10 gallons and "make sure" there's fuel in the tank. But my concern is that IF the gas guage is correct and a line is clogged... that 5 or 10 gallons would just be that much more i'll have to drain out.

what are your suggestions?

would greatly appreciate any feedback you guys have. thanks in advance.

To see if your fuel line is clear to the tank try blowing in it or put a low pressure air line into the fuel line. If you can blow in it, it isn't plugged and if there is gas in it you should hear it bubble inside the tank. If you have now cleared the line the gas may come back out at you now, so be careful. You could also try rapping on the tank and see if there is gas in it. Start at the top and work your way to the bottom, you should here a change in pitch if there is gas still in the tank.

put some air or blow back into the line from the pump to the tank... if you cant blow by mouth then you know its plugged... you can also have someon listen at the filler in the tank for bubbles.. dont use a match to check for bubbles tho...LOL.. you can also put a little air into the tank and see if fuel or air comes out the fuel line... as for how much in the tank..??? if its a bolt with the tank behind the seat its not too much to remove the seat top and pull the sending unit and look in the tank....

a buddy of mine has an old like 47 chevy dump truck like a 1 1/2 ton or something like that with a hydraulic hoist, pretty nice truck and the his gas gauge does not work and he has a yard stick layin underneath the seat that he shoves in the filler neck, but its an old bolt with the tank behind the seat so its easy to do

Thanks guys... that was something I had not considered yet but will try that first thing in the morning...

One thing I do remember is that when I disconnected fuel line at the pump... there was not any fuel coming out... I used the bypass method simply to get the engine to start and run and also to move the truck. Just had to secure the 2 1/2 gallon tank to the inner fender well in the engine compartment... i know i know... that isn't real smart but I made sure it was away from the belts and fan lol

Also... when i get to the point of removing gas tank... is it easier to remove the bed? I assume it is but just curious... the truck I am working with is a 79 Chevy... but the parts are going to my 65 Chevy 4x4... gas tank between the frame, 350 engine (needs some valve gaskets) and 4 spd tranny... but right now just trying to get the basics out of the way with the fuel line. Thinking I may consider running new fuel line anyway but will try the air test first.

thanks again

on those trucks dual tanks were kinda common...so make sure its not that or the switch valve between tanks.....

Bowtie65; on those trucks just go to what ever side the tank is on;in the rear wheelwells is where the fuel fillpipe is, foward of the rear tires. Take a strait blade(standard flat)screwdriver, that gets the clamp off the hose that goes into the tank. then you can stick it without goin with allsorts off crazy labor.Regards Steve sr.P.S.if it,s a dual tank 79, Do exactly what FATWEED SAID make sure the elec factory changeover valve isn,t stuck inbetween the tanks

Ok guys so far all I have been able to do is blow the line using my air tank... did this 3 or 4 times each time it gurgled than spit out literally 8 to 10 drops of gas. So I pretty well figured the tank was empty. Then I went to passenger side tank and added 5 gallons of gas (made sure switch was flipped to passenger side tank on the dash panel switch) truck started right up and I drove it down our driveway approximately 1/10 of a mile to my neighbors house (he'd told me when I got it started to stop by so he could hear how good it was running)
while sitting at his house the truck died... now will not start again... from the time I added the 5 gallons and started it til the time it died was less than 5 minutes...

my question now is... do i have "CRUDE" in the tank causing a blockage? OR could there be something in the tank (filter or something) that may have dried out?

HELP!!! thanks

Let start off with a little safety. You are working with gas make sure you have a fire extinguisher handy. Not in the house but 5 feet away or closer.

Well my guess is that you move enough of the crude around to get a small supply of gas. While driving you shook everything and it all settle back down and cut off your supply. You didn't say what year your truck is. Hear is what I would do. Find someone with a compresson and run some air through your fuel line again and run it longer. Then you could remove the fuel line and run some more air through the tank ( make sure your gas cap is off). Make sure the fuel line is clear. If not replace it. If you have a shut off valve at the bottom of your tank make sure it is open. You might try to remove it. If you can and you still don't get any gas coming out of the tank then it is time to drain the tank and remove it to have it cleaned.

Draining the tank. You know that there is some gas in the tank. Get your self some flexible hose(fuel line 1/4" works good) and feed it down the filler neck. If you come to a spot that hangs up slowly pull back and then twist while pushing forward. This should get you passed the thing that is hanging you up with the wire. Drain the gas. Remove the tank. Get it cleaned and possibly sealed. reinstall, connect fuel line, add gas, drive truck, enjoy.

Good luck!

Any truck that has sat for any length of time (1 year or more) should have the tank removed and flushed.

You know the engine runs fine with a good fuel supply, and you're going to put this stuff in another truck anyway, so why bother with it?

Just use a new fuel line when you swap the stuff into your '65, and flush the fuel tank before you put it in.

Crud in the tank is bad news.. it can gum up your lines, jack up your fuel pump, and clog up your carb.

New fuel line isnt expensive.. I use that thick rubber hose stuff that has FUEL LINE printed on it.. all the auto parts places sell it for under a buck a foot., just make sure you dont run it around any moving parts or heat sources.. but make darn sure your tank is clear before you hook up a new line, or you'll just end up clogging it again.

Thanks for the advice guys... this helps me a bunch. Think I'll just leave the gas tanks alone for now and focus on keeping a fresh supply line to the fuel pump using the backup up 2 1/2 gallon gas can... that is something that I know will work and still lets me move the truck around alittle bit... main goal was to just get the engine going and i've done that so now we'll focus on the engine... thanks again for all the good advice guys...

till next time, see ya