Late gas tank crossover tube problem

[324tdi]

This is on a GTS-1 race car, M20.

Fuel filter became clogged on a regular basis, figured I would drain tank, check FP sock. THought I had 10 - 11 gallons, got 3 gallons out. Pulled sender, passenger side was empty, drivers side was almost full. Fuel is not crossing back into passenger side.

I have another clean late tank in the shop, tested with compressed air to see how crossover tube worked, could not get air or brake kleen to go through. On the tank in the car, pulled it out and fuel/air seemed to move through the tube fine...

So does it work backwards? Some sort of vacuum created?? Thinking about testing a 3rd tank...Replacing all the vent lines as the tank is out...anything else to look for?


Thanks

Al Taylor
Scuderia Gonzo Alonzo
wabmw25@aol.com

[jlevie]

There is no crossover tube on the late(63L) tank. Fuel returning from the engine bay operates a siphon in the left side of the tank to lift fuel over the hump. Fuel on the right side of the tank has no path (besides sloshing) to get back to the left side. A failure to move the fuel from the left side to the right side can be a lack of sufficient flow from the engine bay (bad pump, obstructed line, clogged filter), or a plugged siphon.

Frequent clogging of the filter means a rusty tank. The tank can be acid cleaned and sealed, or replaced.

[324tdi]

Thanks for the info Jim

I am going to check a 3rd tank, I tested the first 2 with a low pressure pump, the first which was in the car returned to the right side through tube from the return line, did not seem to leave any fuel in the left side which confuses me. The 2nd tank, which has been cleaned out and been stored dry in the shop would not return anywhere, tried to run a stiff wire through the tube but could only get a foot or so, I imagine because of the turns and squeeze of the tube on the left side. I hate to think that the return could be completely blocked on a tank that had been cleaned and stored inside...

These are all late tanks...

Thanks

Al Taylor

[324tdi]

Figuring on replacing all the vent hoses....

[jlevie]

[QUOTE=324tdi;4208566]Thanks for the info Jim

I am going to check a 3rd tank, I tested the first 2 with a low pressure pump, the first which was in the car returned to the right side through tube from the return line, did not seem to leave any fuel in the left side which confuses me. The 2nd tank, which has been cleaned out and been stored dry in the shop would not return anywhere, tried to run a stiff wire through the tube but could only get a foot or so, I imagine because of the turns and squeeze of the tube on the left side. I hate to think that the return could be completely blocked on a tank that had been cleaned and stored inside...
It sounds like the siphon on the second tank is plugged. When working, the siphon will do it's best to push all the fuel from the left side of the tank into the right side, where the pump is. Until the level in the tank drops below the hump fuel will be pretty much equalized. After the level drops below the hump the right side will stay full as the left side empties. That is why the lat tank has two level sensors.

[Eddie Haskell]

FWIW- If you believe it could be the a clog inside the tank blocking the Siphon try this. To clear the clog/stoppage pull the fuel return hose off the hard line close to the tank return. The piece of hose is about 6" length. Keep the hose connected to the tank. The piece of hose dangling dripping a small amount of gas from your gas tank fuel return can be a good indicator that you have clogged fuel return/siphon. The easiest way to clear this clog is with a bicycle brake or gear selector cable. Chuck the lead end knob into a handheld drill and feed it into your dangling fuel return line. You will feel the blockage. Keep the drill turning and use a Roto-Rooter style in and out. Once it clears you will be able to advance the entire cable (5') into the tank. You probably have a rusty tank so the clog will come back in the future. This will help keep it clear until you can perform a high colonic on your gas tank.