Where is this air coming from? 51 Custom

[Old Henry]

I have been chasing a fuel delivery problem for a couple of weeks (here: https://www.fordbarn.com/forum/showthread.php?t=171201). I've finally narrowed it down to this air coming into the settling bowl: http://youtu.be/_gCuj8S0_q0

What are your ideas on where this is coming from? Is it coming in from the fuel line? around the bowl seal? or backwash from a defective fuel pump?

Within minutes of this video the engine died and would not start again.

[Old Henry]

I think I found my problem.

I remembered having a spare fuel pump to look at to see whether the fuel comes into the settling bowl from the middle or the edge. Since it comes in the middle, that means the air is coming in from the fuel line. The fuel in the fuel line is vaporizing from heat. The line in the engine compartment was not hot and hasn't been. So, what other source of heat is near the fuel line that could cause such vaporization? The exhaust pipe?

Mind you I've only had this car for two weeks (and hope not to have it for more than another two weeks) so had never looked underneath it. Now seemed to be the time. Here's what I found:



Dual exhaust had been installed at some point such that the left pipe just an inch from the fuel line for about 7 inches in length. Seems like plenty of heat exposure to vaporize the fuel in there and send the vapor to the fuel pump to disable it. What do you think? (I actually remember hearing of this problem in the past with other's dual exhaust.)

Hopefully by installing a heat shield and insulation it will solve my problem. Sure would be nice. It's been mighty annoying.

Anyone dealt with this and can show your heat shield and insulation?

[wbedwards]

I just repaired a leak in my fuel line this weekend. It had rubbed a pin hole where it was touching the frame about 20" from the tank. It was not enough to stop the engine as yours, but enough to cause the fuel filter to look empty most of the time. It didn't leak on the ground but I guess back into the tank. My line is routed very similar to yours although on a totally different car. The only way I found it was having to jack the car high on the passenger side for another project which then caused the line to fill with gas without suction from the pump and leak out of the pin hole. Now that it's repaired, the fuel filter stays full all the time. I hope this helps some.

[scicala]

Why don't you just move the fuel line away from the exh pipe instead of band aiding it with insulation. Then insulate it for insurance.

Sal

[Old Henry]

Originally Posted by scicala

Why don't you just move the fuel line away from the exh pipe instead of band aiding it with insulation. Then insulate it for insurance.

Sal

I did both. I pushed, pulled, and bent the fuel line as much as I could away from the exhaust pipe plus installed insulation and heat shield.



I'm just going to take it for a drive and hope it's fixed.

[Old Henry]

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Unfortunately, none of that made any difference. The air still came into the settling bowl and killed the car. I'm at my wits end. I'll probably just have to sell the car with its current problem and tell potential buyers about the problem and not let them test drive it more than a mile.

[Bob C]

I'd get a Mityvac and take the gas line off the carb when the car quits and
hook the Mityvac in and see what you get. If you get no fuel and no vacuum I would think you are sucking air. If you get vacuum and no fuel something is plugged.

Bob

[Johnnydidd]

Don't you have a electric fuel pump as a back up? Is your gas cap vented?

[Old Henry]

Originally Posted by Johnnydidd

Don't you have a electric fuel pump as a back up? Is your gas cap vented?

I do on my 47. I'm selling this 51 for the widow of a friend that died last month. It has a vented cap. I've even driven with no cap in case that was the problem. Didn't help.

[41ford1]

Are there any other flex hoses besides the one going to the fuel pump inlet? Those may be a source of air. A Mighty Vac will help you isolate the problem. If you disconnect the fuel line at the tank and fuel pump, then plug one end and pull a vacuum with the Mighty Vac. You will see if it leaks if it doesn't hold a vacuum.

[GSCOV]

cracked or dry rotted fuel pump diaphragm? cracked fuel pickup line inside tank?

[cmbrucew]

Maybe something in fuel tank blocking the outlet temporally
Bruce.

[Ross F-1]

Is there a section of hose where the fuel line crosses the frame rail?

[Old Henry]

Originally Posted by Ross F-1

Is there a section of hose where the fuel line crosses the frame rail?

Yes

[Ross F-1]

I mean in the rear, the area where your pictures are taken? If so, have you tried replacing it?

[Old Henry]

Originally Posted by Ross F-1

I mean in the rear, the area where your pictures are taken? If so, have you tried replacing it?

I misunderstood your question.
The metal fuel line crosses over the frame but there is no hose there.

[BILL WZOREK]

At one point you said that you pulled the filter bowl checked gasket & replaced same
try replacing gasket with " NEW " or take filter out of line.
remove brass fittings at carb check closely I have found one cracked from being over tightened at some time in its life .