Ford 94 carb and vapor lock

[Tudie 36]

Trying to track down a vacuum leak, would a small tear in float bowl gasket cause no flow? I can force air into tank fill and gas flows good into a jar, hook up to sediment bowl and nothing. I'm in process of changing vacuum advance; it looks like someone tried to turn the non-turning nut where line connects and bent it at an angle and also replacing gasket on sediment bowl. I have had to force air prime before, but she has always primed in the past.


Thanks, Greg

[ford38v8]

Greg, it’s hard to diagnose while blindfolded. Tell us more, be specific with correct terminology, and we can help. Identify engine, carb, distributor, fuel pump, and whether you have an in-line fuel filter. From what you’ve said, vapor lock, float bowl, and vac leaks are not related, early & late flatheads differ in vac brake or vac advance. Wild guess tells me your flex line and/or fuel pump are your root problem.

[Tudie 36]

1952 EAB in a 1940 sedan Rat Rod. I have always had an issue with hard starting after sitting a couple of weeks. Today I installed new gasket on the Ford 94 carb, at the bowl not the base, installed new vacuum advance/brake, filled bowl with fuel before sealing up, tightened sediment bowl, fires right up and runs with squirt from bottle but will not pull fuel to fill sediment bowl. Sorry if I’m not clear. Greg

[FortyNiner]

I would start by inspecting and retightening all connections in the fuel line. Also check to ensure that the fuel pump is moving gas.

Troubleshooting isn't flashy but it prevents one from assuming a solution before diagnosing the problem.

[Tudie 36]

The pump was working when I took carb off to check needle and float in carb, I guess there is a chance.

[Ziggster]

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Not familiar with later flathead setups regarding carb/ fuel pump/sediment bowl, but if similar to earlier style setups (e.g. fuel flows through pump first, then sediment bowl, then into carb), I cannot see how fuel stops flowing when you attach the sediment bowl? Is this correct?
Just a quick search on the interweebs shows similar issues with regards to trouble starting after sitting for a few days. A leaking power valve is sometimes the culprit as it will drain the fuel in the bowl down into the intake. Power valves not specific to the 94 have a tiny radius were the seal/gasket seats. This radius prevents the seal/gasket from sitting flush. I doubt this is the direct cause of your issue, but you want to make sure this isn’t causing your bowl to drain of fuel.

[Edit] Had a look at my engine and can’t believe I still can’t remember the setup. Sediment bowl then pump then carb. lol!

[mcgarrett]

Originally Posted by Tudie 36

1952 EAB in a 1940 sedan Rat Rod. I have always had an issue with hard starting after sitting a couple of weeks. Today I installed new gasket on the Ford 94 carb, at the bowl not the base, installed new vacuum advance/brake, filled bowl with fuel before sealing up, tightened sediment bowl, fires right up and runs with squirt from bottle but will not pull fuel to fill sediment bowl. Sorry if I’m not clear. Greg

Just went thru this same scenario with a friends '40 P/U. Problem turned out to be a porous rubber fuel hose at the firewall where it attaches to the fuel pump. We found it was sucking air and not enough fuel to make it run. If you're not sure how old it is, try replacing it before you do anything else. Inexpensive part and easy to replace it. Might save you some grief.

[hueyhoolihan]

Originally Posted by Tudie 36

Trying to track down a vacuum leak, would a small tear in float bowl gasket cause no flow? I can force air into tank fill and gas flows good into a jar, hook up to sediment bowl and nothing. I'm in process of changing vacuum advance; it looks like someone tried to turn the non-turning nut where line connects and bent it at an angle and also replacing gasket on sediment bowl. I have had to force air prime before, but she has always primed in the past.


Thanks, Greg

to answer you're question, i'd say no. but it may leak.

if i filled the floatbowl with gas, and the engine would start and run until the floatbowl was empty, and the sediment bowl in the pump was still empty, i would be looking at the fuel pump. in fact, i wouldn't hesitate to buy a new one just to see if that was the problem. IMO, they're that inexpensive. tried fixing my old one once, and in the end was not worth the effort, time, or money (i.e. price of a couple'a chuck roasts) compared to just getting a new or rebuilt one. YMMV.

the one i'm now running may be this one and have no idea if it will fit your car or not: https://www.speedwaymotors.com/Offen...ump,25400.html

[Terry,OH]

You did not mention removing the fuel pump or replacing the filter. If you replaced the filter what did you put in? A paper filter?? Many seem to have good luck with cork gaskets for the sediment bowl Vs the neoprene. Don't tighten the thumb screw at the bottom of the filter glass bowl with pliers, it can warp the casting.
A tear in the carburetor gasket between the top and and middle castings will not cause fuel to not flow. The carburetor float bowl is vented to atmosphere.

[The Art Doctor]

Modern fuel is engineered for closed loop modern cars. Its vapor pressure is set low to easily evolve in that closed loop. Our open loops allow the low vapor pressure fuel to easily evolve out of the system and into the atmosphere where it does little good to start the car. It also evolves into a gaseous state in a hot fuel line creating a blockage to liquid flow, "Vapor lock". You have a fuel problem. Actually a lack of fuel problem, even with a full tank. To fix that fuel problem you need an electric fuel pump to fill everything back up when empty and secondarily push past the vapor lock created when the fuel vaporizes in the line due to hot engine compartment temperatures. Electric fuel pumps are not a point deduction in EFV8 judging because they are a necessity to ease of usage and functionality in the modern fuel world. I have one in each carbureted car on a switch for activation when needed except during the summer when I leave them on all the time or the car would be stumbling continually; its hot here.

[Sal]

check to make sure the gasket on the fuel pump bowl is good and that the thumb screw is tight. Make sure that all the connections from the tank to the carburetor are tight. The flex line to the fuel pump must not have any cracks or pin holes, that will also cause problems

[petehoovie]

Originally Posted by The Art Doctor

Modern fuel is engineered for closed loop modern cars. Its vapor pressure is set low to easily evolve in that closed loop. Our open loops allow the low vapor pressure fuel to easily evolve out of the system and into the atmosphere where it does little good to start the car. It also evolves into a gaseous state in a hot fuel line creating a blockage to liquid flow, "Vapor lock". You have a fuel problem. Actually a lack of fuel problem, even with a full tank. To fix that fuel problem you need an electric fuel pump to fill everything back up when empty and secondarily push past the vapor lock created when the fuel vaporizes in the line due to hot engine compartment temperatures. Electric fuel pumps are not a point deduction in EFV8 judging because they are a necessity to ease of usage and functionality in the modern fuel world. I have one in each carbureted car on a switch for activation when needed except during the summer when I leave them on all the time or the car would be stumbling continually; its hot here.

[Tudie 36]

I have three spare fuel pumps but not one with sediment bowl, I guess Micheal at Third Genn is about to get another order, If that fixes it, I’ll have an old spare I am getting pretty good at rebuilding/ replacing them. Thanks for all the suggestions. Greg