Non Starting 36 Humpback

[32Bee]

The old girl still won't start and, as far as I'm concerned, it's strictly a fuel problem. As it's been at least two years since I've had her running there isn't
a drop of fuel anywhere in the carb or pump other than that which I've tried
hand filling. The line from the pump to the tank is definitely clear and, for what
it's worth, there is a vented cap on the tank. I've worked the pump by hand and
she spits out fuel fine by doing that but can't seem to be able to pump it from
the tank forward even if I prime the pump with fuel first. So, last night, I thought
about buying an inexpensive syphon pump from Harbor Freight and using it to
suck the fuel forward. However, won't it simply flow back into the tank once I
disconnect the pump in order to reconnect the line to the fuel pump? Also, what
is the function of the two little valves in these pumps and even though my pump
spits out fuel when hand pumped might it be possible one or both of the valves are defective? Any time I've poured a small amount of fuel down the carb, it will
start briefly then die.

[drolston]

Start with the flexible fuel line from the firewall to the fuel pump. Remove it and be sure that it is not disintegrating or swollen shut from alcohol in the fuel.

With the fuel line removed or disconnected, blow on the gas tank filler to be sure you get flow from the tank to the engine compartment. I know it is kind of gross, but that is how I got my '35 and then my '37 primed after sitting for a long time.

You know the pump itself works by hand. With the fuel pump removed from its stand on the intake manifold, crank the engine and be sure the fuel pump push rod moves up and down about 0.2". Put the pump on and after blowing to prime, with the ignition off to avoid any sparks, crank to be sure that each stroke of the pump puts out about a teaspoon of gas. If not, take take the pump apart to be sure the diaphragm is intact, and to clean the valves. Also be sure the filter bowl on the pump has a good gasket and tight seal so that the pump is not sucking air.

If that works, maybe the carburetor float valve is stuck closed. Disconnect the fuel line from the carb and blast the inlet to the carb with carb cleaner, while lightly rapping the top edge of the carb with a plastic or wood mallet to unstick the needle valve.

[Terry,OH]

Just had the same problem. I used a hand vacuum pump to suck several vials of fuel ( couple ounces each) through the fuel line to the connection for the soft line going to the fuel pump. Also replaced the soft flex fuel line. Old fuel is hard to pump and dense.

[32Bee]

I know for sure my flexible hose to the pump is clear and good as it's a Bob Shuman unit so
I'm all set on that. I took my carb apart last week and there are no issues with that such as
a stuck float or needle. I feel the pump is fine as far as the two valves being clean and the
diaphragm is in great shape. So I'm going to either going to blow on the tank filler to force
gas forward or buy a Harbor Freight suction unit to suck the fuel forward. Thanks for your
help so far.

[kurt v]

Maybe a rust pin hole in the fuel line

[drolston]

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Did you check the filter gasket on the fuel pump? The slightest air leak can negate any fuel suction.

[dean333]

I reused the cork gasket on my glass bowl pump, thought it was a good seal. NOT! The slightest non sealed spot caused the pump to suck air and cause the no start. I took the pump off, made a new gasket and filled the bowl with a syringe. Then I tilted the pump side to side to be sure I had a good seal at the bowl before reinstalling the pump. Started right up then.

[tubman]

I totally agree with the above; the slightest air leak in the float bowel gasket can prevent your fuel pump from working. It's kinda strange; some folks have had better luck with neoprene gaskets, while for others (myself included), cork gaskets work better. I think it has more to do with the quality and age of the gasket, rather than the material.

One other thing you should do is to inspect the bowl itself for chips on the sealing lip and flatness. I have a "surface plate" (a 1 foot square 3 inch thick piece of Granite that is perfectly flat). I use it with wet-r-dry sandpaper to nake sure the sealing surface of the bowl is perfect.

[deuce_roadster]

The compression sleeve at the tank may not be making a good seal and sucking air at that point. I experience that with my 40 coupe. Like TerryOH i used a "mighty vac" hand vacuum pump to identify this problem as it kept pulling air bubbles from the tank. After cutting the line off and installing a new compression sleeve, tightening it up, It only pulled fuel without any bubbles. This is pretty rare problem, I would suspect the pump first, try another. The cover gasket can cause it to suck air which is quite common.

[Flathead Fever]

You can Hook a vacuum gauge to the pump and see if it's pulling a vacuum or use your finger over the inlet. You can give it a gas can with a hose to the fuel pump and bypass your tank and lines. You can pull the outlet hose from the pump, crank the engine and check for fuel pump volume. You can gently tap on the carb above the needle and seat to unstick it. You can fill the carb bowl through the vent tube and prime the carb that way. If it sat for two-years, it could be more than one problem in the fuel system, plus the fuel is bad by now. Best to do this kind of stuff outside with a fire extinguisher so you don't burn your garage down.

[32Bee]

Thanks again for all your suggestions. I'm set up this morn to see if I can manually pump
gas from the tank to the engine compartment. If I'm able to accomplish that I'll hook every
thing back together and try starting by battery.