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Flathead Fever · 04-21-2026, 06:20 PM

Like Glenn says, 2 1/2 lbs.is the maximum fuel pressure for a Stromberg, any more than that can open the needle and seat and start flooding the engine. Most people are used to 6 lbs. of fuel pressure on a carb but that's too much for a Stromberg.

There are two kinds of electric pumps, ones that when they are off they are closed, fuel can't get through them. The other type when its off remains in the open position so a mechanical pump can still draw fuel through it. In the Airtex catalog (available online) there are just a couple of electric pumps that have the flatheads low pressure rating and remain "open" so you can use it to prime an engine that has been sitting for awhile and then shut it off and run the engine off of the stock pump.

That doesn't answer the question as why you are only seeing 1 lb. of pressure at the carb unless maybe you have the wrong type of electric pump or something is restricting the flow between the stock mechanical pump and the tank. You can try to disconnect the fuel line from the stock pump on the engine and plug it, then hook a gallon of gas up to the fuel pump and see if your pressure increasess at the carb. That way you have eliminated everything from the stock pump on back to the tank. Be really care fuel to have the power disconnected from that electric pump and plug the line before trying this. If the pressure does not come up at the carb, then the problem is probably the original styles pump. Also, the fuel pump's stock riser, where it bolts directly to the intake. Those bases warp a lot and cutdown on the pump rod's travel. I have a mountain of them out in the garage that are warped and junk, probably enough to cutdown on half of the fuel pump rods travel. When you by used ones make sure to check the flatness of them.

04-21-2026, 06:20 PM	#5
Flathead Fever Senior Member Join Date: May 2010 Location: Yucaipa, CA Posts: 1,494	Re: What is enough fuel pressure? Like Glenn says, 2 1/2 lbs.is the maximum fuel pressure for a Stromberg, any more than that can open the needle and seat and start flooding the engine. Most people are used to 6 lbs. of fuel pressure on a carb but that's too much for a Stromberg. There are two kinds of electric pumps, ones that when they are off they are closed, fuel can't get through them. The other type when its off remains in the open position so a mechanical pump can still draw fuel through it. In the Airtex catalog (available online) there are just a couple of electric pumps that have the flatheads low pressure rating and remain "open" so you can use it to prime an engine that has been sitting for awhile and then shut it off and run the engine off of the stock pump. That doesn't answer the question as why you are only seeing 1 lb. of pressure at the carb unless maybe you have the wrong type of electric pump or something is restricting the flow between the stock mechanical pump and the tank. You can try to disconnect the fuel line from the stock pump on the engine and plug it, then hook a gallon of gas up to the fuel pump and see if your pressure increasess at the carb. That way you have eliminated everything from the stock pump on back to the tank. Be really care fuel to have the power disconnected from that electric pump and plug the line before trying this. If the pressure does not come up at the carb, then the problem is probably the original styles pump. Also, the fuel pump's stock riser, where it bolts directly to the intake. Those bases warp a lot and cutdown on the pump rod's travel. I have a mountain of them out in the garage that are warped and junk, probably enough to cutdown on half of the fuel pump rods travel. When you by used ones make sure to check the flatness of them.