The Stovebolt Site Forums The Shop Area Engine Shop New Fuel Pumps

I have a weak fuel pump and a vapor lock problem. I have a 1956 235 in my 46. The pump came with a used motor and is about ten years old. It appears to be an Airtex 4149 from Advance Auto Parts.

The FLAPS have a variety of manufacturers. Does anybody have experience with what to buy (or avoid)?

I found a Tri-Five Forum and the guy recommended the Airtex 40254 but it is a V8 application. He also recommended the Carter M2999 and Bosch 68553.

Comments? Advice?

It appears the Airtex 4149 does not have the glass bowl with the built in screen.
On a 1946 this would mean the pump check valves are not protected against debris coming from the tank.
A 1946 would have had a glass bowl pump originally like this .
If you use the Airtex you should have some type of filter before the pump.

The Bosch 68553 and Carter M2999 are for a 235 (and 261).

Heed Dave's advice regarding a filter.

I do not have the stock gravity feed gas tank any more. I have a Tanks Inc universal (U1) gas tank mounted under the cab between the frame and the drive shaft. The filler is fed through the bottom of the cab and out the stock fill location. In theory I should not have crud in my fuel pump since the tube is 1/4" above the bottom of the tank.

I thank all of you for the input. I am still changing my mind every other day on what to do.

Unless you hit a bump or go up down a hill.

Every MV I have uses an inline fuel filter (brass disk type AC type T-2) because at some point crud will get into your tank and make its way to the carb. You can hide a small plastic one or opt for a larger metal one... but spend the $20 on it.

Just because you have a new tank and the pick up is off the bottom, don't think you won't get crud in the line. If you need to "see" what I am talking about take a mason jar and place a teaspoon of soil in the bottom. Then carefully fill with water. Then shake. You will see that the dirt is everywhere not just on the bottom. You need to realize that once you start driving the fuel will get sloshed around and mixed up. Unless you have a filter at the end of your pick up tube its placement from the bottom is not critical. You will want the glass bowl fuel pump and possibly a inline fuel filter.

Once again my opinions are worth what I charge for them.

In AC type G, R and AF pumps the glass bowl is not there for filtration... although a brass screen is commonly installed.

The glass dome is a very important part of the pump.. called the pulsator. It increases the pumps ability to move fuel by up to 50%. The small air pocket at the top of the pulsator is compress on the 'suction' stroke. When the intake valve shuts the only thing left to push the fuel is that compressed air pocket.

Almost all 2 valve pumps will have a pulsator either as part of a sediment trap or as a discrete part.