1950 Fuel Pump

[Guest James Conkwright]

HI. Let me first say I'm no expert on fuel pumps. I don't really know anything about them. Here is my problem. I have had a mechanic rebuilding my original fuel pump on my Buick. To my knowledge it has never been rebuilt. It is an original AC pump.

There were 4 check valves within the fuel pump when it was taken apart. 3 of these were exactly the same. When put up to the mouth it was pretty hard to blow air through them. The 4th valve was different. It was much easier to blow air through.

I ordered my kit through Antique Auto Parts Cellar. Good quality stuff by the way! My issue is that the valves within this kit were all the same. They tell me they are supposed to be the same. Bobs also tells me that to his knowledge all 4 valves should be the same.

My fuel pump is not working now. It will not draw gas from the tank. Why did my original pump have three of the same valves and one different? I have an early 1950. Did 1949 have a different fuel pump?

Thanks for the help!

[Guest James Conkwright]

I would also like to add something else. Everyone I've talked to seems to think there is only one style fuel pump for 1950. I always thought this was the case also. Every 1950 Buick I've seen has what the shop book calls an air dome on top of the pump. My pump is flat. It does not have an air dome. The shop book says Series 40-50 should not have an air dome but the Series 70 should. All 40 and 50 series cars I've seen have the air dome which according to the shop manual is wrong.

[JohnD1956]

Hate to see you without an answer, and did not want you to think people were ignoring you. Chances are no one has the information you seek and rather than call it wrong, prefer to say nothing. So here's two guesses which may also be completely wrong:

First, is it possible the valves need to be inserted in different directions? I imagine these are one way valves, and chances are you need two in one direction to pull fuel in, and keep it in when the arm of the pump tries to push the fuel out. The other two should be installed in the opposite direction so the pump cannot pull fuel in from the carburator side.

Second, if I correctly recall the instructions I read several years ago , the diaphragm is supposed to be depressed before you tighten the screws. There is some type of tool to do this with. Without the depression the diaphram does not get enough movement to cause the suction side of the action.

Please, understand that I am not an expert in rebuilding these pumps. But I did do my 56's once and it seemed to work okay.

Edited September 16, 2009 by JohnD1956 (see edit history)

[oldwood]

I just replaced the FP on my 248 and it does not have a dome on top of FP. I ordered my rebuilt pump from Bobs Automobilia.

[Robberbach]

Hate to see you without an answer, and did not want you to think people were ignoring you. Chances are no one has the information you seek and rather than call it wrong, prefer to say nothing. So here's two guesses which may also be completely wrong:

First, is it possible the valves need to be inserted in different directions? I imagine these are one way valves, and chances are you need two in one direction to pull fuel in, and keep it in when the arm of the pump tries to push the fuel out. The other two should be installed in the opposite direction so the pump cannot pull fuel in from the carburator side.

Second, if I correctly recall the instructions I read several years ago , the diaphragm is supposed to be depressed before you tighten the screws. There is some type of tool to do this with. Without the depression the diaphram does not get enough movement to cause the suction side of the action.

Please, understand that I am not an expert in rebuilding these pumps. But I did do my 56's once and it seemed to work okay.

It's been about ten years since I had mine apart, but you are correct. 2 valves pull fuel in and 2 expel to the carb. They work as check calves. one way flow only. You have to take the pump apart and follow the flow of fuel through it, and plave the valves in the correct orientation.

[Guest 1950SuperBlueBuick]

Hi James,

I remember your Grandfather's fastback Special from the 2006 BCA meet in Rochester. What a great looking car. I had the Blue Super Model 52. Must have been 100 in the shade...whew! We discussed our fuel pumps at that time. Mine has the dome on top as a secondary vacuum source for the wiper motor. I think yours being a Special had a different pump and carb. I purchased a fuel line once but it would not fit because the pump fittings were in totally different locations. Right now I'm dealing with Ethanol issues and rebuilding my pump is in order. Thanks to others for the insights on those valves and depressing the diaphram. I'll watch everything as I take it apart.

[Patrick W. Brooks]

Good Morning: The first thing to check is to be sure there is gas in the tank. The second is that there are no air leaks in the line from the fuel tank to the pump. Even pin holes which have rusted through will let in enough air that the vacuum which must exist will not be present. Always look for the simple problem and it will be the solution most of the time. Let us know what you discover. Thanks, Patrick W. Brooks