The Stovebolt Site Forums The Shop Area Engine Shop '54 GMC Fuel/Vacuum Pump

I bought a new fuel pump from Jim Carter, went to put it on last night and it would not go in the block correctly. It looks like the arm that goes into the block is shaped differently than the old one. The old one had a step in it, where the new one is basically square shaped. Wish I had pics available. Does anyone know if there are different pumps for GMC versus Chevy? I think I could grind enough clearance on the arm to make it work but I don't want to do that if I can return it and get the correct one. Also, does anyone know if the pump runs directly off a cam, or if there is supposed to be a pin that sticks out? I tried to look in the engine, but couldn't see anything. The old pump looks like it has been rebuilt, I took it apart and it has new diaphrams in it, I am wondering if there is something wrong with the engine that is not allowing the pump to function.

The fuel pump runs off an eccentric lobe on the camshaft. If the high spot of the lobe is in the right position you will have to compress the lever on the pump somewhat to get the pump to bolt to the block. One alternative is to roll the engine over so the lobe on the cam is away from the pump. This will make the pupm easier to bolt up.

I would make sure you have the corect pump first.

Afu 45 is right on the money. I just replaced my fuel pump last month or so. At first it would not seat properly, then right before I was about to give up and turn the engine over it went right in. When I secured all connections I fired up the truck and it started right away. Good luck with yours!!

I have the federal mogul part # for my original style fuel pump if you think you should try another or different pump.

http://community.webshots.com/scrip...amp;photoID=97994065&security=VOrDcV

Good luck!!

Phillip,

Thanks for the tip, I will try it tonight. I also ordered one from the local auto parts store, I will check it out tonight to see if it is any different than the one I already have. I saw the picture of yours, but mine is the combo fuel/vacuum pump.

The combo fuel and vacumm is a neat pump. I decided not to buy that one because I really never drive my truck in the rain anyways. But, my wipers are pretty slow.....hmm...."Honey, I need to buy some more truck parts!!"...

She loves it when I say that. Right now I am gearing up for some rebuilt guages and a original radio.....a sun visor would be nice....original style fog lamps.....spot lamp.....bumper guards??!! I better stop........

magilla,

I put a combo fuel/vacuum pump on my '54 GMC. I also had a time getting it to fit but I finally got the bolts started and it kinda popped into place as I tightened the bolts. It has worked fine ever since. I guess I just had to compress the arm against the cam. If I'd thought to turn the engine a little I'll bet it would have slipped right into place. Good luck with yours. Also, I had a problem with another fuel/vacuum pump before I put this one on. The vacuum side didn't work and it was making a funny weezing/whistling sound when I hooked it up to the wipers. After I took it off and replaced it with the afore mentioned pump I noticed the the screw that goes right in the middle of the bottom of the vacuum pump side had fallen out. Just needed a new screw in that spot and I could have avoided the hassle and expense of changing the pump, but, after it was out and the new one in I wasn't about to put the old one back in.

54gmc, do you have any pics of your pump installed? I checked out the new pump at the local parts store and it was just like mine. So I went home last night and removed the old pump again. After I pulled it off, I noticed the gasket didn't seem to line up with the hole in the block. When I turned it upside, it fit perfectly! I think the previous owner had it installed upside down! It was about 10 degrees last night, so I didn't get as much done as I hoped, but maybe when it warms up a little I will switch all the fittings around and try it right side up. I guess a vacuum pump doesn't work very good as a fuel pump! If you don't have any pics can you tell me if the smaller side of the pump is the vacuum or the fuel? Thanks!