M37 Fuel Pump - Steel Soldiers::Military Vehicles Supersite

dispatcher1011 · 11-05-2009, 11:43

Hello all, I was just wondering if anyone has had specific experience with M37 fuel pumps... I'm in the market for one since my truck doesn't seem to get any fuel to the carb. Simplest question first- how much fuel has to be in the tank for it to 'pick up' the fuel? I had pulled the tank, cleaned, and reassembled the tank, the fuel pickup seemed to be pretty much at the bottom of the tank, with the cleaned fuel filter element in it. I then put at least 5 gallons of fuel in the tank. Should that be enough fuel? Keep in mind the truck is sitting level, on a cement floor, on its own wheels.

I see that VPW has NOS fuel pumps for $100/exchange. I'm kinda hesitant to pay that for something that has been on the shelf for ? how long. Anyone ever bought one of these?

Then there's always rebuilding one. Anyone have good advice as far as that? I'd probably send it out to have that done, if I went that route.

I think I want to leave the vaccuum/fuel pump on it, as that is probably the way I will leave the wipers, therefore ruling out an aftermarket single (fuel pump only) one.

Just wondering what everyone else's experiences were... thanks!

TACTICAL6 · 11-05-2009, 12:09

Okay, here is what I did, mounted a 24v fuel pump about two feet from the tank. Pumps push better than they pull. It pumps rite through the stock pump with no problems, plenty of fuel. Good Luck

maxim · 11-05-2009, 12:22

The fuel pump is not too intmidating to rebuild. I had one I ran a while then it started to pump fuel into the crankcase because of a leak in the diaphram. Try to get fresh rebuild parts. Check for leaks along the line to the tank. Maybe put a small spurt of air backwards to the tank to see if the line is clear and you can hear air bubble up. Or try to put a 'pony tank' on the line to the fuel pump instead of using the main tank. If the pump will pump from a pony tank there must ba a obstruction or leak in the line some where. There should be a lever on the side of the fuel pump (unless it has broken off like may) to manually pump the fuel pump and prime the carb, you should be able to detect if there is suction.

CGarbee · 11-05-2009, 12:37

The source that I have heard the best feedback on as far as both rebuilds and as a source of rebuild kits these days is Tom at Then and Now

Phone: 781-335-8860
Outside U.S.: 01-781-335-8860
Fax: 781-335-1925
Then and Now Automotive
447 Washington St.
Weymouth Ma. 02188
oldpartstom@aol.com

A nice discussion/review of Tom's work on a M37 fuel pump can be found at:
Matt Gieselman | M37 Fuel pump rebuild

In the above blog, it mentions that the kit is $69.50+ S/H, or that the rebuild service is $145. Not sure when these prices were effective, but it beats a NOS unit that will have rubber that is likely not to be compatable with ethanol blends...

Good luck.

Boatcarpenter · 11-05-2009, 15:05

Somebody correct me if I am wrong here please but I believe the manual fuel pump lever must be in a certain position or the pump will not pump. Yes/no?
Have you checked that.
BC

CGarbee · 11-05-2009, 15:33

Quote:

Originally Posted by Boatcarpenter

Somebody correct me if I am wrong here please but I believe the manual fuel pump lever must be in a certain position or the pump will not pump. Yes/no?
Have you checked that.
BC

I've never had that problem myself, but I have heard about it. If you have the manual lever in the wrong position, it prevents the diaphram from being actuated...then it won't pump...

To add a bit more in response to the original question: Five gallons is plenty to get it running with a dry tank... Check also to ensure that the vent lever on the gas cap is open (if you have the style with the lever) or the entire cap itself is slightly loose (the partial rotation "back" from being fully tight where it will vent but not leak) if the newer style so that you can get air into the tank when pumping. The vent line from the tank to the air intake elbow is sufficient to vent when fording a short distance, but not for a long ride. Usually, this manifests as a truck that runs at idle, but has no high end, no power, and poor throttle response, but check it anyway...

M543A2 · 11-06-2009, 06:43

You can use an electric pump if the tests other guys have recommended point to a bad pump, but I do not recommend pushing it through the stock pump because of the possibility of a bad diaphragm allowing fuel to go into the crankcase. Bypass the stock pump with a section of line. Too much fuel in the oil pan is a real problem, both with lubrication degradation and the possibility of an explosion turning the oil pan into a balloon and the resulting fire possibly badly damaging your truck. A couple of times of seeing the result of that happening is enough to warn me really well!
Regards Marti

ken · 11-06-2009, 09:21

You can still get the replacement airtex pump. I just bought one this summer. It works great. I have the part number around here somewhere.

rosco · 11-06-2009, 10:56

I tried to keep the stock pump, rebuilt it several times, but finally replaced it with a 24v electric. One tendency for the stock pump, is to put out excessive pressure. Actually, when I put in an in-line pressure regulator, cutting pressure to 3#, it ran better. Another tendency is for the lower vacuum part to fail, with associated leaks. Often it fails long before you realize it.

Never had a problem with the manual lever being in the wrong position. It should be spring loaded, and go to a neutral position. If it doesn't, probably needs a rebuild. The pump is not real pleasant to change - its time consuming. Otherwise, the vacuum part was a good source for leaks.

Lee in Alaska

dispatcher1011 · 11-07-2009, 18:04

Allright, so here's the deal. I got the truck running. I was faulting the fuel pump. I should have been a little more, um.. detail oriented, shall we say..? in my diagnosis.

In telling the story, please don't laugh too hard. I'll start out by saying that I am very pleased with the truck, its mechanical condition, and the way it runs. It's been said many times on this forum that hearing your vehicle run for the first time is awesome, and I agree.

When I purchased the truck, it came wth no carbuerator whatsoever. I'm assuming it was used to keep an even nicer M37 on the road, which, hopefully, I shall own one day too...

Shortly after purchasing the truck, I found a good rebuildable core off of eBay. It survived the trip to Iowa, where Vintage Power Wagons rebuilt the carb. Several more parts, linkages, and cotter pins later, and it was mounted.

Enter the beginning of my fuel delivery issues. Carb was bone dry. Nothing. I'd squirt a little gas in the carb, and I'd get some type of a reaction. I had previously pulled the fuel tank, torn it apart, cleaned the element, regasketed, rehosed, resealed and reinstalled the tank. Lines went on like a charm, even without that little panel on the inside of the bed being removed. I initially faulted this as the reason it wasn't getting fuel. Checked, and rechecked my work. Messed with the fuel cap. All looked good.

After checking the tank area again, and associated lines, I pretty much instantly faulted the pump.

Considered my options on fuel pumps. Looked online, consulted 'the board' for advice. Still wasn't sure what in the *&^% I was going to do.

Finally got up the nerve to tear off the fuel pump. Figured, well, no matter what, it's got to come off. Removed the 2 bottom vaccuum lines, no problem. The carb line was already disconnected from my carb, should all come off with the pump. Removed the 2 long 'necked' bolts, again.. no problem........

One line left. It appears there's a rubber line, headed to the metal fuel line. Spray a little blaster on it to get it removed....... but wait....... whats this???

Oh, yeah... there's a brass valve. Guess what? It's SHUT OFF.

Proceeded to remove the fuel pump, now knowing to check THE SIMPLEST THINGS FIRST.

Cleaned up the fuel pump, (never did find a priming lever, or any kind of an external lever on the pump... seems to be an AC part)....reinstalled, and the rest is smooth-running 1954 M37 history.

Thanks to all who offered advice!