Fuel Pump - Failure?

[SierraM37]

Had the M running (parked) yesterday when it just quit. Have spark, fuel in bowl. When I pour fuel directly into Carb, it fires, runs, sputters and then starves. Disconnected the fuel pump hose running into the carb and cranked but no fuel came out. I'm assuming I was a live witness to the fuel pump going out, assuming fuel should spew forth using my test method.

So, if confirmed, is the Fuel Pump a Napa part? Anyone have the correct number?

Thanks.

[HingsingM37]

Assuming you have a unrestricted flow to the pump and no rust or dirt is blocking the line from the tank, then the fuel pump is the issue. If you have the military style pump you will have to get a kit for it. NAPA will not have parts for it that I know of. You can get the civilian style pump with the sediment bowl from NAPA if you want to switch. Or install an electric pump.

[Lifer]

Take a piece of rubber fuel line long enough to hook one end to the line from the carb and put the other end in your mouth. Blow gently and you should notice the air flow. If you do, your fuel pump probably gave up the ghost. If you don't, you have an obstructed fuel line.

If it is blocked, repeat the blowing thing with compressed air to see if it clears the line.

[N1VSM]

To ad to the "to do" list, check your fuel pickup line in the gas tank. If you have the filter there, it may be clogged. Much cheaper to replace a filter or line then rebuild the fuel pump or carb.

[SierraM37]

OK - when I blew gently on the line running from fuel pump to carb, it flowed and there appeared to be no restriction. When I got the truck, I drained the fuel tank and put 5 gal of fresh in it. Haven't driven much more than 2 miles so there should be plenty of fresh left.

There is a filter just prior to entering the fuel pump which I haven't R&R'd and it is the civy pump with the glass bowl, which is full and clear.

[Carter]

" When I got the truck, I drained the fuel tank and put 5 gal of fresh in it. Haven't driven much more than 2 miles so there should be plenty of fresh left. "

There should be, but try adding another 5 and see what happens. Some of these trucks have a short fuel pick-up tube and when down to the last several gallons they suck air and not gas, leaving a couple of gallons remaining in the bottom of the tank.

[Nickathome]

" When I got the truck, I drained the fuel tank and put 5 gal of fresh in it. Haven't driven much more than 2 miles so there should be plenty of fresh left. "

There should be, but try adding another 5 and see what happens. Some of these trucks have a short fuel pick-up tube and when down to the last several gallons they suck air and not gas, leaving a couple of gallons remaining in the bottom of the tank.

I can second Carter's statement here. My truck died on the side of the road last fall. After much trepidation as to what was wrong, I found out the truck had simply run out of gas. However, that's not to say the tank was bone dry, it wasn't. I had probably 1 to 2 gallons of fuel in the tank, but the pickup tube sits about 3/4 of an inch from the bottom of the tank and was sucking air.

So, if you haven't driven much, and you put 5 gallons into the tank, what you burned and what may have gotten out through evaporation, you may not have as much fuel as you think you do.

[N1VSM]

I can second Carter's statement here. My truck died on the side of the road last fall. After much trepidation as to what was wrong, I found out the truck had simply run out of gas. However, that's not to say the tank was bone dry, it wasn't. I had probably 1 to 2 gallons of fuel in the tank, but the pickup tube sits about 3/4 of an inch from the bottom of the tank and was sucking air.

WOW! I'm glad I'm not the only one... I did the same thing - dead in the driveway, but of course right at the end between 2 very large trees, so that no one could get in or out. Took a bit for the light to dawn, but after dumping 5 gal. in the tank (happiness is a full Jerry can! ), she started right up (after enough cranking to get gas to carb., that is).

[SierraM37]

OK - I added another 5Gallons - still no worky. Replaced the pump with the Napa civvy version and it fired after the bowl filled up. Problem solved.

Are these pumps serviceable so they can be added to my parts bin?

thanks for everyones help.

[m-37Bruce]

I can second Carter's statement here. My truck died on the side of the road last fall. After much trepidation as to what was wrong, I found out the truck had simply run out of gas. However, that's not to say the tank was bone dry, it wasn't. I had probably 1 to 2 gallons of fuel in the tank, but the pickup tube sits about 3/4 of an inch from the bottom of the tank and was sucking air.

WOW! I'm glad I'm not the only one... I did the same thing - dead in the driveway, but of course right at the end between 2 very large trees, so that no one could get in or out. Took a bit for the light to dawn, but after dumping 5 gal. in the tank (happiness is a full Jerry can! ), she started right up (after enough cranking to get gas to carb., that is).

Ditto here as well!
My truck has a WC engine in it, (10 years older than the truck) no fuel pump, unless my Zenith Model # 29 has one in it's innards.
I have just finished my gas tank, rebuilt sending unit and uber cleaned fuel pick-up, wait and see, I guess?

[Nickathome]

Well, my problems started when I trusted my gas gauge. My gauge was showing 1/4 tank when I ran out.....So now, I know that when the gauge starts to get below a half, that I had better head for the nearest gas station.

[monkeymissile]

Are these pumps serviceable so they can be added to my parts bin?

thanks for everyones help.

The pumps are very serviceable, I had mine rebuilt by Then & Now Automotive in Weymouth, MA; all new valves and diaphragms, works great!

[peter e mark]

Stop guessing and install a 0-15 PSIG pressure guage on the fuel line after the pump. Then install a 30" - 0" VACUUM guage on the inlet line to the pump. Crank your engine. Look at the guages: The book says the pump is to deliver 4.5 PSIG to the carb. What does your pressure guage read? Now look at the vacuum guage: If you see no vacuum at all, or very little (.5" vacuum ) the pump can't pull the fuel OR there is a large air leak in the fuel line and the pump is sucking air. Disconnect the fuel line to the inlet of the vcacuum guage , which is still connected to the fuel pump inlet. Crank your engine. If you develop a vacuum now, it means the fuel pump is capable of pulling, and there is a leak in the fuel line. If the guage don't develop no vacuum now, The pump ani't working at all. If you vacuum gauge pulls high vacuum ( 4.0 " or higher and climbs higher as you continue to crank, you got a restriction. Replace the entire fuel line from the tank all the way to the pump inl;et. And don't forget the in tank filter. The assumption is you already checked this in tank filetr before you did the guage tests. I left these guages on my truck permanently.

[Lifer]

Peter: You have given him some great advice for future reference. If you check a couple of posts back, though, you'll find that he solved the immediate problem by installing a civvy fuel pump. That would pretty much indicate that his original fuel pump was FUBAR, wouldn't it?

[m-37Bruce]

I was working on the godess this am, blew the fuel lines out, that was the easy part. Removed the disposable fuel filter, then I realized where my fuel pump was, the mechanical type, just below the Zenith Carby.
I am assuming it has a check valve of some type, as I could not blow from the carb in reverse.

http://www.photoshop.com/accounts/14681 ... f39c9049f4

http://www.photoshop.com/accounts/14681 ... 0598e05417

I've added a couple of links to some pics, one of the Carby, the other of the mechanical fuel pump, it appears to be missing something, as it has a spare or extra bale behind the bale that holds the settling bowl to the pump?
I wanted to do this before I reinstall the relined tank and wiring harness.