Fuel Pump Issues, Help!

[aspeltz]

Upon purchase of my 1951 85LS my first project was to connect the fuel system. When doing so, I noticed the fuel pump was pumping little fuel and eventually quit. I had the fuel pump rebuilt. Installed the rebuilt fuel pump. I ran the truck on a portable tank straight into the carb and still no gas coming forward from the main tank. Gas tank level is at least 15-20 gallons in a 50 gallon tank. Engine never runs long enough to heat fuel for a vapor lock issue. I have ran the truck for at least 5-10 minutes at a time with the gas cap on and off. There is no other fuel pump near the tank. I can't be sure that there is not a crack in a fuel line. The only thing I hear leaking is an air leak from a brake line I have off to repair. It is just capped right now until I can bend a new line. I have to pump the bulb on the portable tank so I can't be under the truck too long to inspect. Any suggestions would be great.

[fxfymn]

Your post is not entirely clear; does it run on the portable tank, but not on the factory tank? If so, the most obvious place to look is inside the factory tank. It is very common to have the pick up blocked by rust or other debris.

Have you tried blowing air back through the fuel line that runs from the tank to the fuel pump? Check for a non-factory installed fuel filter that is blocked as well.

[41chevy]

Are you running the truck with the portable tank hooked to your rebuilt fuel pump? If not have you tried it that way?

I would first make sure the line from the tank to the pump is clear of gunk by blowing low air pressure through it. Check to be sure that the rubber hoses are not cracked, leaking or collapsing. Also the "sock" on the fuel tank pick up in the tank could be clogged up.

[aspeltz]

fyfymn

The truck is started and runs when drawing fuel from the portable tank. While the engine is running the fuel pump should be pumping gas from the main tank through the line up to the carb that is disconnected. Except that is not happening.

[aspeltz]

_41chevy

_{The portable tank goes directly into the carb. I could run it through the fuel pump. Then I could rule out a defective pump. Will air pressure also take care of a clogged sock on the pick up tube or do I need to remove the tank? There is plenty of stuff in the way in order to get the tank off.}

[thomastractorsvc]

Low pressure air should unblock the ful line/ pickup tube/ sock. The fuel line may also be broken so it can not create sucktion to draw fuel from the tank. Blowing air into the line should help determine if that is wrong. If the line is split or if the tank is dirty that will need to be taken care of or every time you add fuel or get the tank sloshing you will have problems.

You answered your own question with hooking th portable tank to the fuel pump, just because it the pump is rebuild does not mean it is working.

Keep us posted

[609albert]

Is your tank mounted under the frame or over the pump area ? also you may have to prime the fuel pump(fill it with gas) , the worst thing it could be is if it works off a pushrod or cam shaft on the engine, in that case you may want to look into an electric fuel pump.

[yarnall]

The tank in my AC and 405 A both had screens in them that got clogged and would not let fuel out of the tank. I cut the screen off of the A model and cleaned the screen on the AC. My 85 LS had 2 Napa electric fuel pumps on it when gotten. I replaced them with one and that worked well until the oil pan got filled up with gas at macungie this year. I am going to put a pressure regulator in the line to try to avoid this in the future. My A model had an aftermarket electric fuel pump which was rebuilt and worked for a short time them we replaced it with a Napa electric fuel pump. I did take tanks off of all three and had them cleaned. The tank on the A model was so bad I had to have a new one made. My father's B85 also uses a electic Napa fuel pump. They cost about $100 and eliminate the concern of the mechanical pump. We are more concerned with them running than being original. I'm sure you have already checked, but make sure there is not a clogged fuel filter in the line somewhere. It is amazing how muuch fuel it takes to keep a 707 running.

Mike

[other dog]

...and like 41chevy said, if it has rubber fuel lines the inside of the line will suck together and cut the fuel flow off when they get old sometimes, and it will still look fine from the outside. I had this happen before on a cabover KW.

If you go with an electric fuel pump, the closer you mount it to the tank the better, rather than closer to the carb, so it will push the fuel.

[41chevy]

Low pressure air should unblock the ful line/ pickup tube/ sock. The fuel line may also be broken so it can not create sucktion to draw fuel from the tank. Blowing air into the line should help determine if that is wrong. If the line is split or if the tank is dirty that will need to be taken care of or every time you add fuel or get the tank sloshing you will have problems.

You answered your own question with hooking th portable tank to the fuel pump, just because it the pump is rebuild does not mean it is working.

Keep us posted

Exactly !!

[Loadstar]

Yarnall, what do you think caused the gas in oil pan? Just curious......my fuel pump is wired to the ignition key. Thanks

Aspeltz, Good luck, probably something simple......And not terribly aggravating

[fxfymn]

Filling the crankcase with fuel happens when the fuel pump keeps running if the carb float sticks open. The fuel fills the intake manifold until it finds an open intake valve that allows the fuel to run into the crankcase. Not all that uncommon; it usually liquid locks the engine as well so the starter won't spin the engine.

Wiring the pump through the ignition is the right way to do it. I also have a seperate switch to make sure the pump is off if I need to have the ignition on while I am doing some other work.

I once acquired an almost brand new riding mower that did the same thing. The owner gave it to me because he assumed it was blown up when the oil started blowing everywhere while it was running. The carb had allowed fuel to fill the crank that displaced the oil causing it to blow oil out the breather. New carb gaskets and all was well. When I offered it back he told me to keep it and make sure his wife never found out.

[yarnall]

Yep. That's what happened. As with most older fire trucks, it does not have a key. It has a bunch of swithes and two starter buttons.

[1958 F.W.D.]

Yep. That's what happened. As with most older fire trucks, it does not have a key. It has a bunch of swithes and two starter buttons.

Mike, after your Macungie incident, I now disconnect the batteries on the FWD at any show I go to. (electric fuel pump.)

[fxfymn]

That is why I use a battery disconnect aka Cole-Hersee switch as well. That way all of the wiring is cold when the truck is not being used.

We once burned up a fire station and most of it's apparatus when a battery cable shorted out on a rescue squad (An R Model Mack) while sitting in quarters. In this case the batteries were mounted under the back step and the cable ran all the way to the cab before it went to the disconnect switch. The cable rubbed on the frame rail and shorted out without any overload circuit protection until it caught fire.

[mack mhe9]

just incase i missed it, when its running have you put your finger on the suction side of the fuel pump it should suck your finger tight, ive seen cam lobes wiped out, on other gas eng. but i agree with everyone else, good luck

[aspeltz]

Thanks to everyone that responded.

Update: Still no fuel.

I unhooked the connection at the pump inlet. From that there is a rubber line about two feet long that runs to a hard line. I replaced that rubber line with high pressure fuel hose. The copper line runs all the way to the back of the tank. I unhooked the hard line connection at the tank. I blew air through the entire hard line. No obstructions and no leaks. I blew air into the tank and could hear it bubbling and see vapor coming out the gas cap. With the truck running I could feel very little, if any, suction from the inlet of the pump. I sprayed some gas into the inlet of the pump to prime. It did not take much before it came running back out. I hooked everything back up. I fired up the truck and still no fuel. The guy that rebuilt my pump said the arm on the pump that goes into the block may not be seated right on the cam. I assumed that if the arm gets inserted into the hole in the block and you are able to bolt it up, it must be in the right place. I guess that may not be the case. I might have to remove the pump again? Any suggestions

[fxfymn]

I assumed that if the arm gets inserted into the hole in the block and you are able to bolt it up, it must be in the right place. I guess that may not be the case. I might have to remove the pump again? Any suggestions

Almost right. When you put the pump into the hole you should have to hold pressure up and in while you start the bolts. In essence you are pressing the pump arm and it's spring against the pump lobe.

I had a 66 Ford that wiped out the fuel pump lobe. I used an electric pump to keep it running.

[mack mhe9]

if it is the cam a elec. fuel pumps a good idea,

[41chevy]

Almost right. When you put the pump into the hole you should have to hold pressure up and in while you start the bolts. In essence you are pressing the pump arm and it's spring against the pump lobe.

Sounds like you are on the wrong side of the cam lobe. You will be able to feel some pressure against the pump when you put in the bolt. You will actually use the bolts to pull the pump against the block. Paul

Arm goes under the lobe most time, Heres a pic of the cam lobe on my Willys Go Devil .

[Firemack]

The Fuel Pump arm absolutely needs to be against the cam lobe when bolting it up to the block (and you will feel the pressure when bolting it up). Also to verify that it is working properly you can add a t in the line (pressure side) and add a line to a fuel pump gauge to read the pump pressure and make sure it is indeed pumping. I used this to diagnose that our B75 was actually running out of fuel becuase the fuel pump (just rebuilt) could not keep up with the demand while at operating rpm. It could keep up all day at idle, but would run out of fuel while driving, so use the fuel pump pressure gauge to monitor the pressure at idle and while running. The B75 would drop pressure (typically 2-3 pounds at idle) and run out of fuel (0 PSI) when under load.

Firemack

[Loadstar]

Yarnall, Which Napa fuel pump are you running on your 707 Gas engines? Looking to replace the old electric fuel pump on my Ls85. If anyone has an opinion.....or one they have had good luck with....i'd love to hear it....Thanks Louie

[1958 F.W.D.]

I can't remember which electric pump I have on the 1958 FWD feeding the Waukesha, if I remember I'll look tomorrow. Works well. Have it feeding through the original "stone" type fuel filter and through a large Fram cannister filter, no starving issues at all.

[Loadstar]

Still looking for some advice on which electric fuel pump would do a good job feeding a 707 gas engine. Went to a few shops today on the way home from work......awful lot of blank stares. Any help is appreciated......Thanks

[thomastractorsvc]

AIRTEX or some other universail fit will work, advance, autozone,NAPA have them just check the lift spec and gph. Most are $35-$45 Mr Gaskett makes them to, if you buy on line check out jc whittney or summit