New fuel pump no gas

[SCHRUMGMC]

I replaced the fuel pump, it wasnt pumping right but now its not pumping at all. I made sure the fuel line was clear and they were.. I dont know what to do..im getting fed up with trying to get this thing going and runnning

[pgf545]

I'm not real sure on the 6 cylinders but on small blocks there is push rod and sometimes they drop down and won't push on the fuel pump arm. I am thinking that the fuel pump arm drives right off the cam shaft but not positive. If it does you could have a flat lobe on where the arm rides, It would be extremely rare. I would also check the tank and make sure there isn't a filter on the inlet that might be blocked. The fuel system is pretty straight forward on these old trucks. You might try to take a hose and run it directly from a gas can to the fuel pump inlet. When I worked auto parts we would every once in a while we would get a bad pump from the manufacture. Double check the arm against the original and if you can see if there is a vacuum on the inlet side. Hope this helps


Bernie

[SCHRUMGMC]

Where can I buy a new fuel to pump to carb fuel line, and how would I put it on? would i have to take the fan and stuff off?...I can't get the glass bowl filter to line up with that line..its driving me insane...im starting to think my cam lobe may be bad and may just need to buy a complete new one

[OrrieG]

If i remember right you can install the pump with the lever under the cam lobe and it will not work. You need to turn the engine so the flat part of the lobe is up and make sure the pump lever goes on top of it. If you think it is going flat take a socket extension, wood dowel, etc and hold it against the cam lobe while someone turns the engine over. the dowel should push out once every engine revolution.

Fuel line runs from the pump up to the bottom of the valve cover, across the head then turns back to the carb. Std. parts house will probably not have one but you can get them from lmc, jim carter, etc. prebent with the correct stock fitting. should not have to remove water pump puller, fan etc. If you have access to a flaring tool you could make your own, NAPA and Oriellys has line, some preflared with fitting that might work.

[SCHRUMGMC]

I installed the Lever against the lobe so every time I crank it, it would push the lever

[mr48chev]

1. Most likely you will have to buy a length of steel line and bend up your own fuel line from the pump to the carb.

2. Personally I'd take that farm equipment sediment bowl and put it in the swap meet box and put a real filter on in it's place but you guys all seem to think that they are cute for some crazy reason although they are primarily water traps and not fuel filters.

3. All lines hooked up correctly? No kink or twist in the hose from the steel line from the tank to the pump? The second helicopter I crashed in in Viet Nam had a twisted fuel line where someone had twisted the braided steel line so fuel wouldn't flow though it. Right tank went dry and down we went with a full left tank.

3. Is there sufficient fuel in the tank?

4. Do you have a vented cap on the tank that you positively know is vented?

5. If you have air available blow in the filler to push some fuel though the line to the pump so the pump isn't just sucking air.

6. Some of these AD trucks had a valve under the floorboard that was part of the fitting that the line connected into. You closed that valve when you pulled the fuel pump off so gas wouldn't leak out and some guys even used it as an anti theft device as even if someone got the truck started it would only make it a few feet before it died. It could be that if it has that valve or another valve in the fuel line that it is closed or partially closed.

[OrrieG]

48 that must have been pretty hairy, one of my Army mechanics had switched MOS from Helio Crew Chief after he went down twice, second time shot down.

Schrum, did you put in the new fuel tank or still using the plastic one???

[_Ogre]

a fuel pump is 2 rubber flapper check valves and a bellows that squishes gas past each rubber check valve. if you have any trash in the line or tank trash will get under one valve and the pump won't work any more. sometimes the fix as easy as blowing thru the pump. but if you have more trash in the tank it will suck right back into the valves. install a big plastic fuel filter in line before the pump.

[SCHRUMGMC]

Plastic, it doesn't have a gas cap on it currently, its vented good.. It ran good like this for a while..I hope its nothing major like a cam lobe.

[coralhead]

Originally Posted by SCHRUMGMC

Plastic, it doesn't have a gas cap on it currently, its vented good.. It ran good like this for a while..I hope its nothing major like a cam lobe.

Is it a new plastic tank or the old one you have been using? If you are still using the old tank, do yourself a favor and punch it full of holes and throw it away.

[mr48chev]

From my past experiences with my vehicles old gas tanks have crud in them that new gas tends to knock loose and that crud goes straight to the fuel pump's valves which are usually plastic one way valves with a little spring behind them and block one of those valves open. It's happened to me more than once.

[SCHRUMGMC]

Plastic as stated in the previous post of mine
It has no gas cap on it..I'm literally having to possibly buy a new fuel line from the pump to the carb..I can't delete the ac fuel filter because the gas line will be so loose

[mr48chev]

Not following you on that last one. You don't need to delete the sediment bowl you just need a real fuel filter between the tank and the fuel pump to catch crud before it gets to the pump.

I've added them in the hose between the fuel line and the fuel pump before by using a bit longer hose to make it work.
Have you got any way to put a little bit of pressure on the tank to push the gas through the line to the carb? I've run into some that the pump would not suck good enough on just air to pull the gas from the tank until I pushed gas though the line. I don't know the reason but once they had gas up to the pump they seemed to work fine.

Other things are kinks in the hose or twisted fuel lines. I've seen lines with a full twist in them right at the carb because someone tightened the nut without noticing that the line was twisting.
Also a leaking connection in the line or a pin hole in the line might cause it to not suck fuel and only suck air in through the line.

[OrrieG]

Mr48 I think he is just using a portable plastic can and hose to the fuel pump. Take off the fuel line between the pump and carb and give it a good cleaning and blow some air thru it. Should just be a bracket across the front valve cover and the two end fittings. That will tell you if you need a new one. One other possibility is that you got a bad pump. While you have the line to the carb off make sure you have a good line from the plastic tank to the pump inlet and turn it over to see if gas comes out of the outlet side. Then hook the line to the carb back up and make sure you are getting gas out of it before hooking up to the carb.

[SCHRUMGMC]

I'll have to rig a way to get the AC pump back on, it doesn't line up well now for some reason

I am getting a new hose, well rubber fuel line for now to replace the current one..going to rig it the way it was..I wish one of you lived closer, this thing would be running great

[OrrieG]

Do you have the old pump? They came with the bottom piece facing different directions depending on the application, I had the same issue with my truck. If the bottom piece is held on with screws (6 or 8 if I remember right) you can carefully remove it and turn it to line up. you can also look inside to see if any crud got in and is holding the valves open or damaged it.

[SCHRUMGMC]

I keep everything LOL
I'll look..the new fuel pump is on currently

[SCHRUMGMC]

I'm going to have to take the top of the new fuel pump and rotate it a few so I can line everything up