Fuel pump not pumping gas

[MarkDixon]

I have a 71 240z. My car was running like a champ. I parked it for about a month, and now I have no fuel going through the Pump.

I know the problem is isolated to the pump area, because:

I can detatch the hoes going to the pump and suck gas through the hose.

I can detatch the hose going to the carbs and turn the engine over and no gas gets pumped through the pump.

I even bought a new fuel pump and fuel filter and still the same problem.

I detached the hose on both sides of the fuel pump, turned the engine over, and I feel no suction or output on either side of the pump.

What could this be???

[zbane]

My thought on this would be an electrical issue, especially since it is happening with the new pump.

So, I would start looking at the usual suspects-Fuses and connection points.

Take your time and be thorough.

[Mat M]

I had this prob on one of my pumps. Try dismantling the pump to see if the one-way valves are stuck/varnished. When I dismantled mine, I found that the little rubber oil boot had torn, as well, causing a LOT of grime under the pump.

Also, at installation, it is sometimes tricky to get the diaphragm piston connected to the diaphragm with the spring tight. This part, of course, is key to having the pump function.

[Arne]

My thought on this would be an electrical issue, especially since it is happening with the new pump.

So, I would start looking at the usual suspects-Fuses and connection points.

Take your time and be thorough.

Not applicable, David. The fuel pump on a '71 is mechanical, not electric.

[zbane]

Something new every day, thanks for pointing that out, Arne.

[MarkDixon]

That is correct Arne.

What gets me is it was working fine before I parked it.

I took the pump off and pushed on the spring lever and the pump seems to work fine.

As I said, I bought a NEW pump and installed it. It doesn't work either.

Some how the lever which makes the pump possible is not moving up and down inside the engine.

I could maybe understand on installation the lever could be inserted incorrectly, but it was working fine when I parked it and all of the sudden it doesn't work.

This doesn't make much sense.

[hd240z]

You can pull the pump off the engine and operate it by hand with the suction hose still connected to see if it works that way. If its bad return it and get another new one. If it works by hand then your pump cam must be bad.

good Luck

[racebird1]

Try to remove it and make sure you can see the pump cam in the engine move in and out as you have someone crank the engine. Be carful not to get yourself or a article of clothing caught in any moving parts. I can't believe that it would go bad from siting. Are you cranking it long enough to suck up the fuel? Are you sure you didn't get a crack in the fuel line and are now sucking air in somewhere?

[Arne]

Stop! If you think the pump lever is not moving, DO NOT CRANK the engine any more until you verify that the bolt on the end of the camshaft is tight! The fuel pump lobe on the cam is simply bolted in place. If that is loose, the pump would not pump. But worse, if it comes all the way loose and falls off inside the timing cover you could experience all sorts of damage. Pull your valve cover and check that before you go any farther.

[MarkDixon]

Thanks for all the advise.

I don't think there is an air leak, as I can suck on the end of the hose and pull gas into the filter. Although I can probably suck harder than the fuel pump does.

Wow that didn't sound right at all.

Anyway, I did take the valve cover off and it looks like the fuel pump lobe is on and tight. I will have to promise my wife a few things to get her into the garage to turn the egnition for me.

I'll keep you posted.

[MikeW]

I'd remove the pump and simply try it by hand with fuel hoses straight into a gas can.

[MarkDixon]

fixed it.

I took the valve cover off and manually pumped the fuel pump lever until gas flowed through the pump.

It cranked 1st try.

I guess Racebird was the winner.

If I wasn't afraid of using up my battery trying to start the engine, it would have eventually paumped gas into the carbs.

Now I know if I let it sit for a month it will take a while for the pump to prime.

Thanks guys.