Cav fuel pump not pumping

Hey guys hope you can help. I have a Ford 340 tractor with a CAV fuel pump. If I pull the tractor it will start and run fine. No apparent fuel leaks. When I shut it down it will not restart. The starter turn the motor over fine. I believe the problem is in the fuel pump because. Have fuel at the filter. I have fuel at the pump at the bleed point above the id tag. However at the end of the pump where the lines go on to pump up to the cylinders I have no fuel.

I doubt this is a pump problem, since it runs with a pull start.

The only thing different a pull start does is turn it longer and faster. It sounds to me like a leak letting air in, and losing your prime. These engines can be notoriously hard to start when they have air in the system, a lot of them, the only thing to do is bleed it well at the pump bleed fitting, have it open, then close it while turning the engine, once fuel is spraying out, not dribbling. Then open all the injector lines, (not disconnected, just loosened a few turns) and turn the engine until you see clean, bubble free fuel. This will sometimes take a long time. Once you see fuel, tighten that line while still turning the engine. Tighten each one once you see no bubbles, if you never see bubble-free fuel, find your air leak.

Thank you Mitch. This is happening every time for me. I agree with you that it is loosing prime. Where could the air be getting in? and how do I fix it?

mitch504 said:

I doubt this is a pump problem, since it runs with a pull start.

The only thing different a pull start does is turn it longer and faster. It sounds to me like a leak letting air in, and losing your prime. These engines can be notoriously hard to start when they have air in the system, a lot of them, the only thing to do is bleed it well at the pump bleed fitting, have it open, then close it while turning the engine, once fuel is spraying out, not dribbling. Then open all the injector lines, (not disconnected, just loosened a few turns) and turn the engine until you see clean, bubble free fuel. This will sometimes take a long time. Once you see fuel, tighten that line while still turning the engine. Tighten each one once you see no bubbles, if you never see bubble-free fuel, find your air leak.

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The pump has to be turning for any fuel to come out of the lines. As it will run, I doubt a fuel issue also. As they are a gravity feed, only a plugged line would cause it to suck back and then it shouldn't have any power. Disconnect an injector line at the injector and if it has a good spurt of fuel at that cylinder's turn to fire and your static timing hasn't changed, you may have an engine problem instead. I recently turned out a Long which could be pull started but wouldn't with the starter. I tried oiling the cylinders as I have done on badly worn engines to start but to no avail. Pulled the pistons out and found several broke rings. Only by pulling would it build enough compression to fire.

Does the engine shut down on the key switch or does it have a cable shut down?

IF it had a "helper pump" or lift pump between the tank and the inj. pump, I would say check there first for a drain back situation..
BUT I think its gravity feed to the inj. pump.. you say it has fuel to the filter and bleed screw.. and none coming out of the pipes..
TRY moving the shut-off cable in & out about 5x while you crank it and see if you don't get fuel out of the pipes..
My thinking is a sticking metering valve.. IF you leave the shut-off pulled out, when you shut it down for any length of time.. it will surely stick the valve in the no-fuel position..
and towing the tractor creates enough pressure to unstick it and fire..
I would say check the compression BUT THAT wouldn't account for NO FUEL TO the injectors..
The head and rotor inside the inj. pump could be worn to the point it wont deliver enough fuel to crank the engine..??

Thank you for your feed back guys. If I give it a 2 second shot of ether it will start. It runs fine after it is started, seams to have plenty of power and does not smoke. I had it running and pulled the fuel shut off cable to shut it down. Then immediately hit the starter and it cranked and cranked but did start. I tried moving the shut-off cable in & out 5x and that didn't help. A shot of ether and off it went again. There is no separate pump. just gravity fed to the CAV fuel pump. A diesel mechanic, I knew, told me at the sale I bought it at, that he felt it was the pump. He said fuel was going into the pump but now out of it. Unfortunately he was killed just after I bought the tractor so I'm on my own. I see fuel coming out the lines at the injector but not much when I'm running the starter. I tried cracking the line open once the tractor was running at the injector itself but it just wanted to stall the tractor. No fuel came out. I think I should just take the pump off and have it rebuilt. Looks like I should take the front cover off and mark the cogs before I remove the pump. I'm sure it has to be timed. What is a fair price to have a pump like this rebuilt. I live in South central Pa.

Depending on whats wrong with it.. Some "GUYS" charge 400.00 + shipping if the H&R is good..
And sometimes you can find them on fleebay for 700.00
You have to get the # off the name plate.. to be sure your getting the correct 1..

YOU and ONLY YOU, can decide how much money you wanna sink into this project..
MY 1st option would be>> to do a compression test.. SEEING it only starts on fluid..
A DIESEL compression tester costs around 100-200. from Harbor Freight.. THATS ALOT CHEAPER than a fuel inj. pump.. right.??
AND will tell you the condition of your 30yr old engine..
Your only gonna use it 1x and can resell it for what you payed for it..
DO THE SMART THING MATE.. we're here to help..

I think you are starting by changing a very expensive part that is not likely to solve your problem. Obviously you are getting fuel out of the pump, the engine is running.

If you loosen an injector line and the engine slows down, you are definitely getting fuel through that injector. If your problem is low compression, but it runs good, you can probably get many years of casual service out of it for the cost of a little ether. I have a 3400 (same basic tractor) I use around the shop that does everything I ask, but it requires a little snort to get it in the mood. When it gets where it won't start that way, I'll build it.