John Deere 350c fuel system problems

[Nick Andrew]

Hey everyone. I’ve got a jd350c. Just rebuilt the injection pump and not getting full power. However when the tractor is running if I loosen number 3 cylinder injector line at the banjo bolt the engine revs up. Of course it’s also leaking fuel with he bolt loosened. Loosening the other two banjo bolts makes the engine bog down(seems proper). I’m stumped... Please advise! Thank you

 

[mg2361]

Welcome to HEF Nick!

Who rebuilt your pump? A reputable injection pump shop? Good fuel supply? Air intrusion? Injectors replaced? Injector lines?

This would be a good time for @thepumpguysc to chime in.

 

[Dave Neubert]

Welcome to HEF Nick!

Who rebuilt your pump? A reputable injection pump shop? Good fuel supply? Air intrusion? Injectors replaced? Injector lines?

This would be a good time for @thepumpguysc to chime in.

sounds like he rebuilt the pump himself

 

[Nick Andrew]

The pump was rebuilt by a friend. In fact it’s been torn down and rebuilt 4 times because of this problem. I replaced the injectors. Injector lines are clear. Return lines clear. fuel supply clear. Air bled. Engine starts right up but low power. Yes I realize it probably is a faulty rebuild but before I spend the money I wanted to check to see if there was any other potential problem I had not explored. If anybody has any other ideas please chime in. Other than that I’ll be looking for someone to rebuild this thing preferably as close to California as possible...

 

[Nick Andrew]

Let me revise that last statement. It’s been torn down and rebuilt 4 times and each time there has been some problem. The first two rebuilds was the check valve... replaced on the third and the thing ran great until it sprung a leak out of the main housing. Replaced the o ring and put her back together and now here we are... thanks yall

 

[Delmer]

Have you pop tested the injectors? The only thing that makes sense to me is a badly leaking injector. Sure the lines are going to the correct cylinders? Might run on one and a half?

edit: need a little more info, at what point did you replace the injectors? even a brand new injector could plug with a tiny bit of dirt, I suppose it could hold open with the same bit of dirt?

 

[Nick Andrew]

Have you pop tested the injectors? The only thing that makes sense to me is a badly leaking injector. Sure the lines are going to the correct cylinders? Might run on one and a half?

edit: need a little more info, at what point did you replace the injectors? even a brand new injector could plug with a tiny bit of dirt, I suppose it could hold open with the same bit of dirt?

I have not tested the new injectors but i will. Installed them a few weeks back and they ran with the third rebuild just fine. Pretty sure the lines are going to the right cylinders as they are hard lines and I just put them back into place on the injection pump. I will try testing the injectors today... the confusing part is that if the machine is running and I crack the injector line at the hollow screw/banjo bolt for cylinder three. The machine revs up. If I crack either of the other injector lines it revs down and the machine starts to die off(as it should). Very confusing. Is it possible I’ve got a timing problem?

 

[Dave Neubert]

Take the pump to a rebuilder that can test it on a test stand I think it has to be in the pump try switching the number 3 injector with another one see if it changes if it don't then it has to be in the pump

 

[Nick Andrew]

Thanks for all your replies. Pop Tested the number three injector(brand new) and it wouldn’t even pop a little. Just ordered new one(40$). After it gets in I will see if it runs. If still an issue I will take the pump to my local shop and have them test it. I’m thinking the injector that was not allowing any fuel through has to be it. I’d like to thank y’all for your help. Also Alex at Diamond Diesel in Sacramento,ca for his invaluable information, testing and parts he supplied. Thanks again!

 

[Delmer]

You one lucky SOB! i was thinking, nah, it couldn't be. Must be the injector leaking cause if it was plugged...

I might install the new injector, but leave the cap on, and wrap the open injector line with plastic so it still leaks, but won't get more dirt blown into it, then start it to flush that line for a couple minutes. Don't want to plug the new one also.

 

[Nick Andrew]

You one lucky SOB! i was thinking, nah, it couldn't be. Must be the injector leaking cause if it was plugged...

I might install the new injector, but leave the cap on, and wrap the open injector line with plastic so it still leaks, but won't get more dirt blown into it, then start it to flush that line for a couple minutes. Don't want to plug the new one also.

Good advice. Definitely flushing that line!

 

[Nick Andrew]

Thanks again Delmer. I was thinking the same thing... all I can think is that it was somehow creating back pressure in the pump. It was the very last thing to check also... besides the pump. So of course that’s it.