JD 350C Dozer cuts out

[jerrymo]

Recently my JD350C diesel runs fine for about 15 minutes and then over about a minute loses power and eventually stops. During this power loss it doesn't respond to increasing throttle. It will start right up but within about 30 seconds will stop running. If I wait about 20 minutes it will start fine and run anothert 15-20 minutes before stopping again. This same pattern can be repeated over and over. This is no problem if you want to work for 15 minutes and then rest for 15 minutes, over and over.

I cleaned out the fuel tank and replaced the filter in the tank. I also replaced the fuel filter itself which was clean. When I disconnect the fuel line at the injector pump it gushes when the engine is started, which I guess indicates the regular fuel pump is working fine. I have never done anything to the fuel injection pump or injectors. It sounds almost like a vapor lock to me but I don't know what would cause this or how to fix it (and I could be totally wrong).

I would also add two other points which I don't know have any relevance. The first is that before my tank cleaning, for years there has been a large amount of suction when the fuel cap is released. That seems to be gone now. The second is that the fuel shutoff solenoid has pretty much always been dysfunctional but I don't know if this is related.

Any help would be appreciated. I've got lots of dirt waiting to be pushed around. Thanks, Jerry

[Bob Rooks]

Install a fuel pressure gauge between the secondary fuel filter and the fuel injection pump (0-60 psi gauge will do).
A possible cause is diesel bugs that have corroded your lift pump. Are you sure your entire fuel system is absolutely squeaky clean?

[jdtractor]

hey jerry i once owned a john deere 350 my self 6way blade and winch ,1968 yr, and it did about the same thing.i do custom work etc sometimes for a few folks , i would look at 2 things #1 the return line ,there is a spring and steel ball just inside the fitting that connects to the pump this restricts pressure and prevents fuel from leaving the injector pump and regulates the fuel to the injectors, etc. #2 the injector pump mite need to be replaced or rebuilt, it has what they call governor weights that are made of a kind of plastic that ware out and break ,letting too much fuel out to the injectors etc..... they can be worn out from age or heat over time ive been there and had to replace my injector pump. if the pumps in time (isnt loose or moveable)this is more then likely your problem. i did everything you did to try and get my tractor running ,ended up opening site glass on side of pump ,it let excess fuel flow and the tractor run ,i limped it home about 1/4 mileand replaced the injector pump after calling my dealer etc..... by removeing the ball and spring i told you about 1st after you reinstall the line (no ball or spring) it allows the tractor to run etc.... you wont loose any fuel. i know guys who have ran for several hrs with the pump this way but i dont think its a good idea. i hope this helps you

[DrRick]

hey jerry i once owned a john deere 350 my self 6way blade and winch ,1968 yr, and it did about the same thing.i do custom work etc sometimes for a few folks , i would look at 2 things #1 the return line ,there is a spring and steel ball just inside the fitting that connects to the pump this restricts pressure and prevents fuel from leaving the injector pump and regulates the fuel to the injectors, etc. #2 the injector pump mite need to be replaced or rebuilt, it has what they call governor weights that are made of a kind of plastic that ware out and break ,letting too much fuel out to the injectors etc..... they can be worn out from age or heat over time ive been there and had to replace my injector pump. if the pumps in time (isnt loose or moveable)this is more then likely your problem. i did everything you did to try and get my tractor running ,ended up opening site glass on side of pump ,it let excess fuel flow and the tractor run ,i limped it home about 1/4 mileand replaced the injector pump after calling my dealer etc..... by removeing the ball and spring i told you about 1st after you reinstall the line (no ball or spring) it allows the tractor to run etc.... you wont loose any fuel. i know guys who have ran for several hrs with the pump this way but i dont think its a good idea. i hope this helps you

I have had these issues exactly, on both my 450 c dozer and 2 different 410 backhoes. All have the rotary injection pump with the tendancy to have the governor plate disintigrate. You can have the pump rebuilt and it will cure all the problems. Taking out the check valve ball sometimes won't help if there are little pieces of black material ( looks like rat droppings ) that plug up the exit to the overflow line.

[Bob Rooks]

#1 the return line ,there is a spring and steel ball just inside the fitting that connects to the pump this restricts pressure and prevents fuel from leaving the injector pump and regulates the fuel to the injectors,
What you are referring to is the fuel pressure regulator, check valve assembly. The spring against the steel ball creates a calculated amout of pressure (back pressure if you will) in order to keep the fuel cavity in the injection pump full. If this spring has failed, or the ball and seat have become pitted and corroded, you may not be able to maintain fuel pressure and the cavity can become aerated and require bleeding.That's why I asked you about a pressure gauge

#2 the injector pump mite need to be replaced or rebuilt, it has what they call governor weights that are made of a kind of plastic that ware out and break ,letting too much fuel out to the injectors etc.....
That would create a runaway condition with no control. Chances are that the rack is just stuck or maybe barrels & plungers. Is there oil In the injector pump? Stay out of the governor, please.

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[Bob Rooks]

Taking out the check valve ball sometimes won't help if there are little pieces of black material ( looks like rat droppings ) that plug up the exit to the overflow line.

Those are "diesel bugs". Advanced Diesel Solutions New Zealand They can wreak havoc on a fuel system.

[jerrymo]

Thanks for the ideas. I have some work to do now; check out transfer pump pressure and look at that pressure release on transfer pump. I should add that I did have a runaway episode as well (where the engine spontaneously raced and couldn't be controlled), so maybe after all is said and done, I'm left with an injector pump problem. If it comes to the injector pump do you guys have recommendations about where to go for this in the most cost effective way? Rebuilt units? Companies that rebuild? New?

I am grateful for the help. I will get back with my progress. Thanks, Jerry

[Bob Rooks]

Jerry,
Your fuel injection pump/governor assembly can be rebuilt by your local diesel shop. If it's the rotary type it's a CAV brand. Another place that makes replacements for those (and many others) is Stanadyne.
Mechanical Pumps - Stanadyne

[DrRick]

Thanks for the ideas. I have some work to do now; check out transfer pump pressure and look at that pressure release on transfer pump. I should add that I did have a runaway episode as well (where the engine spontaneously raced and couldn't be controlled), so maybe after all is said and done, I'm left with an injector pump problem. If it comes to the injector pump do you guys have recommendations about where to go for this in the most cost effective way? Rebuilt units? Companies that rebuild? New?

I am grateful for the help. I will get back with my progress. Thanks, Jerry

It is most likely a roosamaster rotary pump. Mine have varied between 450 and 680 bucks to have rebuilt. You should be able to have it rebuilt at any injection shop. They will also try to sell you a set of new pencil injectors, but these are not usually needed if it is the pump disc failing. If you take it off and put it on yourself you will HAVE to borrow the assembly tool in order to not damage the seal upon re installation on the engine. Not hard just careful.