John deere 350c running rough

[MechanicKyle]

Hi
New to the group Just purchased a 1985 JD 350c hade been setting for a few years and engine was hydrolocked with water, removed the injectors and spun the engine to blow all the water out ,filled cylinders with Marvel Mystery oil ,let set for 3 days and spun the engine to remove the oil, poured seafoam in the cylinders and let set for a couple hours and spun the the engine to blow the seafoam out. Reinstalled the injectors and the engine started right up
Everything checked out ok accept for the engine runs rough between idle and about 2200 rpm then clears up runs great with plenty of power as long as I stay at 2200 rpm
Replaced the injectors and didnt help
Checked the check valve on the return line at the stanadyne injector pump and the ball and spring is missing.
I have pulled the timing cover off the pump to try to identify any parts of the flex plate that may have disintegrated but could not see anything but the governor basket
New filter and fresh fuel also
Any thoughts from you guys? Should I attempt to rebuild the pump myself?

 

[thepumpguysc]

Some have tried and succeed, while other have tried and failed miserably..
U need a rebuild manual and special tools.. and remember, that manual is made for an experienced tech w the proper tools..

 

[ultrarunner]

I don't have the ball and spring either... it was always getting clogged.

Mine pulls well but this year had the injector pump rebuilt and runs much better...

Wish I could give more specifics... previously owned a CAT D3 for 17 years without incident.

The 350c is a little mountain goat and I can tow it with my equipment...

Before the pump went out was using bio diesel... neighbor was in the business so don't know if related or just bad luck

 

[MechanicKyle]

I don't have the ball and spring either... it was always getting clogged.

Mine pulls well but this year had the injector pump rebuilt and runs much better...

Wish I could give more specifics... previously owned a CAT D3 for 17 years without incident.

The 350c is a little mountain goat and I can tow it with my equipment...

Before the pump went out was using bio diesel... neighbor was in the business so don't know if related or just bad luck

 

[MechanicKyle]

Ultrarunner
Thanks for the input was wondering if running without the check valve would cause any problems

 

[MechanicKyle]

Some have tried and succeed, while other have tried and failed miserably..
U need a rebuild manual and special tools.. and remember, that manual is made for an experienced tech w the proper tools..

Pumpguy
Thanks for the input I feel confident I could replace the governor basket if that's the problem
The pump internals scare me a bit
I will be contacting a pump shop in the coming days and find out the cost for a rebuild

 

[ultrarunner]

I don't know enough but several times the engine would stop and not always in a good spot

I removed to get it moving to flat ground and it ran normal and have not put it back...

Hoping someone can shed some light.

 

[thepumpguysc]

The “return connector” hold/creates housing pressure to allow the advance piston to move..
Without the connector u have no advance/timing..
Similar to a distributor in a car..
If u would like to contact me directly, I can give u a quote to rebuild it.. THATS what I do..
Just click on my screen name to send a prvt msg.

 

[ultrarunner]

Is it common for the return to be a problem on these older units?

Mine was always getting obstructed and it acted like running out of fuel.

Any truth to bio diesel being hard on these old injector pumps?

 

[thepumpguysc]

Bio fuel is A KILLER to ANY diesel fuel system.. if u let your machine sit for even a month u can pretty much write a check for 1000.00 to get your system cleaned..

the return gets clogged from within.. either sludge from bio fuel or the main reason being the “flex ring” is breaking up..
The flex ring is a polymer ring that joins two parts inside the pump.. it gets hard and brittle over time and starts to break up..
The bits look like coffee grounds or mouse turds..
If u run your machine without the connector, the bits are going back to the tank.. but most importantly, once the bits are gone, the two parts start banging into each other and eventually cause the engine to “run-away”..(u can’t control the speed)
It WILL give u signs tho..
The engine will start to surge or the rpm’s will rise on it’s own.. Eventually u won’t be able to lower it..
If u catch it in time.. a pump rebuild is in order..
Most shops won’t tell u but there is a permanent fix for the flex ring problem.. they want u as a permanent customer..cuz the flex ring WILL break up again and again..