Bobcat 743B with Kubota V1702 random engine speed changes

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dano5535

New member
Joined
Dec 31, 1969
Messages
4
Hi guys, kinda new to this, but hopefully someone can help. I recently changed glow plugs and installed new fuel line, pickup tube/check valve and screen, squeeze bulb, and filter. Had a heck of a time getting all of the air out, and the fuel lines filled, then found the diaphragms in the lift pump punctured. Replaced them with some home made diaphrams I made myself with punches. Flow seems good. Also had to replace a o-ring on one of the injector pumps.

Since then, the engine speed is erratic, and increases and decreases even when the throttle setting is fixed.

Anyone got ideas as to how I can fix this or what is wrong?

Thanks for any help, Dan
 

foton

Well-known member
Joined
Mar 1, 2018
Messages
1,277
I would get a new mechanical fuel pump or make a cover plate and wire in a electric pump . I guess you could check what you have by adding a tee and gauge to see while running what your pressure is, I would guess around 5 psi would be ok, but double check that amount of pressure needed to the injector pump. I guess you could also have a vacuum leak ,that might be why it was hard to prime and would give variable rpm changes
 

brdgbldr

Well-known member
Joined
Jun 1, 2012
Messages
1,165
Hi guys, kinda new to this, but hopefully someone can help. I recently changed glow plugs and installed new fuel line, pickup tube/check valve and screen, squeeze bulb, and filter. Had a heck of a time getting all of the air out, and the fuel lines filled, then found the diaphragms in the lift pump punctured. Replaced them with some home made diaphrams I made myself with punches. Flow seems good. Also had to replace a o-ring on one of the injector pumps.

Since then, the engine speed is erratic, and increases and decreases even when the throttle setting is fixed.

Anyone got ideas as to how I can fix this or what is wrong?

Thanks for any help, Dan
I just read another post on here recently with a similar problem. It seamed to be air stuck in the lines near the injectors causing a "vapor" lock.
 
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