Z750 Fuel Issue

[GuyNixon]

I’ve had issues with the fuel system, and tried to work through them. We have had a new fuel tank, lines, filter and housing. This didn’t change anything so I had the fuel pump reconditioned and still no better. I’m now thinking it could be a governor problem?
The engine starts first time but I need to use a lot of throttle to do this, when running the engine cycles from what I would consider normal revs to almost stalling point then picks back up. If I throttle down the engine will stall. It seam that the hotter the engine gets the worse the problem is. I was hoping to post a video of the engine running but cant seem to upload it. I’m hoping for some advice as I may just be over thinking this and could be a simple fix.

Other info. The Z750 engine is in a boat and set at a 15deg angle ish, the fuel tank is lower than the engine.

 

[thepumpguysc]

I’m just thinking out loud here:
If the fuel tank is lower than the inj pump, I think u would need a supply pump/lift pump to feed the inj pump.??
U said u had the “fuel pump” reconditioned.. do u mean the injection pump.??

 

[GuyNixon]

Yes the injection pump has just been reconditioned, there is no fuel pump but the engine has been working fine up to now
.

 

[alexpops]

Pick up a cheap electric fuel pump and plumb it in between the primary filter and the injector pump. If that fixes the issue, you have your answer. To protect the injector pump, you may want a secondary filter after the electric pump in case it sheds parts after you've made it permanent.

 

[GuyNixon]

Pick up a cheap electric fuel pump and plumb it in between the primary filter and the injector pump. If that fixes the issue, you have your answer. To protect the injector pump, you may want a secondary filter after the electric pump in case it sheds parts after you've made it permanent.

So today I put a inline fuel pump on and unfortunately it made no difference, all is pointing to the governor, I’m hoping a broken spring or something simple but playing with that is above my head.

 

[thepumpguysc]

Doesn’t that engine have a removable plate on the side of the engine, directly on the side where the inj pump lives.?
U could take the plate off and feel if the rack is sticking or if your engine rack is bent causing the problem.

Btw.. thank u for installing the supply pump and trying to diagnose the problem..

 

[GuyNixon]

Doesn’t that engine have a removable plate on the side of the engine, directly on the side where the inj pump lives.?
U could take the plate off and feel if the rack is sticking or if your engine rack is bent causing the problem.

Btw.. thank u for installing the supply pump and trying to diagnose the problem..

It does have a removable plate and the rack is moving freely. Can’t see if it’s bent, I’m thinking it may be a spring snapped but I wouldn’t know where I could get them from.
Thank you for your advice, the problem is getting narrowed down.