Runaway diesel

[Big Bri]

I just bought a used grasshopper 722dt6 with a 3 cylinder diesel. Engine only has 350 hrs. The first two times I cut my yard she performed flawless. Yesterday while cutting the mower would slow down while going up hills to the point of almost dying. (Motor would slow down) I called grasshopper today while at work and they said to
1, change filters
2, drain the fuel tank and start with new fuel and give it a try.
that didn稚 help
next
if that didn稚 work I was told to take off the supply line out of the tank and check for leaks ( put thumb on one end and blow) no leaks there.
so I put It back together and added a little power service clear diesel to see if it might clean an injector
well when I started the mower it went full tilt and I had to pull the air cleaner and shove my shirt into the intake to stop it.
i have since drained the tank and added new diesel from a different store and she still wants to run away.
any ideas?
Thanks for the help

 

[Billrog]

Injection pump fuel rod is stuck. A least that's my guess from my experience.

 

[mercdv]

Having experienced a stuck fuel rack myself that would be the first thing I checked. Take the governor housing off and see if the fuel rack control rod freely moves in and out. It should move pretty much effortlessly. If it doesn't, you have a stuck fuel rack. As long as it is just a gummed up rack and not stuck because of a mechanical part failure, it will be easy to free with a little patience and a good penetrating oil. It could be a stuck governor too but you will figure that out as soon as you remove the governor housing. I am just assuming you already checked the throttle cable.

 

[Big Bri]

I’ve never messed with an injector pump so this will a new venture for me. Will look at it tomorrow

 

[Big Bri]

I did look at the throttle cable and governor and both seem to be working fine. Thanks

 

[mercdv]

I’ve never messed with an injector pump so this will a new venture for me. Will look at it tomorrow

I hadn't either until this year. I had always been told to never touch them because our shop required a certified tech to touch them. Of course, that was until thepumpguysc told me I could fix my own as long as I didn't touch the wrong things. He walked me through the process on here. If you find the rod doesn't move well at all, I can post my write up on what I did to fix mine after listening to thepumpguysc's advice.

 

[thepumpguysc]

Thanks mercdv.. It kinda depends on which type of injection pump he has.. it might be easier than yours to un-stick.
IF you could post a pic of the pump & engine, that would be GREAT..
I know it might be "tricky" to put a pic on the site, so I'll send you my email address..
THAT WAY.. if you have it on your phone, you can send it quicker..

 

[Big Bri]

Thanks mercdv.. It kinda depends on which type of injection pump he has.. it might be easier than yours to un-stick.
IF you could post a pic of the pump & engine, that would be GREAT..
I know it might be "tricky" to put a pic on the site, so I'll send you my email address..
THAT WAY.. if you have it on your phone, you can send it quicker..

Here are the pics as requested. I messed around with it a little this morning before going to work. The in the video you can see movement is limited. Thanks again

 

[Big Bri]

Apparently I can’t up load a video, here are some picks of the limited movement.

 

[aczlan]

Is it sticking due to the shutoff solenoid (top right in the last picture) linkage being twisted and jamming?

Aaron Z

 

[Big Bri]

No, that is moving freely

 

[Big Bri]

lol one extreme to the other. I rocked the lever back and forth pretty fast with a little pressure and it popped free! But now the thing won’t start. I assume it’s now stuck closed?not sure. Had to go to work so I’ll play with it when I get home. Is that something I can open and clean or replace or is that something I should leave for the pros.
Thanks

 

[mercdv]

You've already experienced a run-away.. & got VERY lucky & was able to shut it down..
Do you "really" wanna push your luck??
Shoot me an email... TPG

Highly recommend you take the thepumpguysc up on his offer to help. He will not steer you in the wrong direction.

 

[4570Man]

You've already experienced a run-away.. & got VERY lucky & was able to shut it down..
Do you "really" wanna push your luck??
Shoot me an email... TPG

The grasshopper air filter is stuck outside the engine enclosure and easily accessible. Probably the only thing that saved him.

 

[thepumpguysc]

What bothers me NOW is, it "snapped" free & stuck.. they "normally" don't do that..
Whatever you do.. do not loosen the TOP NUTS..!!
IF you had access to the main control rack, it would be easier to diagnose..
BUT, according to your pictures, you don't have access.. no side plate..
Your just gonna have to bite the bullet & pull it..

BUT NOW, its stuck in the shut-off position.. that makes it harder to remove.. DOABLE definitely, but alittle harder..
Your going to have to raise the pump as far as it will come up & find the little slot in the engine casting..
& TRY to move the rack to that position, so the pump will come all the way out..
You'll probably need to "persuade" it to move.. Just BE CAREFUL.. the parts in there are made of thin pot metal & bend very easily..
The pump removal IN MOST CASES is a DIY project.. so take your time..& have METRIC tools.. a 5 or 6mm Allen wrench will get the pump up..
A 17mm open end wrench will get the lines off.. & a 10-12-13mm sockets for the intake manifold, a pick, needle nose pliers & a screwdriver should get you where you need to go.. Basic homeowner hand tools..
Just get "stuff" out of your way before trying to pull the pump.. don't try to work around something..
email me if you run into problems.. TPG

 

[Big Bri]

Just an update.

Pumpguy, I sent you an email with a pic and video, I’m not planing or removing anything yet. When I turn the engine over now it just cranks but no fire. I think the pump is working correctly as I am getting fuel through the return line when the engine turns over.
I just ordered an engine manual to get a better understanding of what each part is and how it’s supposed to come apart as I am clueless on a diesel. I do much better visually understanding things
Thanks again

 

[1010]

Is it sticking due to the shutoff solenoid (top right in the last picture) linkage being twisted and jamming?

Aaron Z

I agree something isn't right there. The pin is twisted in the bracket and a small hole in the pin is missing a spring or something to make it more effective when it moves.
The entire solenoid looks fairly cleaner than the rest so it could've been worked on before.
That rod coming out of the solenoid needs to be clean under the black rubber boot. If the solenoid only pulls in one direction then a spring must pull the lever back the other way once the solenoid releases the pressure.

 

[thepumpguysc]

Bri.. Loosen the lines AT the injectors in the head, to see if its actually PUMPING fuel "up to" the injectors..
IF not, the rack is stuck or the segments have broken inside the pump..{throttle popped/snapped from wide open}
Just because you have fuel coming out of the return, really doesn't mean anything other than you have fuel UP TO the injection pump.
Basically.. you have fuel UP TO the pump but nothing coming out.. which means the pump has to come off..
lol.. I'm beginning sound like a broken record..lol

 

[Big Bri]

Just to put some closure to this, got the mower running again. Turned out to be a broken spring for the second cylinder in the injector pump. She is running like new again. Thanks to all for the help and insight.