engine speed revving out of control

dan_d · Apr 6, 2012

Hi,
Since the weather is so nice today I planned on getting the cultivator out to clean up the ruts i made from bringing hay out to the horses all winter (since the ground never froze! i've never seen that happen around here

)
Anyways, I went to start the tractor and the battery wasn't strong enough so i put a bit of ether to it when i hooked up the spare battery to make sure it would go. As soon as it started tho, it just fired right up to full throttle even though my foot was off the pedal! Pulled the key out in a panic, but of course it's a diesel (JD 510, late 60's, 1.5L 3cyl 40hp) so that didn't do anything, duh! :ashamed: Then i clued in and shut it down with the pull cable and it stopped as it usually would... I've started it 3 more times and it does the same thing, tho i can get it to run at a reasonable speed if i pull the stop cable out most of the way. The throttle linkages are all fine and the mechanism on the injection pump seems to move ok, so I'm suspecting something went wrong with the governor in the injector pump

The ether is nothing i've never done before in colder weather than today, and i ran it long enough at 'almost off' to clear out the air intake so I'm thinking that's just a coincidence, but i thought i'd mention it anyways. Is there anything else i could check to confirm my theory? Any other possibilities I haven't thought of? Weird thing is that the tractor worked just fine when i used it last weekend when i put hay out, and i'm usually pretty good at noticing when things don't behave or sound quite right.

Worst case the pump is bad and i have to replace it... I have a parts tractor with a good pump that i can swap out until i get this one fixed (or fix it myself... is this possible with only general mechanics tools?) , but i've never taken an injector pump off before so i'm not sure what to expect. I guess the other big thing would be to set the timing...???

Anyone know any good tips/tricks/gotcha's or made any mistakes I could learn from?

Thanks,
Dan

P.S.: should I maybe have put this in the parts/repair forum?

Gordon Gould · Apr 6, 2012

Ether in warmer weather is not a good thing but if it runs reasonable with the full supply mostly choked off you probably did not bend a rod or break your rings. Whether it is possible to damage the injector pump with high back pressure I don't know. But I tend not to believe in coincidences.
I would suggest you get a shop manual before you tare off the pump unless you have done it before. You might need to line up the timing marks and wire back the throttle to hold the governer weights and mark everything so that you can get it back together w/o changing the timing.
Good luck.

Jerry/MT · Apr 6, 2012

dan_d said:
Hi,
Since the weather is so nice today I planned on getting the cultivator out to clean up the ruts i made from bringing hay out to the horses all winter (since the ground never froze! i've never seen that happen around here )
Anyways, I went to start the tractor and the battery wasn't strong enough so i put a bit of ether to it when i hooked up the spare battery to make sure it would go. As soon as it started tho, it just fired right up to full throttle even though my foot was off the pedal! Pulled the key out in a panic, but of course it's a diesel (JD 510, late 60's, 1.5L 3cyl 40hp) so that didn't do anything, duh! :ashamed: Then i clued in and shut it down with the pull cable and it stopped as it usually would... I've started it 3 more times and it does the same thing, tho i can get it to run at a reasonable speed if i pull the stop cable out most of the way. The throttle linkages are all fine and the mechanism on the injection pump seems to move ok, so I'm suspecting something went wrong with the governor in the injector pump
The ether is nothing i've never done before in colder weather than today, and i ran it long enough at 'almost off' to clear out the air intake so I'm thinking that's just a coincidence, but i thought i'd mention it anyways. Is there anything else i could check to confirm my theory? Any other possibilities I haven't thought of? Weird thing is that the tractor worked just fine when i used it last weekend when i put hay out, and i'm usually pretty good at noticing when things don't behave or sound quite right.

Worst case the pump is bad and i have to replace it... I have a parts tractor with a good pump that i can swap out until i get this one fixed (or fix it myself... is this possible with only general mechanics tools?) , but i've never taken an injector pump off before so i'm not sure what to expect. I guess the other big thing would be to set the timing...???

Anyone know any good tips/tricks/gotcha's or made any mistakes I could learn from?

Thanks,
Dan

P.S.: should I maybe have put this in the parts/repair forum?

I'd check the linkage first and make sure that when the throttle lever is in the idle position, the lever on the injector pump is also in the idle position. On most pumps there is an idle adjustment screw that sets the idle rpm so the injector pump lever should be touching this screw.
If it is, then I'd suspect the governor in the injector pump is sticking or failed.
Without a good shop manual that includes the injector pump, I doubt you an rebuild the pump. You'll need to know how to position the engine so that if you remove the injector pump, you put it back in correctly. Again you'll need a shop manual or someone who is familiar with your tractor to guide you.

CJONE · Apr 9, 2012

Like Jerry said check to make sure the stop is actually contacting the idle screw, I have had the arm loosen and slip on the teeth for the throttle shaft. CJ

dan_d · Apr 13, 2012

So after spending all week on this, I finally have a working tractor again! As I suspected, it was the pump gone bad. There's a cover on the top I could take off and see the governor springs which were all fine, but apparently it's fairly common for some washer or disc of some kind inside to disintegrate and allows fuel in where it shouldn't belong, hence the RPMs going crazy. I did notice some plastic bits sitting in that area, and unfortunately the other pump had the same bits so I'm afraid it won't last as long as I'd like, but at least I'm back in business for now and i can get the other pump rebuilt in the meantime...

I was able to dig up the parts blowout for the tractor from deere.com and also came across the shop manual for the Roosa Master pump (DBGFC331-14DH) that is on my tractor, which helped as well. The pump's driveshaft is stuck pretty good in the timing gear and I never ended up being able to get it off, but it turns out that the pump just slides right off the shaft without much trouble. It's also keyed and marked so it only goes in one way, so i just pulled the pumps off both tractors and left the shafts in place, popped the good pump on the old shaft and was good to go. Wasn't quite that easy of course, since it took most of the week, but that's old tractors for you!

For one, I took off way more stuff than I needed to on the parts tractor since I didn't really know what I was up against. I had all sorts of leaks afterwards from moving stuff that hadn't moved in a long time, and I still have one minor one left to deal with, but at least I'm no longer tractor-less; the horses can thank me later :laughing:

A couple of things I learned if anyone ends up finding this thread buried in the ancient archives someday. Surely this isn't new information for anyone "in the know", but i obviously wasn't...

- clean everything in the surrounding area (a very large area since you'll inevitably hit something dirty with a tool or your arm while trying to do something awkward, Murphy's law hard at work for you!) thoroughly with a wire brush, compressed air and brake/carb/whatever cleaner before taking anything apart. And even if you think it's clean, scrub it again to make sure! Easier not to get it dirty than to have to clean it out after the fact!
- If you need to bend fuel lines out of the way, make sure to get them lined up right (in all 3 dimensions!) when reassembling; its a ***** to try and get those banjo bolts in if they're any kind of crooked (especially the right next to the engine block!)
- RTFM! I spent about twice as much time surfing google digging up info (and a few mins talking to the guys at the deere dealer) than i did actually on the tractor. I obviously could have known more going in, but I think i managed to avoid some more costly errors by researching ahead of time. Also found the torque specs for all the connections, some of which were much higher than I expected.
- Washers and seals are (usually) cheap. Replace any that you come across. I wasted a good 2hrs messing with leaky lines for 94¢ worth of washers (and the aforementioned torque specs...)

Cheers,
Dan

Jerry/MT · Apr 14, 2012

dan_d said:
So after spending all week on this, I finally have a working tractor again! As I suspected, it was the pump gone bad. There's a cover on the top I could take off and see the governor springs which were all fine, but apparently it's fairly common for some washer or disc of some kind inside to disintegrate and allows fuel in where it shouldn't belong, hence the RPMs going crazy. I did notice some plastic bits sitting in that area, and unfortunately the other pump had the same bits so I'm afraid it won't last as long as I'd like, but at least I'm back in business for now and i can get the other pump rebuilt in the meantime...

I was able to dig up the parts blowout for the tractor from deere.com and also came across the shop manual for the Roosa Master pump (DBGFC331-14DH) that is on my tractor, which helped as well. The pump's driveshaft is stuck pretty good in the timing gear and I never ended up being able to get it off, but it turns out that the pump just slides right off the shaft without much trouble. It's also keyed and marked so it only goes in one way, so i just pulled the pumps off both tractors and left the shafts in place, popped the good pump on the old shaft and was good to go. Wasn't quite that easy of course, since it took most of the week, but that's old tractors for you! For one, I took off way more stuff than I needed to on the parts tractor since I didn't really know what I was up against. I had all sorts of leaks afterwards from moving stuff that hadn't moved in a long time, and I still have one minor one left to deal with, but at least I'm no longer tractor-less; the horses can thank me later :laughing:

A couple of things I learned if anyone ends up finding this thread buried in the ancient archives someday. Surely this isn't new information for anyone "in the know", but i obviously wasn't...
- clean everything in the surrounding area (a very large area since you'll inevitably hit something dirty with a tool or your arm while trying to do something awkward, Murphy's law hard at work for you!) thoroughly with a wire brush, compressed air and brake/carb/whatever cleaner before taking anything apart. And even if you think it's clean, scrub it again to make sure! Easier not to get it dirty than to have to clean it out after the fact!
- If you need to bend fuel lines out of the way, make sure to get them lined up right (in all 3 dimensions!) when reassembling; its a ***** to try and get those banjo bolts in if they're any kind of crooked (especially the right next to the engine block!)
- RTFM! I spent about twice as much time surfing google digging up info (and a few mins talking to the guys at the deere dealer) than i did actually on the tractor. I obviously could have known more going in, but I think i managed to avoid some more costly errors by researching ahead of time. Also found the torque specs for all the connections, some of which were much higher than I expected.
- Washers and seals are (usually) cheap. Replace any that you come across. I wasted a good 2hrs messing with leaky lines for 94｢ worth of washers (and the aforementioned torque specs...)

Cheers,
Dan