D722 rough idle, fuel injection pump issue

markn

New member

Equipment
K008
Dec 18, 2018
1
0
0
Chicago, IL
I have a K008 with a D722 that I bought at an auction recently and I did change all of the filters and lubricants. The machine seems to run fine under load and I would not suspect that there is a problem except for a noticeably rough idle. I did spend considerable amount of time troubleshooting this issue and I was not able to figure it out. I used an IR camera to check the heat signature on the exhaust manifold (when the engine was cold to warm up) to see if there is any variation and I noticed that cylinder 3 is doing most of the work while cylinder 1 is almost completely cold. I then swapped the injectors between cylinders 1 and 3 and the result was the same with cylinder 3 still the hottest. I then proceeded to crack the fuel lines to the injectors and the result was that cylinder 1 had no impact when the line was loosened and when the line was cracked on cylinder 3 the engine sputtered badly and almost died, and cylinder 2 had minor impact. I also removed all three fuel lines completely to see if there is fuel squirting from all three pump ports when engine is cranking and there is fuel coming out from all three, and it seems relatively even. However I cannot determine whether there is sufficient fuel coming out just by looking at it. I also checked the compression and its 450PSI on all cylinders. So I'm not sure what else to try. I did remove the injector pump and I checked the springs and pistons for any physical damage and I did not find anything obvious. Can the pump be faulty in this case? I would hate to spend a considerable amount of money on a new pump just to try and see if it improves things. Any ideas would be appreciated.
 
Last edited:

armylifer

Well-known member
Lifetime Member

Equipment
BX1860, FEL, RCK54P MMM, BB1548 Box Scraper, Quick Hitch, Piranha Bar, BX6315
Mar 26, 2013
2,060
786
113
Thurston County, WA
Early last fall my tractor started running a little rough at idle. I did not do any of the things to discover why that you did. However I thought that maybe my injectors were getting a little gummed up because most of the time my tractor is running at about 1500 rpm unless I am mowing or improving rocks. Anyway, I decided to start running WOT for a few days no matter what work I was doing. That definitely helped. After I did that for a few days I put in some injector cleaner and now it runs like a new engine.my tractor has the same engine as you have. I have 919 hours on the clock. Hope this helps.
 
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North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
31,562
7,375
113
Sandpoint, ID
I did remove the injector pump and I checked the springs and pistons for any physical damage and I did not find anything obvious. Can the pump be faulty in this case? I would hate to spend a considerable amount of money on a new pump just to try and see if it improves things. Any ideas would be appreciated.
Pull the pump and the injectors and have them tested.

I suspect you have a pump issue.
 

200mph

Well-known member

Equipment
L4740-3 Cab, FEL, Fnt Snow Blower L2185, LP Finish Mower, LP Rotary Mower
Mar 3, 2017
1,228
61
48
PA
A LOT of fuel issues can be corrected by just RE-TORQUING the top nuts on the injection pump.. THEY MUST BE TORQUED.. DO NOT tighten w/ a socket BY HAND..
Torque is 30-35 FT lbs..
I want to learn...

Can you explain how/why this is the root cause for fuel issues?

I'm not that familiar with the pumps and trying to understand why torquing the nuts would be the case. ie: What happens when the are under torqued? Over torqued?

Thanks in advance for your explanation.
 

thepumpguysc

Member
Aug 8, 2018
267
1
16
Sunny South Carolina
Inside the pump & under the top nut{delivery valve holder} is a copper crush washer & a metal to metal sealing area..
Over time & with a little customer help, the top nut becomes loose, that causes the metal to metal seal & the copper washer to allow the full shot of fuel to leak internally & that fuel gets sent back to the fuel tank.. or leaks into the oil over time or causes external leaks..
SO if u tighten it back up, u stop that action & your pump/engine runs a lot smoother..
I just explained UNDER torqueing..
OVER torqueing distorts the copper gasket & metal to metal seal area and puts undo pressure on the internal components & can distort it enough to stop things {control rack} from moving/sliding properly..
IF u don't have a FTlb torque wrench, & I hate to say this {because I have a 300.00 snap-on TW}.. Harbor Freight has them for 10.00 & its good enough for a 1 time use like your doing.. OR u can borrow 1..
I hope this helps.. TPG
 

200mph

Well-known member

Equipment
L4740-3 Cab, FEL, Fnt Snow Blower L2185, LP Finish Mower, LP Rotary Mower
Mar 3, 2017
1,228
61
48
PA
Inside the pump & under the top nut{delivery valve holder} is a copper crush washer & a metal to metal sealing area..
Over time & with a little customer help, the top nut becomes loose, that causes the metal to metal seal & the copper washer to allow the full shot of fuel to leak internally & that fuel gets sent back to the fuel tank.. or leaks into the oil over time or causes external leaks..
SO if u tighten it back up, u stop that action & your pump/engine runs a lot smoother..
I just explained UNDER torqueing..
OVER torqueing distorts the copper gasket & metal to metal seal area and puts undo pressure on the internal components & can distort it enough to stop things {control rack} from moving/sliding properly..
IF u don't have a FTlb torque wrench, & I hate to say this {because I have a 300.00 snap-on TW}.. Harbor Freight has them for 10.00 & its good enough for a 1 time use like your doing.. OR u can borrow 1..
I hope this helps.. TPG
Thanks! I appreciate you taking time to explain both cases (under/over torque).