B7100 injector assistance

STMark

New member

Equipment
B7100HST-D
Feb 10, 2016
2
0
0
Bremerton, WA
Recent maintenance work on this machine. Usual tighten fittings, clean up, grease. filters, etc. 1240 hours. Bought this one new in 1997 and use it on my mini farm. Pulled injectors to clean up using a brass brush to clean off minor carbon on bottom. Re-install no problems, bled filter and pump. But, one injector is not firing. I can feel the first two forward firing via the fuel lines. Fuel is coming to all three. OK, what occurred here? Advice? Thanks

Read through some past posts on injector issues. This machine lives inside when not used. Not cold here. Fuel is clean. Have fuel at all three injectors when turning over and it will start running on two cylinders. I imagine the problem is one being stuck. Removal and install was done carefully.
 
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North Idaho Wolfman

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Lifetime Member

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
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Sandpoint, ID
Are you 100% sure you got all the air out of the line?
One air bubble and they won't work.

If so, then pull the injector and split it apart and look for something that has caused it to get stuck or clogged. ;)
 
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STMark

New member

Equipment
B7100HST-D
Feb 10, 2016
2
0
0
Bremerton, WA
Pulled the injector back out and blew it out with air. Inspected the delivery lines and figured something got inside off the compression fitting. Cleaned those up and reinstalled the works. Took care of it. So, lesson learned about something tiny can cause problem with an injector. Engine does seems to run smoother on start up.
 

Highpockets003

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Aug 3, 2019
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0
ABQ, NM
Hope y'all are still subscribed for this thread. Got a similar problem.


With engine running at idle or even 1/3 throttle, I crack the nuts on cyl 1, 2 and 3 on each injector's back side (see picture). When cracking 1 and 3 nuts 1/8th turn, the engine immediately drops in RPM and fuel comes from the nut's backside and threads. I tighten the nuts back and the RPM resumes its previous speed.



When cracking #2 injector, there is NO change in engine RPM :mad: although fuel comes from the nut's threads and backside. From y'alls comments, I'm assuming the mechanical pump is okay for #2 but...


...guess I need to remove #2 injector and clean with compressed air or disassemble? I don't have any means of checking the line pressures (~1000psi?) coming from the injector pump.


I did listen to all 3 injectors with a screwdriver to my ear, and all injectors are clicking away with the same intensity.



Soooo - clean #2 injector??? :confused:
 

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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
28,286
4,853
113
Sandpoint, ID
Remove the #2 injector, take it apart be mindful of the direction of every component, clean with brake parts cleaner, Pull injector 1 look for the compression ring in both #2 and #1 swap with cylinder 2 then put injector #2 in cylinder 1.
Repeat test.
If it fails on 1, bad injector, if it fails on 2, might be time for a engine rebuild.

If the injector fails, pull all three send them to Oregon Fuel Injection and have them replaced/rebuilt.
 

Highpockets003

New member
Aug 3, 2019
16
0
0
ABQ, NM
Wolfman -



What is the normal range of compression pressure in these cylinders? I'm used to gasoline engines having a good 130-140psi, but don't know about this diesel.


Thanks!
 

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
28,286
4,853
113
Sandpoint, ID
Wolfman -



What is the normal range of compression pressure in these cylinders? I'm used to gasoline engines having a good 130-140psi, but don't know about this diesel.


Thanks!
375psi is the lower limit, if it's in good shape 425 to 450 is normal.
Rebuild is 469 high.