B7100D not starting

Jeremy0722

New member

Equipment
1981 B7100D
May 28, 2026
1
0
1
Ironton, Ohio
I have an 81 B7100, had it since new. Last time I ran it, it blew out a little black smoke a missed some then died. I can get it to restart. Glow plugs are getting hot and fuel is coming from all three injectors. Any help would be greatly appreciated.
 

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Caden

Active member

Equipment
1979 B7100
Apr 16, 2026
142
64
28
Virginia
To me black smoke indicates to much fuel/ too little air, as opposed to starving for fuel.

Therefore I'd start with the easiest but least likely culprit by trying to start the engine without the air filter.

After that my next point to check would be injectors. Dumping too much fuel perhaps?

Also might be worth pulling the valve cover to confirm valves are all moving and adjusted.
 

Russell King

Well-known member
Lifetime Member

Equipment
L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
7,607
2,929
113
Austin, Texas
You probably know this but you need three things for a diesel to run:
1) Air
2) Fuel delivery to the cylinder at the correct time.
3) Compression

Since you mention black smoke it may be getting too much fuel (or not able to burn what it gets)

Check the air cleaner and intake pipes for obstructions.

Buy a diesel engine compression tester or see if you can borrow one from a local auto supply shop. I doubt this is the problem though since you say it ran fine before this started.
 

D2Cat

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Lifetime Member

Equipment
L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
14,879
7,518
113
40 miles south of Kansas City
I would first confirm air filter is clean and no obstruction in air flow. Second, check fuel flow from tank to filter to IP.

You didn't mention how long since last use. That is good information to pass on when wondering why it won't restart. Helps shorten/lengthen the list of item at fault.