I borrowed a friend's 2 man post hole auger (General Model 70). Sort
of a semi-permanent loan. He's got no place to store it. It's got a
5 hp Briggs and Stratton Vertical shaft engine (model 130920, type
0382, build date is 6/8/76). When I got it home it was obvious that
the engine hadn't been run in awhile, and the whole thing appears to
have very few hours on it.
I am having trouble keeping it going. Below is a list of what I have
done so far. This list is not necessarily in exact order, regardless
of what I have done so far, the basic problem persists. I can cold
start it and run it under no load or with a load and it seems to run
fine, but after using it for about 5 minutes (under load), it starts
to die (surging). If I choke it quickly, I can get it to keep going
off and on for maybe a minute or two more, but it ultimately dies
It will do the same under a no load condition, but it seems to take it
a bit longer to occur. Not much mind you, and this may only be my
perception of time.
I have been running it without an air cleaner, but with the air
cleaner screw in place. I have a new foam air cleaner on back order
at a local shop. I'm not using it in a dusty condition, (been too
damp) so I'm not really worried about dirt.
I'm at a loss at this point. I really need an experts advise on this
one. Right now, my thumbs are killing me from running a one-man
(manual) post hole digger.
List of "repairs" to date:
Replaced spark plug (original RC-J8 was still in it) with a C-J8.
Same heat range plug, just not resistor. Though the original still
runs it as goo (or bad) as the new one.
Added a screw-in straight pipe generic muffler (original was
Removed and cleaned tank-mounted (pulsa-jet) carburator. Replaced
diaphram, and main fuel pickup tube. I also put some carb cleaner in
the tank, and a bunch of nuts and bolts and shook it for quite awhile
to clean it. Then flushed it with clean fuel.
It takes it about 3 turns out on the needle valve to make it run the
best (by ear) in all throttle positions under no load. I can start it
with only 1.5 turns, but it just doesn't run great at this setting.
The gas cap venting is ok, not clogged.
Originally cleaned and checked points (.020 gap) and condenser, but
ultimately replaced them as problem persisted. Replaced flywheel key
as the old one was slightly tweaked. Enough that I first thought that
it might have been an offest key, but upon further inspection, this
doesn't appear to be the case.
Pressure checked cylinder cold / warm 65 psi.
Removed head to inpect valves, and cylinder. Though there is some
scoring on one side (bottom) of the cylinder, everything otherwise
looked ok. Appears to be very clean, very little carbon build up, and
crosshatch pattern on cylinder wall still very apparent.
Valves appear to be seating as there is a wear ring all the way around
them, but I don't have a valve spring compressor to do a more thorough
check, or lap. Did not check valve to pushrod gap.
Resistance check from spark plug wire to engine ground reads 2870
ohms. I have not replaced the coil.
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