Dave77F15

Greetings all,
Im new here, I suddenly started having problems with my Briggs 88’ 18HP Twin being very hard to start and stalling after 5 min running. Trying to determine if the problem is terminal or if there is a reasonable way to revive it.

Model 422707, Type 1210-01

1)Hard to start. –
Symptom-
The starter engages the flywheel correctly and the flywheel turns ¾ of a turn and stops, stalling the starter. The starter can’t get past this point. I have been able to “help” it get past this point with my hand and it will sometimes get enough momentum to start “sometimes”
It has always had a similar symptom where you would hear the starter labor slightly at one point on the first rotation but after that it would spin over fine.
Troubleshot
Verified the battery by jumping it to the running truck
Verified the solenoid is good. Even bypassed the solenoid with a cable from the battery to the starter.= no difference starter stalls
Replaced the starter = no difference new starter stalls
Removed the plugs => starter spins fine.

2)Stalls out --
Symptom
After running fine all summer long, I start it up for the usual weekly cutting and it suddenly stalls out after 5 min of running. Can’t get it restarted so I put it up. The next day I look things over can’t find any problems; start it and it runs fine. The next week it stalls again, but with no reprieve now it stalls every time. When it stalls It quickly bogs down and quits. It stalls like someone put there hand over the intake and it will not restart until it is cold.
Troubleshoot
Verified clean filter and tried with no filter. = same problem
Removed gas cap = same symptoms no matter the temp. i.e not vapor lock
Rebuilt the Carb = same problem
Rebuilt the Fuel pump = same problem
Seems to be getting fuel and there is no fuel in the heads or crank case like the needle is not closing.
Verified no obstructions in carb or intake
Still getting spark after it stalls

What do you think? Any ideas?

Is it time to send her down the line to the scrap yard a buy something new?

octaneman

Hi Dave77F15

Does the engine backfire prior before stalling ? Check the charging system and verify battery integrity by doing a load test on it.


post back your findings.

Dave77F15

octaneman
Thanks for the response.

Nope, no backfire just stalls like it is starving for air.
I jumped it to my truck with no improvment. The meter shows about 9V at the starter terminal when stalled. Same voltage reading either through the solenoid or bypassed straight to the starter

Snoopdogie187

Also inspect the wires used for the starting system. Also the wires that are connected to the battery. They may be getting old and not able to carry as much as they should be.
If the wires seem ok, I would try to do a load test on the battery (if you can) or at least change the battery out to test. You can use a car battery (as long as the mower uses a 12 volt system) which deffently would have enough power to start this engine. The only hard part is to connect the battery (I used jumper cables, but I had to watch them to make sure nothing shorted out and the cables didn't hit anything). This would at least see if the battery is the cause or if it is something else.

Also how does the spark plug look? maybe it isn't working how it should when it gets warm.

octaneman

The starter works with cranking amps not volts. The way to test the starter is by hooking up an induction clamp or meter to the positive wire and check the readings while cranking. This will tell you how much current the starter draws. The multimeter readings you took only shows battery voltage, this rule doesn't apply when testing starters. When any battery is bad and load is applied, the readings drop like a stone because the zinc plates inside the battery cannot hold a charge. This would also indicate that the charging system isn't working at all. While the engine is attempting to run, it gives you the appearance that the engine is being starved for air when in reality the real problem is that the battery is being shorted to ground.

Dave77F15

Thanks, I have a clamp meter. I didn't think it through from that view point. I will try it this evening and report back.

Vatar

Have you drained and replaced your oil?

Hard turning and stalling out after warming up is usually a sign that something is seizing in the motor, check for metal particulate in the oil.