Coleman generator (Briggs & Stratton) will not start.


Old 09-28-17, 06:39 AM
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Join Date: Sep 2017
Location: USA
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Coleman generator (Briggs & Stratton) will not start.

I have a 2 nearly identical Coleman 5500 generators from the 1990s. Both have Briggs &amp; Stratton 10 HP engines. During the recent power outage after Irma, I ran them both about 14 hours per day, turning them off at night to conserve gas.<br />
<br />
After 8 days, one of the generators would not start, and I am at my wits end in trying to diagnose the problem. The 2nd generator works fine still.<br />
<br />
Here is what I have done:<br />
1. Verified that the fuel is good and the filter is clear<br />
2. Verified that there is spark at the plug<br />
3. In an attempt to isolate the problem, I exchanged the carb, coil and spark plug from the WORKING generator. The carb, spark plug and coil from the NON WORKING generator work perfectly in the WORKING generator. The know working carb, coil and spark plug from the WORKING generator, when placed in the NON WORKING generator do not solve the problem.<br />
4. Verified there is oil in the engine, and overrode the low oil cut off to test.<br />
5. Cleaned all the contacts on the on-off switch.<br />
6. Sprayed starter fluid in the carb and actually poured a cap of gas in the spark plug hole without success.<br />
7. Opened the head and verified there are no head gasket leaks or cracks<br />
8. Checked to ensure the piston is moving up and down and the valves are moving smoothly.<br />
<br />
It seems like a fuel delivery issue since I have spark, but the starter fluid and manual pour of gas in the cylinder should allow a start if it is strictly a fuel problem (I would think)<br />
<br />
I realize this is an old generator, but it gets limited use, normally less than once a year, and more importantly I have to figure out why it will not start or it will drive me nuts.<br />
<br />
I am at the end of my diagnostic expertise in this.<br />
<br />
Can someone direct me to the next step in figuring this frustrating problem.<br />
<br />
Thank you
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Old 09-28-17, 07:52 AM
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Join Date: Mar 2003
Location: NC, USA
Posts: 17,779
Provide the model and serial number of the engine so we can see what motor we're dealing with.

Did the problem engine sputter or seem to have trouble when it was running?

I would check the valve gaps. I usually get some warning from the engine when the valve gap start to get out of spec. like the engine is hard to start or it sputters and has trouble once it's good and hot.
Old 09-28-17, 08:16 AM
Join Date: Jun 2006
Location: St. Louis
Posts: 2,365
I would suggest checking the flywheel key, if it is partially sheared it can be firing but at the wrong time. Have good one. Geo
Old 09-28-17, 03:20 PM
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Flywheel key is possible but not really likely on a generator.

I would check compression, most auto parts stores have a loaner tool program if you don't have your own.

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