Briggs & Stratton hard to start.

[VTFan]

I have a 18 hp Briggs & Stratton riding mower that had been starting fine all year until the last time I tried to mow. The battery is only a year old and I had it checked and it checks fine. I turned the key and the engine turned over verrrry slow like the battery was dead...it did this several times and then all of a sudden the engine backfires (sounded like a shotgun going off) and then started right up. I didn't dare cut it off until I got the yard mowed, when I pulled it back in the shed and tried to restart it the engine again turned over like the battery was dead. I have no idea what is going on. Any ideas?

Oh....I'm new here and a far cry from being a small engine mechanic.

 

[Rivets]

Start by checking the battery connections, make sure they are clean and tight. Second, check the connection between the battery ground cable and the chassis, again it must be clean and tight. Third, if the battery ground is not attached to the engine, make sure the engine is tight on the chassis. Finally, make sure the starter is tight on the engine. Remember, when electrical troubleshooting, NEVER ASSUME ANYTHING ALWAYS DOUBLE CHECK EVERYTHING.

 

[VTFan]

Everything was clean and tight when I took the battery out to have it tested. Is there such a thing as it building up too much compression and if so is there any way to relieve the compression? Hope that isn't a dumb question.

 

[VTFan]

Ok, tinkered with it some more today. Took the plug out, it was very clean. Turned the engine over a few times...put the plug back in and turned the key and it started right up. I let it run a couple minutes turned it off and tried to restart it and it turned over verrrry slow. Took the plug out again turned the engine over put the plug back and....again....it started right up.

Is something not releasing the compression through the exhaust? Do I need to try a new plug? Getting really frustrated :confused2:

 

[Rivets]

Slow down please, you said you were a new mechanic, it takes time. I don't want to take you down a road you can't handle. Yes, there is a compression release, but going through that is not for a rookie. Other things that could cause this are bad starters, valve problems, even a bad solenoid. Let's try something different, before we decide to go inside. You said you have a good battery, only one year old. I've seen them die in six months. If you have a multi meter, hook it to your battery and try to start the engine. If the battery voltage drops below 10V you will need to replace it. Also, I always recommend the minimum of 325 CCA for an engine of that size.

 

[Fish]

Look at the valve cover and post all of the numbers off of that, you just likely need to simply adjust your valve gaps...

 

[VTFan]

Didn't say I was a new mechanic, just said I'm a far cry from being a small engine mechanic. I can do simple maintenance but nothing like overhauling a motor etc... not a rookie but not a pro.

Had the battery checked and it checked out fine. Had new solenoid put on last summer as well as a new push rod, fuel and air filter.

Once I get it started it runs fine. I don't know if this is possible or not but if the exhaust valve is stuck or the rod is bent or broken won't the internal exhaust gases cause more problems by not being released?

Ok......I'm more a rookie than a pro LOL!!!

 

[Rivets]

Sorry, but I have to go by what I read. More often people post that they know more than what is real. Let's run out electrical by doing the test I asked. If you have a bent or broken push rod, it wouldn't run at all. Possible stuck valve, but that would be low on my list of things to check. If the battery voltage test out good, give this a try. Turn the flywheel screen by hand until you can feel it getting tight on the compression stroke. Continue to slowly turn until it turns freely, stop right there. At this point try to start the engine with the key start. What we are trying to find out is if you are getting to high of a compression for the starter to overcome. You must have a good battery, so that is why I want the battery test done first.

 

[Carscw]

I have a briggs 24hp does this same thing.
I adjusted the valves. Did not help.
Sometimes it's very hard to turn the flywheel by hand.
When it would do this I hooked up the jumper cables and it would spin right over.
I went with a higher cranking amp battery and no trouble any more.

I would do the battery test.
And try some jumper cables.

Like has been said already check every ground.

 

[Phil G]

Is it fitted with the original starter motor? I've had a few in the past where the starter has behaved intermittently. Sometimes the main supply cable where it enters the starter.

Good luck, Phil :smile: