Generator won't start, just sputters and backfires


Old 12-10-13, 07:41 PM
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Generator won't start, just sputters and backfires

I have a Generac 3500 (4375 max) with a GN 190 6.5 hp
I replaced the carb and spark plug. when I pull rope, I get a 2-3 coughs or a flame out of carb. I've tried spraying carb cleaner into carb, but same results.
I have read bits about flywheel, key, timing etc. but would like more info and things to check.
Thank you greatly for any assistance.
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Old 12-10-13, 08:00 PM
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Shut the fuel off. Remove the bowl then turn the fuel back on to see if fuels making it to the carb.
Lift the bowl to see if the fuel shut off.
Checked to see if there's a filter in the tank?
Old 12-10-13, 08:26 PM
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Ok, I turned fuel off, dropped the bowl, turned fuel on, and fuel ran out. lifted the float and fuel stopped flowing out.
I'm not sure about any fuel filter in or on tank, but there wasn't one on the fuel line. I installed a filter on the fuel line itself a few days ago.
Old 12-11-13, 07:57 AM
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It sounds to me as if you have a timing issue which means the flywheel key is probably sheared. I would check that and also it could be a valve problem. If it has overhead valves take off the valve cover and see it the push rods etc. are in place.
Old 12-11-13, 08:13 PM
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I think you nailed it Butcho, I took the OHVI cover off and one of the springs is actually sprung PAST the top of the "bracket" that holds the spring down. It looks like the "lip " that holds the spring down broke off. I can see a broken piece of metal down inside. any advice on how to make sure there are no metal pieces or shavings inside?
Is there a kit I can buy to replace the springs and/or push rods?
Old 12-12-13, 08:34 PM
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You can replace this without removing the head if you connect an air compressor hose to the spark plug hole and pressurize the cylinder. Usually this is done using the hose from a compression gauge. This holds the valve up so that it won't drop down into the cylinder when you remove the retainer. Compress the spring and using a small magnet, pull the valve retainer clips out of the groove. Then let the spring loose and replace the broken retainer and reverse procedure to put it back together.
Old 11-20-14, 01:50 PM
Join Date: Nov 2014
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Thanks for the posting. I had a similar problem with my Wen 3500. I checked the valves and springs under the valve cover and could see nothing wrong. I decided to change the plug to see if that would matter. While checking my user's guide for gap size, I found a sheet of paper that said that the generator needed to be filled with oil before use. I may have done this 5 years ago when I bought it but I am ashamed to say that I haven't checked it since. Like ever. So when I went to check it, and found that it was empty/low, I noticed a small wire coming out of the crankcase. This generator must be smart enough to know when a bone-head like me doesn't put oil in it and it refuses to start. Before adding oil it back-fired, sputtered, and acted like it wanted to start but just wouldn't. I Added oil (20 ozs for this model) and it fired up the first pull.

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