Generac 3500XL info

[rusking]

Hi, brand new to the board. I'm a (52D) power generator mechanic for the Army and am use to the 5K,10K,15K,60K and all counter tactical quite generators but the gasolines not some much. I own a 3500XL Generac and its about 10 years old. I got it up and running two days ago and have had a load on it for about 36 hours straight. LOL powers out and I'm on the computer. I have began to notice a slight backfire intermittent every now and then such as a loss of fuel or spark and then regained. I presume with the age its just plugs etc.. but would appreciate any information as to part and break down of the engine/crab so that i can master this piece of equipment. I downloaded the owners manual's and have schematics and wire diagrams but the mechanic information is somewhat lacking. Any information or help would be much appreciated. Thank you

[Fred M.]

I have a Craftsman generator that is nearly identical to the older Generac 3500XL. (Mine does not have an automotive-style oil filter, but the newer ones may.)

Your problem does not sound quite like any I have had. One that is close, was solved with a new magneto. I notice that the new one has an additional sleeve around the spark wire where it goes through the shroud. I suspect my old one had some kind of abrasion of the spark wire's insulation, that caused a weird intermittent problem.

If you do not have the engine service information, search the web for 0c1103a.pdf. For an engine parts list, search for GN190220.pdf or GN190-220.pdf.

Fred

[Fred M.]

Also check your oil level! The oil sensor will ground the magneto primary winding when oil is low. At first the effect might be intermittent, but you should see the low-oil light flicker.

Fred

[rusking]

an update from the user running it all day and night, the generator would do the resemblance to misfire/fuel loss i descried with a new symptom. Idle control when no load or low load present would cause the engine to die off. Hmm sounds like spark to me. Your guess thoughts?


Also the documentation to reference by the .pdf file you name yielded a different looking motor than i have. But you did note that it needed to be check by casting and i believe i will look at the block and motor info to determine the motor. Please correct me if i misunderstood

[K D Redd]

If you can post a picture of your unit. Two years ago I ran a 11 HP Briggs/ 5000 watt LP fueled generator for 6 days during the ice storm we had. I ran without a hick-up. I changed the oil to MOBIL ONE 10W-30. The last 96 hour of operation I only checked the oil twice as the previous two day I had seen little oil usage. You could be seeing a little carb icing. Add a gas line anti-freeze( Heet ) to your fuel.

Kent

[rusking]

I will get a pic of it up today. But fro a rough it is spot on the picture at the top of this page. I mean to a T.lol I will take some more pictures though with my phone and upload them here.

[airhead]

HI Rusking,
If your engine is popping or backfiring that is an indication that your exhaust valve is partially open during the combustion process. This can be caused by either an ignition system thats firing at the wrong time, valves out of adjustment or water in your fuel system that intermittently hits your spark plug. The first things to check are the most obvious and easiest such as a fouled spark plug ( the more fouled it is the worse it gets ), valve lash ( just pop vave cover off , usually 4 bolts and check clearance per manufacturers specs ie- briggs or generac.
The oil alert sensor was a good suggestion and while your at it look for any wires that may be chaffed and arcing especially prevalent during engine vibrations.
Their are so many variables to consider that it could be alot of different scenarios to consider, but I would have to say that it is an engine problem and not a generator problem ( unless the rotor stopped suddenly and caused the flywheel key to shear , then you are looking at an out of time engine and that would explain the low power output at idle.
Hope my thoughts on your situation can be of some benefit to your dilemna, Good Luck JIM

[Fred M.]

The 3500XL uses a Generac-Nagano GN-190 engine (6.5 HP, 190 CCs). The service info in 0c1103a.pdf, applies to several models of the GN-series of engines.

The idle feature has a solenoid that drops engine speed to where the carburetor's mechanical stop is adjusted. Yours might be set too low. Adjust it for 2280-2400 rpm (38 to 40 Hz), per page 5-1 of 0c1103a.pdf. Of course this assumes that the engine is running properly.

Airhead may be on to something. My generator had a problem, probably from the factory, that turned out to be misadjusted valve clearance. In my case, the generator would run OK but wouldn't deliver full power. With valve clearance corrected, it barely meets specs!

Fred