Why, oh betrayer generator, won't you start?!
May 2, 2011 1:22 PM   Subscribe

Help me get my Generac GP3250 generator started.

I foolishly let the generator sit all winter without adding fuel stabilizer. A couple of weeks ago, I started it up, it ran rough for about thirty seconds before sputtering out. Realizing my mistake, I drained the fuel, added in fresh gas and tried again, but it was a no-go.

The instructions indicate that it has a low oil sensor and will shut off the engine if it detects that as an issue, so I drained and replaced the oil, but that didn't solve the problem.

I cleaned the sparkplug, but that wasn't it, so I replaced it. That didn't get it either.

If I add gas directly to the spark plug chamber, it will run for a few seconds before the gas supply in the chamber is depleted, so I thought it might be a problem with the fuel line, but I removed that and it is unobstructed.

The generator is basically new; we bought it last July and it ran over one eight hour period and then was stored, so I doubt wear and tear would be the issue. And at this point, I think I've exhausted my ability to troubleshoot. The fact that it runs, even for a few seconds, leads me to believe that the reason it's failing is that it isn't getting gas from the tank, but I can't find any reason for that to be the case.

This askme is the last step before I just say "to hell with it" and bring it in to a service and repair shop, but I figured it'd be worth a shot to query the green first.
posted by quin to Home & Garden (11 answers total)
Sounds like you're on the right track. I'm not familiar with this generator, but I'm guessing it's basically the same as a lawnmower engine. Have you dropped the bowl off the carburetor to see whether gas is getting to it? Is there a gas shutoff valve that's in the wrong position?
posted by jon1270 at 1:29 PM on May 2, 2011

Response by poster: I haven't taken apart the carburetor, mainly because I suspect I'd make things worse before I made them better, but the fuel shut-off valve is definitely open.

Oh, and the generator is in the "on" position. I made sure of that as well.
posted by quin at 1:33 PM on May 2, 2011

If it has a fuel filter, check to make sure that it isn't waterlogged or otherwise obstructed.

If it has a carburetor, the contents of the fuel bowl in the carb may be polluted with water/bad gas. Draining that would be my next move. And be careful you don't mess up the float if it has a carb.
posted by mosk at 1:40 PM on May 2, 2011

Would you confirm that this model has a Tecumseh engine? If it's a Tecumseh, you will find that taking off the fuel bowl exposes the main jet - the bronze hex nut contains the jet. There will be one or two holes in the tubular extension of the nut and these have to be clear. Between that and a stuck fuel valve (the valve that the float actuates) you've got 95% of what goes wrong with Tecumsehs.
posted by jet_silver at 1:42 PM on May 2, 2011

Best answer: agree with jet_silver. Get yourself a can of spray "carb cleaner", pull the bowl off the carb, and liberally spray the jet with with cleaner. The gasoline has turned to lacquer in the small channels in the carb. To prevent this in the future, always use fuel additive. In addition, I burn premium in all my small engines because the lower-grade fuels with ethanol in them tend to break down much faster.
posted by cosmicbandito at 1:47 PM on May 2, 2011 [1 favorite]

Best answer: Not winterizing the gas as you let it sit has caused a blockage somewhere in the fuel system. If starting it by putting gas directly into the cylinder hasn't sucked the gas through the system, the next step is to pull the carb and clean it.

Given the cost of a generator, I would take it into a small engine shop and have them do it. You'll pay less than $100 (depending on if they need a carb kit, new gaskets, etc or not).

It's a good idea to ALWAYS keep stabilized gas in a generator, they are often not used on a regular basis.
posted by tomswift at 1:47 PM on May 2, 2011

Every one has pretty much straightened it out. You have spark, you have compression, but gas is not getting to the spark.. You've checked the various dead-man switches, and the lines, so, yeah, next up would have to be the carb.
posted by k5.user at 2:03 PM on May 2, 2011

Best answer: I should add, unlike my roto-tiller, but very much like my weed whacker, I have to leave my generac generator on full choke for a decent amount of time to really warm up. If I back off the choke too soon, it will stall.

Since you said it ran 30 secs before you did anything, that's usually a good sign -- I "kill" my generator after using it by turning the gas shut-off and letting it run out of the last bit of gas that remains. That way, no gas (in theory) is left behind to do bad stuff to the carbs etc.
posted by k5.user at 2:09 PM on May 2, 2011

I've had to deal with gummed-up motorcycle carbs before. Pulling off the bowls and using carb cleaner is a good idea, but if you're not comfortable with that, you can also try putting a double (or triple) dose of fuel stabilizer in, cranking it for a little bit, letting it sit for a day or two, then trying it again. The fuel stabilizer should do the same thing that the carb cleaner would do, and if your problem isn't super-severe, it might be all you need.
posted by aaronbeekay at 3:12 PM on May 2, 2011

I have a Generac generator (5500 something) that had a similar problem a few years ago.

The problem ended up being the low oil sensor switch. I can't remember if I hard-wired it, or disabled it somehow, but I know I did something with the oil sensor switch & haven't had problems with the generator since. And this was after I did all the carb & fuel line things that you're doing now -- with no success.

And of course, I always check the oil when I fill it up w/ fuel.
posted by bricksNmortar at 5:07 PM on May 2, 2011

Response by poster: Update: After confirming that the fuel lines were indeed all clear, I pulled the bowl off the carburetor and hit it with a combination of compressed air and carb-cleaner, which worked, but caused the float switch to stick a bit and gas to come out too quickly. Another round of carefully administered carb-cleaner seemed to find whatever wasn't closing and now the generator seems to be running pretty well.

So thanks everyone.

I also really appreciate the suggestions which are going to help me in preventing thus from happening again.
posted by quin at 1:29 PM on May 23, 2011

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