Generac 5000w generator with B&S engine

[lakelover]

Mid-December, my generator wouldn't start (10 hp B&S engine). It's 14 years old and probably has less than 50 hours on it. I took it locally to a guy with 25 years small engine experience, and he ended up replacing the fuel filter and carburetor.

Now it starts up pretty good, but really stumbles a lot until it's warmed up. As I adjust the choke, it seems to take several seconds (5-10?) until it smooths out and I can tell whether it either needs more adjusting or it's in the sweet spot. The choke has 4 settings, and it seems to run best, once it warms up, on the first notch-next to the choke "off" position. It's about 30? out today.

When it would start before I took it in, I had to run it on full choke to keep it running. The guy noted on the repair receipt that it "surged" until it warmed up, but to me it seems more like it's stumbling. The spark plug is new.

What would cause that? I was thinking of de-carbing it with Sea Foam because it's probably carboned up from running on full choke previously. Think that might help? I'm going to try it hooked in to the transfer switch this afternoon to see if it runs OK as loads are switched on and off.

 

[rbh]

Re: Generac 5000w generator with B&S engine

Old fuel in the carb possibly partially gummed up a passage or two, governors sticking.
Run it under partial load, then full load, then partial load.

Just let it work hard, gennys carbon up over time, the harder you can run it the cleaner it will be.

 

[lakelover]

Re: Generac 5000w generator with B&S engine

Old fuel in the carb possibly partially gummed up a passage or two, governors sticking.
Run it under partial load, then full load, then partial load.

Just let it work hard, gennys carbon up over time, the harder you can run it the cleaner it will be.

Thanks, rbh. I tried running under varying loads and it went well, no appreciable variation caused by the load switching. It seems you're saying to exercise the governor - would it serve the same purpose to spray repeated spurts of Sea Foam into the carb so it slows down and recovers? I have the cylinder soaking now.

I don't use the gen. much, just for power outages. Now that it's running again, I'm going to have a schedule of running it for a while every week. It's a "semi-permanent" installation. For use, I run the power through a basement window about 3' away to the transfer switch.

 

[bigdee]

Re: Generac 5000w generator with B&S engine

Thanks, rbh. I tried running under varying loads and it went well, no appreciable variation caused by the load switching. It seems you're saying to exercise the governor - would it serve the same purpose to spray repeated spurts of Sea Foam into the carb so it slows down and recovers? I have the cylinder soaking now.

I don't use the gen. much, just for power outages. Now that it's running again, I'm going to have a schedule of running it for a while every week. It's a "semi-permanent" installation. For use, I run the power through a basement window about 3' away to the transfer switch.

View attachment 221633

My generators ( I have 3) all act this way under no load when first started especially in cold weather. After it runs for about 5 minutes it gets better and there is an adjustment on the air filter intake that allows it to be moved close to the heated muffler.
Also the idle adjustment screw is critical to prevent surging under no load. Yes even though the generator does not actually run at idle speed "no load" is considered idle and the idle mix adjustment screw controls surging.

 

[dolluper]

Re: Generac 5000w generator with B&S engine

Run it with some stableizer till the next time it's needed will save you headaches......governor will only control max speed

 

[Tim Frank]

Re: Generac 5000w generator with B&S engine

Sounds like you need carb. work by someone that knows their stuff.

Now why didn't we think of that?

I took it locally to a guy with 25 years small engine experience, and he ended up replacing the fuel filter and carburetor.

I know. Maybe find a guy with THIRTY years small engine experience.

Just out of curiosity, was it colder than usual in December in your neck of the woods?
It was colder here in December than I can say in DSC....and every small engine I run struggled a bit.
You aren't very far south of me.

 

[bigdee]

Re: Generac 5000w generator with B&S engine

My generators ( I have 3) all act this way under no load when first started especially in cold weather. After it runs for about 5 minutes it gets better and there is an adjustment on the air filter intake that allows it to be moved close to the heated muffler.
Also the idle adjustment screw is critical to prevent surging under no load. Yes even though the generator does not actually run at idle speed "no load" is considered idle and the idle mix adjustment screw controls surging.

I found this article that describes more in detail of what I was trying to get across in my previous post.

?At no load, the low speed jets come into play ? these are the first to get plugged with varnish when gasoline is allowed to set for long periods and dry out. When the load drops off on your generator and the throttle closes down, the low speed jets need to feed enough gasoline to keep the engine running smoothly. If they?re plugged and can?t provide enough fuel, the engine begins to stall. As the speed of the engine drops, the governor opens the throttle and high speed jets take over. The engine speeds up above the governor setting and the governor backs off the throttle again to where the low speed jets cause the engine to stall again ? this oscillation continues until more load is applied or you shut it down in disgust.?

 

[MH Hawker]

Re: Generac 5000w generator with B&S engine

run it awhile with sea foam in the gas that will finish cleaning it out.

 

[lakelover]

Re: Generac 5000w generator with B&S engine

Just out of curiosity, was it colder than usual in December in your neck of the woods?
It was colder here in December than I can say in DSC....and every small engine I run struggled a bit.
You aren't very far south of me.

December was definitely colder, but this problem has been coming on for a long time. It got harder and harder to start, and I pretty much knew it was from neglect. There were probably periods up to a year over its life where it sat without running. And no preventive measures, in fact you might even call the neglect abusive!

The gas was stabilized, but still pretty old. I only began a regular starting routine last summer. I know, I know, smart, eh?

When it was being worked on, the first carb they ordered was defective, and they had to send it back and get a second one, which worked.

By the time I was done fooling with it yesterday, I was pretty well satisfied. I had sprayed about 1/3 can of Sea Foam thru the carb as it ran, and put some Sea Foam in the gas tank too. I'm going to get another can of spray and repeat the process, it can't hurt.

 

[mla2ofus]

Re: Generac 5000w generator with B&S engine

Cheapest and best mod to a genny engine is an inline gas valve. Close the valve and let it run 'til it dies.
Mike

 

[Fishing Dude too]

Re: Generac 5000w generator with B&S engine

Cheapest and best mod to a genny engine is an inline gas valve. Close the valve and let it run 'til it dies.
Mike

Both my genny's have this. The old one had rubber grommet that went bad in tank along with hose filling carb with rubber slim.

 

[lakelover]

Re: Generac 5000w generator with B&S engine

Cheapest and best mod to a genny engine is an inline gas valve. Close the valve and let it run 'til it dies.
Mike

It has a valve at the bottom of the tank, I'll start doing that.

Having a genereator that doesn't start is the same thing as not having a generator. Like the old saying, "if you don't have a dog that comes when you call it, you don't have a dog".

 

[rbh]

Re: Generac 5000w generator with B&S engine

As I had mentioned carboning up is an issue "Over Time".
We have a 4.0onan CCK that runs the manlift on our bucket truck it would run 7.5 hours a day 5 days a week+- and over a short period of time it started running really poorly and died, we did a compression test and there was no compression so we replaced with a spare we had.
Tore it down and got 1/8 cup of carbon/guck out of each cylinder, (cleaned up the valves and seats/piston face and head) and put it back together.
It started right up and I believe we had around 110+- PSI on the compression.

 

[arks]

Re: Generac 5000w generator with B&S engine

The gas was stabilized, but still pretty old. I only began a regular starting routine last summer. I know, I know, smart, eh?

Get in the habit of draining the fuel twice a year. I do it spring and fall. It gets used in the mower so it's not wasted. Use Stabil of course!

 

[lakelover]

Re: Generac 5000w generator with B&S engine

Get in the habit of draining the fuel twice a year. I do it spring and fall. It gets used in the mower so it's not wasted. Use Stabil of course!

Since I figure on starting it every week & running for a while, I'll only put in a gallon or so at a time, so it will always be getting refreshed. I use Stabil in everything but my boat gas, which doesn't sit around for long!

 

[cajun1]

Re: Generac 5000w generator with B&S engine

Try checking the oil level with the dipstick unscrewed, I know that doesn't sound right but came from the generator tech guys. If you check it screwed in you are running around the low oil shut down.

 

[lakelover]

Re: Generac 5000w generator with B&S engine

Thanks, oil level is good. Mine doesn't have a dipstick, but a cap. The oil is right up to the level that's specified in the manual. I had a time in the past where it wouldn't start, and low oil level was the problem. I was surprised how little it was down too. Topped it up and that took care of it that time.

 

[Boomyal]

Re: Generac 5000w generator with B&S engine

I have a Coleman 5500w generator that I use about every 3-4 weeks. I have had it since 2003. It has a huge gas tank in relation to how often and how much I use it so the gas stays in it for at least two or so years. I only ever fill it with stabilized non-ethanol premium. I have never had an issue with it.

I believe with decent stabilized gas that you are better off leaving it wet, than running it dry. As I do not like to have to repeatedly pull the starter rope, I always give it a quick squirt of starter fluid before I fire it off. It always starts on the second pull. Even in the cold of winter I can barely get the choke off before it wants to start sputtering.

 

[Boomyal]

Re: Generac 5000w generator with B&S engine

I have a Coleman 5500w generator that I use about every 3-4 weeks. I have had it since 2003. It has a huge gas tank in relation to how often and how much I use it so the gas stays in it for at least two or so years. I only ever fill it with stabilized non-ethanol premium. I have never had an issue with it.

I believe with decent stabilized gas that you are better off leaving it wet, than running it dry. As I do not like to have to repeatedly pull the starter rope, I always give it a quick squirt of starter fluid before I fire it off. It always starts on the second pull. Even in the cold of winter I can barely get the choke off before it wants to start sputtering.

Hmmmm? How did this double post happen???

 

[lakelover]

Re: Generac 5000w generator with B&S engine

Yesterday I thought I had it running pretty well. It sat overnight and I tried it again today. It took several minutes and constant fiddling with the choke to keep it running until it warmed up, and then several more until the governor stopped hunting back and forth, maybe up to 5 min.

Here's a video I made of it running after a hot restart. This is a brand new carb....idle screw is adjusted 2 full turns out from seat. I feel it used to and should run better than this.

Sorry, definitely not HD.