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Honda GC190 backfiring through carburator won't start


Bogspores's Avatar
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04-15-07, 09:21 PM   #1  
Honda GC190 backfiring through carburator won't start

I've got a Northern Tool (NorthernStar) 2700psi pressure washer with a Honda GC190 engine and a Comet pump....

I've had the unit for 3 years, and haven't had any issues whatsoever, until today...

I last used the unit 2 weeks ago, and it was working fine when I shut it down...

Today, when I attempted to start it, I notice it was backfiring (TRUE BACKFIRING, THROUGH THE CARB, NOT THE MUFFLER) on each pull....I started troubleshooting, and here's what I have so far...

Fuel tank - FULL, FRESH GAS
Spark Plug - Worn, but producing a SOLID SPARK
Air Cleaner - CLEAN
Oil - FULL

After several pulls, and hearing the backfire, I figured the engine was flooded...I pulled the plug, and sure enough, it was soaked with fuel...No problem, I dried it off (with a quick blast from a mini-torch) and cleaned it up with some emery paper, regapped and set aside....I pulled the cord several times to vent the cylinder of excess fuel, then dried the cylinder with my mini-torch (burning off remaining fuel)...I reinstalled the plug, and tried starting again...

Once again, the engine began backfiring on EVERY PULL, through the CARB...I've heard people refer to "backfiring" but they are usually describing the pop heard from excess fuel in the muffler...

My engine is truly "backfiring" through the CARB....not the muffler....I can see wisps of smoke and see excess fuel in the air cleaner housing while I'm pulling the cord...I pulled the air filter cover and filter out, to observe the backfiring directly...

I continued to trouble shoot for at least another 2 hours, before giving up....

This one has me stumped!...

The engine acts like it's flooding, so I held the throttle WIDE OPEN during the starting process...Again, more backfiring, but no start....

I varied the choke setting throughout the entire range while pulling, with no success...

It's almost as if the intake valve may be stuck open, allowing the combustion event to flow back through the carb....this is just a guess, but about the only thing I can come up with...I attempted to pull the OHV cover, but gave up, when I couldn't get the sealant to let loose of the cover...

I've ordered a new carb for 25.00 and hope to have it installed Wednesday, so I can try and see if the carb is the culprit...(yeah, I'm lazy, and figure the $25 is cheap compared to cleaning the carb!)....

Up until today, the engine has performed well, except for "surging" while at idle....Under load, it runs strong...

I'm open to any and all suggestions for getting this engine up and running again...

Please help!...

Thanks in advance for helping me out...

 
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cheese's Avatar
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04-16-07, 12:41 AM   #2  
I believe you hit on the problem when you mentioned the intake valve being stuck open. I might try a new plug first, just to eliminate it (a plug can spark nice and pretty and still be bad)...but unless the carb is flooding really bad, I think you'll find the problem when you remove the valve cover.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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04-16-07, 12:40 PM   #3  
Thanks for the speedy reply!....

Yeah, I'm hoping the valve isn't stuck open (or not closing properly) since this will be a repair beyond my skills....

I'll follow your suggestion, and pick up a new plug, just to eliminate it...

Thanks again!...

I'll repost if I get it fixed and running....

 
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04-16-07, 08:53 PM   #4  
If the plug doesn't do it, go ahead and pop off the valve cover. You might see the problem there.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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04-17-07, 06:26 PM   #5  
Success!

Woo Hoo!......SUCCESS!.....

I pulled the valve cover off, and immediately saw the problem....

The intake valve was stuck open, just as we thought!....

I got a pair of pliers, and carefully pulled it closed, then worked it up and down a few times to ensure it wasn't binding....It seems to move smoothly, which makes me wonder why it stuck open in the first place?...

I put the cover back on, and it fired up on the FIRST pull.....

Thanks again for the help on this one!....

Glad to be a member of this site!...

(Now I've got an extra carb if anybody needs one!)

 
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04-17-07, 08:50 PM   #6  
Glad you got it! I don't know why it would have stuck like that. Sometimes if an engine is VERY hot when it gets shut down, I suppose oil can cook around the valve stem and help it stick. Also if water got in the intake while it was sitting unused, it could rust the valve in place. The fact that it was surging at idle last time you used it makes me wonder if maybe there isn't a little water in the bowl of the carb. It also might mean the engine was hotter than usual when you shut it off last time, since it was running a bit lean. The leaner an engine runs, the hotter it runs.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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04-17-07, 08:56 PM   #7  
You're probably right about the water in the intake, rusting the valve stem....

We had a big storm blow through here recently, and the engine was stitting on the front porch, unprotected in the rain and wind....I thought it was up far enough to prevent exposure, but that wasn't the case...

Now, I'd like to fix the "surging" issue....it's not really that bad, but annoying to hear...

Thanks again for all the help!...

 
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04-17-07, 09:00 PM   #8  
Surging is usually an indication of a lean fuel mixture (carb restriction). Unless...the surging on this is actually the engine revving up and down due to an unloader valve problem. Does the pressure hose jump a little in time with the surging?


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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04-18-07, 07:17 AM   #9  
I haven't noticed the hose pulsation along with the surge, but it most certainly could be....I'll have to pay closer attention the next time I use it...

I may try and richen the mixture a tad, just to see if the surge goes away...

 
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05-13-10, 03:43 PM   #10  
I got the same thing

Just got one in the shop. It has a bent exhaust rocker arm. Engine timing is good and no bent valves. Pop the valve cover and take a look.

 
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05-24-10, 07:24 PM   #11  
Honda mower:
HRR2163TDA GD
MZCG-7287618

Intake valve was stuck open, exhibiting same symptoms as original post in this thread. I wash the mower after every use as well as let the carb run dry before putting away. Maybe I got a little over zealous with the water hose?

I thought I had a bad gas problem and added an inline filter as well as new spark on top of cleaning out the carburetor and lines before it dawned on me why the intake was constantly backfiring.

I was able to remove the rocker, pin, valve spring keeper and spring by hand and then used pb blaster, a brass hammer and needle nose pliers to work the valve free. I also removed the seal around the valve stem and cleaned the inside. After working the valve in and out and coating in penetrating fluid (pb blaster) it moved up and down freely and rotated freely with my finger tips.

I am waiting for the RTV on the valve cover to dry overnight. I'll try it out in the morning and report back. I'll post pictures soon too.

 
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