HRX2172hxa starting and surging help needed

hjbreese2

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I'm new here, but not new to working on lawn mowers. I have not worked on many Hondas. Most of my experience is with Briggs and Stratton engines. I tried searching for the symptoms this mower is having, but only found threads where the problem was addressed from a "old equipment" type viewpoint. I have replaced a lot of the parts which could cause surging issues with new, genuine Honda parts.

I have a Honda HRX2172HXA. All of the parts I just replaced are genuine Honda parts. I flushed the gas tank, put in new, fresh, gas, replaced the carburetor (all springs and linkages are in their correct locations), all carb gaskets, changed the spark plug (checked the gap at .031), checked the magneto gap, changed the oil, and replaced both cutting blades. I have a new air filter. I have not installed it yet because of the surging issue.

I don't know if the starting and surging issues existed before I started working on the mower. When the mower was brought to me the gas tank was dry, the oil needed changed, the spark plug had a lot of black coloration on it (not clogged or burnt, but discolored), the bottom of the carburetor had a reddish film leaking out of it, and the cutting blades were beat up really bad. The mower had been sitting idle in an outdoor shed for over a year without being started. I was told that when the mower last ran, and that the engine seemed to run a little slow. He could not remember if the mower ran "well" before storing it. No, he did not treat the gas before storing it.

I took apart the carburetor to see what condition it was in. There was a clear, gelatinous buildup in it, the bowl gaskets were dried out, and there was some corrosion in the float bowl. I decided that for $16 for a genuine Honda carburetor, versus about $10 for bowl gaskets, it was not worth trying to rescue the carburetor, so I ordered a new one with all 4 new gaskets (all the gaskets between the intake port to the air filter housing.) I changed the carburetor & gaskets, oil, cutting blades, and the spark plug after receiving the parts.

The engine will not start without using a tiny shot of starting fluid whether the engine is hot or cold. When I do give it a little shot, it starts right up, but it surges horribly about once every 1-2 seconds no matter what position the throttle is set to. There is no smoke from the exhaust, and no pungent smell from the exhaust. When I engage the blades, the engine smooths out for the most part but still surges. If I run the engine for several minutes to make sure it is warmed up and shut the engine off, it will not start again without the aid of starting fluid. I removed the engine shroud and made sure that all the gaskets are aligned properly and did not "slip" out of position during their installation. All linkages and springs are clean, move freely, and do not appear to be stretched.

We have had a LOT of rain recently, so I have not been able to try and cut any grass with it yet, so I don't know how it performs when cutting grass yet.

Have any of you seen this issue? If you have, please tell me what you did to fix it.
 
Last edited:

shiftsuper175607

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Sep 11, 2013
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I'm new here, but not new to working on lawn mowers. I have not worked on many Hondas. Most of my experience is with Briggs and Stratton engines. I tried searching for the symptoms this mower is having, but only found threads where the problem was addressed from a "old equipment" type viewpoint. I have replaced a lot of the parts which could cause surging issues with new, genuine Honda parts.

I have a Honda HRX2172HXA. All of the parts I just replaced are genuine Honda parts. I flushed the gas tank, put in new, fresh, gas, replaced the carburetor (all springs and linkages are in their correct locations), all carb gaskets, changed the spark plug (checked the gap at .031), checked the magneto gap, changed the oil, and replaced both cutting blades. I have a new air filter. I have not installed it yet because of the surging issue.

I don't know if the starting and surging issues existed before I started working on the mower. When the mower was brought to me the gas tank was dry, the oil needed changed, the spark plug had a lot of black coloration on it (not clogged or burnt, but discolored), the bottom of the carburetor had a reddish film leaking out of it, and the cutting blades were beat up really bad. The mower had been sitting idle in an outdoor shed for over a year without being started. I was told that when the mower last ran, and that the engine seemed to run a little slow. He could not remember if the mower ran "well" before storing it. No, he did not treat the gas before storing it.

I took apart the carburetor to see what condition it was in. There was a clear, gelatinous buildup in it, the bowl gaskets were dried out, and there was some corrosion in the float bowl. I decided that for $16 for a genuine Honda carburetor, versus about $10 for bowl gaskets, it was not worth trying to rescue the carburetor, so I ordered a new one with all 4 new gaskets (all the gaskets between the intake port to the air filter housing.) I changed the carburetor & gaskets, oil, cutting blades, and the spark plug after receiving the parts.

The engine will not start without using a tiny shot of starting fluid whether the engine is hot or cold. When I do give it a little shot, it starts right up, but it surges horribly about once every 1-2 seconds no matter what position the throttle is set to. There is no smoke from the exhaust, and no pungent smell from the exhaust. When I engage the blades, the engine smooths out for the most part but still surges. If I run the engine for several minutes to make sure it is warmed up and shut the engine off, it will not start again without the aid of starting fluid. I removed the engine shroud and made sure that all the gaskets are aligned properly and did not "slip" out of position during their installation. All linkages and springs are clean, move freely, and do not appear to be stretched.

We have had a LOT of rain recently, so I have not been able to try and cut any grass with it yet, so I don't know how it performs when cutting grass yet.

Have any of you seen this issue? If you have, please tell me what you did to fix it.

You have an air leak at the deflector plate between the carb and the engine.
you have the motor
then a gasket
then a plastic spacer
then a gasket
then the carb

spray some WD40 using long red nozzle to carefully direct flow at engine area each side of plastic spacer...if surging stops...replace gaskets with new.

I had to put a bit of form a gasket maker also...seems plastic can warp
 

hjbreese2

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Joined
Sep 23, 2018
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You have an air leak at the deflector plate between the carb and the engine.
you have the motor
then a gasket
then a plastic spacer
then a gasket
then the carb

spray some WD40 using long red nozzle to carefully direct flow at engine area each side of plastic spacer...if surging stops...replace gaskets with new.

I had to put a bit of form a gasket maker also...seems plastic can warp

Thanks for the advice.

I removed the carburetor and reinstalled it without the filter housing temporarily so that I could get to where you are talking about with the engine running (I had to fashion two spacers using a couple of nuts that the bolts would slide through so the bolts would not bottom out.) I started the engine and sprayed some carburetor spray through a red straw around the carburetor insulator. I did find a spot where the engine ran very smoothly for a few seconds. I know this means I found the air leak. I don't know if the insulator gasket, the insulator, or the air guide is the culprit, so I guess I'll just replace all 3 pieces. Since I already replaced both the insulator gasket and the air guide, I am assuming that the plastic insulator is what is causing the leak. It's about $6 for all three. I may get extra gaskets since they are all so cheap.
 
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