HRX217HYA Backfire through Muffler

[HONDA-GUY]

Ok need some help here. I recently had my Honda HRX217HYA mower in the shop which ran fine with no problems other than a clip director issue. The local Honda dealer had to replace the clip director door along with some other pins and clips that were loose causing my issue. I got it back from the shop after about 3 weeks brought it home started right up, cut the front yard and had no issues. Stopped mower to refuel and when I pulled starter rope there was a backfire and black smoke that came out the muffler. Mower started and ran smoothly indicating no issues. I shut it off again after about 15 minutes and started it up and same thing happened. So I let it run for couple of minutes, shut it off, started it no backfire so I cut the side yard shut mower off to take it into backyard pulled rope and it backfired, small puff of black smoke but started and ran fine. I'm not sure how involved it is to replace the clip director parts, is it possible that they had to pull the motor off the deck to do so and in doing so the timing is somehow incorrect? The mower is still under warranty but I don't want to have to put it back into the shop if its something simple. I have not hit any roots, sticks, rocks or otherwise with it so I don't think it could be a flywheel key or anything of the sorts. It only backfires when cord is pulled and engine is starting up. Does not do it when shutting down and it runs smoothly in between. It sounds like it might have a miss here and there while idling but not sure if that's related. Mower was purchased in April of this year so is still pretty new. Any help and advice would be greatly appreciated!

 

[HONDA-GUY]

For some reason thread posted twice my apologies. Was having internet connection issues at time of posting.

 

[robert@honda]

Backfiring happens though the exhaust OR intake. In most cases, it's the exhaust, on an engine like this, with a "lost spark" design. Each turn of the flywheel energizes the coil and fires the plug, both on compression and exhaust strokes. If the mixture is too rich, excess fuel can ignite on the exhaust stroke.

Too rich mixture can happen when the air supply is restricted:
a. engine was tipped over the wrong way and air filter is clogged with oil.
b. air filter is clogged with dirt/debris
c. choke not working properly, sticking open when it should close.


Since the mower was not backfiring before you took it in, I'd be on the dealer to make it right, especially since you are still under warranty. Might want to quiz the dealer and see what they say. Give the dealer a chance to make it right. If, like Mr. Jagger said if (you) "can't get no...satisfaction" for sure contact Honda Customer Relations at 770-497-6400. Have your mower's serial number, dealer info, etc. when you call.

 

[HONDA-GUY]

Backfiring happens though the exhaust OR intake. In most cases, it's the exhaust, on an engine like this, with a "lost spark" design. Each turn of the flywheel energizes the coil and fires the plug, both on compression and exhaust strokes. If the mixture is too rich, excess fuel can ignite on the exhaust stroke.

Too rich mixture can happen when the air supply is restricted:
a. engine was tipped over the wrong way and air filter is clogged with oil.
b. air filter is clogged with dirt/debris
c. choke not working properly, sticking open when it should close.


Since the mower was not backfiring before you took it in, I'd be on the dealer to make it right, especially since you are still under warranty. Might want to quiz the dealer and see what they say. Give the dealer a chance to make it right. If, like Mr. Jagger said if (you) "can't get no...satisfaction" for sure contact Honda Customer Relations at 770-497-6400. Have your mower's serial number, dealer info, etc. when you call.

Robert,
Thanks for the info! I pulled the spark plug and checked it out, it is pretty black on the top and electrode. There is no physical damage to the plug i.e. No cracks, bends or melting. So I'm wondering if the fuel has always been too rich and it's a coincidence that it has just started backfiring so soon after picking up from dealer. It will also only backfire when engine is warm or hot, on a cold start it just fires up like normal. Also it's not a black soot or anything just looks burnt

 

[robert@honda]

So I'm wondering if the fuel has always been too rich and it's a coincidence that it has just started backfiring so soon after picking up from dealer. It will also only backfire when engine is warm or hot, on a cold start it just fires up like normal. Also it's not a black soot or anything just looks burnt

Sounds like a normal plug. Most modern small gas engines are tuned lean to meet emissions regulations, so unlikely the engine was delivered from the factory in a rich condition. Generally, a rich condition is due to a stuck choke, blocked air cleaner, etc. Something that would reduce the airflow, but not the fuel delivery.

Again, best to get it back to the dealer and let them sort it. Be sure to communicate with them all the details, and have them discuss what is and is not warranty before work is started to avoid any surprise.

 

[HONDA-GUY]

Sounds like a normal plug. Most modern small gas engines are tuned lean to meet emissions regulations, so unlikely the engine was delivered from the factory in a rich condition. Generally, a rich condition is due to a stuck choke, blocked air cleaner, etc. Something that would reduce the airflow, but not the fuel delivery.

Again, best to get it back to the dealer and let them sort it. Be sure to communicate with them all the details, and have them discuss what is and is not warranty before work is started to avoid any surprise.

Thanks for the info Robert I'm going to contact dealer and ask them. Could it possibly be the fuel itself? Reason I'm asking is from day one I have been using tru fuel in the mower as I could not find any ethanol free fuel, I recently found some 87 octane ethanol free fuel and added that when the existing fuel ran out in the tank. So part of me is wondering if perhaps the fuel is the culprit. It doesn't backfire at all on cold start and when warm it only does it every so often like maybe every 5th-10th pull. I let engine warm up for 5 minutes shut it down then restart let run and repeat process to see how often it is doing it. Then again if something is "stuck" fuel wouldn't necessarily matter.

 

[robert@honda]

Could it possibly be the fuel itself?

Maybe. Easy enough to drain, flush and refill with for-sure fresh fuel.

It doesn't backfire at all on cold start and when warm it only does it every so often like maybe every 5th-10th pull.

Reproducible backfire when cold does lean (pardon the pun) to a choke-related problem.

 

[HONDA-GUY]

Backfiring happens though the exhaust OR intake. In most cases, it's the exhaust, on an engine like this, with a "lost spark" design. Each turn of the flywheel energizes the coil and fires the plug, both on compression and exhaust strokes. If the mixture is too rich, excess fuel can ignite on the exhaust stroke.

Too rich mixture can happen when the air supply is restricted:
a. engine was tipped over the wrong way and air filter is clogged with oil.
b. air filter is clogged with dirt/debris
c. choke not working properly, sticking open when it should close.


Since the mower was not backfiring before you took it in, I'd be on the dealer to make it right, especially since you are still under warranty. Might want to quiz the dealer and see what they say. Give the dealer a chance to make it right. If, like Mr. Jagger said if (you) "can't get no...satisfaction" for sure contact Honda Customer Relations at 770-497-6400. Have your mower's serial number, dealer info, etc. when you call.

Robert,
Do you know if the engine needs to be removed from mower to repair/replace the clip director?

 

[robert@honda]

Robert,
Do you know if the engine needs to be removed from mower to repair/replace the clip director?

All the Clip Director parts can be R&R (removed and replaced) without engine removal.