Briggs 17.5 hp running lean & hot

Hello, Just like to say You's have a Great Forum Here..
I have a Briggs 17.5 hp. Mod. 31C707 Type 0026G1 Code 080205ZD that I replaced for the original 10 hp. in my Simplicity Cavalier (rear engine rider) 8 yr.'s ago. It always ran great, until breaking the Alum. Intake push rod that wore thru at the rod giude. It was at that time just ideling in my driveway to warm up when it broke (see photo) I repalced Both push rods, rocker arms & adjusters (being that they weren't pricy) I checked guide plate But found No wear ?? that was strange... So I set the Valve lash (.004 In. ~ .006 Ex.) It started right up & sounded Great in slow & fast & while mowing. But after about 25 min.'s it started lose power/stumbling then would stall. Thats when I notice it was running alot Hotter that usual & the plug showed it running very lean. I've seen alot of the previous post here about the broken push rods & ones that ran for 20 min.'s got hot & after it cool ran good but the getting hot cycle would repeat. (that one was solved when the carb. was replaced.) I did remove my carb. to inspect & clean it But found no obvious problem with it & reinstalled it ..yet to be tested running it. My question is do you think it's a carb. problem as it was in the previous post. I was about too pull the head supecting valve problems. I'm cocerned it's going to over heat & sieze up next. What do you think, Is this Lean/Hot condition common & related to the carboration ?? Do I have (2) unrelated problems a the same time? (broken push rod & carb. issues).....It would be NICE to Hear it's just the carb. to save me from futher inspection & unneeded disassembley...
I also used a compession test gauge, that acheived 85 P.S.I after 4 cycles

Has it got a Walbro or Nikki carb, try a richer mix if you can, also check the cooling take off the cover see if its clean under there to let air flow.

Hello & Thanks for your reply Engineman, It was the Walbro LTM # 1497 697203 I only see the (1) idle Mixture adjustment scew on it's top that was set to mid range between the (Turn Right stumble /Turn Left stumble) Under cowl was clean nothing blocking the air flow. I blew out a lot of dust from under the flywheel thou.
My concern is that it running Hot & Lean is a new condition.

We had a similar issue not long just like this..... I forgot the name of the guy, but he took the air shroud off and started the engine the air vane on the fly wheel wasn't turning.... So no air flow at all.........

Hope this helps .........

Let us know Mon Ami ~!~!

Boudreaux In Eunice La. said:

We had a similar issue not long just like this..... I forgot the name of the guy, but he took the air shroud off and started the engine the air vane on the fly wheel wasn't turning.... So no air flow at all.........

Hope this helps .........

Let us know Mon Ami ~!~!

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Hello & Thanks Boudreaux in Eunice for your help. Unfortunately my fan is well attached to the flywheel & it makes alot of air flow. I'm going to try to use the machine soon & see if the problem remains, if so I'm going to work on the Carb. Again...

Hello EngineMan & Boudreaux In Eunice La. & THANK YOU FOR YOUR HELP !!
UPDATE on my "running lean & stalling prob. It's was hard for me to solve this one, But I did seem to resolve this issue, & thought I 'd let you guy's know what I've discovered. Just the background info. This engine was swapped in to replace the orig. 10 Hp. 11 yrs. ago with No running/ fuel issues. The problem I found was it was running out of fuel At 3/4 of a full fuel tank now !! Yep, I pull fuel line prior to filter when it stalled out. (no Fuel) being the carb. location to fuel supply is higher now than the old 10 hp.. This is what got me on the right track.... Thou it was running the tank dry previously?? I can only "assume" it was siphoning it somehow to run the tank dry.... The Carb. must have started venting to end the siphoning....So it really wasn't running lean, per sa. But leaned out do to lack of available fuel. I found it baffling at the time...being that it Never had that prob prior. So Now I have to fill tank prior to it's 3/4's (run out)level. Now it runs great once more!! (tho I have the "new issue " of a low fuel available capacity) I can feel safe running the machine now that I found out that I wasn't a Major running lean Carb. prob. after all. Have you ever heard of such a problem like this ?? Not me, It' a first. I'm glad I was able to figure it out & cut that grass again w/out worrying about blowing it up.
Thanks Again.
Regards,
Briggs 17.5

Thanks for letting us know..:thumbsup: yes tank should be above carb unless you have a pump..!

EngineMan said:

Thanks for letting us know..:thumbsup: yes tank should be above carb unless you have a pump..!

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Hello Engineman & Thanks for your reply! Yes, I agree, But don't you find it a bit Strange that it was running the gas tank empty for 10 yr's ....Then all of a sudden it just started to starve for fuel (at 3/4 of a full tank) recently ?? Yep, I'm considering adding a pump to get back to using it's full tank capacity. But as I said, I'm Glade I can still use the mower safely for now. Thou I can only cut 95 % of my Grass till I have to add fuel to finish (So.. Close) Lol. It's really limited it's run/use time if I had bigger jobs the way it is Now Unfortunately thou.