Please help

[Swage33]

I have a 17.5 hp B&S intek ohv on my 42" mtd riding mower. So far I have replaced the battery, solenoid, spark plug and have also had the starter rebuilt. I'm getting fire to my plug, the exhaust is clear but when I try to start it all it does is backfire through the air intake. Why is it doing this and what can I do to fix it?

 

[Phil G]

I have a 17.5 hp B&S intek ohv on my 42" mtd riding mower. So far I have replaced the battery, solenoid, spark plug and have also had the starter rebuilt. I'm getting fire to my plug, the exhaust is clear but when I try to start it all it does is backfire through the air intake. Why is it doing this and what can I do to fix it?

Have you got a model code and type code? all it does is backfire through the air intake
Has to symptons of a sheard flywheel key or sticking inlet valve. What's the compression like?

Did it stop in use?

Good luck, Phil :smile:

 

[mechanic mark]

FAQ | Lawn Mower Safety Tips | Briggs & Stratton


Results

 

[Swage33]

model 31G777, type 0172 E1, code 090601ZA. No, didn't quit in use, I was able to start it a few weeks ago by jumping over the solenoid. When it stopped cranking at all I feared I burned up my starter so I had it tore down and checked out...the guy said there was nothing wrong with it. SO...new battery, solenoid, spark plug...it cranks now from the keyswitch but it wont start. I did notice something when I had the cover off of the engine...when cranking, the engine blew air out through the air intake....could I be cranking backwards?

 

[pugaltitude]

Compression related component has failed.

Head gasket or valves.

Any oil in intake?

 

[Swage33]

no, no oil in intake

 

[pugaltitude]

Starter motor wouldnt allow to turn backwards as pinion would not engage flywheel unless its seized in engage position.
Start by removing rocker cover and inspecting valves and push rods and checking valve clearances https://www.google.co.uk/url?sa=t&s...wQFjAA&usg=AFQjCNEjPDkxPVZBZvd9OX_uIqlaL9Pc5w

 

[nfk]

Could also be compression release not operating properly

 

[Fish]

Just remove the valve cover and tell us what you find....

 

[mechanic mark]

model 31G777, type 0172 E1, code 090601ZA. No, didn't quit in use, I was able to start it a few weeks ago by jumping over the solenoid. When it stopped cranking at all I feared I burned up my starter so I had it tore down and checked out...the guy said there was nothing wrong with it. SO...new battery, solenoid, spark plug...it cranks now from the keyswitch but it wont start. I did notice something when I had the cover off of the engine...when cranking, the engine blew air out through the air intake....could I be cranking backwards?

Adjust valves per manual.