272xp is killing me

[cabin16]

Hello all,
Inherited a 272xp that wasn't running . No spark ended up being bad switch, changed coil and plug with oem for good measure. Set gap with business card. Bad gas cleaned out tank replaced gas line and rebuilt carb. Couldnt' find a filter locally so cleaned it in an ultrasonic cleaner and blew it out. Will not start, pulled plug seems dry.
Any suggestions would be appreciated

 

[Marshy]

Check compression and flywheel to make sure it's for a 272.

 

[kz1000]

Spin it over with a drill and see what the spark looks like, if the spark is good then add a little mix to the plug hole after you put the recoil back on and see if it fires. Good luck.

 

[Adirondackstihl]

Impulse Hose?
Not sure if the 272 has an impulse hose or a solid manifold, but impulse pressure/vacuum is another place to look

 

[Landmark]

Try it will air filter off and mix down plug hole as kz said

 

[cabin16]

Will try mix in the hole in the morning. Getting good spark, When I had the muffler off the piston looked beautiful no scoring at all. Impulse hose? Solid manifold? Not sure
Almost ready to break out the bow saw

 

[huskihl]

It's got a manifold block between carb and engine. The impulse corridor could be plugged or cracked

 

[weimedog]

DO the standard stuff... carb kit and make certain (as was said already) the pulse circuit from cylinder through intake manifold "block" to carb is clear. One place to pay attention to is the gasket between the carb and manifold block... there is a really thin area between the impulse channel and actual intake port I've seen the gasket fail there. AND if the carb is plugged internally with dirt or corrosion that can drive you nuts as well. I've also been frustrated at times with a sticky needle (sticks in the seat) in those carbs.

 

[Big_Wood]

if you reused to gaskets for the intake it could be as simple as you installing one upside down plugging the impulse passage. don't take offense to this as i don't know your level of experience but i have also seen newbs rebuild carbs closing both needles pulling and pulling wondering why it won't even fart LOL.

 

[rattler362]

If you it gets to hard on you just send it to me just kidding the guys above have gave you some good advice.

 

[cabin16]

Ah, no offense taken. The gasket between the carb and the block has a small hole either side so it doesn't appear that orientation should matter. Is there a picture or exploded view some where that shows this detail?
Thanks for all your help, this site is pretty amazing , the knowledge that is freely shared here is first rate.

 

[Big_Wood]

the one in between the intake and cylinder is the one you wanna check out. if it didn't end up that far apart another possibility is the gasket slipped out of position.

 

[huskihl]

When you rebuilt the carb, the metering diaphragm gasket goes on the carb first. Then the diaphragm. (Cant remember if the metering diaphragm sits flat on top of the needle or if theres a fork on the needle that the diaphragm sits into.) Then cover.
On the other side, the reed (or pump) diaphragm goes on first, then gasket, then the cover.

 

[griffonks]

Feed some mix into the cylinder head. Replace the spark plug. Pull the recoil choked once or twice then try it again unchoked.

If it won't bark then pull the muffler and look for scarring. Verify that the muffler is not plugged

If that's ok, verify spark at the electrode.

If that's ok check the flywheel.



Sent from my SCH-R530C using Tapatalk

 

[backhoelover]

i just had the same problem it was a bad air leak not allow enough inpulse to work pump diaphragm see if this help

 

[griffonks]

i just had the same problem it was a bad air leak not allow enough inpulse to work pump diaphragm see if this help

This is quite possible, especially at the o-ring on the pto oil pump seal.

But it should fire under prime if there's a leak.

Sent from my SCH-R530C using Tapatalk

 

[backhoelover]

i had one leak so bad one time wasnt fueling carb matter of fact i have a 272 on the bench complete rebuild
oring is 1-1/4 x 1-1/8 x 1/16 that way you dont have to pay 3 to 10 dollars for a dang o ring

 

[backhoelover]

check nozzle check valve
refer to walbro service manual

 

[Oldsawnut]

Hmm something killing me I kill it back ....Could be a lot of things... As mentioned before a little mix in the carb throat will narrow things down greatly.. Just make sure no starting fluid and not too much mix you don't want to flood it out. But you sound savy enough to know that anyhow

 

[cabin16]

Tied up with graduations this weekend, will try the mix directly into cylinder and then go from there. I'm pretty sure I did the carb rebuild properly, took some pictures and just reversed the process. The fact that the plug is dry seems to point to one of the airleak issues. I will soldier on and keep you guys posted. Thanks again for all the great information.