856 dies after 30 minutes

[pfrederi 20,659]

My neighbors 856 starts and run ok but will die after 30 minutes or so.  Sits for awhile and will restart....Problems like this are frequently brought up here.

 

Since I have a good running 856 we started by swapping coils and gas caps and spark plug cleaned the points and gapped.  it starts easy runs well but .. no go

 

Changed plastic inline filter had some crud in it.  Looked in the tank looked good didn't see any obvious pluging of the filter screen.  Replaced fuel line to carb ... no go

 

Pulled carb lots of crap inside  serious cleaning over night soak ultra sonic cleaner and carb kit.  Float was ok.  ... no go

 

What am I missing....

[adsm08 4,545]

Could be in the carb.

 

I have this one particular carb for a K181 that produces a similar symptom. It will start, run OK for a while, and then slowly loose power as it warms up until the thing just dies. Sometimes it pops and surges, sometimes not, ambient temp seems to be the determining factor there.

[ri702bill 12,237]

Paul try a Zenon bulb inline spark checker. Could be a bad coil....

[pfrederi 20,659]

5 minutes ago, ri702bill said:

Paul try a Zenon bulb inline spark checker. Could be a bad coil....

Swapped coil from my 856 that runs great B&S spark plug tester shows spark

 

7 minutes ago, adsm08 said:

Could be in the carb.

 

I have this one particular carb for a K181 that produces a similar symptom. It will start, run OK for a while, and then slowly loose power as it warms up until the thing just dies. Sometimes it pops and surges, sometimes not, ambient temp seems to be the determining factor there.

  Guess  that is next step swap carb but his is now probably cleaner than mine 

[adsm08 4,545]

6 minutes ago, pfrederi said:

 

 

  Guess  that is next step swap carb but his is now probably cleaner than mine 

 

Just because it is clean doesn't mean it works right. I've cleaned my problem unit 6 ways from Sunday, there is just something wrong in the body of it.

 

Also, check the condition of the inside of his fuel tank. I have had debris block the tank outlet of dirty tanks too. If it just restricts flow instead of cutting it off it can take a bit for the problems to start, and then they improve after it sits and this catch up. With the mention of debris in the filter and carb this is a possibility. Also pull and inspect the sediment bowl if there is one. I've had similar situations develop in there, up in the top where you can't see. Nothing filters fuel going into the sediment bowl, it just gets screened coming out, so there are passages in there that can also become blocked.

 

Also, what is he using for a fuel pump? That tank isn't high enough to gravity feed.

Edited 4 hours ago by adsm08

[squonk 46,844]

Out side of swapping in a carb you changed everything except maybe the condenser?

 

For the heck of it check the connection at the switch and the wire to the coil. I had my 1267 at the show a few years back and the screw that holds the coil feed wire at the switch vibrated loose and it died. Maybe a little heat build up there from a bad connection?

[pfrederi 20,659]

52 minutes ago, adsm08 said:

 

Just because it is clean doesn't mean it works right. I've cleaned my problem unit 6 ways from Sunday, there is just something wrong in the body of it.

 

Also, check the condition of the inside of his fuel tank. I have had debris block the tank outlet of dirty tanks too. If it just restricts flow instead of cutting it off it can take a bit for the problems to start, and then they improve after it sits and this catch up. With the mention of debris in the filter and carb this is a possibility. Also pull and inspect the sediment bowl if there is one. I've had similar situations develop in there, up in the top where you can't see. Nothing filters fuel going into the sediment bowl, it just gets screened coming out, so there are passages in there that can also become blocked.

 

Also, what is he using for a fuel pump? That tank isn't high enough to gravity feed.

 

Actually I was thinking about the fuel pump I was thinking of running direct tank to carb.  As long as you kept the tank half full gravity should work and if that solved it then new pump

 

The debris in filter had probably accumulated over several years  maintenance is not his strong point carb gunk was ethanol blobs.. .. didn't see any trash in the tank but will look again.

33 minutes ago, squonk said:

Out side of swapping in a carb you changed everything except maybe the condenser?

 

For the heck of it check the connection at the switch and the wire to the coil. I had my 1267 at the show a few years back and the screw that holds the coil feed wire at the switch vibrated loose and it died. Maybe a little heat build up there from a bad connection?

The last time it died I went over and ran it until it died again.  pretty sure now it is fuel related as i could keep her going for a little bit by adding more and more choke..

[squonk 46,844]

59 minutes ago, pfrederi said:

 

Actually I was thinking about the fuel pump I was thinking of running direct tank to carb.  As long as you kept the tank half full gravity should work and if that solved it then new pump

 

The debris in filter had probably accumulated over several years  maintenance is not his strong point carb gunk was ethanol blobs.. .. didn't see any trash in the tank but will look again.

The last time it died I went over and ran it until it died again.  pretty sure now it is fuel related as i could keep her going for a little bit by adding more and more choke..

Yes most likely fuel but remember, a rich mixture fires easier, Remember Racinbob's issue with his magnum that would die but it would run somewhat with the choke. Turned out it was his coil that was bad,  

Edited 3 hours ago by squonk

[wallfish 20,033]

Something in the tank eventually clogging off the gas ????

[pfrederi 20,659]

Breakthrough  Died again but no gas in the inline fuel filter.  Looked in tank didn't see anything but wiggled the screen with a screw driver and gas appeared in the filter.  Still didn't see the problem got a swab and rubbed it up and down the screen got some yellow gummy stuff.  Looks like a paste version of the yellow ethanol gumballs that show up in the carb bowl.  Tomorrow pulling tank to clean it and I think I am just removing the screen.  He is only up here in the summer and has old metal gas cans.  I imagine it formed in what ever gas was left in his cans over the winter it was diluted by new gas but still was there.

 

 

Thank you all!!!

Edited 2 hours ago by pfrederi

[rmaynard 17,218]

This is so "clogged gas cap vent". I know you checked, but have you tried running without the cap?

[squonk 46,844]

12 minutes ago, pfrederi said:

Breakthrough  Died again but no gas in the inline fuel filter.  Looked in tank didn't see anything but wiggled the screen with a screw driver and gas appeared in the filter.  Still didn't see the problem got a swab and rubbed it up and down the screen got some yellow gummy stuff.  Looks like a paste version of the yellow ethanol gumballs that show up in the carb bowl.  Tomorrow pulling tank to clean it and I think I am just removing the screen.  He is only up here in the summer and has old metal gas cans.  I imagine it formed in what ever gas was left in his cans over the winter it was diluted by new gas but still was there.

 

 

Thank you all!!!

I had the same thing sort of on my 953. There was no screen on the tank and the shut off valve got clogged. It looked yellowish and gummy but it was actually real fine rust particles. Well no way I was removing the tank so I tossed a little chain in the tank and with a long screwdriver I swished it around. Then flushed the tank. Then we have these real strong magnets that came with a dialysis machine maintenance kit at work. They are used to catch any metal that may have gotten through the water filters. They are about the diameter of a dime. I placed one of these near the tank outlet to catch any fine rust. 2 years and no more clogs. 

Edited 2 hours ago by squonk

[kpinnc 18,398]

I'm joking of course. Always loved this meme...