cold exhaust on cylinder 3 gas 50/50 mix oil and gas

[lawnmowerman]

anyone have any ideas why cylinder number 3  would be cold  and oil is at least half gas  . and i am getting good spark on all plugs, and do you think having my fuel injectors sent out to be checked will help ?

[Cogswell]

How did you verify you have spark on that  cylinder?  I wouldn't rule out an injector issue but the fact that it's cold points to the fuel not being ignited. I would dig deeper there 1st before chasing the injectors. 

[DannoXYZ]

You can test injectors yourself to see if they're leaking.

[lawnmowerman]

55 minutes ago, DannoXYZ said:

You can test injectors yourself to see if they're leaking.

i have tested them to see if they squirt  and they seem to work fine  i dont know how to test them for leaking

[lawnmowerman]

1 hour ago, Cogswell said:

How did you verify you have spark on that  cylinder?  I wouldn't rule out an injector issue but the fact that it's cold points to the fuel not being ignited. I would dig deeper there 1st before chasing the injectors. 

pulled the plug out and turned over engine . pulled the injectors out and tested them they seem to work . now i think im going to test a pressure regulator 

 

[Grum]

A ruptured diaphragm in the FPR will cause fuel to be sucked into cylinders 3 & 4 via vacuum hoses.

[Cogswell]

The odd piece of the puzzle is why #3 is cold.  How could the plug be functioning and leaving the cylinder cold?   Maybe the plug has a cracked insulator?  Or maybe a deteriorated HT lead . . . ?  Or the spark is weak and appears to be working visually but doesn't deliver enough energy to ignite the fuel air mix under pressure.  Maybe I should ask - how cold is cold - cold as in "can grab the header tube cold", or just "not as hot as the others" . . . Any additional color on that?

 

[airwalk]

Very low or nil compression would do it. Curious to learn if this ever is solved/resolved...

[Grum]

6 hours ago, Cogswell said:

The odd piece of the puzzle is why #3 is cold.  How could the plug be functioning and leaving the cylinder cold?   Maybe the plug has a cracked insulator?  Or maybe a deteriorated HT lead . . . ?  Or the spark is weak and appears to be working visually but doesn't deliver enough energy to ignite the fuel air mix under pressure.  Maybe I should ask - how cold is cold - cold as in "can grab the header tube cold", or just "not as hot as the others" . . . Any additional color on that?

 

 

3 hours ago, airwalk said:

Very low or nil compression would do it. Curious to learn if this ever is solved/resolved...

 

If it is a ruptured FPR Cylinder 3 won't fire because of the excessively rich mixture of raw fuel drawn in. Another effect of this can be the smell of raw fuel from the exhaust.

 

A similar example is to start your bike from cold and have it run for just a few seconds. Turn off and come back the next day and try and start your bike, there is a very good chance it won't fire up or extremely reluctant to, a flooded over rich mixture is now in the cylinder. This has caused a lot of heartache for a vfr1200 owner,

and I've experienced the similar effect on my 8gen.

It's the reason why you have a "Flooded engine start procedure" in your owners manual. The cylinders need to go through a purge process to get back to an ignitable air/fuel mixture.

 

Another scenario. A few years back I had my 2013 Mazda 3 cold in the driveway, washed the car, started it up and drove it 25ft into the garged and switched off. The next morning I dam near flattened the battery trying to start it. I had to follow the flooded engine start procedure before it finally spluttered into life. A very common known issue with that generation of Mazda 3. The simple fix is to always run the engine long enough to be slightly warmed.

[lawnmowerman]

7 hours ago, Grum said:

 

 

If it is a ruptured FPR Cylinder 3 won't fire because of the excessively rich mixture of raw fuel drawn in. Another effect of this can be the smell of raw fuel from the exhaust.

 

A similar example is to start your bike from cold and have it run for just a few seconds. Turn off and come back the next day and try and start your bike, there is a very good chance it won't fire up or extremely reluctant to, a flooded over rich mixture is now in the cylinder. This has caused a lot of heartache for a vfr1200 owner,

and I've experienced the similar effect on my 8gen.

It's the reason why you have a "Flooded engine start procedure" in your owners manual. The cylinders need to go through a purge process to get back to an ignitable air/fuel mixture.

 

Another scenario. A few years back I had my 2013 Mazda 3 cold in the driveway, washed the car, started it up and drove it 25ft into the garged and switched off. The next morning I dam near flattened the battery trying to start it. I had to follow the flooded engine start procedure before it finally spluttered into life. A very common known issue with that generation of Mazda 3. The simple fix is to always run the engine long enough to be slightly warmed.

 Cold as not even warm  to the touch,  I just purchased a fuel pressure regulator on line at Partzilla but it will be a week or so until i get to putting it on. I will let you know if this fixes my problem when i get .

[Grum]

Just to update. This thread seems to have crossed over to this one.

Fix was a new Fuel Pressure Regulator.