115 4cyl backfire!

B

bustab

Seaman Apprentice
Joined
Mar 16, 2008
Messages
48
I have a 97 115 inline four. starts and idles good. On the hose i rev it up and get a big back fire. I put new plugs in same thing. I pulled the new plugs and noticed them all very wet, so assume it's running too rich. Did a sync and checked timing, and set idle mixture. Still no change. Removed carbs cleaned everything still no change. when i pull two plugs i get a lot of exhaust gasses coming out of the plug holes. This is normal on two cylinders I assume? What else can be causing this backfire and running problem? Any help or ideas would be much appreciated. Thanks in advance.
I pulled the bottom hose off of the threaded check valve on the bleed hoses and fuel poured out
 
B

bustab

Seaman Apprentice
Joined
Mar 16, 2008
Messages
48
Re: 115 4cyl backfire!

Ok I don't know whats going on. Timing is dead on. Blue spark on all four cylinders. changed all cdm's, new plugs, I checked all check valves in the bleed lines, cleaned carbs and reset idle mixture screws. The motor starts and idles great, but as soon as i give it throttle it backfires like crazy sometimes stalls. Does anyone have any ideas on what can be causing this? compression great on all four, sync and link dead on. noticed water leaking from water jacket so i replaced both those gaskets behind the plate. Any suggestions would be much appreciated. Thanks again
 
M

MercGuy

Petty Officer 2nd Class
Joined
Jul 20, 2006
Messages
195
Re: 115 4cyl backfire!

When you write

"On the hose i rev it up and get a big back fire."

Do you mean that you are running it out of the water on a flushing attachment ?

Mine has always backfired on a flushing attachment, but runs fine in the water. I have always assumed that it doesn't run right w/o the back pressure from being in the water.
 
B

bustab

Seaman Apprentice
Joined
Mar 16, 2008
Messages
48
Re: 115 4cyl backfire!

Ya with a flush attachment. now it seems only to backfire at idle, and a puff of smoke. this isn't a normal thing. If I throttle up it goes away. I just put a known good stator on no change. Seems like a misfire if i pull #1 or #2 plug wire while running no more backfire. but I guess thats normal seeing as it only runs on those two at idle. I'm lost
 
M

MercGuy

Petty Officer 2nd Class
Joined
Jul 20, 2006
Messages
195
Re: 115 4cyl backfire!

Wouldn't it be easier to just put it in the water and see how it runs ??
 
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