Thread: What would make my ski backfire?
03-14-2007, 03:14 PM #1
What would make my ski backfire?
Is this an ignition problem? On my bone stock 97 GP1200 when I was winterizing it she was back firing at anything over idle. I was having problems with it that seemed to me to be fuel related. The ski was running great on my week long vacation and on the last day I put over 5 gallons of marina fuel in it. After that she was never the same. It would idle fine in the no wake zone but when I would get on it she would bog in one spot then seems to cure itself and be fine. Once it came back down to idle it would idle fine but had a spot where it would bog out, then run fine. Now I start it on the hose and it idles fine but when you give it a little gas she back fires real bad. So far I checked out the compression and it is fine on all 3 cylinders. I was told this could be a needle and seat problem? The boat has under 80 hours on it. At first it seemed like fuel issues, now it feels like ignition. Any one ever hear of this problem?
03-14-2007, 03:35 PM #2
Most likely you have a timing problem...backfire is when the fuel ignites at the wrong time..... Are you useing a advanced key? You may also have a broken or miss seated reed. which could also cause a backfire, but my money is on a timing issue. What mods have you done to advance the timing....have you ported the motor recently? Just some things to look into.
03-14-2007, 04:05 PM #3
you may have water(picked up in you last fueling) sitting in your carb's ... it sucks but you may have to disassemble em to get the last bits out...
03-14-2007, 04:11 PM #4
Look at your rear seal and see if its still seated.
Your symptoms started with marina gas.
Use a gas can as a fuel source and see if it runs.
You might get lucky.
Reeds could be bad from backfire or it could be the ignition.
You can ohm out coils wires etc and check the ignition.
Might as well look for crap in the carbs too.
Hopefully its just bad gas.
03-14-2007, 08:55 PM #5
Also guys, I DID take apart the carbs. They were real clean. All I did was clean out the small filter on the fuel pump side. Scott, I will check the seals tomorrow.
There has been no timing advance or porting, it is bone stock
03-14-2007, 09:12 PM #6
03-14-2007, 09:44 PM #7
I had a problem like this before it turned out to be a broken reed. You can run the engine on a hose with the airbox or flame arrestors removed, when you reeve the engine a little you can feel air coming out of the top of the carb that has a broken reed.
03-15-2007, 05:57 AM #8
Reeds or the infamous rear seal leak....
03-15-2007, 10:46 PM #9
Nope, the rear seal is still in there. It could be be the reeds then. That will take me a few days to investigate into.
03-26-2007, 09:24 PM #10
The reeds looked perfect in my opinion. Will this crack be obvious to see? I have a spare set of reeds, I will install them just in case. The rear seal hasn't popped of either.
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