hungryhungryhippo
Recruit
- Joined
- Aug 15, 2010
- Messages
- 3
Motor has been dying at WOT after about 20 seconds, and dying fairly abruply (you can hear the RPM start to drop for about 3 seconds, then it dies). I did a compression check via a Seloc manual and came up with the folloiwng:
Cyl 1: 97 psi
Cyl 2: 103 psi
Cyl 3: 105 psi
I ran them via the "lanyard removal" method and had the throttle in neutral (idle). Book says to check at WOT but when normally operating the boat you can't even turn it over if the lever isn't in neutral. Didn't try cranking at WOT with lanyard removed. Didn't cross my mind at the time.
Anyway, those pressures are at an idle setting. Book says should be around 116.5 psi with a maximum delta of 15 psi. Would a WOT check make those values higher, meaning I might not actually have low compression? I have not decarbonized or anything yet. Plugs are fairly new and look semi-tan, normal according to the manual.
I've already replaced the tank to engine fuel line and primer bulb. When the motor dies I immediately run back and check the bulb and it's still firm. I'm wondering if the fuel filter is plugged or if the pump isn't supplying the carbs enough at WOT. Runs great up to about 2500. Anything after that and it loses RPM for a few seconds then dies.
My biggest concern at this point is the compression. Basically a good/bad engine decision. I'm hoping that it isn't overheating and then dying. If the compression seems reasonable at idle setting, then I'll pursue fuel starvation troubleshooting further.
Any advice on the compression?
Edit: It occurred to me I could leave the throttle lever in neutral and use a wire tie to manually hold the throttle open at the carbs, just for the compression test. Bad idea?
Thanks
Cyl 1: 97 psi
Cyl 2: 103 psi
Cyl 3: 105 psi
I ran them via the "lanyard removal" method and had the throttle in neutral (idle). Book says to check at WOT but when normally operating the boat you can't even turn it over if the lever isn't in neutral. Didn't try cranking at WOT with lanyard removed. Didn't cross my mind at the time.
Anyway, those pressures are at an idle setting. Book says should be around 116.5 psi with a maximum delta of 15 psi. Would a WOT check make those values higher, meaning I might not actually have low compression? I have not decarbonized or anything yet. Plugs are fairly new and look semi-tan, normal according to the manual.
I've already replaced the tank to engine fuel line and primer bulb. When the motor dies I immediately run back and check the bulb and it's still firm. I'm wondering if the fuel filter is plugged or if the pump isn't supplying the carbs enough at WOT. Runs great up to about 2500. Anything after that and it loses RPM for a few seconds then dies.
My biggest concern at this point is the compression. Basically a good/bad engine decision. I'm hoping that it isn't overheating and then dying. If the compression seems reasonable at idle setting, then I'll pursue fuel starvation troubleshooting further.
Any advice on the compression?
Edit: It occurred to me I could leave the throttle lever in neutral and use a wire tie to manually hold the throttle open at the carbs, just for the compression test. Bad idea?
Thanks
