1996 Force 120HP

[captaincanuck71]

Boat runs well at lower speeds but will stall out at full throttle. If bulb on fuel line is pumped boat will keep running. I'm thinking fuel pump. Bought a rebuild kit. Pulled the pump off and it looks very clean, no visible holes in diaphragms and they are flexible and not hardened. Held diaphragms up to the light and can't see any issues. Will throw the rebuilt pump on and put the boat back in the water and test it. If boat still stalls out what would be next step?

 

[racerone]

Test run with another tank and hose.----Or perhaps low PRESSURE in the crankcase that operates the pump.

 

[captaincanuck71]

OK thanks, will test run and post how that went.

 

[captaincanuck71]

If cylinder compression is good then vacuum should be good unless there's another issue down the line. Would you know what cylinder compression should be at?

 

[racerone]

It is CRANKCASE compression pressure that drives the pump.----Post actual cylinder compression.----That may offer a clue.

 

[captaincanuck71]

K will do, just charging the battery. Thanks.

 

[racerone]

your location?

 

[captaincanuck71]

Manitoba, Canada

 

[racerone]

It takes near 30 hrs for me to drive to Winnipeg.-----Too far away to look at this motor

 

[captaincanuck71]

Ha I would think so!
Here are my readings l, I am assuming they're reasonable...
Top cylinder--133
2--140
3--140
Bottom--140

 

[racerone]

Good numbers.----See post#2

 

[captaincanuck71]

Haven't had it on the lake yet but will give it a run and if same old story will find a portable tank and hose.

 

[captaincanuck71]

Well 3 loops around the lake at full throttle no stalls. I disconnected the fuel line at the nipple on the side of the boat going to the fuel tank and dropped that line into a jerry can. Next I'll reconnect to the nipple and do another test run. If it stalls out the problem is somewhere upstream of there.

 

[captaincanuck71]

Well I reconnected the fuel line to the boat tank and took it for a spin. Two times around the lake at full throttle. So must have been the fuel pump...