200 xp wot surge

[Jons69chevy]

Hello Again Everyone. I have a fresh 1989 200 xp that is surging at wot. The motor has around 6 hours on it with all new bearing, pistons, rings, all new electronics and rebuilt carbs. I am running a 4 blade 25 pitch prop and all I was getting was 4900 rps. I have had this surging problem for some time now but only at wot and trimmed close to all the way up. I had my passenger pump the bulb when the motor started surging and not only did the problem stop, but the rpms climbed up to 5400. I am using premix fuel with the vro disconnected and have put in new fuel lines and bulb. Can the vro pumps get week and cause a problem like this or should I be looking at something else? Any other suggestions? As always, help is appreciated....Jon

 

[CharlieB]

Re: 200 xp wot surge

When squeezing the primer bulb cures the lean condition (and that IS what was happening) you can bet money that the fuel pump is failing

OR

there is a small air leak INTO a fuel line/fitting between the primer bulb and the fuel pump.

You almost toasted those new pistons.

EVERY rebuild gets a NEW fuel pump, water pump kit AND thermostats (poppet valve also if the system uses one) they are cheap insurance against ANOTHER rebuild.

 

[Jons69chevy]

Re: 200 xp wot surge

Thanks for the info. That is what I was thinking, but just needed someone else to tell me before I believed it. Now I am glad we didnt run very long. With the way this motor has been for me the last couple of years, it may have made me run it up into the woods or throw a match to it and swim home if it would have blew up again. Would you happen to have a part number for a pump to run premix fuel? I really do appreciate your help.

 

[johnboy1]

Re: 200 xp wot surge

You might look at your primer solenoid. Mine had a small crack at the coner that caused it to surge.