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loeweb
06-26-2011, 07:41 PM
Hello all. I've been having some minor boat troubles and hopefully someone can help me get to the bottom of it. The boat is an 88 prostar with a 4160 carb. The boat runs great at skiing speeds and idling speeds, but when running around 3800 rpms and above the boat hesitates and cannot hold the speed for more than the length of the course. I'm thinking I have something wrong with the secondaries maybe a sticking float or a bad a tuator. What's everyone think

Kevin 89MC
06-27-2011, 12:22 PM
I think that is around when the secondaries open. I think the holley website has a way to see if the secondaries are opening. If that was the issue, though, I think it would just top out around 38 but run OK. What is the condition of your fuel filter & water separator? Reason I ask is I had a high speed stalling issue recently that ended up getting resolved after replacing both filters.
Good luck
Kevin

loeweb
06-27-2011, 08:49 PM
I have already changed both the fuel and water separator filter. I'm hesitant to take off the check valve on the tank in fear that it will break. If it does break can I run without it and if not where can I get another?

thatsmrmastercraft
06-27-2011, 11:50 PM
A few things come to mind:

Fuel supply inadequate due to the following...
Fuel filter clogged
Float level low
Power valve not operating(usually they fail full rich, but...)

Ignition not keeping up with load...
Plugs, dist cap & rotor, wires, coil

What happens at full throttle?
What is top speed and RPM?

prostar190jap
06-28-2011, 12:59 AM
I'm having the same exact problem with my prostar 190. Runs fine at lower speeds but started to sputter or "starve" at around 3800 RPM. I took the carb off and come to find out, my secondaries are corroded shut. I'm taking it to my carb guy (Fuel Curve West) for cleaning and rebuild.

Kevin 89MC
06-29-2011, 03:19 PM
I have already changed both the fuel and water separator filter. I'm hesitant to take off the check valve on the tank in fear that it will break. If it does break can I run without it and if not where can I get another?

Yeah I snapped my check valve piece, the two pieces are aluminum, possibly did not have anti-sieze put on at the factory. Luckily my local MC dealer had one in stock, because no other plumbing shops did, and you can't run witout it, unless you rig up something to bypass it.
Might be time for a carb rebuild. I did mine, not too bad of a job. Cleared up my carb issues.
Good luck,
Kevin