ProV200 lack of power - continued

[dilb1229]

This is a continuation of my thread from June of last year. Embarrassed to say I haven't had a chance to work on boat for past year as it I had moved and it was 200 miles away.

Anyway, motor (1991 ProV200) would start and idle just fine, but had limited power on the lake. Could get to about 4000 rpm, but not with enough power to pull a skier. Had cleaned carbs (twice), swapped fuel pumps with another (used) set I had, drained the tank, used Sea Foam/StaBil, etc. Last year's results: No difference. It ran just about the same with 1) gunked carbs and old watered gas, 2) clean carbs with mis-adjusted floats and old, no-water, gas, 3) clean carbs with mis-adjusted floats, fresh gas and different fuel pumps, and 4) clean carbs with floats corrected, fresh gas and different fuel pumps.

On to this year. Bypassed fuel tank, water separating fuel filter and squeeze bulb and ran directly from portable can. No difference.
Rebuilt carbs - this time got rebuild kits instead of just cleaning. Soaked each for 10-12 hours before reassembly.
Mechanic checked compression - all good. Plugs seemed to go from slightly rich to mostly dry, in pairs from top to bottom. Visual check of electrical/electronic components - no sign of overheating or other problems. Checked prop - possible spun hub, but couldn't be sure. Said to check it on the ramp while still on the trailer. Said it sounded like we had eliminated the fuel system.

Went to ramp to try to check if prop was the problem. Now, motor won't rev above 1700 rpm under load. This is different. Kind of sounds like flooded, but doesn't die, just won't rev up. (Still starts and idles fine). It will rev up easily with no load. (Yes, I now know you are not supposed to do that, but I've done it for 20+ years with this motor.) So can't tell if prop is OK or not as can't develop power, but at 1700 rpm, water was churning pretty good.

Going to pull the top carb off and re-check my assembly. Really only two things to set, idle screws (and it idles fine) and the float level. Am sure all three are the set up the same. Will also swap fuel pumps and plugs with others I have and try again.

What else could it be (that I can check without any special tools)? Air/vacuum leak? Where/how to check? Other?

Thanks for your help, now and in the past.

Steve

[99yam40]

Easy things to test to start out with.
Compression, spark(or KV at plugs), timing at idle and WOT, fuel pressure/vacuum.

If all of those are in spec then you are left with fuel to air ratio.
Vacuum leak or just wrong jetting. Some motors have different jets in the different carbs.
If you did not put carbs back where they cam from or you moved jets then you will have a problem

If you are loosing spark or have weak spark the check ohms and peak voltage into CDI and out of it. Coil ohms and plug wire & cap ohms also.

Not much you can do without the proper equipment/tools and a service manual for your motor

[BQUICK]

I had one doing the same thing. Pickup linkage for timing (plastic) was broken so it wasn't getting any timing advance.

[dilb1229]

Thanks to both of you. Compression is good. We do have spark on all cylinders, but don't know how strong it is. Motor starts easily and idles smoothly at about 700 rpm. I did double-check the small removable brass jets. Manual says higher number goes under the plate and that's what I have. I'll check the timing linkage and do what I can to search for vacuum leaks.

Now correct me if I'm wrong on setting the float level. With carb upside down and with the needle, float and gasket in place, (needle fully inserted), you measure from the top of the gasket to the top of the float. By top I mean the upper side of each as you are currently looking at it.

Will also take apart fuel pumps and check diaphragms for any holes.

Thanks again.

[dilb1229]

Success, though I don't know from exactly what.

Saturday: I re-set the floats in the carbs. All were slightly high, but I think still within specs. Changed out the fuel pumps to another used set. Diaphragms all looked good on both sets. Changed out the plugs to another used set. Gaps were within spec on both sets. Here's the kicker. Fuel filter was 2/3 full of water with some debris. Put in new filter.
Sunday: After a brief run-up on the ramp to again check the prop, the rpms were back, but still not sure if the power was back. No time to take it for a spin. Checked fuel filter upon return. No water or debris.
Monday: Back to the lake. Ran like it hasn't in more than a year. Full power and up to it's 6000 rpm limit.

There was not a thing done on Saturday that hadn't been done a couple of times in the past year. Mystified, but thrilled it's back to normal.

[99yam40]

with that much water in the filter, you will end up with it in there again when the boat tilts in the right direction.
And if you are running ethanol fuel the water will mix with the ethanol part of it and phase out.
I would look at cleaning the tank