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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through March 18, 2009 » Help diagnosing cooling issuse (maybe) « Previous Next »
By DG (dgunthert) on Wednesday, June 11, 2008 - 6:50 pm:    Edit Post Delete Post
So I'm trying to determine a performance issue with my 97 MC Prostar 205.

Short story, boat runs okay initially. After 20-30 minutes, at most, it starts to lose power under load. Still runs fine in neutral.

There had definitely been some water in the tank, so I completely drained the tank, replaced the fuel filter, replaced the diaphragm on the fuel pressure regulator, replaced the plugs. I've also replaced the rotor and cap.

A mechanic I know has been trying to guide me in the right direction and asked about engine overheating. I never considered this as the engine temp gauge seems to function and never indicated an issue.

While I'm not entirely sure what I'm looking at, the impeller looks okay (pic attached).
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Also, when running the boat with a fake-a-lake, there's a good volume of water coming from the exhausts. However, within a 5 minutes or so, the risers become too hot to touch for more than a few seconds. So, if it's not the impeller, what's the potential issue?

 
By Rob (lowdrag) on Wednesday, June 11, 2008 - 9:54 pm:    Edit Post Delete Post
If you think it's overheating, the second check I'd make after the impeller would be the thermostat.
 
By George Aslinger (mobv) on Thursday, June 12, 2008 - 4:16 am:    Edit Post Delete Post
Check for blockage of water at the transmission/oil cooler in addition to the thermostat.
 
By Steve (olskooltige) on Thursday, June 12, 2008 - 8:04 am:    Edit Post Delete Post
Pull the plugs and check the condition of the ceramic. You might need to clean some carb. It could just be running lean. Chalky plugs will indicate this, and you might need to get debris out of the carb.

(Message edited by olSkoolTige on June 12, 2008)

 
By Adam Curtis (acurtis_ttu) on Thursday, June 12, 2008 - 8:44 am:    Edit Post Delete Post
I had a 96 PS 190 and my transmission/oil cooler used to get plugged up all the time.
 
By nacho (denverd1) on Thursday, June 12, 2008 - 8:58 am:    Edit Post Delete Post
doesn't sound like a cooling issue IMO. I'm thinking fuel delivery. How old is the fuel filter? carb rebuild if new.
 
By DG (dgunthert) on Thursday, June 12, 2008 - 10:16 am:    Edit Post Delete Post
The fuel filter and plugs are brand new, as mentioned in the OP.

The boat has EFI, not a carb, so there's nothing to rebuild.

 
By nacho (denverd1) on Thursday, June 12, 2008 - 10:21 am:    Edit Post Delete Post
Ok, you pry have two fuel pumps. one high pressure, one low. Been known to cause problems. IIRC, the high pressure pump is electric and can short out. { www.tmcowners.com } giving you the loss of power.
 
By Jay (jayc) on Thursday, June 12, 2008 - 1:43 pm:    Edit Post Delete Post
My bet is a bad coil. Quick and easy to swap out so try that.
 
By nacho (denverd1) on Thursday, June 12, 2008 - 2:10 pm:    Edit Post Delete Post
doesn't seem to me like it would fire if the coil was bad... my .02.
 
By Jos (jtnz) on Thursday, June 12, 2008 - 3:16 pm:    Edit Post Delete Post
Our boat was doing that too, fine in neutral, a slug under load, apart from every now and then she would jump out of the hole and run like she should. We changed the coil lead because it was shocking people (was gonna change the rest but I haven't got a set that fit yet) but I think we had water in the gas... The motor is a carbie Chev 350.
 
By Jos (jtnz) on Thursday, June 12, 2008 - 3:30 pm:    Edit Post Delete Post
Your problem almost sounds like the same vapour lock issue the guy with the Supra had a few weeks ago though, I don't remember his name off hand.
 
By Jos (jtnz) on Thursday, June 12, 2008 - 4:35 pm:    Edit Post Delete Post
Found the thread http://www.wakeworld.com/MB/Discus/messages/3183/578834.html
 

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