What's wrong with my boat?
 

In the wake of Saturday's TOPPS poker run, my 29 Fountain is headed for the repair shop and I'm curious what all of you guys think the problem (or problems) is (are). It's a '96 HP500 single carb, not EFI.

Ran great for the first 1 1/2 legs. Then we stopped for a no-wake zone. Getting back on plane there a sort of rattling noise that we determined only happened in gear and under load (i.e. not at idle). After leaving the second stop, no more noise, but she was sluggish to plane, my water temp gauge was all over the place and the buzzer was going off. We got on plane and a while later, my electronic compass quit (oh, the depth gauge was screwy going into the second stop also). After about an hour's ride up the bay, we slowed for the inlet and she sounded kind of rough. When we got back in the lake at the other end of the inlet, 2500 rpm was all she'd give.

So, anyone care to give me their expert opinion before my mechanics try to talk me into some really expensive repairs?

Valve springs are an issue with HP 500's and possible reversion with the stock exhausts. Check out the archives in Powerboat mags Teague on Tech column. Do a comp. check and remove the valve covers and check the spings.

Regards,

Mark S.

Thanks! Compression check was the first thing my mechanic said he'd do. I am aware of the valve spring issue and with 185 hours on her, that could be it. I was hoping to make it to winter and do them then on prospect.

Jana,

With a broken valve spring, comp check may still yield good results. Sometimes the broken inner valve springs (they break before the outer ones). can "corkscrew" and hold the valve open too, showing low comp. Hope for the best!!

Good Luck-

Mark S.

If the valve spring is the problem then why the buzzer going off & depth gauge going wacky? Blown head gasket? More that one problem? Water pump for high water temps, & electrical problem (ground) for compass & depth. May be multiple problems? Who you take it to?

There may be an electrical problem that is the root of it all. A bad ground circuit could cause all the problems including poor performance. The depth and compass are very susceptible to "dirty" power-as is the ignition module. Be sure to tell whoever looks at it ALL of the strange things that happened-it may lead him/her to a fix quicker.

Electrical would be my Guess, NOT the valve springs, Due to the other things that went wrong, Valve springs wouldnt do that to your compass and depth finder

Bob

I agree with the electrical. Check there first.

I'm suspecting electrical also. Check you main grounds to the engine.

Electrical. Something must have come lose. Your ignition is not going to work properly at a lower voltage.
Dan

I'm guessing electrical also. Probably the main harness connection to the engine. I've also had corrosion on my ignition module plug in that made the boat run like crap.

I have found in my kind of limited and certainly frustrating electrical troubleshooting exp. " All Roads Lead to the GROUND! I have been bitten on many accasions chasing problems around in circles only to find a bad ground connection somewhere.....even knowing this I did it agian a week ago on my trim pump...took the whole thing apart checking brushes and looking for burnt windings..nothing..jump it across a battery on the bench ....it was the stinking ground connection in the boat....Go right for your grounding cicuits first ....esp. when electrical goodies are acting wierd...

and what Griff said

Thanks guys! You're all confirming what I suspected. Something in the electrical system most likely failed. (Considering that the darn cable ties that hold the main part of the wiring harness up always pop loose, I figure something got broken or knocked loose from the thing bouncing around half the day.) However, the weird metallic noise that happened first could be something else.
Turbojack - Parkside is getting first crack at her, simply because she's there. If that doesn't work, I think I'm going to try Mars Marine. I can limp her over there without messing with the trailer.

Belt loose on circ pump and alternator?
Might explain overheating (which would also cause spark knock under load) and weird electrical oddities (as batteries dropped in voltage).

While it was acting oddly, did the trim system still work okay? Was you battery selector switch in its usual position?

Just throwing out stuff to think about.

She didn't overheat. The water temp gauge just went nuts (mostly it read too low - like around 100). One of my friends confirmed plenty of water out my exhausts and I still had normal water pressure. Trim was fine and with only one battery, the switch has only one "on" position. Just waiting for the mechanic to get to her and give me a report.

Update
 

Well, it's not just electrical. The mechanic found water in cylinders 5 and 7. (No wonder she wouldn't plane.) He got the water out, oiled the cylinders and is going to pull the motor and check everything. Could be as simple as a head gasket or something more. Thank goodness the season is long down here.