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Old 07-10-2013, 07:54 PM
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JimN JimN is online now
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Join Date: Jul 2004
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Originally Posted by alfie623 View Post

thanks for helping with the info. I haven't seen a new or used impeller. The reason I joined here and posted the question is to learn from what the people on here can share.

I bought the boat from a long time neighbor and at 39 years old I'm on my 39th year on the same lake. I also have a Boston Whaler with a Mercury outboard, having grown up on the lake I've been boating for all my life.

I have the Owner's Manual from Mastercraft and is't very helpful in directing me back to the local dealer. I'm more of a hands on guy and I'm trying to learn about this stuff myself. Is there a service manual available for these boats? I'd rather purchase that and do the work myself then rely on a dealer's service department who isn't emotionally or financially invested into my boat. I would consider myself knowledgable on engines too....

Now, I assume you are referring to the water pump impeller. I can pull that and take a look at it's condition but before I do that I'd like to pull the code that's tripping the light and see why it's doing so.
Mastercraft doesn't make it easy to call them for tech support.....will a pre-OBDI code reader pull the generic codes or do I need to mimic a GM product (i.e.- a 1999 corvette)?
If pre-OBDI you mean the plastic code reader with a couple of LEDs (maybe) and a small switch or the metal piece that's kind of like a little fork, that will work fine. You could use a paper clip, too- it just needs to connect terminals A and B in the DLC (Data Link Connector) at the rear of the engine. Release the gas struts that support the engine cover to make it easier to get to it. Rather than just let it open all the way and rest on the floor, you can release the supports and lift the front of the floor behind the engine, gently slide it forward and lift it out of the way- I usually laid a piecve of carpet ir a moving blanket on the vinyl to avoid damaging it but since the top of the motor box is vinyl, it shouldn't be a problem.

Their tech support is mainly for dealers, not so much for customers. They may release some technical info, but they really would rather that MC boat owners go to the dealers. The main problem with that is there aren't really enough to provide good national coverage AND make it possible to get a boat back quickly.

The MC service manuals are less for the accessories and more for the engine, its control systems and a troubleshooting section. The rest of the main info came from their technical training sessions and at this point, I doubt they spend a lot of time on the mid-90s engines, or anything that came before. When I went the first time, the stated assumption was that we all knew how to work with carbs and distributors with points and if we took more than fifteen minutes for this, it was a lot.

If you can't find a MC LT-1 manual, get a Corvette manual. While the ignition is Northstar (and info for this can be found in other more recent GM cars), the rest of the engine is basically unchanged from what went in the cars with the exception of the raw water cooling system, exhaust, bleeder lines for the cooling, fuel lines/pump and obviously, the transmission. That said, your symptom sounds more like a loose wire (possibly a ground wire, at the rear of the engine) or possibly a sensor letting you know that it sees something it doesn't like. If it happens again, listen carefully for detonation (spark knock). If you hear this, it could be the knock sensor.

I would hold off on any other guessing until after reading codes. If you find none, the four steps we were taught were:
1) Verify the complaint
2) do a visual inspection- along with this, listen and smell for trouble (burning oil, plastic and rubber)
3) if it's an intermittent problem, wiggle the wires that may be causing the complaint. This would mean that wiggling wires on the alternator or something else that's totally unrelated won't reveal a problem with the injection/fuel pressure/one sensor when the others work fine.
4) Once the solution has been found, make sure it has been 100% successful.

If engine performance is at issue, check fuel pressure first, at Key ON/Engine OFF, idle, 2000 and WOT. This must be done with the engine under load- checking it on the trailer or in neutral doesn't work and isn't valid.
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