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View Full Version : High idle after full throttle 351w PCM carburated


liledgy
09-17-2009, 09:06 PM
Boat has high idle after going full throttle. Shutting it of and restarting boat brings idle back to normal. Usually idles at 600 but goes to 12 to 1300 after full throttle.

ROB
09-17-2009, 11:55 PM
Are you sure that you don't have a sticky throttle linkage. It could be as simple as some lubrication.

88 PS190
09-18-2009, 12:32 AM
When my motorcycle did this it was the mechanical advance hanging up, cleaned and relubed and it solved the problem.

You don't mention what year your boat is, so I can't tell for certain if you have mechanical advance or electronic ignition with out. If you have a mechanical advance unit you can go to the FAQ in the general discussion section. There is an article about installing a conversion kit and it shows the weights under the point plate.

If its racing pop the cover check your thottle linkage, and then if not check those weights. Sticky or weak/broken springs and you could have that problem.

TMCNo1
09-18-2009, 12:50 AM
When my motorcycle did this it was the mechanical advance hanging up, cleaned and relubed and it solved the problem.

You don't mention what year your boat is, so I can't tell for certain if you have mechanical advance or electronic ignition with out. If you have a mechanical advance unit you can go to the FAQ in the general discussion section. There is an article about installing a conversion kit and it shows the weights under the point plate.

If its racing pop the cover check your thottle linkage, and then if not check those weights. Sticky or weak/broken springs and you could have that problem.


Here's the link to the tutorial showing how to remove the stuff and get to the springs and weights during the EI/Breakerless installation, http://mastercraft.com/teamtalk/showpost.php?p=133221&postcount=25

thatsmrmastercraft
09-18-2009, 12:57 AM
Are you sure that you don't have a sticky throttle linkage. It could be as simple as some lubrication.

Carb linkages are designed to be operated without lubrication. When there is a problem with full range of operation not being available, it is usually because the linkage has accumulated some gunk and needs to be cleaned with carb cleaner. Of course that is in a perfect world and sometimes a little WD-40 goes a long way.

88 PS190
09-18-2009, 01:10 AM
Of course that is in a perfect world and sometimes a little WD-40 goes a long way.

I find graphite dry lube works pretty well for things like that. No grease/wax to gather gunk back up. And if you have a little tube of it around you'll find 1000 uses.

liledgy
09-18-2009, 01:48 PM
Thank you for the replys. I have an 83mc, but the boat invquestion is a 94 Bimini skier that my good friend owns. He bought this bought brand new after selling his 81 slot, most of his friends including me told him not to buy a off brand for $15000.00 and buy a used mc orbu or tique. Allhe heard from us was " it ain't gonna last". Suprisingly, this boat has been amazing! It's a mc knock off but it handles as good as any boat I've ever been in. It also has an articulating front scag which maybe the reason for the great handling. We ski on a private lake so it doesn't take the beating like it would on public waterways and he takes very good care of it( probably more so because of all of us former naysayers). I'm a MC guy but this Bimini is a great 3 event tournament boat.

88 PS190
09-18-2009, 02:09 PM
Unfortunately I cannot tell you for sure what a 94 Bimini skier has for its ignition system. Should be quite similar though, often with some of the for lack of a better word 'off' brand boats they lag behind as far as say electronic ignition etc.

So I would guess it has a mechanical advance mechanism.

liledgy
09-18-2009, 03:00 PM
It does have electronic ignition. I am going to pass the info. On to him about the magnets and throttle cable.

TMCNo1
09-18-2009, 03:25 PM
It does have electronic ignition. I am going to pass the info. On to him about the magnets and throttle cable.

Uhhhhhhhhhhh, what do you mean by "magnets"????????????:confused:

Monte
09-18-2009, 03:27 PM
Uhhhhhhhhhhh, what do you mean by "magnets"????????????:confused:

Well, that is simple, those are the things you use to hang pictures on your refrigerator;)

88 PS190
09-18-2009, 03:36 PM
Well there are magnets in the breakerless ignition, that's how its triggered.

The question is if its like the retrofit system linked, where you are utilizing the mechanical weights vs spring advance mechanism, or if its a more modern version utilizing a computer to provide the advance. I doubt this, unless it was aftermarket.

thatsmrmastercraft
09-18-2009, 05:01 PM
I find graphite dry lube works pretty well for things like that. No grease/wax to gather gunk back up. And if you have a little tube of it around you'll find 1000 uses.

Agreed. It is also one of my favorites.

ISail
09-19-2009, 11:51 PM
My 91 Prostar r mixtuw 351w and Holley was doing this. Turns out the idle air mixture screw on one barrel had screwed itself all the way in, and the po had just turned the idle up to compensate. After a run, some gas was dripping into the 2nd barrel so it was idling on both barrels, after a few minutes, it slowed down. A good adjustment fixed her right up.