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Misfire at altitude |
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Hamlin 
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Joined: November-19-2006 Location: United States Status: Offline Points: 57 |
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 Topic: Misfire at altitudePosted: September-15-2015 at 2:43pm |
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I don't get too many opportunities to take the '94 Nautique out these days, but had a chance to bring it up to our cabin a few weeks ago. In preparation, I changed the oil, added some gas dryer to the tank and filled it up. It is stored indoors in a low humidity environment. I hooked it up to the garden hose, primed it with a splash of gas down the carb, and it fired right up. After a minute I dropped it to idle and it ran nice and smooth as usual.
However, up at 5000 ft. elevation, I started it while still on the trailer on the ramp with the pickup in the water as is my usual procedure. It fired right up but was missing very badly. I ran it for a few minutes thinking it would clear up but it never did. I pulled it out of the water and dragged it back home a few weeks later. Having read horror stories about coil pack failures, I expected whatever was causing my problems, it would be expensive. Back at home this weekend I thought I would figure out what was wrong. No water in the oil so I hooked up the garden hose and it fired right up and ran smooth with no missing whatsoever. Any ideas on what I should check next? My thought is to get it out on the water here at sea-level and see if it misses under load. Any other thoughts? |
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quinner
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Joined: October-12-2005 Location: Unknown Status: Offline Points: 5828 |
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Posted: September-15-2015 at 5:24pm |
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Fuel goes bad pretty quickly these days, how old is the gas?
Based on your coil pack comment I am guessing you have the protec ignition, are the coil packs leaking at all?? IIRC all you can do is change plugs and wires to Tune it up. The conversion kit to change out the ignition is around $500, may be money better spent towards that. |
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backfoot100
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Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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Posted: September-15-2015 at 6:01pm |
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I assume by your post that the fuel is probably old. At altitude you should have fresh fuel and definitely run premium.
You say you primed it with gas down the carb. Is it truly a carb or TBI???? What ignition do you have? |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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desertskier
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Joined: December-19-2006 Location: Az Status: Offline Points: 1115 |
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Posted: September-15-2015 at 6:04pm |
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I was negligent in regards to changing my fuel filter for a few too many years and the adhesive in the filter broke down and started clogging my carb. It looked like small pieces of rubber gasket material floating in the fuel filter housing. Boat ran like crap. Might be worth checking the fuel filter. If your protec is failing there are a couple of things you can check before swapping it out. Take the large connector off the protec coil pack and clean it with alcohol or electronics cleaner and then screw it in and out a few times. Try disconnecting the oil and temp switches on the engine (not the gauge sending units). When the switches detect low oil pressure or high water temp they short to ground and the protec will go to limp mode. The protec works fine if they are disconnected. The last thing is to check the voltage at the 12.5 amp breaker on the back of the engine. Measure with the key on, engine can be off. It should read close to battery voltage.
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desertskier
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Joined: December-19-2006 Location: Az Status: Offline Points: 1115 |
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Posted: September-15-2015 at 6:07pm |
High altitude you run low octane. |
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TRBenj
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Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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Posted: September-15-2015 at 6:09pm |
Thought you could get away with lower octane at altitude because of the lower oxygen content in the air? If I'm not out to lunch on that, 87 should be fine on a stock engine... The recommended 89 near sea level is probably not needed most of the time on a stock 8.5:1 Ford engine. |
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phatsat67
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Joined: March-13-2006 Location: Indiana Status: Offline Points: 6157 |
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Posted: September-15-2015 at 6:18pm |
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Mine drinks 87 like HW drinks Coors Light.
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desertskier
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Posted: September-15-2015 at 6:21pm |
Isn't Indiana below sea level? |
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Hamlin
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Joined: November-19-2006 Location: United States Status: Offline Points: 57 |
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Posted: September-15-2015 at 8:54pm |
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It had less than a 1/4 tank of last years gas. I put in some gas dryer and fired it up at home and it ran fine. I filled it with 89 octane before dragging it up the hill.
It misfired at altitude but runs fine now that it's back in the valley. If it was bad gas, I would have expected it to misfire when I first ran it on last years gas. I'm stumped (not unusual) Yes- still has the Protec coils so I'll give them a close inspection and look for leaks. |
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Jonny Quest
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Joined: August-20-2013 Location: Utah--via Texas Status: Online Points: 2957 |
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Posted: September-17-2015 at 10:10pm |
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Sure does sound like a Pro-Tech that is acting-up. When mine died, it was running just fine. I was pulling a skier and the engine slowly died...just like it was running out of fuel. I was able to re-start the engine, but it ran very poorly. It finally died and would not re-start. I had to be towed back to the marina. Not good -- I was at Lake Powell, UT and the tow distance was almost 30 miles.
I yanked the Pro-Tech off and installed a Davis Unified Ignition HEI distributor. The engine has never run better. M35820RD Part Number JQ |
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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backfoot100 wrote: