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GT40 intermittent loss of power at speed

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Bri892001 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bri892001 Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2017 at 3:23pm
Just on a lark, try fiddling with your engine kill by the throttle (if it has one, not sure what years have this).

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JayG80 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JayG80 Quote  Post ReplyReply Direct Link To This Post Posted: September-11-2017 at 4:01pm
Any Solution Chris196 ? I'm in a similar situation.

Update, GT40 was running great before Hurricane Harvey. (Edit - see next post - Not bad plugs)

Turns out to be bad spark plug or plugs. The plugs were new Jan 2017 and only have 40 hours on them. I had inspected them but they were the last thing to change since they were only 8 months old. The rest of the hair pulling effort is posted below in case you're interested.

I was stuck out of town when it hit and dumped 4 ft of rain. My boat sits in a boat house on a cradle. Protected by roof and boat cover.

Finally got home and ran the boat,. It had been 2 weeks sitting. The boat idled great but stumbled at 2000 to 2600 rpm. Fuel pressures were OK.

The cover blew part -way off in Hurricane and exposed the gas tank vent. I figured it possible to get water in the gas via the vent. We had a ton of driven rain.

Added Heet to tank, then later in the day added 15 gallons of premium fresh gas. New FCC filter and short hose. No good. Put in an old HP fuel pump from previous parts swapping expedition.

Removed and inspected plugs. All clean with tan color. Re-install

Remove and clean AntiSiphon.. New Cap and Rotor plus fuel relay from reserve stock.

Pumped gas tank empty and added fresh.

Installed a new Borg Warner TFI Module purchased from Auto Parts house.

Put in new Autolite 764 plugs torqued to 12 ft lbs. Gap .045 Success, I hope...
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JayG80 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JayG80 Quote  Post ReplyReply Direct Link To This Post Posted: September-20-2017 at 2:40pm
Well my victory was short lived. Ran fine for 1 week.

The engine is stumbling again on acceleration. I put in new spark plug wires today and it didn't improve anything.

The stator inside the distributor will wiggle side to side. The boat started performing ok just after I changed the plugs and also pushed the PIP to the left. I mistakenly blamed the plugs.

I read on poor man's thread that someone refastened the PIP on the stator hall effect sensor. Mine will wiggle left to right about 1/8 to 1/4". I tried it pushed left and right now neither providing any improvement. Any suggestions?

Thanks
Jay

2002 Ski Nautique GT40 860 hrs
Electrical Recap - New Cap & Rotor. Plugs & Plug wires. TFI Module, Fuel & ECM Relays.
Fuel Recap - Drained gas tank and fresh. Clean Antisiphon, New FCC Filter and short internal hose. Swapped High Pressure Pump. Pressures 38 psi/ 35 psi idle

EEC-IV Code reader for Key On Engine Off shows no issues

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JayG80 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JayG80 Quote  Post ReplyReply Direct Link To This Post Posted: September-21-2017 at 8:40pm
OBD 1 Code reader shot Code 21 ECT failure.
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JayG80 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JayG80 Quote  Post ReplyReply Direct Link To This Post Posted: September-25-2017 at 1:24pm
The Code 21 was coincidental. I replaced the 5 yr old thermostat, it had a sliver chip of rust from the thermostat casting housing cover. The engine was running too cool as verified by IR Thermometer but the new stat put it in the correct operating range.

I pulled the distributor and once it was out, I could readily see the problem. The PIP Hall Effect sensor was hitting the inside of the rotary vanes. I must have pushed in the proper place at the time I swapped spark plugs.

A new distributor seems to have cleared my issues. My wife and I skied this morning and the boat ran great.

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chris196 View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote chris196 Quote  Post ReplyReply Direct Link To This Post Posted: July-02-2019 at 1:23pm
Ok this is really old and sorry I didn't update the thread with final solution.
I'm going to describe what problem was but I don't have diagrams in front of me and it was 2 years ago.
It was the 50amp ( I think it's 50, not positive) fuse coming off the positive terminal of the battery that lives in the battery compartment. It is now replaced with a 50 amp breaker.

Should have checked that earlier for sure. It was confusing because it wasn't blown, I still had 12 volts at points downstream of it. It was a corrosion issue and I guess it could not pass enough current through the connector as the engine required.

Thanks,
Chris
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MrMcD View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: July-02-2019 at 2:09pm
Good to Know. Thanks
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