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boat motor goes into limp

Tacho

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i have a 05 ultra with 496 mag runs great off trailer after a couple of hours of sitting in cove boat leaves great then falls flat on its face won't throttle up after turning key off an on boat resumes power for a couple of min maybe more or less sometimes any help with this problem would help ran diagnostics no codes
 

CobraDave

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A common theme recently is to check spark plugs. A faulty plug makes the motor do weird things
 

Tacho

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when had boat serviced they said didn't need plugs but makes sense mechanic can't seem to figure it out would you recommend good mechanic in havasu
 

Runs2rch

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when had boat serviced they said didn't need plugs but makes sense mechanic can't seem to figure it out would you recommend good mechanic in havasu

Start simple. Water psi sensor will cause the same issue you described.

Fuel psi issue or TPS is my guess. Sensor is telling the PCM info causing the limp/guardian mode.
 

AzGeo

Fair winds and following seas George.. Rest Easy..
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inline Merc fuel filter, AHEAD of the water trap/fuel pump system, it may be your problem .

Merc put out a 'bulletin' about "installing inline 10 micron fuel filter", because the 'water trap filters are 20's (larger holes)' which was allowing the fuel injectors to be clogged .

If you have one of these 'silver inline fuel filters', that's where I would start .

Trailer to the water, particles fall down in the silver body, then as you run the motor, the fuel flow 'picks up the pieces' and clogs the little plastic filter inside the silver body . Turn it off, let the pieces 'settle to the bottom' start the process all over again .
 

AzGeo

Fair winds and following seas George.. Rest Easy..
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Start simple. Water psi sensor will cause the same issue you described.

Fuel psi issue or TPS is my guess. Sensor is telling the PCM info causing the limp/guardian mode.

YES, but low water pressure will BEEP .

Fuel does not .
 

BDMar

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Not sure how you ran diagnostics but, if you have a certified Merc guy use the Merc CDS, it WILL tell you exactly when and why that is happening in fault seconds.
 
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