2000 Air Nautique GT-40 Engine

[droeder]

Motor idles just fine but wont go under load. The boat will only cruise around 10 mph

[2000superdare]

First check all your spark plug wires, sometimes after fogging the motor in the fall you forget to tighten/ or put back all the spark plug wires.

[Tom_H]

Need fuel, air, and spark. Check cap, rotor, plugs, wires for corrosion, replace as necessary. Check fuel pressure at the rail to troubleshoot fuel delivery issues (i.e. fuel pump(s), fuel filter, etc.). Depending on previous maintenance, might just need a significant tune-up (plugs, wires, filters, cap, rotor, coil, etc. etc.), but with your description so far, can't point to any specific item, as it could be any or all of the above items to cause the engine to fall on its face under load.

[droeder]

cap, rotor, plugs are brand new. its like its in S.L.O.W mode. It will rev up in neutral with no problem. It bogs down when it get around 10 mph. I change the ACT, ECT, Oil Pressure sensor and temperature sensor too. is there any other sensor that puts it in SLOW mode?

[Blamey]

How did this start? When last was it running fine?

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[droeder]

it was stored for two years. It ran perfect before I winterize it in 2015.

[droeder]

like there is no power under load

[t.franscioni]

Is the fuel good? Did you put stabilizer in the fuel when you laid it up for two years? After two years stabilizer or not I'd drain the whole system and put in fresh fuel. First guess given you replaced everything you said you replaced would be lack of fuel. Maybe due to clogged or gummed up filter and or injectors, fuel pump going bad not making enough pressure to feed the engine under load, bad fuel pressure regulator???

i think the knock sensor will put it in slow mode also. Again if fuel is bad it could detonate and trigger slow mode....

[SilentSeven]

Help with a bit more information:

- when loaded and it won't accelerate, how does it run? Smooth? Rough?
- what was the last item messed with / serviced on the engine and when?
- you say you wintered it. How exactly did you winterize the engine?


+1 for fresh fuel. Run some techron on similar though it.

Here's a post from another forum where the owner had a similar problem

Was able to find a PCM Mechanic who was very helpful. There is a oil pressure sensor under the oil filter with a tan wire going to the computer that monitors things. Said that sensor is the problem 90% of the time when its going into power reduction mode.

From SKIDIM - http://www.skidim.com/SWITCH-OIL-PRE...info/R020015A/ Looks like you can disconnect this sensor to open the circuit to test if this is the culprit.

[2001SAN]

The temperature switch, not sensor, will also put it into SLOW mode. Is the check engine light on?

D.

[Tom_H]

Well - if you've been through all that, I'd be looking real hard at your fuel or fuel delivery. Fresh gas and/or check the fuel pressure at the rail to know if your pumps (high pressure especially) are doing what they should.

[vortech347]

My 99 had the oil pressure sending unit go bad and it went into limp mode. It would idle and rev fine in neutral but would only run 2800 rpm in drive. It's a very simple fix and is cheap to replace. Low temps sensor will do it, too.