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sbrewer715

Monsoon 325 motor runs but lost power from all 4 left cylinders.

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sbrewer715

I have a 2000 Malibu Wakestter VLX that has lost power. Boat seemed to be fine at the end of last summer but did notice a little loss of power or boat just didnt seem to be running as good as usual on last weekend before putting up at end of season for Winter. When I got the boat out a few weeks ago for the summer the boat cranked right up and sounded fine but when put in the water the boat just had no power and could not pull itself up on plane and would make a popping sound (could not determine the source) and even at full throttle could only get to around 2000rpm. I read some of the forum posts Sunday after returning from Lake and found several threads about fuel issues. Ordered a new Fuel filter and fitted this weekend, but then found another filter right off the fuel tank which I did not see so removed and blew it out, and will get a replacement for it ready to replace this coming weeknd. Tested boat again and seemed to have a little more power but still could not get up on plane well and struggled to make 2500rpm. No dealer for 100 miles so trying to get all the basics done myself before making the trip and probably letting the boat sit at the dealer for the rest of the summer. Checked Distributor and rotor this weekend. Does anyone have any other suggestions or does it sound like the boat is starving for fuel. Its the Fuel Injected Monsoon 325, and it revs freely when in Neutral not pushing any type of load up to about 4000rpm. Was going to clean all the fuel injectors as mentioned in some of the posts but also wondered if this might be the fuel pump. The boat has very low hours for the year, had 160hrs when I bought it 2 years ago and now has 212hrs. Was immaculate when purchased and appeared to have been meticulously maintained. Boat performed great the first 2 summers with the exception of that last weekend at the end of last summer. 

Did some more testing on the boat this last weekend and actually discovered that I dont appear to be firing on the entire left bank of Cylinders (looking at the motor from inside the boat). I removed each plug on that side of the motor and tested for spark which appeared to be ok. Plugs however appeared to be dry and I would assume if not firing they would be wet from fuel. This leads me to believe that I may not be getting fuel to that side of the motor or I have lost the signal that commands the injectors to fire. I find it hard to believe that the fuel rails and hoses on that one side could be blocked and or a weak pump would deliver fuel to the right side only. Thinking that this is probably an EFI controller issue or connection problem on the wiring to the left side fuel injectors. Does anyone have a wiring diagram that might show me the signal to the injectors and what level of signal should I be expecting at each injector (5v, 10v, 12v  etc).  Any suggestions or additional troubleshooting tips would be awesome. Going to test cylinder compression but again dot think I could of lost all 4 cylinders ??

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Steve B.

Oil looks okay? I think next I would check fuel pressure on the rails.  Good luck with it,

Steve B.

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Bozboat

Borrow a fuel pressure gauge from an auto parts store and check the pressure at key up and idle and full throttle.   I bet its something simple and moderately expensive like the fuel pump.

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williemon

So plugs on left side look different than those on right? If the left sidr fuel rail is first in the fuel path from the pump, then trash and debris will clog those injectors first. I think 12 volts runs the injectors but the computer adjusts the duty cycle or the on time. I was able to fmake an injector open using a 9 volt battery.

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sbrewer715

Ye

On 6/25/2016 at 10:25 PM, williemon said:

So plugs on left side look different than those on right? If the left sidr fuel rail is first in the fuel path from the pump, then trash and debris will clog those injectors first. I think 12 volts runs the injectors but the computer adjusts the duty cycle or the on time. I was able to fmake an injector open using a 9 volt battery.

Yes fuel pump is on the left side of the motor closest to the rail that feeds the injectors that appear to not be getting any fuel. I removed the complete rail and injectors this last weekend and made sure fuel was actually getting to the injectors. Actually fired the boat up with the rail and injectors removed (probably stupid thing to do) but had no fuel coming out of the injectors. Your probably correct about those injectors being plugged and hopefully a good clean or rebuild will do the job. Hoping its not the electrical signal that has messed up as this might be alot harder to fix. Any advise on a good injector cleaner that I can let them soak in etc.

On 6/25/2016 at 10:25 PM, williemon said:

So plugs on left side look different than those on right? If the left sidr fuel rail is first in the fuel path from the pump, then trash and debris will clog those injectors first. I think 12 volts runs the injectors but the computer adjusts the duty cycle or the on time. I was able to fmake an injector open using a 9 volt battery.

The plugs dont really look that different but have good spark on all 4 cylinders so would assume if fuel was getting to them and not igniting they would be wet. I can pull all 4 plug leads from the left side of the motor and engine note and idle does not change one bit, but the motor sounds fine and will rev freely to 4000+ rpm. Very bizzare, never would imagine the motor could run and sound so normal on 4 cylinders?

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sbrewer715
On 6/24/2016 at 3:50 PM, Bozboat said:

Borrow a fuel pressure gauge from an auto parts store and check the pressure at key up and idle and full throttle.   I bet its something simple and moderately expensive like the fuel pump.

Do you know what pressure I should expect to see for Key up, Idle and Full Throttle.

 

thanks

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footndale

You can test the injector this way.

 

 

Edited by footndale

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sbrewer715

Thanks for the video link. Also made up an electrical tester to clean and pulse the injectors this coming weekend. Hope removal and cleaning is going to get this issue fixed.

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