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mgb1974

Random Running/Power Issue- 325 Monsoon

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mgb1974

My 2002 VLX with the 325 Monsoon engine has a weird running issue. 

If I idle around waiting to get a boarding up and by the time we hit it to pull the boarder out of the water. It has no power, just kind of chugs along around 5-8 mph. 

Stop it and put it in neutral and rev it up a few times and its fine. No running issues at speed. It happens almost every time out at least once. Not noticing any smoke when reving it up. 

This year replaced, Fuel Filter, Fuel Pump and Spark plug Wires. Spark Plugs are about 3 seasons old. On about 3rd tank of gas for the season so doubtful its water in the gas. 

Threw some injector cleaner in the tank last time out. 

Anybody have this issue? Fix?

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Levi900RR

Did you look at the plugs? Feels like a fuel thing to me. Have you looked at the throttle body?

Edited by Levi900RR

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tellushow

So when in neutral it revs up smoothly with no apparent issues?  How about hole shot without boarder in tow?

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mgb1974
6 hours ago, tellushow said:

So when in neutral it revs up smoothly with no apparent issues?  How about hole shot without boarder in tow?

Yeah no problem in Neutral. Hole shot is when it happens but it doesn't happen all the time. It usually after running it for awhile. I then stop the boat(dont turn it off) rev it up in neutral and hole shot is back to normal. At speed its fine. 

 

 

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MadMan

This could be the dreaded vapor lock.

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mgb1974

Im leaning toward it being injectors. Took off the flame arrestor and cleaned that(wasnt really that dirty) and cleaned out the throttle body. It had some carbon build up but not super bad. 

 

 

Put a can of Sea Foam in it and see how it runs Thursday. If issue happens again pulling all the spark plugs and pulling injectors to clean them. 

Just now, MadMan said:

This could be the dreaded vapor lock.

Have some doubts that its vapor lock, since I rev it up after it happens and then put it in gear and hole shot with no issues. Vapor lock would need a cool down period?

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MadMan
27 minutes ago, mgb1974 said:

Have some doubts that its vapor lock, since I rev it up after it happens and then put it in gear and hole shot with no issues. Vapor lock would need a cool down period?

Revving up in neutral requires much less fuel than when loaded in gear.

Vapor lock doesn't really need a cool to clear, just needs to purge vaporized fuel that the fuel pump can't pump.

Edited by MadMan

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footndale
2 hours ago, MadMan said:

This could be the dreaded vapor lock.

Vapor lock usually gives you a "won't run or won't start" engine.

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mgb1974
22 hours ago, footndale said:

Vapor lock usually gives you a "won't run or won't start" engine.

Yeah agree. Im guessing injectors, about the only thing I havent replaced in the last 3 years. See how it runs tonight with some seafoam in it. 

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iliketoski

How many hours?  Doesn't seem like you'd need new injectors.

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Levi900RR

My boat only has 150 hours and I'm pretty sure I'm having some injector issues... 

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mgb1974
On August 4, 2016 at 10:30 AM, iliketoski said:

How many hours?  Doesn't seem like you'd need new injectors.

Around 1000 hours. 

I put sea foam in the tank and went out today. Was a lot worse today. I think I'm going to pull the injectors and bench clean them.

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mgb1974

Pulling Injectors tonight. Replaced Cap/Rotor(had minor corrosion). 

Boat was worse on the water with it happening alot more. Other then hole shot it ran fine, hit 42mph (GPS) at 4900RPM which is probably about top with the 1235 prop. 

Off to Norris Lake Friday for a week... So need to get this fixed ASAP. 

 

Not sure if anybody else has any insight? 

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Kmfish87

Check plugs (and/or replace) are they wet? They are cheap. Replace the fuel filter as well, another cheap repair. Check timing. Always do the cheap/easy stuff first even if it has been done recently.

You said plugs were replaced earlier this season, were they gapped right?

Checked fuel pressure?

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MadMan

The 2 sensors that I think are most likely to cause this issue are the TPS and MAP.

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Levi900RR

Does your boat have an Idle Air Control Valve? That is what was getting me trouble last year. BUT, have you looked at the spark plugs? 

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Bozboat

as kmfish suggested,  check the fuel pressure at key up, idle and wot.

 

Fuel pumps don't seem to last long.  I am on my third in six years.

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mgb1974
54 minutes ago, Bozboat said:

as kmfish suggested,  check the fuel pressure at key up, idle and wot.

 

Fuel pumps don't seem to last long.  I am on my third in six years.

Brand new fuel pump with maybe 10 hours on it, changed Fuel filter also at the same time. Ill double check pressure. 

Ill pull plugs also tonight. 

1 hour ago, Levi900RR said:

Does your boat have an Idle Air Control Valve? That is what was getting me trouble last year. BUT, have you looked at the spark plugs? 

Yeah it does. Wondering if I should just go and get a new MAP and IAC sensor tonight? Looks like Autozone has replacements in stock. 

Runs strong and smooth other then occasionally hole shots. 

Edited by mgb1974

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formulaben

For sure I would change the TPS and MAP, as they are definitely cheaper than the fuel pump.  Doesn't sound to me like an IAC problem? 

I know it seems pointless but I would also replace the spark plugs (and cap, rotor & wires if due.)  There was an epic thread here some time ago...long story short after lots of $$$ it ended up being the spark plugs and everyone gave diagnosis here and there and everywhere, and nobody thought of the plugs...

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Kmfish87
22 minutes ago, formulaben said:

For sure I would change the TPS and MAP, as they are definitely cheaper than the fuel pump.  Doesn't sound to me like an IAC problem? 

I know it seems pointless but I would also replace the spark plugs (and cap, rotor & wires if due.)  There was an epic thread here some time ago...long story short after lots of $$$ it ended up being the spark plugs and everyone gave diagnosis here and there and everywhere, and nobody thought of the plugs...

Like I said, plugs and fuel filter are cheap and easy...

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Steve B.

Hope you can narrow it down to one thing. Let us know your progress,

Steve B.

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mgb1974

Pulled all the injectors last night. I had one that had a partially clogged screen. Not sure what the stuff that was in there but it looked like a build up of micro debris/Fuel Varnish. The rest of them were all dirty. 

I sprayed them with Carb cleaner and then put them in a ultrasonic heated bath. Screens looked new afterwards. 

Im guessing this was the issue but no way to for sure tell till I get the boat on the lake. 

Also removed the MAP sensor and cleaned it. It looked good. Might pick up a new one with a set of plugs to bring with me if the problems keeps happening. I can change those out pretty quick on the dock. 

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mgb1974

So as a follow up. Found the issue, unfortunately it was on the lake the first day we got there.

This season I also had my 4 way gauge was acting up. Temp seemed to be working but gas was not. I replaced it with a new one a few days before I left for the trip (Didnt take the boat back out on the water after replacing).

As soon as I launched the boat and headed to the house on the water realized I was running hot. Long story short found out that my raw water pump was leaking causing the flow to be less and go into limp mode temporarily as it hovered around the limp mode point. With the gage acting up it never showed greater then 160 so I never would of guessed it was over heating slightly. The pump was shot and must of been leaking for awhile and got progressively worse over the summer

Overnighted a raw water pump to the lake house and was good to go after that. 

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