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Bobkatz

Boat Missing between 1k and 3k RPM's

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Bobkatz

A little background - 2000 VLX with 614 hrs. w/5.7 Monsoon

We bought the boat 5 years ago with 589 hrs. on it and we use it about 5 hrs. per year. We used it for the first time this year yesterday with fuel that was in it from last year but would have been stabilized. When getting up on plan it misses until about 3,000 -3,100 RPM's then clears out(using old school terminology). I don't remember it doing this last year but who knows. I don't have the maintenance records from the previous owner so I don't know what has or hasn't been done. I have done nothing but change oil, winterize, stabilize fuel, clean and wax (after the 5 hrs. of use each year - lol!) It idles fine about 650 rpm's then misses under a load to 3000 RPM's then will run to 46 MPH/4900 RPM's. As I recall this is about where it was speed/RPM wise when we purchased it 5 years ago. I was going to start by pulling the plugs and see if they show me anything and go from there. If anybody has any thoughts or ideas where the problem may lie I'd love to hear them.

One idea I have is since we only use it 5 hrs. per year, not always towing, we use less than a tank of fuel per year so some of the fuel, thou stabilized, is probably from the summer of 2013 possibly creating the problem( fyi - the fuel does not smell bad - again old school). All thoughts/comments are welcome?

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CTSunsetter

Sounds like the fuel injection/fuel bar/fuel pressure issue that some Monsoons had. Ping smoothwaterman for more details on that.

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Bobkatz

Thanks SkySki. I don't know what ping is??? I tried an instant message and smoothwaterman is not set up to receive them.

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jfw432

When you say "miss" do you mean it hesitates once initially when you give it gas and then accelerates like crazy or it's real sluggish and continuously exhibits what feels like a misfire but eventually gets on plane? Does the engine sound like it's tapping or anything?

Edited by jfw432

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tvano

fwiw i'd find a way to address that old fuel problem on an annual basis. siphon, whatever it takes.

search for fuel hammer. i think that was the term. fuel line to the injector rail would pulsate/ resonate causing problems.

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Bobkatz

Lube,

No hesitation whatsoever just exhibits and sounds like a misfire up to about 3k rpm's. I can feel a slight vibration when its missing during acceleration. No tapping, no pre-ignition "ping", no rod knock, no valve clatter, no unusual sounds other than it feels likes its dropping a cylinder below 3k. It will accelerate hard if I want to we just don't run it that hard. My kids would rather be pulled on a tube @ 25mph than anything else and thus we don't need to run it what I would consider hard. Ideas?

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Bozboat

have you looked inside the distributor cap and at the rotor? When were they changed last?

When did you change the fuel filters last?

How old are the spark plugs?

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Bobkatz

Spam Happy,

Going to pull the plugs in the next couple of days(boats not here). I've never opened the distributor cap or changed anything but oil. It has run well up until yesterday. We have only used it 25 hours in the 5 years we have owned it. I do not know what was done prior to us owning it but was told by the dealer(who sold it new, who we bought it thru and who maintained it) that it was maintained with an open checkbook by the previous/original owner.

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grandude

The distributor cap is the most likely cause, probably more so than plugs. You could have fuel issues going on as well , but a distributor cap in a boat is kinda like taking a shower with watch that's not 100 % water proof. It's probably OK for a while but will eventually cause an issue. Distributor caps shouldn't just be changed as a repair. They should be changed as regular maintenance. At least inspected and changed when they look bad. A good one with brass contacts is only around $40. A nasty cap will cause nasty plugs and bad performance. I would change BOTH considering you haven't done any maintenance other than oil and are trying to solve a problem. I'd start with the spark related items and fuel filter, then go from there.

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