2004 searay sundeck 200 wont go past 3500 RPM

04searaysd

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I have 2004 searay sundeck wont get over 3500 rpm. It is a merc 5.0 serial number 0M682713. Fuel injected. I
things I have done
1:check compression
2: checked plugs
3: replace fuel water seperator filter.

I am thinking maybe fuel pump but where is this at? Does it have a low pressure and High pressure, is it mechanical fuel pump (wouldn't think so because its fuel injected) Any Idea
 

NHGuy

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Did anything else change? Prop? Dirty Hull? Over weight? The pump is electric, it's checked with a pressure guage.
 

tpenfield

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Yes, tell us a bit more history . . . like what RPM did it used to get up to? When did this happen? anything else that would help.
 

04searaysd

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So I keep my boat in the water at the marina. Parked it last sunday ran great, went an drove it on saturday and it got to 3500 rpm, running about 7 mph,. It used to get to 4400 rpms go about 40mph. Didn't change prop, nothing else changed.
 

04searaysd

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There was a change I put a grill on the swimdeck with a regular home size propane take, Extra weight would be about 80lb on the very back of the boat. Do you think that would cause the problem? Its only 80lbs but i guess since its on the very back. Cant get on plain and go
 

Bondo

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Ayuh,.... Sea life on the hull could be enough, but the grill on the back ain't helpin',....

A home sized propane tank is 100 lbs of gas in a 40 lb tank,...
 

04searaysd

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Yes I get that. But with extra weight I would think i would be able to get to the RPMs but not go as fast
 

tpenfield

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If you are going that slow at that high of an RPM, then I would be suspecting the prop hub or the engine coupler . . . 100 lbs of grill on the back is not going to kill the performance that much IMO.
 

04searaysd

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is the prop hub or the engine coupler something that just goes bad? it was working great one day but not the next day. I will be working on it tomorrow. Just makes it tough because I cannot take it out of the water because the lake is flooded and all the ramps are closed.
 

Bondo

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is the prop hub or the engine coupler something that just goes bad?

Ayuh,..... While there's always an underlyin' reason,.... Yes, one minute it's workin', 'n the next , minute it's broken,....

Swap the prop, 'n try it, that's the easiest 1st step,....
 

04searaysd

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Is the prop something i can change while its in the water. If not I will have to wait a couple of weeks till the water lowers and they let me pull it out of the lake
 

jkust

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You can very easily change the prop but the problem is if you drop any of the pieces if you are actually floating behind the boat while changing it in deep water. If you can change it in knee deep water then it is a no problem situation. Get a large crescent wrench or a floating prop wrench, throw it into gear or keep in neutral but get a piece of 2x4 to hold the prop still and just swap out the prop and hub.
 

tpenfield

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Is the prop something i can change while its in the water. If not I will have to wait a couple of weeks till the water lowers and they let me pull it out of the lake

shallow water and no butter on your fingers would be best to change the prop while it is in the water . . . done that once or twice.
 

Bondo

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Ayuh,..... I've done it hangin' off a dock, but backed up to a beach is way better,....

Tie the wrench to yer wrist with a piece of string, so's ya can retrieve it,...... ;)

Spare hardware is handy to have too,... 'n ya still wanta grease the prop shaft before ya slide on the other prop,...
 

04searaysd

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Thanks for all the info. I will be working on it today. First thing i will do check the Fuel pump pressure, if that is fine replace the prop. Does anyone know how much fuelpressure I should see? I am guessing this is just like a car there is a shrader valve on the injector rail?
 
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04searaysd

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SO i measured fuel pressure when switch is turned on it is about 40lbs when start motor it bounces betweekn 40 and 46 lbs
 

04searaysd

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I got it fixed. Just out of guessing i swapped Distributor Caps and rotar. Fixed the problem
 

04searaysd

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Now my boat wont start at an idle. When press the bottun on the acelerator handle and move it foward it starts. But wont start when the handle is all the way up. When i get it started and put the handle up it shuts off. I measured fuel pressure and it is at 38lbs. Replace fuel water filter. any ideas
 
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