# 92 mariner magnum 3 no balls after 4000rpm



## s.w.a.t.t6935 (Aug 7, 2012)

I have a 92 mariner magnum 3 150 2.5ltr. Runs good and strong up to 4000rpm 3/4 throttle like it has no more power it's on a 18 1/2 ranger 692 fisherman. 17pitch prop. I have changed my plugs and wires fule line from onboard fule/water separator to the motor including new ball and inline fule filter still nothing after 4000 rpm. Did notice the inline filter does not stay more than half way full any input would be greatly appreciated thanks


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## KaGee (Sep 8, 2006)

Stupid question... did it ever do over 4000 since you owned it?


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## s.w.a.t.t6935 (Aug 7, 2012)

No I just bought it a few monts ago and after we got to take it out a few times every thing I read is saying it should be 5300 for full throttle but it's the same speed 4000-5300 and just seems like it has no more to give


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## K Metzger (Jun 11, 2010)

It's possible your under propped what size prop is on it? I have a 690 with Yamaha 175 with a 21 pitch 14.5" 3 blade.i realize the motors are totally different animals. Ranger can tell you which size prop was recommended with your boat and motor set up at time of manufacturing. Just give them your serial number.


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## s.w.a.t.t6935 (Aug 7, 2012)

Thanks k metzger I was also thinking that a 17p on the boat now but not shure how to find out what was on it originally


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## s.w.a.t.t6935 (Aug 7, 2012)

I'll call them tomorrow it have a 14.5" 3 blade 17 pitch


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## Popspastime (Apr 1, 2014)

Sounds like a fuel problem to me..


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## buckeyebowman (Feb 24, 2012)

K Metzger said:


> It's possible your under propped what size prop is on it? I have a 690 with Yamaha 175 with a 21 pitch 14.5" 3 blade.i realize the motors are totally different animals. Ranger can tell you which size prop was recommended with your boat and motor set up at time of manufacturing. Just give them your serial number.


Prop is what I thought as well. I have a 15 HP Merc long shaft that had the prop redone numerous times, and after the last time the performance really suffered. I sprang for an OE prop and the difference was night and day! 

And 17 pitch seems a little shallow, but you'll have to see what Ranger says. It could be that above 4000rpm it doesn't matter how fast you spin it because it won't move any more water, which won't make the boat move any faster.

It will be interesting to see how this turns out.


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## Popspastime (Apr 1, 2014)

My feeling is this motor aught to spin at at least 5500 rpm's no mater what boat you put it on, 4K is 6 to 7 inches of pitch correction and I really doubt its that. If he said it was running at 5200 I'd say you were over propped and needed to drop a few but WOT at 4K your way off the mark.I'd start backtracking on the fuel lines from the tank thru the bulb to the motor. After that fuel pump then ignition (coils) and things like that. I'd also like to think your fuel filter should be always full.


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## harryhunter (Jun 15, 2014)

What size fuel line did you put on? You might want to try a larger one if you put a small one on . also I would check spark & compression .also make sure you only have one fuel filter .


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## s.w.a.t.t6935 (Aug 7, 2012)

harryhunter said:


> What size fuel line did you put on? You might want to try a larger one if you put a small one on . also I would check spark & compression .also make sure you only have one fuel filter .


. Put on 3/8" hose that is what was in it and spark is what it should be compression is 115 each cylinder and i replaced the inline and the water separator mabe I should replace the line from inboard tank to the separator


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## KaGee (Sep 8, 2006)

3/8ths line should be sufficient for any motor.


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## G.lock (Apr 1, 2014)

Friend bought a used boat, outboard but same problem, no top end.
Turns out it was old gas, boat had been unused for two years. Tried a portable tank with fresh gas and ran much better, after flush of inboard tank and Seafoam treatment through motor it ran great.


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## harryhunter (Jun 15, 2014)

Ya I was going to say check the linkage to the carb . get good 100 % gas & seafoam to clean carb with.might be some water in your gas.


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## mastercatman (Jan 30, 2005)

The motor is running to 5300rpm, but no gain in speed beyond 4000rpm is how I'm interpreting this. If this is true, then it is a prop issue, not an engine issue. Increase your pitch to apply power to the prop through the full rpm range.


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## mastercatman (Jan 30, 2005)

If it is not running past 4000rpm, then it could be bad fuel, weak fuel pump, etc... 
If it is not cutting out the engine when full throttle is reached on the lever, it isn't likely to be the above problems. Generally, bad fuel will cause the engine to run poorly. A weak fuel pump that is not keeping up with demand will cause the engine to sputter/cut out in the upper rpm ranges. How does the engine run at idle? If the engine runs seemingly well, that could also point to a prop issue, meaning that it is trying to push too much prop. 
Verifying that your prop is correct according to the manufacturer standards is a good place to start, but not always an easy answer to achieve, if at all. It depends on the manufacturer and how their boats come from the factory. Many come without engines and are rigged and prepped by the dealerships. I used to work for a boat dealer as a parts counter employee.


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## s.w.a.t.t6935 (Aug 7, 2012)

When I bought it it sat for a year has stunk so I took no chances I sucked out 30 gals of stale gas once I couldent get any more out I took it to the gas station put in 20 gals of hi grade along with a bottle and a half of sea foam the boat runs great starts right up idles great but once u get up to 4000rpm (3/4 throttle) and go over their is no more power just a steady 36mph I called ranger and they can't tell me what prop was on it from factory if it was a bad fule line between the tank and water separator I would think the boat would run like **** from the get go


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## sherman51 (Apr 12, 2011)

with a 17p prop you shouldn't have any problems getting more than 4000 rpm's. but I'm not sure what your saying. is it turning 5300 rpm's at wot or 4000 at wot??? if its getting 5300 but not gaining any speed past 4000 you could have a pitch problem. or your speedometer could be off. if its turning 4000 rpm's at wot it could be the tach is on the wrong setting. most tach's has an adjustment on the back for different motors. what rpm does it idle at?? how fast is your boat at wot?
Sherman

ha you answered most of my questions while I was posting this.


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## s.w.a.t.t6935 (Aug 7, 2012)

From 4000-wot(5300) no gain


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## s.w.a.t.t6935 (Aug 7, 2012)

So after I ton of research I found a chart that tells me wot say it should be 5000-5500. And the magnum 3 is the same motor as a mercury xr6 And if u look up the 692 fisherman with a xr6 they are running any where between a 19-23 p props so mabe the pitch is what's getting me mabe the props washing out possible?


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## Popspastime (Apr 1, 2014)

Ok now i'm really confused..this motor does 5300 rpm right now?


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## Shortdrift (Apr 5, 2004)

s.w.a.t.t6935 said:


> From 4000-wot(5300) no gain




I interpret this as saying..............".I increase the throttle when I pass 4000 rpm and then the rpm's increase to 5300 with no gain in speed". If this is correct, you have a pitch problem as has been suggested.


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## s.w.a.t.t6935 (Aug 7, 2012)

Yes it'd does 5300rpm From 3/4 throttle 4000 rpm. 36mph To wot 5300rpm their is no change in speed


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## s.w.a.t.t6935 (Aug 7, 2012)

Short drift has it right


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## s.w.a.t.t6935 (Aug 7, 2012)

It currently has a 14 3/4 17 pitch prop I think I'm gunna try a 19p to see what happens if this wether would make up its mind thanks every one for the help


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## Misdirection (Jul 16, 2012)

s.w.a.t.t6935 said:


> It currently has a 14 3/4 17 pitch prop I think I'm gunna try a 19p to see what happens if this wether would make up its mind thanks every one for the help


That will lower your rpm's at WOT by about 400 and increase your speed at WOT.


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## Popspastime (Apr 1, 2014)

s.w.a.t.t6935 said:


> It currently has a 14 3/4 17 pitch prop I think I'm gunna try a 19p to see what happens if this wether would make up its mind thanks every one for the help


Ok.. got it.., If at 4000 rpms it seems to drop off in performance to 5300 rpms but does tach the rpm's you need to look at a lower pitch and not a higher pitch. For every inch of pitch you add you eat 200 rpm's off the max per inch of prop you add. So if you go from a 17 to a 19 and your top was 5300 with the 17 your new top will be around 4900, not were you want to go. Your max WOT right now is 5300 rpm's and your right where it's supposed to be so the next thing you do is TRIM the motor for more hull speed and performance. By trimming the motor skagg as close to the transome as it will get will get you out of the hole quicker, get it on plane quicker, but will not max the motor in most cases. Usually the hull will run low in the bow because thats the way the motor is trying to push it... now.. After on plane if you start raising..(or moving the lower skagg) away from the transom (raising the motor) 2 things will happen.. the rpm's of the motor will rise and the bow will start lifting out of the water making it run faster across the water. The motor now is trying to lift the bow out of the water by changing the angle and it will do it until it surpasses the optimum height your boat runs out of the water. Most bass boats have lifting chines that actually help in the process to get it on the PAD where they are designed to run at high speed.
Just wanted to explain TRIM a bit so you might understand there's more to WOT rpm's then just a prop. Higher the motor comes out of the water the higher the rpm's go and the faster you run across the water. Simply by raising or trimming the motor will or can add another 500 rpms to the top end performance. Didn't mean to be so long winded but I guess there's only one way to explain it. If I'm wrong I'm sure.. there will be more comments following.


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## sherman51 (Apr 12, 2011)

I have to agree with pops on the trim. if your not trimming the motor out this could be a big part of your problem. your turning optimum rpm's for your motor with the 17p prop. if you go to a 19p its going to lower your rpm's by around 400. and its going to hurt your hole shot and overall performance. if the motor is left in the full down position after you reach that magic 36 mph your pushing so much water it wont go any faster.

go out with the 17p in the full down position to get up on plane. as soon as your on plane start trimming the motor up. but don't go to far or you'll blow the prop out. with a little practice you'll know just how far you can go. if your boat starts to porpoise then just trim it back down a little for your best ride.
sherman


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## backfar (Sep 24, 2014)

I'm in agreement on the trim issue also....I would look at the trim of boat 1st...IF you are properly triming boat and not plowing water OR have the trim back so far its getting cavitation.....the next thing I would blame is the prop itself...it could be the prop is getting cavitation at 400rpm and just isn't sucking anymore water through it....I've personally seen this before and the prop was junk....good luck hope you get the problem fixed


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## s.w.a.t.t6935 (Aug 7, 2012)

Yes boat is trimmed out


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## harryhunter (Jun 15, 2014)

With every thing said & done . I would try another prop the one you have might have a bent blade .


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## sherman51 (Apr 12, 2011)

harryhunter said:


> With every thing said & done . I would try another prop the one you have might have a bent blade .


yes if the motor is trimmed out and not to much trim I would try another prop.
sherman


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## fastwater (Apr 1, 2014)

sherman51 said:


> yes if the motor is trimmed out and not to much trim I would try another prop.
> sherman


...and it would be a 19p.

With the 17p you probably have a great hole shot...but...

...I ran a 19 on my Merc. 150 and 17 1/2 glass bass boat and it really liked that setup for what I was trying to achieve with that rig. Top end was about 55. Had room for more top end if I bumped up a pitch but needed great hole shot as that's what I was concerned with more so than WOT. Needed to get on top quickly down in Fla. fishing the grasses and most of the time there just wasn't that big of openings of clean water.

Your boat being an 18 1/2' and probably alittle heavier then my 17 1/2' may just like that 19 pitch 3blade on both sides of the fence. You'll lose a little bit on the hole shot but pick up more speed on the top end.

Four blades are a whole different story.


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## sherman51 (Apr 12, 2011)

X2 on the 19p fastwater suggested.
sherman


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## s.w.a.t.t6935 (Aug 7, 2012)

Thanks guys for all your input


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## Gottagofishn (Nov 18, 2009)

Reading through this I was wondering if it could be one other thing. What if the engine is mounted too low? Could that be the issue? Has this always been an issue with this boat?
Who rigged it?


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## firemanmike2127 (Mar 17, 2013)

The style of propellor can make a significant difference. Blade shape/profile, construction material, rake, & # of blades are all factors that will affect the performance of your combination. Has this prop ever been rebuilt ? Are the blades cupped on the trailing edge ? Is it in good overall condition ? Brand ? If you have a generic aluminum prop on there that's been rebuilt a couple of times that could be an issue. There are some props out there that are real clubs & perform extremely poorly. I would encourage you to try some other good props on there & do some further performance evaluation. Look around on the Bass & Walleye boats forum to see if you can find someone with a similar rig to get a recommendation on what prop they're running & some performance #'s. Some other thoughts for consideration: Is the installed height of the engine correct ? The anti-cavitation plate should be flush or +/- 1/2" with the bottom of the hull as a general starting point. Higher engine mounting heights will reduce the parasitic drag at higher speeds, but can negatively affect the hole-shot. Is the boat 'heavy' ? In other words, does it weigh what it's supposed to ? There are some waterlogged hulls out there, even though that's probably a long shot in this case. Additionally, what about the bottom of the hull ? Is it true ? A boat that has a 'hook' will never perform well. Check the last 4-5' of the hull with a straight edge to confirm that the boat doesn't have any deficiencies that will negatively affect the performance. Mike


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## firemanmike2127 (Mar 17, 2013)

Additionally, are you certain that the tachometer is accurate? If you know someone that has a good digital timing light with an advance feature you could verify that the reading you see on your dash mounted instrument is correct. I always like to double check the factory installed tachs (especially the older analog instruments) whenever I'm propping out a boat. Be sure that the readings are identical between the 2 instruments throughout the RPM range (up to WOT). I have also seen where people will mistakenly choose the wrong setting on the selector switch (not all tachs have this option). Mike


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## s.w.a.t.t6935 (Aug 7, 2012)

After all the running and checking props it not my problem it almost seems like it's not advancing in timing I have to baby it to get the rpms up


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## fastwater (Apr 1, 2014)

s.w.a.t.t6935 said:


> After all the running and checking props it not my problem it almost seems like it's not advancing in timing I have to baby it to get the rpms up


Is this something new from your post #23?



s.w.a.t.t6935 said:


> Yes it'd does 5300rpm From 3/4 throttle 4000 rpm. 36mph To wot 5300rpm their is no change in speed


Is the mtr now missing at higher rpm or bogging down like lack of fuel???


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## s.w.a.t.t6935 (Aug 7, 2012)

No not bonging almost like it's not advancing the timing and giving it more spark to burn the fule pulled plugs their not wet. Runs great at idle Next step is to take it some where I'm thinking it's the stator possible like on the high end of it mabe they can test it


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## fastwater (Apr 1, 2014)

s.w.a.t.t6935 said:


> No not bonging almost like it's not advancing the timing and giving it more spark to burn the fule pulled plugs their not wet. Runs great at idle Next step is to take it some where I'm thinking it's the stator possible like on the high end of it mabe they can test it


Or one of the switch boxes breaking down???

Think getting the electrical/spark side of things tested at this point is a good idea.


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## s.w.a.t.t6935 (Aug 7, 2012)

I'll check that thanks


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## Marinette Sportfisherman (Apr 13, 2010)

when was the last time you rebuilt the fuel pump? it needs to have ethanol proof gaskets or it will break down the material.. start simple its a easy 15 minute rebuild


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## s.w.a.t.t6935 (Aug 7, 2012)

It was the switch box got it fixed today she runs like top thanks for all the inputs


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## buckeyebowman (Feb 24, 2012)

NICE! Glad you got it figured out.


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## humpty dumpty (Nov 30, 2013)

It was mentioned above about different props some are cupped that grab more water than ones that are a straight prop,, but one thing you must keep in mind is to stay within the recommended rpms at WOT. if you put a prop on with too much pitch you will lug your motor causing overheating, eventually leading to shorting the life of you motor. it is similar to trying to tow a heavy trailer with a motor too small to pull it. All props are designed with a certain amount of slippage built into them,,, You should load your boat to your most common weight during useage go to WOT with a accurate tach and make sure it falls within rpm limits. Stainless props cut the water easier with less drag,, but the down turn is if you hit something in the water unlike aluminum props that bend, stainless props are stronger and transfer that energy into the gearbox and the weakest area will be what gives way. good luck, learned this from an excellent marine mechanic with over 40 yrs experience. I am not saying this is your problem,, just saying just something to check,,
HD,


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