How To Simulate The Motor In Water

evinrudexp

Seaman Apprentice
Joined
Apr 13, 2006
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34
Hey Guys,

Im Trying To Diagnose My 1988 150 Hp Evinrude Xp Vro. It Stalls Out When Under Load So I Was Wondering How Can I Immitate The Boat Being On Water When Its Actually Sitting On The Trailer???

Any Insights Would Really Help.

Thanks To All!
 

F_R

Supreme Mariner
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Jul 7, 2006
Messages
28,195
Re: How To Simulate The Motor In Water

You can't without a dynamometor.
 

tashasdaddy

Honorary Moderator Emeritus
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Messages
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Re: How To Simulate The Motor In Water

you can't. i would check compression first. when were the high speed jets last removed and cleaned and the carbs rebuilt.
 

freddyray21

Commander
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Jun 10, 2006
Messages
2,460
Re: How To Simulate The Motor In Water

you can use a test wheel in place of the prop, but cheaper to take it to the lake.
 

F_R

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28,195
Re: How To Simulate The Motor In Water

A test wheel is indeed effective....in a very large, properly baffled and vented test tank. 150 horsepower is an awful lot to dissipate any other way than putting it in the lake. Those are awfully restless horses when you get them excited.
 

rickdb1boat

Supreme Mariner
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Jan 23, 2002
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11,195
Re: How To Simulate The Motor In Water

Leave it on the trailer and back it into the lake. Just make sure it's strapped down good before you put the gas to it...
 

jtexas

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Re: How To Simulate The Motor In Water

Leave it on the trailer and back it into the lake. Just make sure it's strapped down good before you put the gas to it...

back it down just enough to get good water pressure - that'll load it up for sure.

chock your wheels.
 

tashasdaddy

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Re: How To Simulate The Motor In Water

yeah, that works, but don't be surprized when someone complains, about you eroding the ramp.
 

darrklim2

Petty Officer 1st Class
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Jul 5, 2007
Messages
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Re: How To Simulate The Motor In Water

yeah, that works, but don't be surprized when someone complains, about you eroding the ramp.

Yes, this is a very big problem around here. People who drive their boats on the trailer and then leave them running in gear at high rpms. This really ruins the ramp for others. :(
 

evinrudexp

Seaman Apprentice
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Apr 13, 2006
Messages
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Re: How To Simulate The Motor In Water

Thanks for all the great replys. Leaving it strapped to the trailer in the water sounds like the best way to go. Im not sure if the ranger will be happy about that though! I think they have a sign to prohibit working on your boat at the ramp. I thought a test wheel would have been a good idea but I guess I wouldnt have the same back pressure from the muffs.

The carbs have not been rebuilt in years. Is that where I should start?
 

jtexas

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Re: How To Simulate The Motor In Water

good compression? good spark? rebuild carbs.
 

evinrudexp

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Re: How To Simulate The Motor In Water

good compression? good spark? rebuild carbs.

Okay I will do the compression check today and the spark check.

To check the spark do I simply check that a spark exists or is there more to it? I got a tool from pepboys thats for a "no start" spark check. I could set the gap in a clear tube to see the spark. Am I not allowed to let the motorstart with this tool hooked up?

I forgot to mention that my motor stalls out under load but there are instances where it starts to stall and then take off out of the whole like a bat out of hell! Could the spark work on and off?
 

iwombat

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Jul 12, 2006
Messages
3,767
Re: How To Simulate The Motor In Water

Spark check:

Remove all the plugs.
Hook up your spark tester to one wire and ground the others with nails against the block or wire or whatever.
Crank the motor over with key, or jump the solenoid withe the ignition in the run position.
Check for bright spark jumping a 7/16" gap.
 

jtexas

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Re: How To Simulate The Motor In Water

Clogged carbs are rarely an intermittent problem...but spark can be. if it you get a good spark across 7/16" proceed as if its good.

let's clarify the symptoms: you launch the boat, it starts and warms up fine, put it in gear and idle through the no-wake zone, put the hammer down and A) she dies? or 2) she accelerates a little but just doesn't have any power?
 

iwombat

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Re: How To Simulate The Motor In Water

Huh . . .

Didn't know 2 followed A.


:)
 

Evinrude Boater

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Re: How To Simulate The Motor In Water

There's three kinds of people in the world, those that are good at math and those that aren't.
 

evinrudexp

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Messages
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Re: How To Simulate The Motor In Water

Clogged carbs are rarely an intermittent problem...but spark can be. if it you get a good spark across 7/16" proceed as if its good.

let's clarify the symptoms: you launch the boat, it starts and warms up fine, put it in gear and idle through the no-wake zone, put the hammer down and A) she dies? or 2) she accelerates a little but just doesn't have any power?

I did the spark check and I did see a very thin line of spark that jumped accross the gap. It wasnt a bright blue spark like I imagined Id see! They were the same on all 6 cylinders.

Okay so I idle through the no wake zone and when I put the hammer all the way down she wants to die until I pull back. She may accelerate a tad but then slow down, and I mean a tad! If I dont put the hammer all the way down but maybe 1/2 or so she wont die but she wont accelerate either. And then the mystery...sometimes she will want to die and then take off like a bat outta hell!
 

evinrudexp

Seaman Apprentice
Joined
Apr 13, 2006
Messages
34
Re: How To Simulate The Motor In Water

Spark check:

Remove all the plugs.
Hook up your spark tester to one wire and ground the others with nails against the block or wire or whatever.
Crank the motor over with key, or jump the solenoid withe the ignition in the run position.
Check for bright spark jumping a 7/16" gap.

Woops I might have done my spark test incorrectly...

Should I have taken the spark plug off??? :)

I just unglugged them all?
 

iwombat

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Re: How To Simulate The Motor In Water

Yes, you should take the spark plugs all out.


Got no idea what glugging or unglugging is.
 

jtexas

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8,646
Re: How To Simulate The Motor In Water

if you unglug the glugs, you'll want to use jumpers to ground the glug leads to the engine block, as a precaution to keep from smoking the coils. Not sure taking the plugs out will make a difference.

The tester connects to the spark plug boot on one side and the engine block, not the spark plug, on the other.

check to be sure the timer base moves smoothly without sticking when you advance the throttle.
 
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