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7.5 HP Evinrude won't rev out

T

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I've got a 7.5 Evinrude on a 14' tinner, I believe it's a 1981 model.

It will start on the first pull just about every time, runs and idles so smooth it is ideal for trolling but it will not rev out when it's time to go home. Bogs and chugs along and seems horribly underpowered. Plugs look like new and do not appear to be at all fouled. Any help would be greatly appreciated.
 
Do a compression test.-----Then check for spark that will jump a 3/8" gap on each lead.----How did the motor run last year for you.----If it is a new to you motor a new water pump impeller should be installed.----To me it sounds like it might be running on 1 cylinder.
 
racerone said:
Do a compression test.-----Then check for spark that will jump a 3/8" gap on each lead.----How did the motor run last year for you.----If it is a new to you motor a new water pump impeller should be installed.----To me it sounds like it might be running on 1 cylinder.
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I don't have a compression gauge but feels good pulling it over. It is a new to me motor and has run like this as long ass I've had it. It seems like it runs too smoothly to be only firing on one cylinder? Also the plugs look identical and look to be in very good condition.
 
Haha, that would be ideal! unfortunately I'm guessing you aren't in Saskatchewan Canada.

It's hard to find anyone that wants to work on older small engines anymore and it's something I have little time to fiddle with as I farm full time.

So when I do have that downtime I'd rather go fishing than fiddle with the motor.

It will be something simple I'm sure, it's not a complex machine.
 
Likely is running on one cylinder. They will run very well on one---just no power. You will have to do some troubleshooting to find out why.
 
I might be driving through your province later on this summer.-----I do know why shops do not work on older motors.----With astronomical labor ( spell it tax rates ) the cost of repairs adds up quick.-----New motors made by robots are the ticket for most folks.-----I agree those 7.5 HP motors like yours run really sweet if in good condition.
 
Ok, thank you frdgator I'll check the spark on both cylinders, maybe it's a simple as a dead coil pack or something but I'd never of guessed an engine would run this well on 1 cylinder and both plugs look like an identical burn but who knows.

racerone, If you want to do a little work on a little 7.5 'rude and/or a 150 Johnson Fast Strike, let me know!
 
My good friend and log building mentor was born in Moose Jaw. We built log structures together in NW Ontario from 1980s until he died at ago 92 in 2001. He disliked Moose Jaw for lack of trees, deep forests and lakes. His name was Walter Booi. Probably a name long forgotten out in Saskatchewan but well remembered and known in Northwest Ontario. He was a living legend......also a darn good mechanic.
You can test for one cylinder run at idle by removing the plug wires one at a time and you will find right away if one cylinder is firing or not. As you might think if only one cylinder is firing the other one would be wet all the time. It is possible that the high speed main jet is partially plugged and it is starving for fuel at higher speeds.
 
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No sorry that name doesn't ring a bell to me Timguy but I've only been here since 2010, moved here from Central Alberta then but grew up in Ontario. That's funny that a log builder came from Moose Jaw as it is bald prairie, just about any tree here has been planted, very good fishing in the lakes that we do have here and there are some big lakes, far better in that regard than Alberta. I fished lots of lakes in Ontario and some in Alberta and have found the fishing in SK to be far superior to the others. Fished a little in Manitoba as well that was very good too. That's a good point about pulling plug wires one at a time I don't have one of those spark gap tools and it's a 60 mile trip to go get one, I'll try with a screw driver and make sure it'll jump a decent gap. took the fuel pump apart and the diaphragm appears ok. The motor in question is an E8RCIC
 
Discovered a couple things, 1 be sure to only take the horizontal screws out of the fuel pump. Live and learn I guess. I believe I got it back together correctly. I can blow in the inlet but not the outlet.

And then 2 when checking for spark the bottom plug wire came off in my hand from the coil, looked to be corroded and burnt through. Could be the culprit. Can you replace just the plug wire or do you have to buy the coil with the plug attached?
 
I just rebuilt a 60hp, put it back together and it would not
run right. I checked and rechecked everything just to
find out it was a intermittent SPARK PLUG WIRE.
I disassembled that wire and recrimped it solid.
Now the motor starts perfect, idles perfect and runs
perfect.
Don't over look the simple things.
 
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There doesn't appear to be a crimped end at the coil, just a few short frayed wires

What kind of end should it have?
 
It looks like the original coils had the spark plug wire molded into coil itself somehow. Both my coils have a grey goopy, epoxy looking but rubbery feeling stuff dripping off of them, I'm pretty sure these coils have been getting hot and are leaking insulation or something and that's what allowed the plug wire to come off. I think I better replace both coils, that could explain my lack of power.
 
Yes you should replace them. They can also arc "internally" and foul your spark. These external coils often crack too....then they cannot be trusted.
Walt moved to NW Ontario as a youth. Picked up a broad axe and never set it down.
 
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