72 50HP No Power (Compression Results)

jayhawkokie

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Mar 21, 2008
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The boat totally lost power in the water, and in an earlier post on this forum I was told it could be an ignition problem.

I could only find one new coil in town so I replaced one of the coils that was badly cracked and am getting another new coil in tomorrow. I checked both coils with my induction timing light and it shows spark to both plugs.

I borrowed an inline spark plug tester and I get no light on the tester to both plugs. I put the boat in the water and put it in gear, at full throttle I couldn't get it to run much above idle speed. Setting on the trailer with the hose muff on it starts and runs great, and I put in gear and quickly advanced the throttle up and back to idle and it seemed to run and accelerate fine.

I can pull the plug wire off the old coil and the engine still runs, when I pull it off the plug with the new coil the engine dies, telling me that perhaps I don't have enough fire from the old coil to fire the plug under compression.

I'm wondering if I also need to replace the power pack, it looks like it's been around for awhile.

I hope someone can help me, there are fish out there waiting for me.

Jayhawkokie
Grand Lake O' the Cherokees Oklahoma
 

jay_merrill

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5,653
Re: 72 50HP No Power

Re: 72 50HP No Power

Ability of the engine to "run fine" on the muffs, and then bog down when it is actually pushing the boat, is a classic sign of a cylinder not performing. Whether that lack of power development in the affected cylinder is due to lack of fuel delivery or ignition, is always the fifty dollar question.

Since you have another coil coming anyway, replace the one that you think isn't firing and see what happens. If you replace it, but still get no spark, you could have a bad power pack or a bad sensor.

Lets see what happens after the coil replacement and take it from there.
 

jayhawkokie

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Re: 72 50HP No Power

Re: 72 50HP No Power

Thank You for the input Jay. My issue is similar to the one raygussy is having so I'm watching his thread closely.

Trying to eliminate fuel issues I switched to the other tank just in case there is a problem with the first tank , the bulb pumps up good and tight. I pulled the fuel connection to the fuel pump and pumped the bulb, I'm getting gas to the fuel pump.

I live 1 mile from the boat ramp so i backed into the water and started the engine, it ran up to full throttle the first time as slick as a button, but when I tried to advance the throttle the second time the engine bogged down and died after running a short time.

I tried pumping the bulb when the engine was chugging slowly along at full throttle but that didn't help pick up any rpm. I could never get it to start again after it died. Now that it's setting in the driveway it starts right up after it's sat for awhile.

I will get the new coil in Joplin tomorrow and put it on, I'll report back my findings when I get it installed.

Thanks for your help.

Jayhawkokie
 

jayhawkokie

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Re: 72 50HP No Power

Re: 72 50HP No Power

When I went to the Evinrude dealer in Joplin, MO today and told their mechanic my symptoms and the diagnostics I had ran. He suggested that I rebuild the carbs before throwing any more expensive parts at the engine.

I'll report back in a few days let y'all know if it's running right or back to square one.

Jayhawkokie
 

jay_merrill

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Re: 72 50HP No Power

Re: 72 50HP No Power

You may not need to rebuild the carbs entirely. If one cylinder isn't getting fuel, the problem may be due to a bit of junk in it, most probably in the high speed jet. One of the ways to check is to remove the cover on the air silencer and simply look down the throat of the carb. I suggest putting the boat in the water and having a friend drive it while you do this.

I have found that the fuel spray from the high speed nozzle is usually visible just by looking into the carb, but some people tell me that "shooting" the light from an inductive timing light into the throat, aids in this. Either way, you should be able to see the fuel moving in the carb. If there is no visible fuel spray from the high speed nozzle, or it looks to be considerably less than what you see in the other carb, chances are that a piece of junk has gotten into the high speed needle valve on the affected carb.

You should be able to get the carbs off of the motor without disturbing the linkage between them. If so, you should then be able to take the bowls off of the carbs to inspect and clean them. I believe that your carbs have fixed HS orifice plugs ("needle valves"), which require a special, narrow screwdriver to remove. If you surf the threads here, there is a post on the issue, and advice on how to make the required tool.

Generally speaking, I don't recommend this sort of half baked fixing of a carb, but if you just want to get your motor going for the holiday weekend, you can save some time by not disturbing the linkage, etc.
 

jayhawkokie

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Re: 72 50HP No Power

Re: 72 50HP No Power

Thanks for the input Jay, I got the carbs cleaned up and new kits in them. They were pretty clean looking to begin with, I made sure the main jets were squeaky clean before reassembly. I was able to remove the carbs without disturbing the linkage.

I put it in a barrel of water and it started right up. I tried to get the idle screws adjusted, but wasn't very successful. I did notice a rpm change on both carbs when I was trying to adjust the idle. I was able though to run it up to full throttle and back down several times and it seemed to run good. I kept killing it trying to adjust the idle. After running the engine for several minutes it became almost impossible to start until it sat for several minutes.

I have spark on both cylinders, but it still dies when I pull the plug wire off but continues to run on one cylinder when I pull the wire off on # 1.

I'm going to O'Reillys tomorrow and get their compression tester.

Thank You for your input Jay.
 

jay_merrill

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Re: 72 50HP No Power

Re: 72 50HP No Power

OK - just be careful of running your motor up to "full throttle" in a barrel. In fact, I recommend that you not do it at all. Unless you have a test tank, you have to run it up in neutral and that isn't going to tell you anything. The motor has to be under a load to reveal what level of performance you are getting, and doing this when it isn't in gear could easily damage your motor.
 

jayhawkokie

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Re: 72 50HP No Power (Compression Results)

I got O'Reilly's compression tester, it's not the differential type, you crank the engine and read the gauge.

#1 was 85#
#2 was 145#

I'm still having igniton issues, when I pulled the #1 plug (which is new) it looked like it did when I took it out of the box. I put the plug on the wire, held it to ground and had some crank the engine, the spark looked very weak, I did the same on #2 which has a brand new coil and the spark looked weak on that one also, but the engine started and idled fine.

With the low compression on #1 I know I need a rebuild, but I've decided not to spend a lot of money on this engine and get something newer. I would like to be able to use this engine for the rest of the summer is possible while looking for a replacement engine, that is unless I can do a top overhaul and not spend a lot of money.

If I resolve the ignition issue will the engine run good enough to get me to my fishing holes on the lake?

Where do I look next as far as the ignition?

Thanks for your help.

Jayhawkokie.
 

jonesg

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Feb 22, 2008
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7,174
Re: 72 50HP No Power (Compression Results)

You might try spraying some seafoam engine decarb into the cylinders, its possible the ring is stuck due to carbon .
A new engine will develop the same problems if not serviced properly.
 

jayhawkokie

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Re: 72 50HP No Power (Compression Results)

Okay folks bear with me, hope I don't wear out my welcome trying to figure this situation out myself.

I ran another diagnostic step, I switched the plug wires and switched the coil lead on the powerpack, still getting the same results, it will run on the #2 but not the#1, this shows me both the new and old coil are working properly.

I rebuilt both carbs, making sure tha main jets were clean, but I'm thinking maybe the #1 carb still has a blocked passageway and that cylinder isn't getting gas. The plugs are new, and after running the engine for several minutes the #1 plug (the cylinder with low compression) was clean as new, the #2 plug showed the cylinder was firing, there was traces of oil and carbon on that plug. I'm going to pull the #1 carb again tomorrow and clean it better and hope that fixes the problem.

Am i headed in the right direction? I'm an old Scotchman (the missus calls me cheap) and I love to dive into things like this myself to save a few bucks. Beside that, there is satisfaction in doing it yourself.

I'll try the Seafoam after I get both cylinders firing together.

Jayhawkokie
 

JoeCrow

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Nov 1, 2007
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218
Re: 72 50HP No Power (Compression Results)

145# on one cylinder and 85# on the other?
Sounds like you may have a problem there
I think the cylinders should be within 10% or 15% of each other
 

R.Johnson

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Sep 24, 2003
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4,446
Re: 72 50HP No Power (Compression Results)

That's only 60 lbs. difference! Never needlessly pull the head on a twin cylinder 50. Try seafoam! JESUS CHRIST.
 

tx1961whaler

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May 31, 2008
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5,197
Re: 72 50HP No Power (Compression Results)

R. Johnson is correct. It would take an act of God to make up the 60 lbs difference. No "miracle in a can" for this one. You have to pull the head and see what's up with that cylinder.
 

FillupD

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Re: 72 50HP No Power (Compression Results)

I just cleaned up my keyboard after spittin Mountain Dew all over it. Now that is funny R.J
 

jayhawkokie

Petty Officer 3rd Class
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Mar 21, 2008
Messages
92
Re: 72 50HP No Power (Compression Results)

I'm going to pull the #1 carb back off and tear it back down, it has to be plugged still.

I'm going to try the "Miracle In a Can" just for the helluvit, can't hurt. I'm just trying to get the engine running good enough to chug out to the fishing holes a few more times.

As far as I'm concerned this motor is trash, I'm looking for a replacement. It will be for sale "CHEEP" is someone needs a spare parts motor.

Jayhawkokie
 
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