I need a second opinion

J

JakeCo88

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Feb 3, 2012
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I have a 1956 Evinrude Fastwin 15 that has been giving me trouble, but I think I have found the problem, I would just like a second opinion from those more knowledgeable before I start tearing things apart.

I could never get my engine to run for more than a few seconds before it would die. I did some looking online and found it might be the compression, i.e. not enough to get a good combustion. I don't have a pressure gauge to determine my exact compression, but I can hold my thumb over the spark plug hole and turn it over, so I'm guessing it is less than desirable. I had been attempting to use a 24:1 oil/gas ratio as suggested on here. I added a little more gas (about a 12:1 ratio) and it ran fine, just smoked a lot. Don't worry, I only did this for about a minute.

My thought now is I need a set of rings. The cylinders themselves are fine, no scoring. My biggest question is: Is there anything else that I need to do to improve compression?
 
L

Lyle29464

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Mar 10, 2009
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1,261
Re: I need a second opinion

If it will start low compression is not the reason it dies. I believe you need to look at the fuel system. Carbs first then work your way back.
I would drain everything and then put the correct oil mix in and change the plugs. maybe a good additive setting in the system for a day or so will clean things out. But a good carb cleaning would be first on my list. You can get a compression gauge for $20.00
 
K

kodibass

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Re: I need a second opinion

As I live where there are none I cannot say for sure, however I have read on this site that Auto-zone, pep-boys and maybe other national auto parts stores will loan for free a compression tester, and many other types of tools. Be worth checking out. good luck
 
JB

JB

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Re: I need a second opinion

Don't even think about improving compression until you do a correct compression test and get results calling for improvement, Jake.

I agree with Lyle. Your problem is not compression, it is fuel supply.
 
F

F_R

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28,195
Re: I need a second opinion

Have the coils been replaced? Have you even looked? ALL 1956 Evinrudes have bad (cracked) coils unless they have already been replaced. You will never get it to run right till you do.

P.S. It usually gets blamed on the carburetor. Not saying you don't have a fuel supply also.
 

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1946Zephyr

1946Zephyr

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Re: I need a second opinion

Totally with F_R. A lot of times ignition problems will make us believe there are carb problems. Truthfully, the carbs on these are pretty darn good and don't give trouble near as much as the ignition system does. If someone has by chance changed out the coils, make sure that the spark plug leads were replaced along with them. Often times if people replace coils, they just shove the old wires intot he new coils and the connection is not that great. Whenever I refurbish an ignition system, I disassemble the whole thing, clean it entirely and reassemble it, with fresh new lube on the mounting rings. That way, I shouldn't have to mess with it again for many years, except to check the points. Those old 15's are good reliable motors and pretty tough. If they're tuned right, they do great.
 
kfa4303

kfa4303

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Re: I need a second opinion

+1. Great old motor you got there, and if it will start, then the compression is probably ok for now. I would starrt at the top and work my way down the motor. First inspect/replace any faulty ignition components (see links below for how-to). You can get coils and tune up kit right here at iboats for about $20 each. I would suggest some new 7mm copper core spark plugs wires (not graphite automotive wires) too, if you can find them. No try to confirm a nice strong bright blue spark that can jump a 1/4" gap. You can get a gap tester at any autoparts sores for about $5. Once spark is established, you can move on down to the carb. I would get a rebuild kit from here at iboats, also about $20 and just start fresh. It's not a bad idea to replace the fuel lines too. Just take them with you to the auotparts store and they can cut some new ones to length for a couple bucks (Note: the line going from the tank to the motor is thicker b/c it's under vacuum). See link(s) below for complete step by step on the carb rebuild. Now that you have compression, spark and fuel she should run. Now whether she "goes" is up to the gears, but we'll deal with that once you got her vroom-vrooming a bit. Give these links a read and holler if you get stuck.


http://www.duckworksmagazine.com/06/columns/max/index6.htm

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm (different model than yours, but same procedure)

http://www.outboard-boat-motor-repa...hnson 5.5 HP 1954-1964 Carburetor Tune-UP.htm
 
F

Fishing4Walleyes

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Apr 7, 2012
Messages
40
Re: I need a second opinion

I have solved similar symptoms with a fuel filter more than once in my days and it is the easiest item to diagnose. Open a the fuel line just below the filter and see if you have sufficient flow to run a motor.
 
oldybutagoody

oldybutagoody

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Re: I need a second opinion

Just to clarify, if you say you added GAS to your 24/1 Gas/Oil mix, you reduced the amount of oil (increased the ratio) so your mix was more like 30 or 35/1, not 12/1. Running with not enough oil is one of the best ways to kill your motor. Your fastwin has roller bearings on the crank and rods so most say you can run with 24/1 gas to oil ratio but I run 16/1 on my 57 fastwin because the wristpins do not have roller bearings. Too much oil won't hurt it. Too little WILL.
Also, use all the advise you've been given about the ignition and carbs. The thumb test over the spark hole doesn't tell you anything. If, AFTER you've updated the ignition and cleaned the carb (w/ new float), you find that the compression is low, it isn't necessarily the rings. Mine had low compression and it was a blown head gasket.
JakeCo88 said:
I have a 1956 Evinrude Fastwin 15 that has been giving me trouble, but I think I have found the problem, I would just like a second opinion from those more knowledgeable before I start tearing things apart.

I could never get my engine to run for more than a few seconds before it would die. I did some looking online and found it might be the compression, i.e. not enough to get a good combustion. I don't have a pressure gauge to determine my exact compression, but I can hold my thumb over the spark plug hole and turn it over, so I'm guessing it is less than desirable. I had been attempting to use a 24:1 oil/gas ratio as suggested on here. I added a little more gas (about a 12:1 ratio) and it ran fine, just smoked a lot. Don't worry, I only did this for about a minute.

My thought now is I need a set of rings. The cylinders themselves are fine, no scoring. My biggest question is: Is there anything else that I need to do to improve compression?
Click to expand...
 
J

JakeCo88

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Messages
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Re: I need a second opinion

Thank you all very much for the help.

UPDATE: I checked the compression today and it is around 60 pounds. I have previously inspected the coils and they appear to be okay. I checked the spark again today by putting a screw driver in the wire and I was getting a good strong spark across a 1/4 inch gap. I have also replaced the head gasket. So I guess I'll try rebuilding the carb and see what happens.

I guess I'm just a little confused why it won't run at a 24:1 ratio but will at a 48:1 ratio. It seems to me if it were the carburetor it wouldn't run in either case.

oldybutagoody said:
Just to clarify, if you say you added GAS to your 24/1 Gas/Oil mix, you reduced the amount of oil (increased the ratio) so your mix was more like 30 or 35/1, not 12/1. Running with not enough oil is one of the best ways to kill your motor. Your fastwin has roller bearings on the crank and rods so most say you can run with 24/1 gas to oil ratio but I run 16/1 on my 57 fastwin because the wristpins do not have roller bearings. Too much oil won't hurt it. Too little WILL.
Click to expand...

Oldy, your right, my math was backward, it would have been more like a 48:1. And thanks for pointing out the danger, but no worries, I only let it run for a minute or so that way.
 
HighTrim

HighTrim

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Re: I need a second opinion

Your compression is too low to run that 15. Try a decarb to free up the rings, as that is likely the issue since the bores are good and the head gasket has been done.
 
A

atrok3

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Re: I need a second opinion

just curious did you go to a auto part store and barrow one of the gages. I was just wondering because I had the same reading on a pair i used from auto zone and it read about 1/2 what it was
 
1946Zephyr

1946Zephyr

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Re: I need a second opinion

Yea, sometimes it's a good idea to try a second testor. And this might be one of those times. :D
 
kfa4303

kfa4303

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Re: I need a second opinion

HighTrim said:
Your compression is too low to run that 15. Try a decarb to free up the rings, as that is likely the issue since the bores are good and the head gasket has been done.
Click to expand...

I'm thinking decarb too. Do a search here in the forums for Seafoam and you'll find all kinds of info. Afterwards, I'd try not to run it at such a lean mix. These old girls do need a fair bit of oil in the mix and 48:1 is a lot less than normal. It may also be a dirty issue, in which case the rebuild will help. Keep us posted.
 
lindy46

lindy46

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Re: I need a second opinion

I wouldn't put money into parts until you see if you can get the compression up. Do a decarb as suggested. A decarb removes the carbon buildup in the cylinders and on the rings. If you have sticky rings, it could be causing the low compression readings. If you can get the compression up to around 100psi, then you can start on other issues, like a carb rebuild.
 
F

floatingwoody2006

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Joined
Feb 2, 2006
Messages
500
Re: I need a second opinion

Compression does seem a little low, but most of the 1954 era motors i have had..And it's been lots, have averaged around 74lbs on my manual napa tester. Could be the tester, could be you need to pull a couple more times on the rope. If it goes no higher than 60, let it sit for a minute to see if the pressure drops. You said there was no scoring on the cyl. walls..After the 60 lb reading, squirt a small amount of oil in the holes and pull it again. if it goes up, you may have scoring or stuck rings you didn't notice. decarb it, rebuild the carb, fresh gas, and ill bet your off. That's a nice old motor..If the impeller was replaced and they didn't get the small o-ring under there back on, it could choke on it's own exhaust, or allow water into the head, i believe. It's been a few years sense i was into one, so don't take my advice too seriously.
 
J

JakeCo88

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Re: I need a second opinion

atrok3 said:
just curious did you go to a auto part store and barrow one of the gages.
Click to expand...

floatingwoody2006 said:
Compression does seem a little low, but most of the 1954 era motors i have had..And it's been lots, have averaged around 74lbs on my manual napa tester. Could be the tester, could be you need to pull a couple more times on the rope. If it goes no higher than 60, let it sit for a minute to see if the pressure drops.
Click to expand...

I did borrow a tester from a local store. I also took you advice and tried giving it another pull; the pressure jumped up to around 75. I think I'll start with a carb kit and then a decarb.
 
J

JakeCo88

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Messages
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Re: I need a second opinion

Secondary question: Can anyone tell me what the part number is for the float for my '56 fastwin carburetor? I have the rebuild kit number as 18-7043, but as I understand, that does not include a float.
 
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