1973 evinrude 55 HP fouling out plugs

[dbmstr124]

I have a 1973 Evinrude outboard that was just rebuilt. It has 145 psi on both cylinders. I have been mixing the gas pretty lean (35:1) to break it in and lately it has been fouling out plugs 30 seconds after I floor it and take off. I put a 10:1 mixture in it tonight and took it out and it planed out rode great for 15 seconds and then can't get over 1/4 throttle out of it again. I had a little water in the gas and changed this. My next guess is maybe the coil packs or wires are crap and maybe the NEW plugs aren't getting the signal at a high enough voltage to burn????? Have you ever heard of this or do you know where to buy these coil packs? Thank you.

 

[HighTrim]

Re: 1973 evinrude 55 HP fouling out plugs

What plugs are you running and what pitch prop are you pushing the boat with? Why are you running it at 10:1? First during your break in (generally considered the first 20 hours or 40 gallons of gas) you need to provide for extra lubrication. Generally 25 to 1 at wide open throttle. To do this you need to add additional oil to the fuel supply. On a non oil injected engine this means running two pints of 2 cycle oil to every six gallons of gas. On an oil injected engine this means adding one pint of oil to every six gallons of gas. The other precaution is to limit and vary your RPMs. A general rule of thumb is not to exceed 85% of max rpm during the first 10 hours. Also don't run your boat at a constant RPM for more than a couple of minutes. It is important to vary your R's even if by only a few hundred RPM's while breaking the motor in.

 

[MikDee]

Re: 1973 evinrude 55 HP fouling out plugs

Ditto! ^^^

 

[dbmstr124]

Re: 1973 evinrude 55 HP fouling out plugs

Thank you. I was told to run a mixture like around 35:1. I ran the 10:1 today just to see if it would help the problem but it didn't. So with 2 pints to every 6 gallons that is about a 2 or 3:1???? That will help. I am also going to check the spark plug wires and make sure they are sending a good enough spark. I'm not sure on the pitch of the prop. I really appreciate your responses. I will let you know what happens. thanks again.

 

[samo_ott]

Re: 1973 evinrude 55 HP fouling out plugs

WAIT. Don't run it at 2 or 3 to 1. Remember, oil mixture is a ratio, not a percentage. Your normal mixture for that engine would be 50:1 which is 2 ounces of oil in every 100 ounces of gas. For the break in period running at 25:1 or 35:1 is good. Running any lower a ratio will foul up the plugs with excess oil. Don't keep changing your ratio. And as HT said, don't run it wide open.

When you say fouling the plugs, do you take them out right after this happens? And what do you see?

 

[dbmstr124]

Re: 1973 evinrude 55 HP fouling out plugs

I understand. On the bottle of oil it said for a 25:1 ratio put 8 ounces of oil for 1 gallon of gas. I thought this was pretty excessive but I did it. So I have a 5-6 gallon tank, 5 gallons is 80 ounces so that should be around 2 ounces of oil if I top off the tank around 6 gallons???? I take them out and they are a dark brown color and oily, wet. Is there a good way of testing the spark plug wires? Do you know the resistance they should read with an ohm meter or possibly holding the plug out of the block plugged in and checking for spark would do? Thanks again everyone

 

[samo_ott]

Re: 1973 evinrude 55 HP fouling out plugs

No. There's 128 ounces in a US gallon. So for 5 Gallons it's 640 ounces... So 50:1 would be 12.8 ounces... 25:1 would be double that (25.6 ounces)... for 5 gallons...

Use a spark tester to test the spark, or hold the wire 3/8" from block and pull (hard to do by yourself)

 

[rodbolt]

Re: 1973 evinrude 55 HP fouling out plugs

your describing trash/water in the fuel system and or a weak fuel pump. what was the cause of the first failure? are you sure this is a 73 55? is it a two cylinder or a 3 cylinder?
plugs just wont foul that fast.
and once trash or water get in the carb there is only one way to get it back out, remove,disasemble,clean and reasemble the crbs.
testing spark at an RPM OTHER than the problem RPM is useless in this application. as it runs at idle we already know the system is capeable of spark at low speed.
but the reason for asking are you sure about the engine is over the years I have had a few 3cyl 60 HP motors with 55 covers and I cant remember if OMC made a 55 in 73. I know 75 did but cant remember about the 73 production run.

 

[dbmstr124]

Re: 1973 evinrude 55 HP fouling out plugs

I ran the boat about 3 hours total and ran at all RPM's including full throttle and the boat did fine. One day I was driving home at full throttle and the boat slowed down and then bogged and would not get over almost a 1/4 throttle without bogging down. Now I put new plugs in it and new gas with an 8:1 mixture. I took the boat out, floored it, it planed out and then bogged down and wouldn't get up again. I pulled the plugs and they were fouled. The first set I pulled when this happened had drops of water on the plugs. The next set after that had no water on them but were fouled out wet with oil. I now need to pull the plugs again and check the spark. I will check maybe the spark is no good I hope. The engine is electric start and is a 55 HP to the best of my knowledge and according to the title. It is a 2 cylinder. I will take a picture of it tonight if possible and check it out and also of the plugs if possible. I really do appreciate the help with all of this. Thank you.

 

[samo_ott]

Re: 1973 evinrude 55 HP fouling out plugs

I doubt the engine would run on 8:1. Or do you mean 8 oz oil to 1 gallon of gas?

 

[DJ]

Re: 1973 evinrude 55 HP fouling out plugs

I ran the boat about 3 hours total and ran at all RPM's including full throttle and the boat did fine. One day I was driving home at full throttle and the boat slowed down and then bogged and would not get over almost a 1/4 throttle without bogging down. Now I put new plugs in it and new gas with an 8:1 mixture. I took the boat out, floored it, it planed out and then bogged down and wouldn't get up again. I pulled the plugs and they were fouled. The first set I pulled when this happened had drops of water on the plugs. The next set after that had no water on them but were fouled out wet with oil. I now need to pull the plugs again and check the spark. I will check maybe the spark is no good I hope. The engine is electric start and is a 55 HP to the best of my knowledge and according to the title. It is a 2 cylinder. I will take a picture of it tonight if possible and check it out and also of the plugs if possible. I really do appreciate the help with all of this. Thank you.

You are losing a cylinder. THe water drops on the plug is key.

You have a bad head gasket or side cover (exhaust) gasket. Both are easy fixes. I'd do both.

Parts are availble here on iboats.

 

[dbmstr124]

Re: 1973 evinrude 55 HP fouling out plugs

I have taken some pictures. Forgive me it is a 50 HP. Here are pictures. I pulled the carbs and they are clean as a whistle. Here are the pics with descriptions. Thank you. To the person who said bad head gasket or side cover, please explain how to fix these? I am very capable of fixing them on a car so this shouldn't be bad. Is the head gasket on the top of the cylinders? Is the side cover for the powerhead? Thank you

 

[dbmstr124]

Re: 1973 evinrude 55 HP fouling out plugs

I just talked to a boat mechanic and he said right away that he thinks I'm sending fuel right to the back of my block because of a bad fuel pump or something so I'm going to check that. Does that make sense to you? Thank you

 

[Solittle]

Re: 1973 evinrude 55 HP fouling out plugs

I suggest that you re-read rodbolt1's post on carbs. They may look squeeky clean outside but be fouled inside. Your symptoms point to the carbs.

 

[DJ]

Re: 1973 evinrude 55 HP fouling out plugs

As I mentioned, the WATER on a plug is KEY. I've been through this.

The head gasket is obvious. Those are the BIG bolts holding on the cylinder head. But!!!! While you're at it, remove the small bolts holding on the head cover. That is the head water jacket. Replace the thermostat, while you're in there.

The side cover is just that. It is the big steel cover on the starboard (right side-while looking from the rear) of the engine. It's a big cover with a big gasket to match. Again, an easy fix.

You know, you really need a manual. It's the best $35.00 you will ever spend. You need some other mantenance too. Such as:

1. Water pump service.

2. Lower unit lube and service.

3. carb rebuild-maybe-but probable. Fuel pump rebuild too.

Take care of that old girl and she will run forever.

All this stuff is really inexpensive, in the long run.

 

[dbmstr124]

Re: 1973 evinrude 55 HP fouling out plugs

I will pull the cylinder head off and check the gasket and also the stbd side cover gasket. I will also check the fuel pump and all of that. I am just hoping the water isn't from maybe getting too cold and cracking the water jacket, but if it did I wouldn't hold 150 psi compression on it I would think. I will let you all know what the problem was when I get it torn down. Thanks alot.

 

[DJ]

Re: 1973 evinrude 55 HP fouling out plugs

I will pull the cylinder head off and check the gasket and also the stbd side cover gasket. I will also check the fuel pump and all of that. I am just hoping the water isn't from maybe getting too cold and cracking the water jacket, but if it did I wouldn't hold 150 psi compression on it I would think. I will let you all know what the problem was when I get it torn down. Thanks alot.

150/lung is GOOD! I doubt it froze.

You can't check a gasket, all you can do is replace it. I'll bet that's your issue.

 

[Lakester]

Re: 1973 evinrude 55 HP fouling out plugs

You know, you really need a manual. It's the best $35.00 you will ever spend. You need some other mantenance too.

hello dmster...

this is what 'they' told me, too. also an oe parts manual. the Lakester Special came with the oe service manual. but i followed 'their' advice and also got the oe parts catalog.

i read and use both frequently. when not reading them, i am studying them...

good reads and helpful.

dont forget to read the torque specs and note sequence if u pull ur own heads. i just did that to my engine. i admit, i prob got my parts a bit TOO clean... LOL, but now bores, piston crowns, head combustion chambers, all mating surfaces and water plate passages, etc... are ready for gaskets. all head and plate bolts n threads chased with tap n dies... and cleaned with air. as soon as the paint on heads dries... guess i will button ' er up.

at first i wasnt going to do the head gaskets... but... after 36 yrs... the clamp loads have to have relaxed. any ways.. fate got in my way and i HAD to do it. oh well... glad for the experience.

go ez when undoing those small thread bolts. they may break if stuck as i found out...

http://forums.iboats.com/showthread.php?t=232709

#7

while i had serviceable compressions on all holes re: CR test... i did note some combustion chamber by-products had seeped past the metal sealing ring in head gaskets... top cyls... and showed black traces over to the water jacket side. no doubt some losses there, but imo... minimal at best. new should be better... replacing 3 head bolts, too. i plan not to paint head bolts so i can tweak the torque wrench on them and my plugs at regular intervals...

regards,

lakester

 

[dbmstr124]

Re: 1973 evinrude 55 HP fouling out plugs

PROBLEM FIXED!!!!!!!!!!!!!! I put a new vacuum hose on thats between the fuel pump and the block and tadaaa....problem fixed. I took it out for a 20 minute drive, stop, go, floored and everything in between and it was all just a vacuum line with a crack. Thanks for all the help from everyone who replied.

 

[Lakester]

Re: 1973 evinrude 55 HP fouling out plugs

PROBLEM FIXED!!!!!!!!!!!!!! I put a new vacuum hose on thats between the fuel pump and the block and tadaaa....problem fixed. I took it out for a 20 minute drive, stop, go, floored and everything in between and it was all just a vacuum line with a crack. Thanks for all the help from everyone who replied.

way to go, db!!!

glad to hear it!

regards
lakester