1972 Evinrude 65 hp help, Compression test failed and no spark. Help me with Diagnosi

[SigSaurP229]

With Compression numbers of 45 PSI dead even across all cylinders. Engine has not been overheated and have also diagnosed a no spark condition on Cylinder number 2


Little history this motor runs and Idles perfect. This motor will rev up to WOT in neutral. I know don't do that it has only been done twice in an attempt to trouble shoot.

I have run the motor for the last two years trouble free, until earlier this year I broke a fuel fitting. I had to limp home on it.

This weekend I repaired the fuel line and tried to take it out. Got just out of the no wake zone and the motor would not plane the boat it felt like I was trying to run at about half throttle.

I parked the boat until today when I put it in water in the shop and started it up. She started with the first twist of the key as usual. While running I covered each one of the carbs with my hand and could hear the motor stumble each time I choked one of the carbs with my hand.


I pulled out the spark tester and tested each cylinder spark Cylinders 1 and 3 hard spark Cylinder 2 had no spark. I swapped the coil from Cylinder 3 and 2 after swapping the coil Cylinder 3 still had spark and cylinder 2 still had no spark.

Checked compression which shocked me because the motor runs great and idles and revs perfect. It showed 45 PSI dead even on all three cylinders I put aprox a table spoon of oil in each cylinder and compression shot up to about 120 90 and 90 though by the last two compression checks my battery was getting weak.


Soo how should I proceed from here. What is the possible prognosis I am thinking worn rings or bad head gasket, I just wouldn't think that worn rings would have even compression.

 

[F_R]

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. Help me with Diag

You better not buy any lottery tickets, with the luck you are having. Strange that the compression and spark would both go south at the same time, but so be it.

Pull the cylinder head and see what you can see. If the gasket isn't blown, and it probably isn't, then you have catastrophic engine failure. The lack of spark is the least of your worries, probably a power pack.

That motor is infamous for getting water into the cylinders from a warped exhaust cover baffle plate. When it does, it causes much grief. I'm very surprised that you can even get it to run at all with such low compression. Are you sure your test is valid?

 

[SigSaurP229]

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. Help me with Diag

I rented a compression checker from Autozone so I was kind of wondering if I didn't just get ahold of a bad tester or something. It is really surprising to me that it would run that low as well. Not only does it run it runs REALLY well idle is normal. I feel a good draw on all carbs. I figured with compression that low if it did run it would be sputtering and kicking the whole time but like I said it will rev all the way to 5k rpms in the tank and never miss a lick. Once again I know this is a bad idea and was only done once.

I just can't seem to believe that it has that bad of compression and idles as well as it does. When on the lake Saturday the engine ran extremely smoothly but just felt like it had half the power it should have.

So if I pull the head to I need to immediately take the block and have it and the heads machined to match? The next step in diagnosis would be pulling the head?

Maybe I should try getting another compression check gauge before pulling the head as well to make sure that I haven't just gotten a bad tool?

I am also putting a good full charge on my battery tonight before I check compression with that gauge again as well.

I also thought it strange compression and spark would die at the same time.

 

[F_R]

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. Help me with Diag

I sort of doubt the compression is that bad, or it wouldn't run. I think your problem is the spark. The motor is running on two cylinders. "Draw" through the carburetors means nothing, other than the pistons are not busted or something like that.

 

[boobie]

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. Help me with Diag

Try a different compression gauge.

 

[SigSaurP229]

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. New comp numbers

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. New comp numbers

Soo I went and swapped out the compression gauges today. New numbers sort of this time the compression it 110 psi max, but was bleeding down so fast I could barely see the numbers. Though I thought at one point I could hear air hissing out of the gauge the compression numbers are much more inline with what I thought. Compression I could get was 110 110 and 105. So I would think that compression is a little on the low side should be 125 +/-. But the could news is all three cylinders are within 5% of each other and high enough so I would think that comp numbers should be ok. I should concentrate more on finding the missing spark on cylinder 2

 

[boobie]

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. New comp numbers

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. New comp numbers

Your spark prob sounds like a bad power pack or timer base prob. Go to CDI Electronics.com for a trouble shooting procedure.

 

[1kruzer1]

Re: 1972 Evinrude 65 hp help, Compression test failed and no spark. Help me with Diag

Agreed. Your compression numbers are EVEN, and that's the key. You've already seen that compression gauges can be wildly inaccurate for exact numbers, so who knows if you've actually got 110 pounds or 130. It doesn't matter. Leave the cylinder head alone and find the problem with spark on # 2 cylinder. Fix that, and I bet she runs good again. Good luck.