1972 65 hp Evinrude poor performance update

[nagel88]

I've finally got back to looking at my recently acquired '72 Evinrude 65 hp (65ESL72S). The problem is poor idle and poor high speed performance. It seems to be losing a cylinder while running. I've tried some suggestions from my last post. The spark will jump a 7/16" gap easily on all cylinders when cranking. The compression (using my crappy tester) from #1 to #3 is 105, 127 and 130 PSI. The carbs have been kitted and seem to be functioning OK. Plugs look good (QL77JC4).<br />What do you make of this and where do I look next?

 

[nagel88]

Re: 1972 65 hp Evinrude poor performance update

To clarify a bit, while trying to adjust carbs while running muffs, the engine starts easily enough but after a short time begins to develop a stutter as if 1 or more cylinders are cutting out.<br />When I did run the boat on the water, it didn't quite have the power to get a 15' boat on plane at full throttle.

 

[itstippy]

Re: 1972 65 hp Evinrude poor performance update

The mods will probably combine your two posts; they get separated as people reply to one and not the other and pretty soon people can't keep straight what's been said & done and what hasn't.<br />Your compression readings suggest a problem in cylinder #1. Keep that in mind.<br />Let the motor idle on the muffs until it startets idling roughly like you say. Then take a rubber-handled pliers and pull the plug wires one at a time, putting them back on each time. See if pulling a wire affects the idle. If it does, good. That cylinder's firing. If it doesn't, then that's the problem child. While you're at it, hold the plug close to the block and check the spark jump. If you find a problem child cylinder(pulling the plug wire does not affect idle) but the spark is good that tells you something too. Probably bad fuel flow to that cylinder. If the spark is bad, it's a spark problem (duh). Report back.

 

[steelespike]

Re: 1972 65 hp Evinrude poor performance update

Trouble shooting should only be done with a manual following proper procedures.My manual also describes what components are likely to cause what symtoms.<br />Check all ignition wires for worn spots especially where they may rub.Be sure all connections are clean and tight.Don't forget the grounds.Try to determine if you are losing spark to one or more cylinders.<br /> Your compression is all over the place.It isn't likely to cause serious problems with performance<br />if all else is good.But you need to try to get the compression more even with a decarb treatment.<br /> See if a little choke helps performance.

 

[nagel88]

Re: 1972 65 hp Evinrude poor performance update

OK, I'll find some suitable pliers and try pulling the wires. I'll report the findings.

 

[nagel88]

Re: 1972 65 hp Evinrude poor performance update

WHOOOOOEEEEEEE! Those suckers really put out some voltage! I got a jolt right through some plastic handled pliers and leather gloves. For my second attempt I attached a ground wire to the pliers and solved that problem.<br />OK, on #1 the engine dropped speed, and spark came out of the boot and jumped to the grounded pliers.<br />#2 definitely dropped RPM and also had good spark.<br />#3 made no difference but had good spark.

 

[BF]

Re: 1972 65 hp Evinrude poor performance update

maybe the spark plug in #3 is bad. Then it would spark when you pull the boot (via ground through pliers), but plug might not spark when boot is connected. Should affect rpm if it's firing. This was done after you had warmed it up and it was running poorly, right?

 

[nagel88]

Re: 1972 65 hp Evinrude poor performance update

yes, I ran it till I until choke opened fully and was off fast idle.

 

[nagel88]

Re: 1972 65 hp Evinrude poor performance update

Here's the next thing. I put clean plugs in the engine and started it. The engine seemed to load up a bit while on choke. I put clean plugs in again and got it warmed up and idled down. I began to slowly work the idle screws until I was getting a noticeable increase in RPMs. When I worked down to #3 I couldn't get a response whether I ran the screw all the way in or out to specs plus another turn out.<br />Sounds like an issue with #3 carb. I can get it off and make sure the idle passages are absolutely clean and clear. What about high speed, tho? If the main jet is plugged, would this affect both idle and top end? I would not think, from my experience (I worked on small engines for 10 years), that the bottom carb is getting no fuel at all in the bowl.<br />Any suggestions?

 

[Solittle]

Re: 1972 65 hp Evinrude poor performance update

You are on the right track in cleaning the carbs.<br /><br />To verify that the problem is with the carbs and not electrical swap the coils, spark plug wires & plug between #1 and #3. If the problem moves from #3 to #1 then you have a bad plug, wire or coil.<br /><br />Do you have the manual?

 

[nagel88]

Re: 1972 65 hp Evinrude poor performance update

yes, I have a genuine OMC manual. Since my last post I pulled the carbs. This time I removed the plug over the idle passages and went over the whole works with a fine-tooth comb. (I should have done 1 and 2, but I was in a hurry). <br />Now I'm definitely getting some life out of #3, as it now responds to adjusting the idle screw. It's still a bit erratic, all in all, but going thru the rest of the carbs the same way and adding some new plugs might really help, I suspect.

 

[nagel88]

Re: 1972 65 hp Evinrude poor performance update

That's all I can do for now. I'll be on the road for a week and I'll post any developments when I get back to work on this beast. Thanks all for the advice so far.