75 evinrude 3rd cylinder not firing

[jherlyn]

Alright, I have been racking my brain here, and I need some help.

Third cylinder (as in third from top) is not firing. The Evinrude is a 1975 hustler 75 HP and it idles great on two cylinders...In the drive way. Took it out to the lake, it won't stay running. So I took it home, ran compression test. It passed with flying colors. But when I pulled the spark plugs, I noticed something. Now just the day before I changed all three spark plugs, and when I pulled the third from the top, it is as shiny as it was out of the box while all the others darkened. I switched 2 and 3 and it runs, so spark plug is not a dud. I'm thinking.....coil!

So I switched the coils around to see, and the problem stays with the cylinder, not the coil. Now I'm stumped. I heard it could be a clogged jet on the carb, but even then I should get SOME darkening on the spark plug.....Right?

I went to my local marina, and he's telling me that it could be three things: The power pack, the trigger, or the base points. He says he can run a test to see which one it is considering most of these parts aren't made anymore and they are on the pricey side to buy when found.

So my question is: should I run the test or is there something I'm missing. Also, anybody who has had experience with this let me know which one is the bigger culprit.

Thanks for your help. This is killing me because I restored this boat over two years with my own two hands. Now the only thing stopping me from water is this possibly four week long ordeal to fix this motor, and I have to do it on someone else's schedule. ARRRGGHHHH!!!

 

[boobie]

Re: 75 evinrude 3rd cylinder not firing

First off get an open air gap spark tester from Auto Zone and check the spark on all three cyls. Should jump a 7/16" open air gap. If you don't have spark, stop there and get the ignition system fixed. But if you do, take the air box cover off, start it up on muffs and squirt some pre-mix fuel in the bottom cyl. If it picks up you got carb probs. Those spark testers are around $8.00 at most parts houses.

 

[jherlyn]

Re: 75 evinrude 3rd cylinder not firing

I forgot to mention, but I do have spark. That's why I'm confused. And I just got done reading through some threads and many higher ranking posters claim that fuel delivery problems such as this don't just affect one cylinder. I see spark, though I could go buy a tester just to make sure...

My problem is that the marina guy is talking about base points and base timers(trigger) up around the stator being bad, but from reading forums this just doesn't seem like a common problem. So I guess a quick recap is.

-visible spark at plug
-compression good at all 3 cylinders (125lbs)
-spark plug not a dud
-coil is good
-fuel problems usually don't affect one cylinder (especially to the level where the cylinder doesn't fire AT ALL and the plug shows)

Is there a way to test if it is the power pack?! Marina guy says no but I dunno. Or is there a way that the stator could be off to where the spark never comes at the right time to light the fuel. UUUGGGHHH! so confused. Want to go boating but he can't look at it for another two weeks!!!

Any help would be greatly appreciated.

 

[motorboater1]

Re: 75 evinrude 3rd cylinder not firing

hi if you have spark on #3 only could be two issues scuffed piston skirt which i doubt or a problem in #3 carb ie: stuuck float or clogged high speed orifice if h/s orifice is clogged nothing else in carb gets fuel good luck and also there is a powerpack out put test but you will need a stevens PEAK reading volt meter voltage to coil should be 180v or higher lee

 

[boobie]

Re: 75 evinrude 3rd cylinder not firing

I guess I haven't worked on as many outboards as these "higher ranking posters" have for them to say you can't have a carb prob on one cyl. How did you check your spark, by grounding out the plug?? O' well, I guess you got everything together so, good luck.

 

[Big flop]

Re: 75 evinrude 3rd cylinder not firing

Good spark on all 3? the power pack passes test.
If the motor sat during 2 year restoration,
clean and kit all three carbs.
Check fuel pump, a bad diaphragm can flood
the cylinder that pumps it, (wash it clean)
The motor is to new for points.

 

[jherlyn]

Re: 75 evinrude 3rd cylinder not firing

I guess I haven't worked on as many outboards as these "higher ranking posters" have for them to say you can't have a carb prob on one cyl. How did you check your spark, by grounding out the plug?? O' well, I guess you got everything together so, good luck.

Sorry, I didn't mean to come off rude, just veeeryy frustrated. But from what I'm gathering here, it seems that I need to check the fuel pump and squirt some fluid into the lower carburetor to see if it takes off.

Truth is yes, I bought this boat for 100 dollars and two years and 3900 dollars later, its almost ready. I fired this motor every year, and it seemed to run fine, but like I said, its only on 2 cylinders and, to be honest, this is how it could've been firing this way ever since I acquired it. I'm hoping its a fuel problem, for two reasons. One, this marina guy I talked to seems to be telling a whole different story than you guys, and I think I trust the voices of a thousand people versus one. Two, your guys' fix is allloooottt cheaper.

Any other suggestions would be helpful, and I'll keep you posted from what I find tomorrow.

Edit: If it was a scuffed piston, would that have shown up in my compression test. Please let me know

 

[F_R]

Re: 75 evinrude 3rd cylinder not firing

Your motor is no different than any other multi-carburetor motor--the cylinders that are fed by a certain carburetor won't fire if that carb is plugged up. Each cylinder is fed by it's own carburetor. It would make sense that the lowest carburetor would get the gum from stale gas in storage (gravity). And the high speed jet is in the very bottom of the carburetor float bowl where the last dregs of fuel lie.

A blown piston skirt with compression is a rare possibility, but that would be looking for the odd-ball on the basis that you are saying everything else is ok. If you have good compression, it probably is not a piston skirt.

Summing up, if you have 7/16" spark, the powerpack and related ignition parts are ok. The compression is good, you say. I guess we can assume water is not getting into #3. My money is on #3 carburetor.

 

[Sixmark]

Re: 75 evinrude 3rd cylinder not firing

One thing you can try is to take a spray bottle of pre-mix gas and while the motor is running spray it into the carb for the cylinder that you think may not be getting fuel, if there is a noticeable difference in how it runs, then you have found your problem.

 

[jherlyn]

Re: 75 evinrude 3rd cylinder not firing

Thank you guys for all your help. it was a fuel problem, the minute I sprayed pre-mix in it it fired up. Now I have to tear out the carb and see whats wrong, but you guys saved me a lot of money here.

Anyway, it'll be a couple of days because I have to do the lower end on my friend's mercury 115 horse first. Sometimes it feels like I'm running a damn boat shop. My theory is there are 2 types of people in this world: breakers and fixers. And unfortunately it seems that the breakers far outweigh the fixers.....sigh. Oh well, maybe I can get my boat out next weekend.

Thanks again.

 

[kenmyfam]

Re: 75 evinrude 3rd cylinder not firing

And hopefully no damage done from running without enough lubrication in there.