1973 Evinrude 6hp Weak/Intermittent Spark?

[Cleric40]

Hi All,

Picked up a 1973 Evinrude 6hp not running. Soaked and cleaned carbs and got it running this past weekend and ran pretty well and revved up fine in neutral. Once I put in the water and put it in gear is where I noticed very little power. The engine struggled to push aluminum boat more than 2-3mph and often sputtered but never could reach high RPMs. Didn?t seem to be a fuel problem as squeezing the bulb didn?t make any difference. I checked the fuel filter and no major debris. Cleaned anyways.

Checking compression, both cylinders are in the 90s.

Evaluating the ignition, is where I think the problem lies. Bottom cylinder seems to have a nice strong spark even turning the flywheel by hand (with plugs out) and top cylinder has a much smaller/thinner and somewhat intermittent spark when turning by hand. Only get a spark every time when using the pull start and even then it?s not nearly as big or snappy as lower cylinder. Checking the coils, they appear to be new and not cracked. Both resistance readings on the primary and secondary side of both coils are roughly the same. Continuity to plugs is good.

One of the points shows some pitting and I tried cleaning, sanding them with sand paper and set gap to 0.020 but still have weak spark issue.

I plan to remove points and sand down further and try again until I can order new but Could points being pitted cause the weak and intermittent spark?

 

[PapJones]

Fouled spark plug? Careful sanding down points. I use a saffire nail file and then polish surface with knife sharpening hone. Clean with alcohol or other degreaser. Check condensers. Maybe switch them to see if that makes any difference. My 1972 Johnson 6 was doing the same thing at the end of last year and I am just now getting around to fixing it. Good luck with your challenge!

 

[AlTn]

pull the spark plug boot and terminal end off the top plug spark plug wire..cut off 1/2" off the wire and reattach the terminal end and boot..did this affect your spark?.. you can also do the same thing to the coil end of the wire and screw it back onto the the spike in the coil....if necessary to replace the ignition wire it's 7 mm. copper core...

 

[oldboat1]

Would replace points and condensers. Dress the new set of points and set at .020. Should be J6C plugs gapped at .030 (Clean and regap, or replace.) Running temp. OK? Replace the impeller if not sure how old it is, and check the thermostat.

 

[tomhath]

As the others said, weak spark and pitted points indicates a bad condensor.

 

[Cleric40]

Thanks Guys, I was able to work on the motor a bit last night and did a few things. Snipped off 1/2" plug wire and sanded pitted points a bit. After reassembly spark seems to be much better and motor running stronger. I tested it in the bucket but plan to test on the water tonight. I will report back later on how things go!

I will also plan to replace points and condensers when i can get the parts in.

Stay tuned!

 

[Cleric40]

Ok guys, now I'm stumped.

Took her out on the water and didn't have much luck. She fired up just fine and ran ok for maybe 2 mins but still couldn't get to full throttle. Then it got worse, started to bog out then eventually would only run on choke. Had to limp her back to shore by playing with choke.

So I pulled her out of the water, took her home and tried running her on the stand in the bucket. Same scenario. Thinking it could be plugs I went to store and got fresh plugs. No luck.

The way she was acting, seemed like it had to be carb (already cleaned once but figured I'd clean again) I also tested fuel pump and seems to working fine.

Now all back together, WONT START! Not even a little Pop with starting fluid! Checked spark and its still strong.

I'm completely stumped and frustrated Any help or suggestions would be greatly appreciated. Trying to go fishing this holiday weekend

 

[oldboat1]

Get an adjustable spark tester and test for spark (basic magneto test). $10 at an auto parts store.

 

[Cleric40]

Ok guys so before shutting down for the night, I was able to get a little bit of a Pop last night using starting fluid so it's not a total bust.

I will try to get a spark plug tester today, but I think after cleaning points and reseating plug wires I think spark is good and it is now fuel delivery related at this point.

One new question, while rebuilding the carb once again last night I noticed that the small cork gasket around the high speed jet seemed to be worn out and deteriorating. So I left it out when rebuilding so it wouldn't dissolve or clog up anything. Is this gasket absolutely necessary? I will try to get one on order or look at making one for the time being (trying to go fishing this weekend)

#21 on diagram >>>> https://www.marineengine.com/parts/...302S&manufacturer=Evinrude&section=Carburetor

Seeing that it ran with only the choke on leads me to believe its perhaps the high speed jet? But i thoroughly cleaned it. What do you guys think?

 

[Vic.S]

Ok guys so before shutting down for the night, I was able to get a little bit of a Pop last night using starting fluid so it's not a total bust.

I will try to get a spark plug tester today, but I think after cleaning points and reseating plug wires I think spark is good and it is now fuel delivery related at this point.

One new question, while rebuilding the carb once again last night I noticed that the small cork gasket around the high speed jet seemed to be worn out and deteriorating. So I left it out when rebuilding so it wouldn't dissolve or clog up anything. Is this gasket absolutely necessary? I will try to get one on order or look at making one for the time being (trying to go fishing this weekend)

#21 on diagram >>>> https://www.*****************/parts...302S&manufacturer=Evinrude&section=Carburetor

Seeing that it ran with only the choke on leads me to believe its perhaps the high speed jet? But i thoroughly cleaned it. What do you guys think?

Yes that gasket is necessary!

BTW links to sites who iBoats see as competitors are blocked.

If yo want to link to parts diagrams etc use the official BRP parts website:

 

[Cleric40]

Thanks I kinda figured with the link but for some reason I couldn't post a picture...so thank you for posting!

Anyways, I will try to make a new gasket out of a rubber stopper or something until I can order a new one or maybe rebuild kit.

Do you think this would be causing some of the poor performance issues seen?

I know the main jet is CLEAN, can see through all the holes just fine.

 

[Chinewalker]

Have you replaced the fuel hoses? If they are at all deteriorated, they may be allowing small bits from the inside to clog up your now cleaned carb. Can drive you nuts as you clean the carb, then gunk from the hoses fouls things up again.

 

[Cleric40]

I have replaced the fuel line from tank to motor but not the smaller hoses from fuel pump to carb. They appear to be in good shape as the whole motor is in good shape but I will double check tonight.

I have been reading that it could be an air leak or a fuel system/pressure issue. So another question, during my testing I have had my fuel line setup as follows

Motor>>Quick Disconnect>>Fuel line>>Primer Bulb>>Fuel Line loose into gas tank opening (not using quick connect)

Basically i have the loose line dunked into a small 1 gallon tank. The bulb stays hard during my testing and pumping while running doesn't affect engine speed but was wondering if this could a possible issue? This is also how i have run it on the boat but into a bigger 6 gallon tank. Hose has always stayed below fuel level and in the fuel

 

[kbait]

Fuel delivery to carb sounds fine. Replace that nozzle gasket, and fuel line pump to carb (5/32"). If spark jumps 1/4" from each lead in open air, you should be good to go.

 

[Cleric40]

Update: still not running well in the boat

After Another carb soak and clean I got motor all back together. Tested spark with tester and jumps a good gap! Got it running well on the bucket. Idles well, revs up well.

Then on the the lake, here's where I was let down. She fired up first pull and putted out just fine, but once I went full throttle it didn't run with much power. Boat was maybe going 5mph. And motor wasn't reaching full rpms.

I tinkered best I could, checked that both cylinders were running and they were.

The interesting part was it progressively got worse the longer I was out there. She barely revved up at all when trying to make it back to dock. I felt engine and it didn't feel overly hot or anything.

Here is a video of it running before it got worse. You can hear it sounds like it is trying to rev up but just can't get there. Video is with engine in full throttle position

http://youtu.be/6RA98EAjuog


What do you guys think? Why does it get worse? What could I look into?

 

[Cleric40]

Holiday weekend Bump

Anyone check out the video?

 

[Xcusme]

Gees...why the choke....is it needed to keep ideling or running , or what???

 

[Chinewalker]

Definitely skipping from one to two cylinders. Time to revisit your ignition work. Check to make sure all wires under the flywheel are tucked out of the way and not rubbing on anything.

 

[scottmm73]

Cleric40, did you come up with a solution?