1976 85 hp starting/running issues

[punkytuu]

Hi, I just bought a boat with a 76' 85 hp evinrude. It started and ran good in the sellers driveway and when I took it to the lake for a test drive 4 weeks later, I drained the battery trying to start it. It appeared to have weak or no spark on bottom right plug. I then put in 4 new ngk crossover for the l77jc8. No improvement. the next day, I tried again with no luck. (118-120 psig on all 4 cylinders, gas on the plugs, good battery, fresh gas/oil mix, some gas running out of front of carbs. Bulb does not get as hard as my 88' 88hp and does not stay hard. ) A few hrs later, I turned the key and Bam! it starts right up and idles good, goes into gear, stayed running for 20 minutes with earmuffs on. I pulled the fuel and ran it out of gas. hooked fuel line up and pumped bulb and it started back up many times and took it over to a local lake and ran it around good for 20-30 minutes, and on the way back to boat ramp. it cut out like somebody turning off the power and then right back on. it seemed like it was running on 2 cylinders. 6-8 times doing it for 2-3 seconds each time. I installed a new powerpack and it wouldn't start, with many tries. Then, the next day, Bam! it starts up, runs, starts back up a few times, and now, nothing. still showing 3 good sparks and one weak/bad one. When it ran, it reached 5300 rpm with good power and no sputtering. Any help would be great. Greg

 

[iwombat]

Re: 1976 85 hp starting/running issues

Couple of things first off.

1) You need to put champions back in. That motor will not run properly with the NGKs.

2) Never run a multi-carb'd two-stroke out of gas on purpose. One carb goes dry before the other and fails to deliver lube to the cylinders it services.

---

Now, on to the problem at hand. Make sure your motor is turning at least 300 rpm while cranking. Polish up the battery terminals and check the battery wires.

Next, I see no mention of a spark test. Did you do a proper spark test? What did it show?

 

[tashasdaddy]

Re: 1976 85 hp starting/running issues

i would say you are due a carb cleaning an rebuild with carb kits.
completely swap positions with the weak coil with one that has good spark, if the problem follows the coil replace it.

 

[punkytuu]

Re: 1976 85 hp starting/running issues

I will put new L77-jc4 back in. I do have a RPM gauge and will check the starting RPM. I'm not sure what the proper way to check spark is, but I removed all the plugs and checked for spark and all were good except lower left was weak and erratic (Held the plugs about a half inch from a ground and got a good arc) I did check the coils by switching the inputs to the coils on the left side and the weak spark is now on the top coil, and then switched them back. I will also order a set of carb kits.

 

[tashasdaddy]

Re: 1976 85 hp starting/running issues

as i said, swap that coil, with a known good one, and see if the weak spark follows the coil.

 

[punkytuu]

Re: 1976 85 hp starting/running issues

The weak spark does not follow the coil.

 

[F_R]

Re: 1976 85 hp starting/running issues

You should check the spark with the plugs installed. It will crank faster with them out and fool 'ya. It will not produce a spark if not cranking fast enough.

But that doesn't explain the momentary misfiring at speed. Somethng else is going on which we can only guess at. The first thing I would try without a bunch of expensive test equipment is disconnect the black with yellow stripe wire from the power pack. That is the kill wire and you won't be able to shut it off with it disconnected, but if it has a fault in the wire or ignition switch, you will have weak or no spark when connected but ok when disconnected. That wire carries 300 volts and will arc out if contaminated with dirt, water and crud. BTW, "good" spark is jumping a 7/16" gap. Will it do that?

 

[ezeke]

Re: 1976 85 hp starting/running issues

Sounds like the float valve is sticking in one of your carburetors. When you rebuild them, make sure to install the clips that connect the float arms to the needles.

 

[punkytuu]

1976 85 hp starting/running issues

Hi, I just bought a boat with a 76' 85 hp evinrude. It started and ran good in the sellers driveway and when I took it to the lake for a test drive 4 weeks later, I drained the battery trying to start it. It appeared to have weak or no spark on bottom right plug. I then put in 4 new the ngk cross for the l77jc8. No improvement. the next day, I tried again with no luck. (118-120 psig on all 4 cylinders, gas on the plugs, good battery, fresh gas/oil mix, some gas running out of front of carbs. Bulb does not get as hard as my 88' 88hp and does not stay hard. ) A few hrs later, I turned the key and Bam! it starts right up and idles good, goes into gear, stayed running for 20 minutes with earmuffs on. I pulled the fuel and ran it out of gas. hooked fuel line up and pumped bulb and it started back up many times and took it over to local lake and ran it around good for 20-30 minutes, and on the way back to boat ramp. it cut out like somebody turning off the power and then right back on. it seemed like it was running on 2 cylinders. 6-8 times doing it for 2-3 seconds each time. I installed a new powerpack and it wouldn't start, with many tries. Then, the next day, Bam! it starts up, starts back up a few times, and now, nothing. still showing 3 good sparks and one weak/bad one. When it ran, it reached 5300 rpm with good power and no sputtering. Any help would be great. Greg

 

[bowman316]

Re: 1976 85 hp starting/running issues

Kinda sounds like an electrical shorting problem. Like loose wires somewhere are preventing starting, then they shift and everything is good again.

Just my guess.

If you think it is running on 2 cyl, unhook all but one plug, and it should start, if it doesn't that cyl is dead

 

[tashasdaddy]

Re: 1976 85 hp starting/running issues

double posting in the forums is not appreciated.

 

[ezeke]

Re: 1976 85 hp starting/running issues

And, BTW, here's a link to an excellent thread in the Enine FAQ forum; it has some checks that you can easily perform that may help: http://forums.iboats.com/showthread.php?t=188767

You might also want to check that the powerpack leads are wired to the correct ignition coils; click the thumbnail for a diagram.

 

[iwombat]

Re: 1976 85 hp starting/running issues

By proper spark test, I mean with a spark tester and not with the plugs grounded against the block. If you search this forum for spark tester you'll get lots of information.

It sounds like your problem could be a lot of different things, or even two things working together. Using a spark tester will tell you if you've got more than the one weak coil, since the plug-against-the-head method will produce false positives.

Personally, I'm leaning toward the stuck float theory as being one of the problems. But, there's probably an electrical issue as well.