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77 Evinrude 85 HP need a hand w ignition problems

jon

Regular Contributor
" Hi,

This engine has a mo


" Hi,

This engine has a model # of 85790S and a serial # J001073. I got it in an unkown state and found that it had compression, but was lacking spark on two cylinders, here's how it went.

First, I verified that there was still no spark on the port side and that there was spark on the starboard side, using a spark tester. Switch lead (from power pack) to coil for starboard side w/ lead from port side (1&2 and then 3&4); found that the lack of spark switch sides as well. Put it back together in original way. Next, switched "sensor" leads from port side to starboard side (1&2 and then 2&4), found that once again, lack of spark switched sides.

At this point, I decided that it must be the sensor coil and checked resitance between sensor leads for coil 1 & 3 and then 2 & 4. Resistance was 7.8 for bothe; this appears to be in spec. . Last, tested for resistance between ground and those leads, found it to be infinity (no continuity), which was also to spec.

I put everything back together again and then did a spark test on the each cylinder and found that all but one cylinder, on the port side, were now firing. The cylinder that was not firing would fire for a couple beats and then quit. I double checked that by switching the sensor, this condition would change, and it did, and then tested it all again and found all cylinders had stopped firing. I checked the ignition switch lead (on the power pack), there was no continuity to ground. I disconnected the ignition switch lead to be sure, without change.

I don't know if this means anything, but even when the engine is not being turned over, I've been getting lots of shocks out of the power pack and leads around it. I'm thinking it's just the stored voltage?

Should I still assume that it's a sensor coil? Does it sound like possibly something else? How might I trouble-shoot this now? Any/all help appreciated,

Jon "
 
"Jon.... In reading through yo

"Jon.... In reading through your trouble shooting explanation, it would seem that the timing base assy (sensor) is faulty. However, keep in mind that the engine must turn over approximately 300 rpms in order to have the stator supply enough voltage (300v AC) to the powerpack in order to energize it properly. A slower cranking speed will result in erratic/intermitent spark.

Are you testing the spark with the spark plugs out, and using a properly charged battery? Is the starter cranking properly?

Joe
"
 
" Joe,

Glad to hear fr


" Joe,

Glad to hear from you - I pulled out all the plugs and used a good battery, while applying a 50 amp charge to it. I think the starter was operating at peak performance, it sounded the way I'd want it to, if I was going to try and start it up. I was testing spark using the plug wires and a spark tester, set at about 1/4 inch; I'd bring it in some if I didn't find spark, but it never helped. I also noticed that one of the screws for the cover on the power-pack was missing, and found it floating around under the cowel - it appears I may not be the first one to try and sort out this problem. Well.. unless you have another trouble-shooting idea, I think I'll swap the sensor coil and see where that brings me. Do you know of a safe way to check for signal on the sensor leads, how I might use a test light or spark tester directly on them? Thanks again,

Jon "
 
"Jon... If you switched the se

"Jon... If you switched the sensor leads from the timer base, at the point where they connect to the powerpack, and the lack of spark switched sides, that proves the circuitry in the pack is okay. It also proves that one sensor in that timer base is faulty. Your method of testing... using the components themselves as test equipment is exactly the way I'd do it, and I wouldn't be using anything else in a different fashion.

Note that the test gap on that type ignition should be 7/16" with a strong blue flame , not 1/4".... just a reminder.

Joe
"
 
" Thanks Joe, going to scrape

" Thanks Joe, going to scrape up a sensor coil and will let you know how it goes from there.

Jon "
 
" Joe,

Well, I just c


" Joe,

Well, I just checked with the local outboard salvage yard and they claim they don't have used ones, can't get new ones and that my only option is to send it out to have it re-wound..? The exact quote on this too was that it is "very expensive"... I'm not sure if I believe them.

Anyway, I'm going to check with precision mfg., but am probably going to need the part #. Is it going to be on the coil somewhere?, or do you know it or know how I might find out or possibly another avenue for parts, if precision can't help?

Jon "
 
There should be lots of used

There should be lots of used ones around.Should not be expensive at all.
 
"Jon..... Just for the heck of

"Jon..... Just for the heck of it, I checked the new price and found it to be approximately $340.00 (WHEW!!). I didn't think I had any left but checked anyway. To my surprise I have one new one left in stock. If you can't locate any, I'd take $205.00 for this one and take care of the shipping etc.

Joe
"
 
" Sparky,

That's what I


" Sparky,

That's what I thought as well, there's lots of these engines floating around; I'll be checking with a couple more local on that. Haven't called precision yet, was hoping to get a part # on it.

Joe,

You aren't kidding about that WHEW! ($340)... It's a deal and if I pay $205 to anyone on that, it will be you. It may not be quite worth it though, as I can probably dig up another complete engine (with a bad powerhead) for not much more than $300. This engine has sat on it's side for two years, with milky gear lube, and the compression is OK, but not great - around 90 and even. It's also missing the tilt tube and some hack (worse than me even
) managed to snap off some (all except 1) bolts that hold the tilt/trim assembly to the swivel bracket. The tilt works great, so I'm thinking it was a misguided attempt to remove the engine and that the tilt tube just got lost in the shuffle. The lower unit has also had some "work" done to the gearcase.. it's been filled in with some welds and then very nicely smoothed down.

So, I'm thinking to get it back to fairly solid condition, it's going to take, at least, a sensor coil, some lower unit work/investigation, carb cleaning/rebuild, a tilt tube, some drilling and then probably a water pump impeller will be in order. It's a little early now to spend $205.. don't want to throw too much $$ at it yet. Probably will winterize and look for a match or trade. Thanks again Joe,

Jon "
 
"Jon.... All of the above is u

"Jon.... All of the above is understood. The OMC part number is 581900. Good luck.

Joe
"
 
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