1984 Johnson 90hp bad power pack?

[SiLiconD17]

I bought a 17' Aquasport with a 90hp V4 Johnson on it and when I had first purchased it the motor was running fine. I suspected the previous owner had overheated it, so I pulled the heads to inspect and didn't find anything worth rebuilding it for so I put it back together with new head gaskets and flushed out the water passages in the block, cleaned and tested the thermostats, and flushed out the crap in the lower unit. Compression is well within spec and close on all 4 cylinders, fheew.

So after that, it sat for a while as I had purchased a house at the same time and was in the process of moving things and repairing the house, etc, you all know how the story goes. I recently tried cranking it, and it just isn't getting any spark. I got some intermittent spark on one bank. I had a crappy volt/ohm meter so a few weeks ago I just cleaned and tested all the grounds and connections on the power packs, coils, etc and put on some new plug wires. Now that I have a good volt meter, it is not getting any spark whatsoever with a spark plug tester. I have disconnected the stop switch wiring and also tried with the rectifier disconnected, still no spark on any cylinder. I have also pulled the flywheel and cleaned it, everything looks A-OK beneath (timer base, stator, etc). So today with a better Fluke voltmeter, I tested the wires coming from the power pack and into the coils, and one power pack seems to be outputting on both wires and the other one doesn't output jack. Being that my Fluke doesn't measure peak voltage, I just tested DC V on each lead and at regular intervals (when it seems it should spark), I am getting 2.5-3.5V from one power pack, and nothing from the other. I tried swapping the power packs between banks and the "bad" one still outputs nothing, the "good" one outputs the same as on the other bank. Should I really try with a voltmeter capable of measuring peak voltage, or is my test good enough and I can consider the one power pack failed?

Also, if the power packs are outputting and I am still not getting spark, is it safe to say the coils are all toast? They look original and in sad shape, but it was running on all 4 cylinders when I first bought it. I am close to replacing both power packs and all 4 coils, but obviously saving money would be nice.

 

[boobie]

Re: 1984 Johnson 90hp bad power pack?

I'd say the pack was bad but before replacing it you could also swap the coils once to see what happens.

 

[emdsapmgr]

Re: 1984 Johnson 90hp bad power pack?

That engine has dual identical power packs. Each controls the spark to the plugs on one head. Use an inductive timing light to see what spark each plugwire has at cranking rpm's. You can further test by swapping the two power packs. If the "no spark" problem moves when the pack moves, you have your culprit. Spark plug coils are usually pretty reliable, but also can be swapped for testing purposes as boobie indicated.

 

[Faztbullet]

Re: 1984 Johnson 90hp bad power pack?

I tried swapping the power packs between banks and the "bad" one still outputs nothing, the "good" one outputs the same as on the other bank.

Since you swapped packs and still have no fire check your battery voltage first as low cranking RPM will effect spark. Also remove plugs from cylinders to see what happens. Disconnect the harness at red plug and jump solenoid and retest as you could have a short in harness. If still no spark start testing trigger as rare for both charge coils to fail on stator....

 

[SiLiconD17]

Re: 1984 Johnson 90hp bad power pack?

I know the battery is charged (reads just over 13V), and I have already replaced the battery cables as well as the short lead from the starter to the positive terminal. It is definitely turning over quicker than 250RPM. I tried swapping coils around and I'm just not getting any spark on what I guess to be the "good" power pack. I found a Mallory replacement power pack for $61 online and I can do the coils for about $20 a pop, so I'm thinking I'm going to go ahead and replace all that. Thanks for the help guys!

 

[emdsapmgr]

Re: 1984 Johnson 90hp bad power pack?

Follow Fastbullet's suggestions. A stator or timer base could be the problem, since you've looked at the packs and coils. Both expensive items. There should be cranking output voltage specs for both parts. A special "peak-reading" voltmeter will measure output at cranking rpm's. If you don't have a factory service manual, check out the online troubleshooting info for your engine at cdielectronics.com.

 

[SiLiconD17]

Re: 1984 Johnson 90hp bad power pack?

Well, you guys inspired me to do a little more troubleshooting. I have the Seloc manual which somewhat helps, and I had already gone through the manual at cdielectronics.com, that was very helpful.

With the suspected good power pack, with a timing light it is firing on both coils at what appears to be correct intervals. With the suspected bad power pack, the timing light doesn't fire at all except for once when I stop cranking it over. When I swap power packs between banks, I get the same behavior (suspected good power pack is timing correctly, suspected bad power pack nothing except once at the end). When I pull the plugs, it does not seem to be arcing on any plug/coil/bank, and with a spark plug tester like I said I get nothing. I also tried with brand new spark plugs.

Would I be correct in determining that the timer base is OK? Resistance tests as per my Seloc manual are OK, except for on the 4-pin connector (between the timer base and power pack) between the B-C terminals on both banks it is about 65ohms, manual specs 40 +/- 10 ohms.

I am going to get with a buddy of mine that does electronics for an airplane refitting company to see if I can borrow his peak voltage tester to test the stator. If the stator was bad, would it still show up on a timing gun yet not have enough energy to spark?

 

[SiLiconD17]

Re: 1984 Johnson 90hp bad power pack?

To add to that, I ran to a boat salvage yard today and had a field day there. I found tons of stuff for some other outboards of mine, but I picked up 2 used coils cheap. I tested on my suspected good power pack with the new coils and still no spark. I'm beginning to think stator, since I am getting the right timing from the timer base and yet still no spark. While cranking it with the spark plug checker plugged in however, I did one time get a flash.

 

[Faztbullet]

Re: 1984 Johnson 90hp bad power pack?

This is going to sound funny but smack the pack thats not firing with a rubber mallet while cranking and see if it starts firing (no to hard but firm) If this dont work pull the white wire from either amp connector as this is the bias wire thru timer base and retest.

 

[emdsapmgr]

Re: 1984 Johnson 90hp bad power pack?

Have you tried to fire the ignition with the main control box harness disconnected? Sometimes the key switch or control box harness can cause problems. (The key switch provides the ground to kill the packs when in the "off" position.) If you disconnect the red plug harness inside the cowling, then temporarily try to jump the starter with automotive jumper cables and a known good battery. See if you get any fire. If still nothing, at least you know it's probably an engine/ignition problem and not the key switch/control box.

 

[SiLiconD17]

Re: 1984 Johnson 90hp bad power pack?

Well, to follow up, I did isolate the wiring harness and still no go. I ordered a good used stator and timer base on eBay (I hate using eBay, but I got the stator for just $60 and timer base for $30). I hadn't even tried testing the output to the power packs, but I suspected a bad stator since the timing seemed to be there. Swapped on the new stator and BAM! Spark! The power pack that I suspected bad was still not getting jack, so I threw on the spare one I bought at a local boat yard for $25 and BAM! Spark all around! Someone disconnected the oil injection, so it was real hard to start and I had to resort to splashing a little fuel mix into the throats of the carburetors with a beer bottle to get it going, but after some convincing it fired right up and runs like a raped ape! Everything is A-OK, temps, compression, cooling system, etc. Next up is reconnecting that oil injection...

I do have to say however, I was very impressed with Southcentral Outboards up in Illinois (who I bought the stator and timer base through eBay from). I didn't expect much from the prices, but the stator and timer base I got were in excellent condition and seriously could have passed for new or reconditioned. The wiring harnesses were all there and wiring in excellent shape. If anyone wants to give them a try, their phone # is 618-487-9499. I for one will be doing business with them again!

Thanks again for the help guys!

 

[boobie]

Re: 1984 Johnson 90hp bad power pack?

You'd be better off if you left the vro oiling system off of it and mixed your fuel 50:1. Less probs.