Low Ignition Voltage

[Culpy14]

Hello everyone,

I have a 1991 Evinrude 90HP V4 that is giving me some ignition problems.

Backstory is the motor overheated and caused a whole bunch of headache. The heads and block were warped, the coils blew, the rectifier blew, the powerpack wasn’t working, and the stator resistance was out of spec by 50ohm.

I did the backyard machine technique of glass and sandpaper, which is less that 0.0015” with a feeler gauge. It brought the compression back to 100 102 102 105. I’m considering that a pass.

I replaced the coils, rectifier, power pack, and stator.

After running the engine for about 4 hours, the power pack swelled up.

Retested everything as follows:

1) tested the spark at a 1/2” gap and failed on 3/4 plugs. Fail.

2) tested resistance on the coils and received 350ohms on each one. Pass

3) put my DVA into the primary boot on the coil. 3 reading at 120v and one at 100v. Failed.

4) tested the timing voltage when cranking and each prong had 1.5V. Pass

5) I tested resistance on the timer connector and had 35ohms. Pass

6) tested voltage from each connector prong against engine ground. No voltage. Pass

I then replaced the power pack again.

Put the new power pack in and it ran. It was rough, but I also took the time to clean the carbs, put in the new fuel pump (vro delete) and I didn’t set the new floats right and gas was coming out the overflow. So when I would go to throttle up it would die, which I believe was gas overflow.

So I fixed the carbs and put them back in. Now the motor won’t start.

I took the fuel line off the new pump and cranked it. It’s definitely working.

I then start my ignition troubleshooting again. This time there is no spark at 0.01in gap. I put my DVA in the boots of the primary coil and now I have 80V. That’s a fail. So I move back to the trigger and still have the same values, so I eliminated that.

I tested my stator:

1) resistance of stator across the two prongs on the connector is 550ohms. Pass

2) I test the voltage when cranking and there is 118V. Fail

3) I test the prongs to engine ground and both are OL. Pass

4) test voltage to engine ground and get 1.5V. Failed.

Looks like a ground.

I put my old stator in and run through diagnostics. Same readings on testing voltage to ground of 1.3V.

This completely baffles me because I knew the engine would run (not well) with my old stator, and if the stator was grounding due to a short in a coil or wire, it would surely not be the same issue as my old one.

Anyone have any input on this?

 

[racerone]

Compression is an issue.----Remove bypass cover on the 100 PSI cylinder and have a look at the rings.

 

[Culpy14]

Compression is an issue.----Remove bypass cover on the 100 PSI cylinder and have a look at the rings.

I did scope them with the powerhead off. The grooves are still there in the piston and the rings look free, although maybe hard to determine with a scope.

 

[havoc_squad]

I did scope them with the powerhead off. The grooves are still there in the piston and the rings look free, although maybe hard to determine with a scope.

Leak down test would be in order likely. That's going to tell you for sure how much power is escaping at TDC when combustion occurs.

Compression gives you an idea, leak down gives you the cold hard facts.

I'm going to guess you have 20% or more leakage on the gauge in at least one cylinder. I'm curious if your crankcase cover seal is still intact or got messed up in the overheat.

 

[Culpy14]

Leak down test would be in order likely. That's going to tell you for sure how much power is escaping at TDC when combustion occurs.

Compression gives you an idea, leak down gives you the cold hard facts.

I'm going to guess you have 20% or more leakage on the gauge in at least one cylinder. I'm curious if your crankcase cover seal is still intact or got messed up in the overheat.

How would that produce a no spark during cranking?

 

[racerone]

Some will argue.-----Some simple checks for you to do.------Charge battery and have your battery load tested ( even if new ! )-----Take starter apart for inspection and ohm test on armature.----Inspect battery cables.-------Your testing indicates unusual issues.------If flywheel does not turn fast , you will not have spark !!

 

[Culpy14]

Some will argue.-----Some simple checks for you to do.------Charge battery and have your battery load tested ( even if new ! )-----Take starter apart for inspection and ohm test on armature.----Inspect battery cables.-------Your testing indicates unusual issues.------If flywheel does not turn fast , you will not have spark !!

Thanks!

I sent the stator back to cdi and it came back fine. So I went to the starter and replaced it. It’s much better but still no spark, so I left the battery on the charger last night. We’ll see what kind of spark I get today.

If it’s no spark I’ll replace the battery and probably the cables.

I think you’re right though; the flywheel isn’t spinning fast enough to get my ignition system working.

 

[ONERCBOATER!]

If nothing else is discovered and after following everyone else's advice... cause mine isn't as well thought out sometimes and definitely not as experienced as many here.

I would suggest wacky Voltage readings that do phantom things can be a scuffed or cracked wire leaking or partially grounding perhaps when vibrating but not when still... just an idea... and definitely check it after the more learned folks ideas...if you still can't find the issue.
Edited...due to left out thought.

Sometimes cranking in the dark while observing motor and wiring will shed light on electric issues.

Sean

 

[Culpy14]

An update on this:

I replaced the starter because it was pretty **** to begin with. This got my cranking RPM’s up, to where one bank was firing.

I swapped the coils to the other bank and the problem followed it. So I concluded the power pack (4th new one) was fine. I replaced the coils and it blew a coil on start up, on the bank i first noticed went dead. I put in one of the coils that was weak up still working when I started this whole thing (oem part).

I’ve also replaced the battery cables because they were quite ****.

Any suggestions? Do cdi parts suck on omc’s? Seems like my shitty oem coil works when a new cdi coil blows a coil somewhere else.