1989 90HP Rude Ignition, where to start?

[peterskeeter]

Hello all, I can use some help with a possible ignition problem I'm having. I did a few searches and can't find too much. My 1989 90HP Evinrude Crossflow is acting up. 2 weeks ago on my way back in, the engine would all of a sudden drop RPM's when cruising around 4500 RPM. It would all of a sudden drop to about 3500 RPM and then bounce back up to 4500 in a minute or so and drop back down to 3500 RPM. Trying to see what it would do, I opened her up to WOT, and she would pickup to wide open and after a minute or so, cut out again. I figured it could be a coil pack dropping out as some looked old and one had cracks through the insulation. I changed all the coil packs with brand new ones and installed new plug wires. Took it back to the launch. It ran great for about 10 minutes and then back to the same old sh*t! Except this time it ran really rough and would not plane the boat anymore, had to put put back to the dock. Matter of fact, it would no longer even idle as it would kill. Perhaps it dropped two cylinders? Brought it back home and put it on the muffs and it sounded normal and would idle. I notice it is doing this when all the way warmed up. My temp alarm works but is not sounding when the motor loses power. My VRO has also been removed and I use premix. Any ideas? I hate to throw more money at this with no fix. Sorry for the long post. All ideas are welcome. I am competent at working on these things but the ignition on this motor I find to be complex! i wish it had points!!!

 

[ezeke]

Re: 1989 90HP Rude Ignition, where to start?

Do a compression test first and report the results cylinder by cylinder.

You will need an inductive timing light and a helper to test for spark under load through the range of RPM.

 

[peterskeeter]

Re: 1989 90HP Rude Ignition, where to start?

Boat has been at my Dad's house and getting to it has been tough. Was finally able to test compression this morning. Here are the results on a warm engine:

Cylinder #1 125psi
Cylinder#2 123psi
Cylinder#3 125psi
Cylinder #4 125psi

Haven't been able to put her on the water and test timing under a load. I did however test the timing while she was warming up before the compression test and the timing is on so far.

 

[reeldutch]

Re: 1989 90HP Rude Ignition, where to start?

make sure the powerpack ground is clean and tight

 

[peterskeeter]

Re: 1989 90HP Rude Ignition, where to start?

UPDATE!

Went and tried it again today on the water. Timing was good under a load. Same thing occured today, boat ran great for the first 15 minutes and then started missing intermitently. After it started missing I stopped on the bank and cleaned the ground to the powerpack. Fired it back up and the tach started acting funny and it didn't solve any problems. The tach would only read up until 2,000 RPM then it would return to Zero when revved any higher. Also want to note it idled funny. Checked all the plugs for fire with the timing light when acting up and all were firing. However, when the motor was reved from idle, it appeared as if it was firing less at times rather than firing more with the increased RPM. Got home, put it on the muffs and the tach returned to working perfectly fine and the motor idled great again. Obviously its something electronic. Any ideas???

 

[Charlie in TX]

Re: 1989 90HP Rude Ignition, where to start?

I am not the expert here but I believe you are using the timing light differently than what is intended. Under normal conditions, the timing light is to set the timing. You are looking for loss of spark. When your motor sufferers from loss of power, connect the inductive timing light to each plug wire, one at a time, an make sure you have spark to each plug.

 

[jonesg]

Re: 1989 90HP Rude Ignition, where to start?

The symptoms described would steer me in the direction of the rectifier with a factory sercice manual and a peak reading meter.
www.outboardbooks.com
and
http://cgi.ebay.com/ebaymotors/Mari...tZMotors_Automotive_Tools?hash=item35a473afc8

Then there would be no guessing.
I'd try using a spark gap tester to check spark at a 7/16th inch gap too.

Outboards will run without the rectifier but a bad rectifier will take out the spark, so a troubleshooting proceedure is to disconnect it and see if spark returns, if yes , then replace it.

 

[peterskeeter]

Re: 1989 90HP Rude Ignition, where to start?

I am not the expert here but I believe you are using the timing light differently than what is intended. Under normal conditions, the timing light is to set the timing. You are looking for loss of spark. When your motor sufferers from loss of power, connect the inductive timing light to each plug wire, one at a time, an make sure you have spark to each plug.

Yes Charlie, that is exactly what I did with the timing light when the motor acted up. I used it to see if all plugs were firing when it stumbled. But when the motor was running normal, I used the light to check the timing on CYL #1.

Jonesg, I appreciate the advice and will try disconnecting the rectifier next time it acts up. When I disconnect the rectifier, should it run normal up to WOT?

 

[emdsapmgr]

Re: 1989 90HP Rude Ignition, where to start?

You've may have two different issues going on here. They may not be related. The electronics on the powerhead are divided into two systems, the ignition system and the charging/starting system. The tach on your engine is driven from the rectifier/regulator which is part of the charging system. If the rectifier/regulator is not working properly, the battery will not recharge properly and an erratic tach is a sign that it may be malfunctioning. The factory manual provides test procedures for checking the rectifier/regulator in the charging system. The ignition side drives/controls the spark. Not unusual for ignition problems to occur once the powerhead reaches normal operating temps. Heat tends to break down weak components. The factory manual provides test procedures for ignition components. While the power pack would be #1 on my list of componets to check, I would also test the stator output and the timer base output. Testing these components do require special equipment, such as a special peak-reading voltmeter and a common volt/ohmmeter.

 

[jonesg]

Re: 1989 90HP Rude Ignition, where to start?

Yes Charlie, that is exactly what I did with the timing light when the motor acted up. I used it to see if all plugs were firing when it stumbled. But when the motor was running normal, I used the light to check the timing on CYL #1.

Jonesg, I appreciate the advice and will try disconnecting the rectifier next time it acts up. When I disconnect the rectifier, should it run normal up to WOT?

Get the meter I listed for you, its priced at .50cents on the dollar.
That and the factory service book will show you how to test each component, throwing parts at the problem would be expensive.

 

[peterskeeter]

Re: 1989 90HP Rude Ignition, where to start?

I have a voltmeter currently that has many functions. I'm not sure if it does peak voltage but my father is an electrician and I'm sure he may have something. I have a service manual and have tryed following the CDI test procedures found on maxrules.com. Problem is, some of my wiring doesn't seem to match the color of wires stated in the test procedures for my particular engine. Does this engine have S.L.O.W? By the way, when it starts to act up, the water coming from the cooling system is cool and the heads are cool to the touch, I can hold my fingers on them after running WOT. I do want to check the powerpack, it just isn't clear to me exactly how to test it.

 

[bktheking]

Re: 1989 90HP Rude Ignition, where to start?

There are only a handful of meters that do peak voltage, I've got 3 and none of them do.

 

[emdsapmgr]

Re: 1989 90HP Rude Ignition, where to start?

I believe the SLOW system was on the V6 engines only, with the 35 amp alternator. Are you working with the factory manual, or an aftermarket version?

 

[jonesg]

Re: 1989 90HP Rude Ignition, where to start?

I have a voltmeter currently that has many functions. I'm not sure if it does peak voltage but my father is an electrician and I'm sure he may have something. I have a service manual and have tryed following the CDI test procedures found on maxrules.com. Problem is, some of my wiring doesn't seem to match the color of wires stated in the test procedures for my particular engine. Does this engine have S.L.O.W? By the way, when it starts to act up, the water coming from the cooling system is cool and the heads are cool to the touch, I can hold my fingers on them after running WOT. I do want to check the powerpack, it just isn't clear to me exactly how to test it.

Get the genuine factory service manual fer cripes sake, the test proceedures are spelled out very clearly, its all in the black bits. ( aka; ink )
www.outboardbooks.com

Heres a homemade Peak reading adapter, buy the parts at ratshack.
Theres only 3 components, took me 45 minutes to assemble, hey I'm a cook.
http://forums.iboats.com/showthread.php?t=299903

 

[peterskeeter]

Re: 1989 90HP Rude Ignition, where to start?

Thanks Jonesg for the schematics, that is pretty interesting what you've got there. As far as my service manual goes, I believe it is a Chilton's manual. I have to check though, it is at my Mother's house about an hour away from where I am right now. Looks like I will have to get the OMC factory service manual for these detailed procedures...

 

[bktheking]

Re: 1989 90HP Rude Ignition, where to start?

I believe the SLOW system was on the V6 engines only, with the 35 amp alternator. Are you working with the factory manual, or an aftermarket version?

According to my manual slow was on the 120 and 140 motors 88-90.

Slow limited to 2500 rpm and would be a sign of overheating. I'd be pulling the flywheel off and start by inspecting the condition of your stator, feeds the powerpack and the rectifier, too much coincidence that tach and spark are an issue.

Or take it one step further and test the stator, DVA time.

 

[peterskeeter]

Re: 1989 90HP Rude Ignition, where to start?

A LITTLE UPDATE!

Put the boat on the water today again, same thing. It ran great for 15-20 minutes, no problems. After that, I was able to get it to act up again. I isolated the problem to one cylinder not firing, the port side bottom cylinder. Haven't gotten around to testing DVA values yet because my tools are an hour or so drive from where my boat is at. As far as the tachometer acting up, it was totally related to a connection getting wet at the back of the engine when running/coming off of a plane with the hood off. I dried the connection when it got wet today and the tach was back to normal, not a relevant problem. Do you think this intermittent miss on one cylinder is powerpack related now until further testing?

 

[ezeke]

Re: 1989 90HP Rude Ignition, where to start?

Swap the ignition coils and see if the problem follows the coil. If the ignition coils are discolored, cracked, swollen or poorly connected, replace or correct.

Ignition coils that test good can break down when heated with no obvious outward signs.

 

[peterskeeter]

Re: 1989 90HP Rude Ignition, where to start?

All coil packs and wires are brand new as of last week

 

[jonesg]

Re: 1989 90HP Rude Ignition, where to start?

All coil packs and wires are brand new as of last week

dang, that would have been to easy, I'd still do a coil swap and see if the problem follows the coil. Sparkplugs can be suspects too, even on new components...especially if it was dropped.

Its a bit of a pain swapping parts around, but its cheaper than buying a powerpack or whatever only to find it was a cheap part.