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View Full Version : Bizarre Ignition Issue - Please Help


PeteS
07-18-2005, 08:33 AM
I'll try to keep this as short as possible, with all facts, so it is easier and less time consuming to draw conclusions. Last August I installed an Prestolite electronic ignition. It ran fine, and has since then, but always has had rough re-starts.

About a week ago I realized that during the install, I had forgotten to bypass the ballast resistor per the instructions. I realized that maybe that was what was causing the hot restart issues, so I set out to fix the problem this weekend.

After bypassing the resistor, here is where the odd behaviors started. Boat starts fine, runs great for the first 2 minutes or so. Then, the RPM's start dropping. Starting at 750, all the way down to 200 before stalling. The volts are around 25 from the positive post on the coil while running, and about 11 on the post when the key in on with the boat off.

Next I tried disconnecting the orange solinoid wire, thinking that maybe it was drawing from the coil when running, causing the loss of power. No change, so I did the same with the choke wire, no change.

Still not knowing what to do, I thought maybe the coil wasn't putting out enough power for the electronic ignition module, so I replaced the coil. No change.

After getting frusterated, I wired everything back up the way it was originally, with the 12v from the ignition going through the ballast resistor, before heading to the coil. My voltage dropped to 8 at the coil with the key on (which was expected), boat off, and suprisingly, my voltage while the boat was running jumped to 56 from the positive post on the coil while running. The RPM's stabilized, and the boat was running fine. The rough hot restart issues maintained, as expected. I'm stumped.

I get a full 12 volts from the ignition wire regardless of the connection to the resistor or direct to the coil. So I don't think it is some sort of short from the ignition. I can check spark to all cylinders, but I don't think that is the issue. I'm leaning towards either a ignition module issue, or somewhere the wiring is funky. Thanks in advanced for the help and reading this lengthy post.

BriEOD
07-18-2005, 08:41 AM
Sorry Pete no help from me. I would recommend calling DIM and speaking with Vince or Richard.

hardycm
07-18-2005, 09:03 AM
Pete,

Two thoughts: 1) Disconnect the grey wire from the coil and see if that helps. I'm in the process of fixing a prob on mine where the tach wire seems to be intermittently shorting out the coil -- doubt its your prob, but worth a shot. 2) i talked to Vince the other day and he mentioned a few people got bad modules that would run for about 20 minutes and then die. Could be that your module is screwed up.

PeteS
07-18-2005, 09:05 AM
Sorry Pete no help from me. I would recommend calling DIM and speaking with Vince or Richard.
No problem, Bri. Thanks for taking a look at it. I'm going to call Richard this afternoon to get his take.

PeteS
07-18-2005, 09:11 AM
Pete,

Two thoughts: 1) Disconnect the grey wire from the coil and see if that helps. I'm in the process of fixing a prob on mine where the tach wire seems to be intermittently shorting out the coil -- doubt its your prob, but worth a shot. 2) i talked to Vince the other day and he mentioned a few people got bad modules that would run for about 20 minutes and then die. Could be that your module is screwed up.
Two good points, Hardy. Thanks. Do you think that maybe it is a bad module, and because it is underpowered (8 volts after the resistor) it isn't failing. But when you power it as spec'd, (full 12 volts), that's when it fails after a few minutes?

I noticed a decent amount of heat from the distributor at 12v, and much less at 8v. This was done by touching the aluminum section on the bottom, as I didn't have a thermocouple or anything.

hardycm
07-18-2005, 11:34 AM
No clue -- I can understand basic electrical systems, but when you get microprocessors involved, I'm lost. You def. did the right thing to bypass the ballast resistor, but I don't know if running at 8 V for a year ruined your module or what.

SKI*MC
07-18-2005, 11:40 AM
I wonder if you fried it when you hooked it up wrong? We accidentally hooked up an electronic ignition wrong once, it ran, just like you were saying. We had to get a new one... :(

87MC Dave
07-18-2005, 12:27 PM
I just converted over to electroninc on my 87 prsotar 19. I had bypassed the ballest resistor as the instructions said and it had a bit of studder. I put the resistor back in line and the studder went away.

PeteS
07-18-2005, 02:37 PM
All things being equal, my biggest question would be why would the electronic ignition function on 8v and not 12v. If it was engineered for 12, why is it struggling?

Maybe it came from the factory with a defect, and because it was always only running on 8, it ran. Granted it ran somewhat crappy, but it functioned still. The problem was never realized until now.

Or, maybe it came from the factory OK, but running it on 8v as opposed to 12v for the last few months screwed up the module.

MCDave, when did you get your electronic ignition kit? Can someone tell me what the voltage is supposed to be on the + side of the coil post while the boat is running? Thanks again for everyone's help and thoughts!

87MC Dave
07-18-2005, 02:56 PM
Just got mine last week. Does the coil say 12v on the coil? I can check for you when I get home this evening and let you know tomorrow, unless someone here knows. I actually went ahead and ordered a new coil from skidim when I was having problems before connecting the Ballest reist. As it turns out my coil was just fine, but at least I have the peace of mind about the correct coil being on the engine. Also not sure because I didn't time mine before the conversion but mine was about 12deg out of time. You may want to put a timing light on it to see where you are at.

PeteS
07-18-2005, 04:28 PM
Just got mine last week. Does the coil say 12v on the coil? I can check for you when I get home this evening and let you know tomorrow, unless someone here knows. I actually went ahead and ordered a new coil from skidim when I was having problems before connecting the Ballest reist. As it turns out my coil was just fine, but at least I have the peace of mind about the correct coil being on the engine. Also not sure because I didn't time mine before the conversion but mine was about 12deg out of time. You may want to put a timing light on it to see where you are at.
We are on the exact same page, Dave. I ordered my coil last week from DIM after having problems with the ignition, as well to eliminate that as the problem. Did you get the coil that says "for use with electronic ignitions"? Mine has a PCM sticker on it, is black with a tan cap.

What exactly did you try when you bypassed the resistor? I tried both putting all wires on one side of the restistor, and had my problems, so I tried the positive post of the coil and still had issues. Maybe to actually tie all of the wires together would be the secret, but I doubt it.

If you don't mind tonight, can I take you up on the oportunity of checking the voltage in the positive post of the coil, with the motor running? I'll do mine as well, grounding to the negative on the coil -- we can make our test valid by both doing such.

Do you think that there is something possibly to do with our wiring schematic that makes the resistor necessary for use? That doesn't make sence either, because BrianM has bypassed the resistor as instructed, and it runs great.

Maybe I'll actually tie all of the wires together tonight, as suggested, to see what happens. I'd like to actually give the ignition 12 volts as reccomended to optimize it's function. But maybe that won't be possible. Thanks a million for your help -- let me know if there is anything you'd like me to check out for you.

87MC Dave
07-18-2005, 05:08 PM
That is the same coil I have. I did the exact same thing you did. I hooked all the wires onto the + post of the coil and the problem still happened. So I put the reist back in line and it the studder went away. I told Vince @ DIM about it and he said it shouldn't hurt the Elect Mod. Have you checked your timing? I think the springs that come with that kit may retard the timing. I put a light on mine and it was 2deg ATDC and it should have been 10deg BTDC. I will check the volts on the going across the coil when it is running and post that tonight when I get home. Check back around 7 or 7:30 and I'll try and let ya know. I would definatly put a timing light on it if you have one. Just to make sure that your timing isn't out.

87MC Dave
07-18-2005, 06:52 PM
Just got done checking the voltage across the coil. I was getting a fluctuation from about 8.4v to 11.9 volts. I put the Black probe on the - terminal ans the Red on the + term and watched the meter. It would go up and down as the engine ran. Hope this helps. If you need it read a different way let me knwo how you want to take the readings and I'll go check mine.

PeteS
07-19-2005, 08:27 AM
Thanks for checking, Dave. Things are even getting more interesting now, as I too checked my voltages last night as well. These numbers are with and without the resistor in-line, as specified below:

1. Positive post on coil, not running w/out resistor: 8.
2. Negative post on coil, not running w/out resistor: 5.
3. Positive post on coil, running, w/out resistor: 12.
4. Negative post on coil, running, w/out resistor: 9.
5. Input post on resistor not running: 11.
6. Output post on resistor not running: 7.
7. Positive post on coil, not running w/ resistor: 7.
8. Positive post on coil, running w/ resistor: 9.

I wasn't able to ground to the negative post of the coil, because the current present. I was getting close to 12 volts out of the black wire from the ignition module. Is this normal?

Is the negative post on the coil supposed to be showing voltage? For whatever reason, I always though it was a ground. I guess I'm not sure exactly what the function of the coil is, and how it works. But I was always getting voltage out of the negative post on my coil, so I was grounding to the engine block for the tests.

Again, the engine runs well with the 12v going through the resistor, but has rough hot re-starts. When I take the resistor out of line, the engine runs great for a few minutes, then starts missing badly and dropping RPM's quickly. Timing was checked and adjusted during the testing. Thanks again!

87MC Dave
07-19-2005, 11:04 AM
I will check mine to the block tonight and see if I get the same readings....

PeteS
07-26-2005, 03:50 PM
After discussion with DIM, and more diagnostics, last week we drew the conclusion that it was in fact a bad module in the electronic ignition.

After replacing the unit yesterday, and then re-wiring, and adjusting the timing, the new kit works great on the full 12v -- in fact, the boat is running the best it ever has. Thanks for all the help from all that assisted.