Motor Misses When Trim is Used

dman4100 · Oct 25, 2011

I have a 1986 Chaparral 187 with a 3.7 driving an alpha 1. I restored the boat and motor 3 years ago and it has performed well with nearly 200 hundred hours on the rebuilt. Recently however when I use the trim toggle to raise or lower the outdrive while underway it causes the motor to miss. This only happens after operating the boat for 10 or 15 minutes and once it starts it keeps getting worse to the point that the motor will miss whether the trim is being used or not. I have checked the wiring for obvious problems and swapped put the electronic ignition for the original with no difference in how the boat performs.

Any ideas on what might be going on?

Don S · Oct 25, 2011

Re: Motor Misses When Trim is Used

Bad ground, low battery, charging system not working.
When you run the pump, the voltage is getting too low for the ignition system to get full power.

dman4100 · Oct 25, 2011

Re: Motor Misses When Trim is Used

Thanks for the reply, I am hoping it is the battery and not the regulator or stator. The stator was replaced when the engine was rebuilt still appears to have the original water cooled regulator. Thanks again

Don S · Oct 25, 2011

Re: Motor Misses When Trim is Used

What is the voltage on the battery (using a DVM, not the helm instrument) when the engine is running about 1200 rpm or more?

dman4100 · Oct 27, 2011

Re: Motor Misses When Trim is Used

I have put the boat away for the season so here in Maine it will be sometime in late April when I can get it out to check the voltages. Thanks again for the advice I will follow up in the spring.

dman4100 · Jun 30, 2012

Re: Motor Misses When Trim is Used

Finally got the boat out for the first time since last fall and after checking the voltage I did notice that the system was over charging. The voltage would increase with engine speed to over 16 volts and never regulate as it should. I considered converting to alternator but could not because my dog house is very small with no room to mount the alternator. I did replace the pricey regulator and the system now averages around 3.6 - 3.8 volts which should be good. Took the boat out and it ran fine for about 10 minutes and it started missing as it did before. Using the trim aggravates the miss but it did start missing and will continue to whether trim is used or not. I am now wondering if the coil might be breaking down as it gets heat soaked causing the miss. Does this sound like it could be the cause of the miss??

Don S · Jun 30, 2012

Re: Motor Misses When Trim is Used

now averages around 3.6 - 3.8 volts

I hope you meant 13.6 -13.8 volts, not 3.6 - 3.8.

You might want to have your battery load tested. If you are only charging one cell, it could be your problem. Plenty of voltage, just no amperage.

dman4100 · Jun 30, 2012

Re: Motor Misses When Trim is Used

Yes I did mean to say volts. I did replace the battery with a new one. That is why I was thinking it might be something else as I believe the charging system is now up to snuff.

dingdongs · Jun 30, 2012

Re: Motor Misses When Trim is Used

if you can run the engine up in pitch black and look to see if you have an arcing fault via your leads/cap/coil etc it may throw some light on your missing problem.
is the positive to the trim pump direct from the battery?????

dman4100 · Jun 30, 2012

Re: Motor Misses When Trim is Used

I am not sure if the trim pump is direct form the battery but will check.

Also had not thought about running it in pitch black which I can do and will to see if there is something is arching as you suggest.

Thanks for the idea.

dman4100 · Jun 30, 2012

Re: Motor Misses When Trim is Used

Just got back in from running the boat and when I opened up the doghouse with the motor running in the dark it looked like a lightening storm going on. The plug wires were arching in numerous places particularly behind the power steering pump and the coil was arching from the tower to both negitive and postive terminals. So new plug wires and coil will be ordered. I suspect as the motor warmed up and heat soaked everything the arching gets worse eventually causing the misfire and running the trim made the stituation worse as the voltage gets drawn down while the pump is running.

Anyways I spent a lot on the regulator trying to solve the problem but the over charging was going to catch up with me sooner or later and that is resolved and I think new wires and coil will get me going again.

Dingdongs thanks for the advice and also Don I did have a voltage issue as you suggested thanks for your replies.

dingdongs · Jun 30, 2012

Re: Motor Misses When Trim is Used

lets hope this may solve your missing problems.

dman4100 · Jul 8, 2012

Re: Motor Misses When Trim is Used

I did want to let you know that I got got the boat in the water today for the first time after replacing the plug wires and coil and it ran as it should. It did not skip a beat all day.

thanks

dingdongs · Jul 8, 2012

Re: Motor Misses When Trim is Used

great to know.

Motor Misses When Trim is Used

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