Switch Box

[40magnum]

Switch Box



I have a 1994 Mariner 40 hp magnum tiller steering on a 14' Jon boat. Last week motor ran fine. Last night it took about a 1/8 mile to plane off. At idle and low rpm's motor sounds and feels like it is skipping. No low end power then all of a sudden it has full power. Pulled each spark plug wire off while running and narrowed it down to #4 cyl. # 4 spark plug looks very clean. Swapped #3 &#4 coils and there was no difference. Also swapped spark plugs after the coil swap just in case #4 plug was dead and still no difference. Could it be the switch box? Or does the switch box handle 2 cylinders at a time, meaning I would have a misfire on a another cyl also. Thanks.

 

[Faztbullet]

Re: Switch Box

A clean plug could mean water intrusion from bad lower crankshaft seals.... Check the spark with a spark tester(auto parts) and see if all cylinders are firing....

 

[CSkjerven]

Re: Switch Box

I don't know much about motors, but my dad and I are having similar problems with my motor except mine won't fire on one and two. One thing I was told to try was switching the stator wires around. If that lead to different cylinders firing than your stator is bad and if it doesn't it is your switch box. Here is a link to a very good trouble shooting guide we use http://issuu.com/cdielectronics/docs/troubleshootingguide?mode=embed&layout=http%3A%2F%2Fskin.issuu.com%2Fv%2Fcolor%2Flayout.xml&backgroundColor=000000&showFlipBtn=true

 

[40magnum]

Re: Switch Box

Top 3 cyls have fire. Trigger coil, ignition coil ohm reading were within specs. Stator coil ohm readings were not good also switch box readings were bad.

 

[CharlieB]

Re: Switch Box

Follow the detailed directions in the CDI Ignition Troubleshooting Guide.

Ohm reads are not the best measure of at stator or trigger and should NOT be used to measure a switchbox.

DVA testing is THE most reliable indicator of electrical function.

If the other cyls fire it is NOT the stator, it is either a trigger, switchbox, coil, or plug wire. Test properly, do NOT order any non-returnable electrical part until you have PROVEN the part faulty by DVA testing, it will save you a lot of money by the time you get your motor running correctly.

 

[40magnum]

Re: Switch Box

Where can I get one those DVA testers? Is it something you add to a multimeter?

 

[CharlieB]

Re: Switch Box

DVA adaptors are available for any meter.

You can build an adaptor quite cheaply following the parts list and diagram posted somewhere in this forum.

Sorry, I haven't saved the link. Try searching for DIY DVA adaptor

 

[40magnum]

Re: Switch Box

I did take voltage readings with a Fluke meter with a 600 vdc capacity. Wouldn't that work? It does have a button for peak readings. I tested the switch box and acceptable voltage readings should be 200- 360 vdc. I tested it at 110 vdc so I think it is bad.

Low speed coil on stator should have been between 210-310 vdc. I tested it a 52 vdc.

High speed coil on stator should have been 20-100 vdc. I tested it at 10 vdc. So I think the stator is bad also.

Am I on the right track? According to the manual the ohms and voltage readings are not withing specs. I couldn't find anything that said anything about peak voltage.
Thanks.

 

[CharlieB]

Re: Switch Box

Peak reading meter is NOT an acceptable method. It is telling you you do not have enough voltage for any spark yet obviously you have spark on three cyls!

It is NOT the stator. PERIOD.

A failing trigger, switchbox, coil, or plug wire are the ONLY ways you can lose spark on one cyl.

See the other post on building a DVA adaptor, test the system correctly and KNOW what is wrong.

 

[40magnum]

Re: Switch Box

Thanks again, I'll order one tonight. I've read in other forums that they can be made very cheap but my electrical skills aren't good enough to make one. I found one for just under $40.00 w/ shipping. Do I do the voltage tests the same way?

 

[CharlieB]

Re: Switch Box

Disconnect the throttle cable, Disconnect the triggers from the switchbox, then while Cranking, test each trigger and slowly move the throttle/timing lever to full advance and back to idle, if a trigger wire is broken it should show a drop in DVA when the wire loses contact.

If the trigger test fine, reconnect all wires and test switchbox output to coils. If that fails on #4 order a switchbox. If it does NOT fail, check coil, and plug wire.

Pull the spark plugs and ground all the wires, that will save a lot of strain on the starter and battery.

 

[Faztbullet]

Re: Switch Box

I tested the switch box and acceptable voltage readings should be 200- 360 vdc. I tested it at 110 vdc so I think it is bad.

Low speed coil on stator should have been between 210-310 vdc. I tested it a 52 vdc.

These are AC readings not DC thus the use of a DVA adapter.

 

[40magnum]

Re: Switch Box

I finally got he DVA in today and took the same tests and found better results. Everything (switch box, Stator -low and high speed tests, coil outputs) showed good voltage reading except # 4 cyl on the coil output. It was reading .035 volts on # 4 coil. The manual does not give any voltage values for the trigger just ohms resistance. Do I put the positive lead from the meter on each trigger wire (black, brown, white and violet) and the black lead to a good engine ground? If so, it read zero volts.