Mariner 4m ignition problem

[rainingdatsuncigs]

I have a mariner 4m

serial 6EO S 037640

with no spark. Could anyone advise me on troubleshooting the ignition system and also what year is it please? Have looked on the guides but the only match seems to be a 4A?

 

[achris]

Re: Mariner 4m ignition problem

Your engine is a 4hp, Manual start, short shaft... That's what the 4M means... The series of the engine is 4A... Year is between 1980 and 1987...

Have a look at this post for and explanation of the year... http://forums.iboats.com/showpost.php?p=1842632&postcount=2

Does this help for your ignition problem?

 

[rainingdatsuncigs]

Re: Mariner 4m ignition problem

Thanks for that diagram achris, it's allowed me to eliminate the kill switch as the problem. Do you know any diagnostics i can perform using a digital multimeter to narrow the problem down further?

 

[achris]

Re: Mariner 4m ignition problem

Tomorrow ok? (bedtime for me now)

 

[rainingdatsuncigs]

Re: Mariner 4m ignition problem

Nice one, i'll look forward to enlightenment!

many thanks

geoff

 

[achris]

Re: Mariner 4m ignition problem

I assume you don?t have a DVA for your multimeter?

Disconnect each of these wires from the switchbox before metering. Start by checking the charge coil (brown wire). Meter to ground, you should see some resistance, but not a short. Do the same with the low speed trigger (white/green), and the ignition coil (brown/white).

If you can order the DVA for a multimeter, then we will be able to do the voltage checks. Look here in the iBoats store... http://www.iboats.com/Marine_Store/dm/keywords.dva--submit.Search--submit.x.0--submit.y.0

With the system wired up, check for about 200-400 volts on the charge coil as you pull the starter, and about 2-4 volts on the trigger. If either of those is missing, then disconnect the wire from the switchbox and check again? If the volts appear when disconnected, then you may have a short in the box. If everything is ok going into the box, then measure the output, should be about 400 volts. If there?s still no spark, then the ignition coil is faulty. If the voltage isn?t there, disconnect the coil and measure the output again. If the voltage is now there, then most likely it?s the coil; although it could still be the switchbox?

The only other thing to check is that all the grounds are clean and tight..

Good luck? HTH.

Chris???.

 

[rainingdatsuncigs]

Re: Mariner 4m ignition problem

Thanks for all that good info, I'll be doing the checks while you're asleep so there may be news tomorrow!

Thanks again,

rainingdatsuncigs

 

[rainingdatsuncigs]

Re: Mariner 4m ignition problem

Hi Chris,

An update on my progress for you, mostly good!

I checked the resistances and they all looked good. I have no DVA so my friend and I tried his Fluke multimeter with a little success. Then I had my first brainwave and got out my trusty hand-held oscilloscope and started measuring. I got a voltage from the low speed trigger (green / white), a good voltage from the Brown and the same from the coil feed but still no spark. I was just about to give up and blame the coil when the second brainwave came over me. I swapped the low and high speed trigger wires around and hey presto a fat blue spark! Diagnosis - Low speed trigger not performing correctly. A bit more scoping shows a weak and variable waveform for the low speed trigger and a well defined, regular high speed trigger waveform.

After all that , do you know if there is any adjustment that can be performed on the low speed trigger coil or do you think it may be dead?

I really appreciate all the help thus far Chris!

Best regards

geoff

 

[achris]

Re: Mariner 4m ignition problem

If I'd have known you were a EE, I'd have given you the design of a DVA!!!

No adjustment on the triggers... By the sound of it, it's GTG... (Gone To God)

Chris.......

 

[rainingdatsuncigs]

Re: Mariner 4m ignition problem

I'm no EE but I mess about with electronics, PICs and programming in assembly to keep my brain going.

Go on then, send me the design and I'll have a bash!

regards

geoff

 

[achris]

Re: Mariner 4m ignition problem

It's so simple you'll kick yourself for not coming up with it yourself..

What we are trying to do it to read the peak voltage of a quick pulse.. So, we set the meter to DC volts... We try to load the circuit as little as possible, of course... We pass the signal through a diode (to rectify it, half wave is enough, use a 1000volt diode, 1N4007) charge a capacitor up to store the charge for long enough to see it on the meter. So the cap would go across the meter inputs. We also need a resistor to discharge the cap. I did the calculations for cap and resistor size a long time ago... and I'm in bed at the moment, so I don't have them to hand (even if i did remember where they are)...

From memory....
I based it on a time constant of about 1/3 of a second... RC=1.1T.. I think I used a Poly cap, high voltage of course. I think about 1uF for the cap and resistor about 300K. With this setup you get the best results with an analog meter... I haven't designed one for a digital meter, yet

Have go at that... Let me know what you get....

Chris.......

The first computer I programed was in machine code (hexadecimal)! The computer had core memory... Pre-dated RAM by about 10 years...