1984 omc 2.5l ignition/coil problem

[trikeman72]

ok first off i am new to I/O boats. i am trying to get my engine started and had a no crank and no spark problems.

after going thru the troubleshooting for cranking i located the problem in the slave solenoid.. put bypaqss wire on and cranks with key (woohoo me)

i tried going thru the ignition section and reading thru it and going step by step i know the following...

1... power at the + post with key on.
2. volts is 8.6 after resistor wire.... although when i tested lastnight it is reading 10 not sure if old resistor wire is bad?
3 i removed all wires from coil and tried to test for continuity as per troublshooting thread and found there isnt any if i am checking right?? i question if i am doing it right because i have tried 3 coils 2 used and 1 new and none of them test continuity... i am not an electrical guru by no means so wording will reflect that...
i turn digital multimeter to the setting where it "beeps" when you touch the two leads from tester together.... put one on the tower of coil and touch other to either small terminals on the coil with no wires attached to coil actually holding coil in my hand... nothing... this means coil is bad yes?? i cant get why i have had 3 coils with no continuity especially a brand new one....
also... i was going to get a ballaast resistor to install on motor so i could do away with the ancient inline resistor wire purple from key switch. the one wire that comes from alternator also needs a resistor so i was going to put in a ballast resistor with 1.5ohms to be able to use it for both wires needing a resistor. will this work??

also someone please tell me what the deal is with this coil and what i have to do to fix if in fact coil isnt bad..or if it is i can get a replacement but is that continuity test correct?? i can have seller test b4 mailing me coil least i know its good b4 i start i dont know.
i did install new plugs,cap,rotor,points,condensor,wires on motor...
i am replacing the fuse block under dash tonight (because of corrosion on the glass type connectors etc... i checked the gap on points and they are right...
i thought my problem was in cap with grounded out condensor or something but testing the coil for continuity turns up no result i think coil is bad so i dont test nothing else..
anyhow... please be detailed in answers as i am not good with terminology etc so "talk dumb to me" wont offend me in the least..
thank you very much for the help
bill

 

[Silvertip]

Re: 1984 omc 2.5l ignition/coil problem

Your testing is flawed. A coil has three terminals as you obviously know. You will only measure continuity between the POS and NEG terminals, or between the high tension (tower) terminal and the NEG terminal. The primary side of the coil consists of the POS and NEG terminals to which the primary windings attach. The secondary windings (the high voltage) side connects between the tower terminal and the NEG terminal. Try those checks again. I seriously doubt you have three bad coils. Use an OHM meter for these checks. Continuity means nothing if the coil windings are shorted. All that continuity test proves is that there is not an OPEN circuit. It does not prove the coil is good.

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

Your testing is flawed. A coil has three terminals as you obviously know. You will only measure continuity between the POS and NEG terminals, or between the high tension (tower) terminal and the NEG terminal. The primary side of the coil consists of the POS and NEG terminals to which the primary windings attach. The secondary windings (the high voltage) side connects between the tower terminal and the NEG terminal. Try those checks again. I seriously doubt you have three bad coils. Use an OHM meter for these checks. Continuity means nothing if the coil windings are shorted. All that continuity test proves is that there is not an OPEN circuit. It does not prove the coil is good.

there is no continuity in any combination of touching terminals. rechecked neg and pos as well as tower and neg... nothing.. i emailed shop i bought new coil from and he said that he tested another coil as i have and did get continuity .. in process of sending it back for a replacement.... more frikin down time

i put the multimeter to the omega looking symbol (ohms i think) and obtain no readings meaning no numbers shows up on display... what is supposed to happen when i test how you stated with meter set to ohms?

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

oh i noticed tonight that the old coil i got to try had a crack in it by the tower... glad it was free...
so i have the probably original 1984 coil that was bad and a new one thats bad i guess?

what is the best way to test the coil to be sure that it is in fact bad since continuity doesnt give accurate reading?
i just figured since there was no continuity then no use in testing coil further as it was bad..
then again i would be totally lost as to what the problem is if not the coil... i have proper voltage to pos terminal with key on but nothing comming out of tower wire... also tried hooking a plug to see if spark would jump when plug was grounded to block but that did nothing as well.
thank you for the reply by the way i appreciate your help

 

[Reinell-BRXL-191]

Re: 1984 omc 2.5l ignition/coil problem

in process of sending it back for a replacement.... more frikin down time

You know a 12V coil is a 12V coil, and you can go to autozone and buy them all day from 18 - 40 dollars? (stock vs Mallory Blaster)

Why you shipping? Anyways...

This testing procedure is valid for most coils. Using an ohmmeter, check the resistance between the side terminals of the coil. Do this with all of the wires to the coil disconnected. You should see 0.75 to 0.81 ohm of resistance. Then check the resistance between either side terminal and the center high tension terminal. The reading should be 10,000 to 11,000 ohms. Any significant deviation from these numbers would indicate that the coil is defective.

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

You know a 12V coil is a 12V coil, and you can go to autozone and buy them all day from 18 - 40 dollars? (stock vs Mallory Blaster)

Why you shipping? Anyways...

This testing procedure is valid for most coils. Using an ohmmeter, check the resistance between the side terminals of the coil. Do this with all of the wires to the coil disconnected. You should see 0.75 to 0.81 ohm of resistance. Then check the resistance between either side terminal and the center high tension terminal. The reading should be 10,000 to 11,000 ohms. Any significant deviation from these numbers would indicate that the coil is defective.

Well, azone cnt sell me one without a vehicle to look up...and if i say boat. They say no gots....heck man i went to get a resistor wire andwas toldthey dnt make em....h
so got one offline for 30bux...thus shipping

 

[Reinell-BRXL-191]

Re: 1984 omc 2.5l ignition/coil problem

Well, azone cnt sell me one without a vehicle to look up...and if i say boat. They say no gots....heck man i went to get a resistor wire andwas toldthey dnt make em....h
so got one offline for 30bux...thus shipping

They must not want to help you... just tell them you want a stock coil that looks just like the expensive Mallory coil they have right behind the counter...

tell them ummm.. 1976 Mustang II and to pick their favorite motor... they will bring you out a 18 dollar - "will work fine" coil...

 

[Bondo]

Re: 1984 omc 2.5l ignition/coil problem

ok first off i am new to I/O boats. i am trying to get my engine started and had a no crank and no spark problems.

after going thru the troubleshooting for cranking i located the problem in the slave solenoid.. put bypaqss wire on and cranks with key (woohoo me)

i tried going thru the ignition section and reading thru it and going step by step i know the following...

1... power at the + post with key on.
2. volts is 8.6 after resistor wire.... although when i tested lastnight it is reading 10 not sure if old resistor wire is bad?
3 i removed all wires from coil and tried to test for continuity as per troublshooting thread and found there isnt any if i am checking right?? i question if i am doing it right because i have tried 3 coils 2 used and 1 new and none of them test continuity... i am not an electrical guru by no means so wording will reflect that...
i turn digital multimeter to the setting where it "beeps" when you touch the two leads from tester together.... put one on the tower of coil and touch other to either small terminals on the coil with no wires attached to coil actually holding coil in my hand... nothing... this means coil is bad yes?? i cant get why i have had 3 coils with no continuity especially a brand new one....
also... i was going to get a ballaast resistor to install on motor so i could do away with the ancient inline resistor wire purple from key switch. the one wire that comes from alternator also needs a resistor so i was going to put in a ballast resistor with 1.5ohms to be able to use it for both wires needing a resistor. will this work??

also someone please tell me what the deal is with this coil and what i have to do to fix if in fact coil isnt bad..or if it is i can get a replacement but is that continuity test correct?? i can have seller test b4 mailing me coil least i know its good b4 i start i dont know.
i did install new plugs,cap,rotor,points,condensor,wires on motor...
i am replacing the fuse block under dash tonight (because of corrosion on the glass type connectors etc... i checked the gap on points and they are right...
i thought my problem was in cap with grounded out condensor or something but testing the coil for continuity turns up no result i think coil is bad so i dont test nothing else..
anyhow... please be detailed in answers as i am not good with terminology etc so "talk dumb to me" wont offend me in the least..
thank you very much for the help
bill

Ayuh,... The most common problem with a coil, is Bad Points,....

What do yer Points look like,..?? Are they set right,..??

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

They must not want to help you... just tell them you want a stock coil that looks just like the expensive Mallory coil they have right behind the counter...

tell them ummm.. 1976 Mustang II and to pick their favorite motor... they will bring you out a 18 dollar - "will work fine" coil...

yea... thats what i did for my oil pan gasket actually.... 1970 chevy nova 2.5 presto... asked for coil and they said no gots i really think the whole going postal thing came about from a dude that went to azone and just snapped

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

Ayuh,... The most common problem with a coil, is Bad Points,....

What do yer Points look like,..?? Are they set right,..??

new points,condensor,rotor
set to .019 like sticker on valve cover said
pretty sure they are gapped correct....i could pull the cap and get the lobe on high side and double check em....
oh oh wait.... if it would stop frikin raining that is AAAHHHHHH

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

They must not want to help you... just tell them you want a stock coil that looks just like the expensive Mallory coil they have right behind the counter...

tell them ummm.. 1976 Mustang II and to pick their favorite motor... they will bring you out a 18 dollar - "will work fine" coil...

Funny you say that because i was working on a motor rebuild for my VW trike i built and needed a set of rings right.... well... does anyone else remember the day when u went into napa and said i need a set of 80mm rings and they whipped out the book and said well you can use the ring set from a ????? cut 1/8" of each side and presto??? or was i dreaming back then?
told him wanted set of 80mm rings ... what for? dont matter.... cant look up w/o motor.... dont want to tell you cuz ull say u have to order.... what for?? a weedeaater with an 80mm piston ... no seriously what for? a leaf blower with an 80mm piston? ok man its for a 72 beetle aircooled.... Oh ... id have to order those... couldnt believe it

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

Ayuh,... The most common problem with a coil, is Bad Points,....

What do yer Points look like,..?? Are they set right,..??

well i seen on the troubleshoooting thread most probs in cap... but i got all screwed up when i did the continuity thing on the coil and it didnt work.... figured coil was bad so i got another one... but it didnt test right either ... but if im testing it wrong then who frikin knows..
im goin to get my original coil (since i shipped bad new one back today) and run the ohms test and see what happens... but then again i think to myself... if no continuity coil is bad yes? i feel so stupid with something so simple... just cant wrap my head around the concept of it or something idk...

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

You know a 12V coil is a 12V coil, and you can go to autozone and buy them all day from 18 - 40 dollars? (stock vs Mallory Blaster)

Why you shipping? Anyways...

This testing procedure is valid for most coils. Using an ohmmeter, check the resistance between the side terminals of the coil. Do this with all of the wires to the coil disconnected. You should see 0.75 to 0.81 ohm of resistance. Then check the resistance between either side terminal and the center high tension terminal. The reading should be 10,000 to 11,000 ohms. Any significant deviation from these numbers would indicate that the coil is defective.

mother nature finally stopped peein on my parade yay
going out to test another used coil i have from a working motor (supposidly) not taking anything for granted nowadays...
i did get my fuse block replaced as well as all dash switches and bulbs ... corrosion is a bugger to get rid of geez...

i am going to have to get help with my trim wiring tho... i wired in the correct plug with all new wires for my trim motor and it mesed up something... i have a mercruiser pre alpha outdrive... so if i plug the 3 blade plug into the motor the dash lights comes on with key turned off... i matched the colors of the wires in the controls with the colors of the cable that came with plug... red blue green i think..
also have a purple and blue extra wires... for gauge i think but i dont have a gauge in dash so not worried about that...
anyhow thats something ill worry about once i get the engine to fire
thanks for the help everyone will let everyone know what happens

 

[Bondo]

Re: 1984 omc 2.5l ignition/coil problem

mother nature finally stopped peein on my parade yay
going out to test another used coil i have from a working motor (supposidly) not taking anything for granted nowadays...
i did get my fuse block replaced as well as all dash switches and bulbs ... corrosion is a bugger to get rid of geez...

i am going to have to get help with my trim wiring tho... i wired in the correct plug with all new wires for my trim motor and it mesed up something... i have a mercruiser pre alpha outdrive... so if i plug the 3 blade plug into the motor the dash lights comes on with key turned off... i matched the colors of the wires in the controls with the colors of the cable that came with plug... red blue green i think..
also have a purple and blue extra wires... for gauge i think but i dont have a gauge in dash so not worried about that...
anyhow thats something ill worry about once i get the engine to fire
thanks for the help everyone will let everyone know what happens

Ayuh,.... So,.... Why is this in the OMC forum,..??

'n forget about ohm testin' the coil,...
Put it in, hook it up, 'n power the (+) side, then ground out the (-) side, 'n it'll Fire...

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

because i have an 84 omc 2.5l engine i am working on
thats why its in the thread heading and stated in the thread i started... trim motor is for the mercruiser outdrive..different problem will go in different section trying to get motor to start at the moment...
anyhow.... yesterday and today i replaced the purple wire thinking it wasnt working right because of no voltage reading at the motor with key on... (there is no connector it is hard wired so problem is not in connector) ran another wire from key to resistor then to + on coil..... no spark.... so i started testing again.... i have 12.5v on both sides of ballast resistor..... so since i have 4 of them with different ohm readings from 1.5-2.0 ohms resistance, i gather i either am using the wrong kind of resistor or all 4 new ones are bad??
so.... i have NO CLUE what to check or do now....
i came back in to post here and to reprint the troubleshooting coil/spark section to take back outside with me..
i do remember when i bought a new ignition switch, it said for magneto ignitions on the box... but i never really paid attention to it other than it had the same number of terminals on the back like my original omc one did..... could that be why it isnt working right?? what /where do i start again..?? tryin hard not to saw it in half
thanks for any help/suggestions y'all i apprecaite it

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

UPDATE

ok today i managed to figure out nothing it seams like...

i put the original switch back in because i replaced it thinking it was my no crank problem but that was the slave solenoid...

i dont have any power at coil or before resistor so i put a jumper wire from battery to pos on coil and got spark from coil..
spark thru plug wire was thin and orange right from coil was thick blue... im guessing that is point gap not just right...

i dont understand why i have no power thru the purple wire (replacement) i ran wire from terminal on switch to rear of boat. the wire goes into the ballast resistor and then i ran a wire from other side of resistor to the + terminal on coil.. there isnt power on the switch terminal where the purple wire goes until you turn it to the crank position.( i was able to get voltage going thru resistor while cranking because i hooked tester to it while wife cranked engine over... is that wire supposed to go thru something else before it gets to the engine? like the control/trim wires or something?? i thought it went straight from switch to stern of boat from what i was able to trace back when i replaced it...
it seems like i am missing a step somewhere because there is no power at the terminal on switch where purple wire goes... there was a very faint glow when i tested that terminal at one time today( i had like .29v before resistor but now it dont do anything

please help...

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

wanted to make a note to everyone reading this that i eliminated the OMC engine wiring harness and used a mercruiser one... mainly because i have a MC outdrive and tilt pump so i didnt need all of the solenoids etc...
when i wired the harnesses together i started with a wire in the boat harness looked at manual seen what it was for... such as water temp.... and connected it to the eng harness that went to the temp sending unit on engine..
i did this with all the wires so everything is connected to the right boat side wire... i didnot connect the neutral safety switch wires to anything thinking if i had a corrosion problem there i wouldnt be able to get engine started..
well that worked great because i still cant get it to start....
i dont know if i can locate a diagram of the switch to make sure it is connected up right or not....

if there is supposed to be 12v on + post on coil ... and purple wire goes from switch to coil (mine goes to the ballast resistor then to coil)
then the terminal on switch the purple wire goes to has to be one that gets hot when i turn key on right?

hopeing to get some advice today tryin to get something accomplished today just farting around with odds and ends things til someone gives me a direction to go in to fix spark problem

thank you for help

 

[Bondo]

Re: 1984 omc 2.5l ignition/coil problem

wanted to make a note to everyone reading this that i eliminated the OMC engine wiring harness and used a mercruiser one... mainly because i have a MC outdrive and tilt pump so i didnt need all of the solenoids etc...
when i wired the harnesses together i started with a wire in the boat harness looked at manual seen what it was for... such as water temp.... and connected it to the eng harness that went to the temp sending unit on engine..
i did this with all the wires so everything is connected to the right boat side wire... i didnot connect the neutral safety switch wires to anything thinking if i had a corrosion problem there i wouldnt be able to get engine started..
well that worked great because i still cant get it to start....
i dont know if i can locate a diagram of the switch to make sure it is connected up right or not....

if there is supposed to be 12v on + post on coil ... and purple wire goes from switch to coil (mine goes to the ballast resistor then to coil)
then the terminal on switch the purple wire goes to has to be one that gets hot when i turn key on right?

hopeing to get some advice today tryin to get something accomplished today just farting around with odds and ends things til someone gives me a direction to go in to fix spark problem

thank you for help

Ayuh,... The shift switch is wired from the coils (-) terminal to the switch, to ground,...

because i have an 84 omc 2.5l engine i am working on
thats why its in the thread heading and stated in the thread i started...

It sure sounds like there's Nothin' OMC left on this motor,....

Just Mercruiser, 'n Chevy....

 

[Daviet]

Re: 1984 omc 2.5l ignition/coil problem

It's been a long time, but let me ask a couple of questions.
With the key in the ON position, you should have battery voltage to the input side of the resistor, and aprox 8 volts on the output side of the resistor to the positive side of the coil, is this correct?
When you engage the starter, you should get battery voltage to the positive side of the coil by means of a jumper wire either from the starter solenoid or the slave solenoid.
How many wires do you have going to the positive side of the coil, 1 or 2?

 

[trikeman72]

Re: 1984 omc 2.5l ignition/coil problem

It's been a long time, but let me ask a couple of questions.
With the key in the ON position, you should have battery voltage to the input side of the resistor, and aprox 8 volts on the output side of the resistor to the positive side of the coil, is this correct?
When you engage the starter, you should get battery voltage to the positive side of the coil by means of a jumper wire either from the starter solenoid or the slave solenoid.
How many wires do you have going to the positive side of the coil, 1 or 2?

no with key in on position i have no voltage at input side of resistor...
i have 2 wires going to pos on coil... the one wire comming from alternator and purple wire from switch they both go to the input side of resistor and a wire from output side of resistor to + terminal on coil.

originally i did have 12.5 toresistor and 8.6 at coil with original inline resistor wire... i changed the coil thinking it was bad and have a coil with correct ohms and continuity etc... i lost voltage on purple wire so i thought the wire was bad since it was melted in the engine harness from switch back to eng connector..as well as the inline resistor being corroded etc... so i ran a new wire from switch to resistor (new purple wire) and i dont have voltage in that wire....

the jumper wire your talking about... i believe it is white... comes from starter solenoid goes to alternator and has like a splice or split wire that comes off of it ... that is the 2nd wire going into the resistor with the purple wire from switch.. the book shows 2 resistor wires to pos side of coil... purple wire from swtich and #1 wire in the 2 wire plug on alternator

i dont know what i forgot or did different since ive been changing so many things but i dont understand why i dont have 12v to resistor in purple wire... besides the fact that the post it is hooked to on switch dont have power with key in on position..