long time lurker 1st time poster needs advice

[tominatub]

Hey there, please go easy on me as I'm a bit of a novice at this stuff. I have a 1975 1150 Merc. I think it's 115 hp & has the thunderbolt ignition. I have owned this boat for almost 10 years & it has served me greatly. I'm really good at fixing most of the mech. problems, but I have a iginition problem that is giving me some grief. I'm getting no spark at all. Now I use to have a manual but can't find it so I was hoping you guys could lend a helping hand. I have checked all my wiring connections - everything is right, sound & tight. I did a search on this board & preformed the "switchbox test" as instructed on several post by "laddies" & "clam". I get no spark from the black wire when I arc it to ground. I was just about to buy a used switchbox from a local boat salvage yard until the guy said he wanted a couple hundered dollars for it & was selling it as-is with no garantees or returns. so I return to my boat & get my meter out & start hoping to find another possible culprit, what I found was that with the Key on, I get 12v on the red & white post on the 4 post side of the switchbox, I also get 12v form the brown post on the 3 post side - what puzzled me was that I get NOTHING from my the green wire going to my coil, that same green wire shows continuity if I touch it & a ground. The black post on the 3 post side also has continuity with ground. I don't know anything about this ignition system, but I think that these wires should not have continuity with ground. Am I right in this assumption? <br /><br /> With this info, should I first buy a used switchbox from Ebay & see what happens, should I buy a new coil, or should I do some more testing to narrow things down. I'm pretty good with my Meter if I only knew how things should read.<br /><br />Sorry to make this so long just wanna make sure I get all the details in. Thanks for being patient with my ignorance. <br /><br />Tom

 

[heybaylor]

Re: long time lurker 1st time poster needs advice

find that manual...<br />the green wire only has power on it when the "switchbox" fires. this is done when the "trigger tells it to...<br />yes the green wire will read to ground through the coil..but should have the coil resistance..not "zero ohms

 

[tominatub]

Re: long time lurker 1st time poster needs advice

okay, I rechecked & want to clarify, I read continuity through the gnd & conv post on my coil, with .01 ohms. I do not read continuity from the HV lead to anything. I also show continuity on the brown post on the 3 post side to ground. <br /><br /> I ran this test:<br /><br /><br /> "MERCURY BATTERY-POWERED CDI TEST <br />FOR DISTRIBUTOR MODELS<br /><br />This test is for the 332-2986 switchbox used from 1967-1978 on all the inlines.<br /><br />This test assumes your coil is good (most all are).<br /><br />DISCONNCT BATTERY <br /><br />1. Turn off ignion<br />2. Disconnect all 3 wires on the distributor side of the switchbox.<br />3. Remove the HV lead from the coil to the center cap (remember it unscrews<br />from cap)<br />4. Reconnect that HV center lead to the COIL side only.<br />5. Position that HV lead about about 3/8" from ground (block, shrouds etc)<br />and find a way to hold it there.<br />6. Jumber the brown and white terminals on the dist. side of the switchbox<br />together.<br /><br />RECONNECT BATTERRY<br /><br />7. Check that you have +12 V at red terminal.<br />8. Turn on ignition and verify +12V at white terminal (on red terminal side)<br />9. Touch the black terminal to ground - unit should cause spark each time<br />you touch ground."<br /><br />suggest by chris in a diffrent post.<br /><br /><br />I failed this test. <br /><br />I guess my question is just which to replace 1st, the coil or the switchbox?

 

[Laddies]

Re: long time lurker 1st time poster needs advice

I have never replaced a coil (transformer) on one of those units, with a DVA or neon tester you can ck for output on the green wire if you want

 

[rodbolt]

Re: long time lurker 1st time poster needs advice

hello<br /> I have never seen a coil failure on these either unless it sank. however I could fill a pickup with dead switch boxes and triggers. the test you did bypasses the trigger,cap and rotor. with still no spark odds are its a bad switchbox. take my advice, buy it from rapair. ya get a year warrenty and it works. hate to see ya shell out big bucks for a used box that fails in a few weeks or less.<br />like laddies said the switchbox output is testable just have to use the correct meter.

 

[tominatub]

Re: long time lurker 1st time poster needs advice

okay, yeah in one of my earlier test I did ( iwas too scared to mention), I jumped the brown & white post & grounded the black on the 3 post side, turn one the key & messured the voltage out of the green post & only got 1.3v when the red white & brown post all had 12v. Now I understand that I didn't have the right meter & wont be doing anymore testing as my ignorance has shown through. So taking your advice I'm going to buy a new switchbox. rodbolt you suggest buying it from "rapair" is this a company that I can find online or something?

 

[tominatub]

Re: long time lurker 1st time poster needs advice

UPDATE>>> still have a fire problem. I got my new switchbox in, replaced it, it now past all the above mentioned test, however I still get no fire. What do I chase after now? after I little searching I think I should fix or replace my "trigger" but how do I go about this.??<br /><br />Thanks,<br /> Tom

 

[Motor Boater Bill]

Re: long time lurker 1st time poster needs advice

Have you examined your wiring carefully? Mercs of the mid-70's have a bad reputation for faulty wires with crumbling insulation. My 1976 Merc 200 had a bad wire to the kill switch, shorting to ground under a clamp. It was like the kill switch was always engaged.

 

[boaterntx]

Re: long time lurker 1st time poster needs advice

I hate to hijack your thread, but I have the same proble, - I get spark from my coil when I jumper the white & brown wires on the switch box off & ground the black, I just don't get anything out the dist.

 

[boaterntx]

Re: long time lurker 1st time poster needs advice

i have been told that I could just replace the trigger, but I can't even figure out how to take off the rotor, much less anything else. a local guy said he would sale me a used trigger for $120.00 another told me 250.00 for a use dist.<br /><br />I really don't know what to do here, just looking for help