1982 V-150 no spark on one cylinder

I had no spark to cylinder #6. I switched coils between 5 and 6, still no spark to 6. I didn't know if the switch box could cause no spark to only one cylinder, so I switched them last night.<br /><br />I expected that if the switch box was the problem, that now #5 would not fire. But after swithing the switch boxes, now #4 is not firing. <br /><br />Any ideas? Can a switch box be the cause of a single cylinder not firing? If not, where should I look? <br /><br />Also, on the four wires grouped together at the top of the switch box, the second wire from the left is black and yellow (maybe black and orange): What is that wire for? Thanks.

Re: 1982 V-150 no spark on one cylinder

Put everything back the way it should, ie so you have no spark on #6.<br /><br />First disconnect the bias circuit (wht wire) between the two switchboxes. If spark returns then it is the switchbox that was working properly that is at fault.<br /><br />Next, switch green leads between the #4 & #6 cylinder at the switchbox. If the no spark condition jumps to #4 and spark returns to #6, then the switchbox is bad and needs replacing.<br /><br />Unfortunately bad switchboxes damage good ones and so its recommended that you replace both. Don't get merc ones either, CDI/Rapair makes much better ones.

Re: 1982 V-150 no spark on one cylinder

Thanks.<br /><br />I didn't have much time last night, so I didn't swithch the two switch boxes back to their original positions.<br /><br />I did disconnect the white wire connecting the two switch boxes, but there was no change, still no spark to #4.<br /><br />I switched the green wires between 4 and 6 and the no spark condition then changed from 4 to 6, but I'm not sure what that tells me, other than the problem is not the coil or spark plug wire.<br /><br />I'm still puzzled about the change of the no spark condition from 6 to 4 after switching the switch boxes. I would have expected, if the switch box was bad that after switching the switch boxes, the no spark condition would have moved from 6 to 5. What could be the cause of the change from no spark on 6 to 4?<br /><br />Also, can I disconnect the black and yellow wire next to the white one? I think it is engine shut-off related to tilt angle.<br /><br />Thanks.<br />Richard

Re: 1982 V-150 no spark on one cylinder

You haven't switched the switchboxes yet.. What you did was switch the wires that go to the coils. There are two switchboxes one on top of the other.

Re: 1982 V-150 no spark on one cylinder

I did switch them. The one underneath is now on top, with all ten wires on each changed to the other.

Re: 1982 V-150 no spark on one cylinder

New development:<br /><br />I bought two used switchboxes on ebay and installed them.<br /><br />I now get spark on all six cylinders. Where the boat is stored, I have no access to water, so while I work on it I'm unable to run it.<br /><br />I took it to the lake over the week-end, thinking it would start and run perfect, but it does not start at all. The starter spins the motor, but no cylinder makes any attempt to actually fire and run. No pops, sputters or anything. I checked again and there is spark to all six. There is fuel in the carb bowls and the choke is operating.<br /><br />Any ideas. Thanks

Re: 1982 V-150 no spark on one cylinder

If you are sure there is spark on all six...and if you have fuel... Then you must lack compression. Take a compression test!<br /><br />FWI. Just because there is fuel in the carb bowls doesn't mean fuel is getting to the engine. You really need to choke the crap out of these engines on a cold start. Retrace your starting procedure for us.<br /><br />And to test the fuel arguement. Spray a premix of fuel/oil down the carb throats and see if she fires up. If she does your carbs are dirty and need to be cleaned.

Re: 1982 V-150 no spark on one cylinder

Thanks Andy,<br /><br />I forgot to mention I did a compression test last week. Lowest had 120.<br /><br />Starting procedure: Pump primer bulb until hard. Push in key for choke (and leave pushed in while cranking), turn key to engage starter, crank for 10 to 15 seconds with no response.<br /><br />I did the above at several different throttle positions, from slightly above idle to about 1/2 throttle. Then cranked for aboput 30 seconds at WOT with no choke to clear in case it might be flooded, but I really didn't see how it could be flooded.<br /><br />BTW, I just recently bought this boat. A couple of weeks ago was the first time I started it. It started fine after about 5 to 10 seconds of cranking and choking. After the initial start, for the rest of the day, it started up immediately with no choke. It ran OK, but seemed low on power. It took a long time to get a 19.5 bass boat on plane. One thing, I think it is probably over-propped. It has a 23 pitch mercury prop. I had a 18' 1984 Champion bass boat with a 1983 150 merc and it had a 21 pitch which seemed about right.<br /><br />After I got the boat back home, I went looking for a reason for low power. I check compression, then checked for spark on each cylinder, finding no spark on #6. Now I've replaced the switch boxes, but for some reason now it won't start.

Re: 1982 V-150 no spark on one cylinder

Are you sure you have the switchboxes grounded to the block?<br /><br />I'm wondering if they are actually working properly also?<br /><br />Do you have a spark gap tester? If so check for spark intensity.. They should each jump a 7/16" gap...<br /><br />Let us know...

Re: 1982 V-150 no spark on one cylinder

Check what KCLOST recommended!<br /><br />Then try spraying the premix of fuel/oil down the carb throats. If it fires you've got dirty carbs.<br /><br />FWI: If one cylinder isn't getting spark it will not stop the engine from running.

Re: 1982 V-150 no spark on one cylinder

Thanks everyone.<br /><br />I have been checking spark with a spark gap tester, but didn't know about the 7/16 setting. It is firing on all six now with the used swith boxes I got on ebay.<br /><br />New Development:<br /><br />I said that there was fuel in the carb bowls. I checked at night without much light, it turns out I have water in the carbs. Someone must have thought it would be real funny to dump some water in the fuel tanks.<br /><br />I pumped most of the water out. Is there some fuel additive/conditioner that will get the small amount of water left in the tank to disperse.<br /><br />Can I leave the wires from the mercury switch to the switch boxes disconnected?<br /><br />Thanks.

Re: 1982 V-150 no spark on one cylinder

I'd go ahead a drain what you can and start fresh, Do you have a water seperator on the fuel line? It should be located beside the starter somewhere...<br />If so that will probably be filled with water, and should be cleaned/replaced....

Re: 1982 V-150 no spark on one cylinder

Before you assume sabotage, <br />--how long did the boat sit?<br />--does it have plastic or built-in metal fuel tank?<br /><br />Condensation is an issue with metal tanks, and water will form in a less than full tank. Heavier than fuel, it will sink to the bottom. Depending on where your fuel pickup is located, and whethrer or not you have a water separator, that may be the cause. <br /><br />Alcohol will absorb water in small amounts, and also mixes with fuel. If there is not too much water, then some alcohol may assist in getting rid of the remaining water. <br /><br />I try to fuel up after boating for two reasons:<br />1. A full tank leaves less room for air, moisture, and condensation, thereby minimising water build up in the fuel system, and:<br />2. Next time I go boating, I am gassed up and ready to go.<br /><br />These days, add reason #3...gas will be more expensive next week, so might as well fuel up now!

Re: 1982 V-150 no spark on one cylinder

"how long did the boat sit?" - 16 hours from prior use.<br />Has plastic tank. <br />I pumped about 2 1/2 or 3 gallons of water from the tank. <br />There is no drain, I pumped out as much as I could. but I estimate there could be as a cup to a pint left, maybe less, maybe more.

Re: 1982 V-150 no spark on one cylinder

Thanks everyone for your help.<br /><br />It seems to be running good now.<br /><br />I'm going to start another thread about water in lower unit.