1988 Inline 6 115 needs help

[BenKeith]

Hope one of you merc guys can save me bunches of money here. Last year motor died while fishing the St. Johns. Local shop there replaced all the electronics with used parts and got it running pretty good. Ended up both trigger modules were bad. One checked bad right of the bat and he replaced that one, but ended up replacing everything else before he finally decided to try swapping out the other.

For the past couple of months the motor has been going down hill. Had to limp three miles back to ramp saturday evening. Motor had dead skip on one or two cylinders. I might take it out in the morning and it runs pretty good, but as the day goes on, it gets worse and worse until it barely runs. It also fouls a plug or too when it starts running bad.

Rebuilt the carbs and fuel pump last year but noticed middle carb is constantly dripping gas now, so it looks like I will be doing them again.

Checked the high speed and low speed stator voltages and they were well within the range the book gives. The high speed was 235 volts at 3,500 rpm. Bias voltage also checks good, about 17 vdc. However, when I check the input voltage to the coils, they are only showing between 105 and 145. At 1,000 rpm, they are at 75 - 85. The thing that buggs me, they are at that same voltage when it's running good and when it's running like crap and skipping badly. I only have the one DVA adapter and using a Fluke 73III DVM and not sure I can trust that reading, sure hate to spend $200 for two new tigger modules just to find I'm still getting the same readings when I install them.

Anybody got any words of wisdome for a non merc mechanic.

Raceman's done told me I would have to put a distributer in it for him to be able to help me.

[Georgia Boy]

If Jeff G does not see this post send him a PM. If Raceman does not know then Jeff probably does, between the two of them they have answered every question I could ever come up with on my inline. Good Luck. ~GB

[Jeff_G]

Check the trigger voltage on all six with the DVA. Make sure the switchboxes are grounded when you do it and nothing touches. Double check the stator at idle or cranking and again at 3,000. Do a resistence check of the stator cold then do the same with the stator warm, you can use a hair dryer to warm the stator.
Definately check the carbs, replace the needle and seats.

[BenKeith]

Jeff,

Thanks, I've only done voltage checks, figured if the resistance changed it would show up in the voltage. The boat is at the lake so this weekend I'll go through all the resistance checks.

I checked the trigger voltage on all six coils #1, 3, 4 and 6 were 105 volts, #2 and 5 were 145 volts. Also did a ground check with meter. Between the ground tabs for each coil and battery negative, I got zero ohms. I also backed the screws out a couple of turns and tightened them back down, just to see if that made a difference.

I plan to take a new set of plug wires and plugs, just to eleminate that posibility. Mainly because that's about what it acts like, a plug or wire breaking down. The plugs in it are fairly new but the wires are original. The wires ohm out good but we know that doesn't mean crap under a load. However, if my input voltage is realy that low, I'm probably hitting the coils with just barely enough to fire the plugs.

If you will check back monday, I should the carbs done, new wires and plugs and all the resistance checks then.