1970Mach1
Seaman
- Joined
- Aug 2, 2010
- Messages
- 71
New here! First off I've had the boat for probably 10 yrs or so. It's a 18ft Stingray with a 3.0L Mercruiser I think it's considered EST ignition. When I first bought the boat I rebuilt the carb and it ran beautifully, wasn't really to bad before but did run much smoother. I also set the timing (ill get more into that later) and adjusted the idle. I docked the boat for a couple years and it ran beautifully and reliable. I bought a house and you know how that goes, no more docking. Anyway last couple years its been acting up. You run it for a bit then I'll sit and wait at a lock idleing and the engine will start to buck and chuck. Feels like it is running on 2 or 3 cylinders. Throw the it in neutral and rev the engine to about 2,000 for a bit to clear it out. It will go back to a smooth idle but only for a little bit. So I took the carb apart and cleaned it, when this started a few years ago. That didn't change anything. Next year I rebuilt the carb with a kit and changed fuel filter. No change. I bought a new cap and rotor from eBay. I took the boat out and no change. However when I got to the ramp the engine died after being on it for hours. Got it home and saw the contact on the rotor burned and melted off. This was a cheap eBay cap and rotor. So I got a Sierra this time but again no change in the idle after it got warm. I'm pretty sure I changed the plugs at that time, I thought I tried to get them at AutoZone but they didn't have and I ordered them from Ebay.
Last year I went over the carb with a fine tooth comb and no change. Maybe I've missed something on the carb I don't know. Last time i had it out when it was bucking it smelled real rich exhaust. So I'm leaning towards ignition, this year I bought a coil and ignition module. The old module didn't seem to have any dielectric grease left. I bought the coil from eBay and it said Sierra but didn't come with a Sierra box so it's probably a cheap one. The module was a cheap one from eBay. I don't have the money to buy the good stuff, so I don't know how good these parts really are. So back to adjusting the timing. Every time I do it by the book I get the same results. I hook up the jumper write to distributor, bypass shift interrupt switch, hook up tach with front ignition wire and a gray wire on side of block. I set it to 1? before to dead center. Unhook all the stuff rev it up to 2200 and its always read way over 12-14?. It's off the timing plate like in the 20's. Both modules do the same thing so I don't know if I do it wrong or what.
So anyway I thought the module would solve all my problems. After changing the coil and module I started it and the idle now is rough is not horrible but definitely not that smooth. If it put the distributor on 6?btdc its pretty nice but not on 1?. I messed with it and set the idle at 750rpm. Got it the best i could. I took the boat and it didn't do the bucking like it has been doing. I'm guessing the old module was getting hot causing that? But now I'm left with not a smooth idle, plus i forgot to mention it use to fire up fast now it cranks a fair amount before firing, this is the same with the old module and coil as the new ones. I've yet to replace the wires due to money. But what do I do now? Try the old module with new dielectric grease? Is the cheap new coil and module ok? I'm at the end of my rope with this boat.
Thanks for the help.
Last year I went over the carb with a fine tooth comb and no change. Maybe I've missed something on the carb I don't know. Last time i had it out when it was bucking it smelled real rich exhaust. So I'm leaning towards ignition, this year I bought a coil and ignition module. The old module didn't seem to have any dielectric grease left. I bought the coil from eBay and it said Sierra but didn't come with a Sierra box so it's probably a cheap one. The module was a cheap one from eBay. I don't have the money to buy the good stuff, so I don't know how good these parts really are. So back to adjusting the timing. Every time I do it by the book I get the same results. I hook up the jumper write to distributor, bypass shift interrupt switch, hook up tach with front ignition wire and a gray wire on side of block. I set it to 1? before to dead center. Unhook all the stuff rev it up to 2200 and its always read way over 12-14?. It's off the timing plate like in the 20's. Both modules do the same thing so I don't know if I do it wrong or what.
So anyway I thought the module would solve all my problems. After changing the coil and module I started it and the idle now is rough is not horrible but definitely not that smooth. If it put the distributor on 6?btdc its pretty nice but not on 1?. I messed with it and set the idle at 750rpm. Got it the best i could. I took the boat and it didn't do the bucking like it has been doing. I'm guessing the old module was getting hot causing that? But now I'm left with not a smooth idle, plus i forgot to mention it use to fire up fast now it cranks a fair amount before firing, this is the same with the old module and coil as the new ones. I've yet to replace the wires due to money. But what do I do now? Try the old module with new dielectric grease? Is the cheap new coil and module ok? I'm at the end of my rope with this boat.
Thanks for the help.
