engine: 5.7 L 1988 Mercruiser alpha 1 open cooled with Q-Jet.
problem: At idle, especially when not warmed up the engine tends to surge in and out. It's done this for a number of years and it's never idled well until warm, but this years it's much more noticeable and to a lesser extent even after it comes up to temp. It occurs evenly. I'm not positive but it seems to occur every other cycle. I'd say once about every second the rpms pulse back momentarily as if it's suddenly under extra load. I think this is perfectly in sync with the engine rpms, and usually around 1200+ rpms the problem seems to go away or is at least no longer noticeable.
My question is, where do I look first? Because it's so cyclical I am assuming it's most likely an electrical issue? Perhaps a cylinder thats not firing? If it were a fuel or air issue it would probably occur more randomly, no? Over the weekend I will pull the plugs one by one to see if there's one that doesn't change the engine load. Aside from that can anyone offer any hints or advice where I else might look?
Thanks.
nat
problem: At idle, especially when not warmed up the engine tends to surge in and out. It's done this for a number of years and it's never idled well until warm, but this years it's much more noticeable and to a lesser extent even after it comes up to temp. It occurs evenly. I'm not positive but it seems to occur every other cycle. I'd say once about every second the rpms pulse back momentarily as if it's suddenly under extra load. I think this is perfectly in sync with the engine rpms, and usually around 1200+ rpms the problem seems to go away or is at least no longer noticeable.
My question is, where do I look first? Because it's so cyclical I am assuming it's most likely an electrical issue? Perhaps a cylinder thats not firing? If it were a fuel or air issue it would probably occur more randomly, no? Over the weekend I will pull the plugs one by one to see if there's one that doesn't change the engine load. Aside from that can anyone offer any hints or advice where I else might look?
Thanks.
nat
