89 chevy 305 engine runs rough till it's warmed up

[Utahgalaxy89]

Hi guys, I have an 89 galaxy 19' with the omc cobra, chevy 305. The boat runs great, and I have done a tune up on it since I bought it. There is one strange thing it does, and I haven't been able to find it online. When I first fire it up, the engine will sound kind of underpowered/ticky and has no power until it warms up. Sometimes I have to shut it off for it to go away. Sometimes when it doesn't want to go away I will just hit the throttle on the lake and it will bog for a second with the tick sound, then suddenly like the flip of a switch the motor sounds great and takes off like a raped ape. I was thinking maybe a stuck valve, but The little info I have found about it, I was thinking maybe something having to do with the choke? I hope someone has dealt with this, Thanks for any input!

 

[MikDee]

It sounds like a faulty plug, or wire. You just have to figure out which one?

 

[Utahgalaxy89]

I have replaced the plugs and the wires, checked the power wire to the starter and motor, and changed the coil.

 

[jbetzelb]

I have an 89 with a 4.3 and it runs rough till it warms up. It doesn't bog. Mine is rough becasue the choke is a little slow to open up. As soon as the engine gets to full temp the choke opens full and it runs perfectly smooth. Not sure on the tick. Maybe some weak lifters. I think the 305 had hydraulic lifters. If they leak down when the engine sits for a while it can take a little bit for them to fill with oil. In this theory the lifter wouldn't be opening the valves properly. This would also cause a tick that would go away once the oil warmed and the lifter pressurized. It would make sense that shutting it off would give it a minute for the oil in the valley to get into the lifters and explain why the tick goes away when you start back up. Without hearing the tick this is strictly a possible theory.

 

[Silvertip]

Once the engine is running (regardless how well) the starter is out of the equation. I have no idea what the tick is unless you describe it in more detail. Is it a single tick, continuous, vary with engine rpm, front of engine, back of engine, high on engine, low on engine, etc. Since you changed plugs, are you certain the correct plugs are used? Just because you replaced them with the same type that you took out does not mean they are the right plug. Oil doesn't get to the lifters via the valley. It drains back to the pan via the valley. Oil gets to the lifters via the oil passages in the engine which are under almost immediate pressure when the engine starts. You have an oil pressure gauge! What does it read with a cold engine at idle, a warm engine at idle, and at full throttle under load. I really doubt this is a valve issue. It sounds more like a choke issue. On a stone cold engine the choke plate should close fully or very near fully. When the engine is started it should gradually open as the engine warms up. If the choke is adjusted to tight, the engine will run extremely rich and act lazy or boggy until the choke opens fully. If the choke is too loose the engine may be hard to start cold and would not idle well during warm up. We really need more detail.