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Misfire after rope in prop

K

kevinj

Advanced Contributor
I have a Mercruiser 5.0L with an Alpha One drive in my 2000 Crownline.

On our last trip out as we got a skier set up I took off from a dead stop and the engine died. I was able to restart but it took a few more starter cranks than normal. I tried to put it in forward gear and it died again then I realized the tow rope was wrapped tight around the prop. UGGGHHH:( I got towed back ro the dock where I removed the prop and got the rope out. I restarted on the dock but again it seemed to crank a lot longer than usual to start.

This week I got around to winterizing the boat. It started okay, again a little hesitation, but now I could occasionally here a backfire in the carb as I increased throttle. In neutral I tried to rev it up and it bogged and died with a backfire in the carb. If I smoothly move the throttle forward it will rev up. There seems to be a slight miss at idle and also at higher RPM.

Everything was running absolutely perfect prior to the rope wrapping so I'm certain this is all tied to the stuck prop killing the engine.

My first thought is that possibly the shear pin on the distributor drive gear broke and now my timing is off. That's the first thing I'm going to look into to solve the issue. If it's not the distributor, what other things could cause this?

Thanks,
Kevin
 
On our last trip out as we got a skier set up I took off from a dead stop and the engine died. I was able to restart but it took a few more starter cranks than normal

The "more cranks than normal" could have been caused by water rushing up the exaust and puckering a valve
A compression test should be the next thing to do
 
It started okay, again a little hesitation, but now I could occasionally here a backfire in the carb as I increased throttle. In neutral I tried to rev it up and it bogged and died with a backfire in the carb. If I smoothly move the throttle forward it will rev up. There seems to be a slight miss at idle and also at higher RPM.
Click to expand...

Ayuh,.... I agree with BD, but For the skippin'/ hard startin'/ backfirin' through the carb,....

I start by checkin' the Contents of the fuel filter for anything but clean fresh gasoline,....
 
Bt Doctur said:
On our last trip out as we got a skier set up I took off from a dead stop and the engine died. I was able to restart but it took a few more starter cranks than normal

The "more cranks than normal" could have been caused by water rushing up the exaust and puckering a valve
A compression test should be the next thing to do
Click to expand...
I really didn't even start to move. I was idling to take up slack in the rope and when I hit the throttle it died. I'll definitely do a compression test to cover my bases.
 
Sounds like a coincidence. You'll have to go through the list of things that are causing this: Timing, carb issues, fuel pressure, etc.

Jeff
 
fastjeff said:
Sounds like a coincidence. You'll have to go through the list of things that are causing this: Timing, carb issues, fuel pressure, etc.

Jeff
Click to expand...

It could be coincidence, but it just seems too strange that the engine ran perfect all season and then it just happens to run poorly after stalling it. However, over the winter I do plan to check timing, compression, etc to track down the problem.

KJ
 
fastjeff said:
Coincidences DO happen--and frustrate the heck out of people!

Jeff
Click to expand...
Oh I know and yes they are incredibly frustrating. I've had plenty of other non-boat related 'coincidences' going on lately and I'd prefer to have some smooth sailing instead.

I downloaded the instructions for setting static timing in a Thunderbolt V ignition. I'll throw my timing light on it and see if the timing is off in addition to testing compression. I really feel like the problem is timing related because it seems the advance isn't working properly. If you give it rapid throttle it there is no RPM response and then backfires in the carb as it tries to pick up. However, if you ease into the throttle the RPM will climb with no backfire and the engine sounds okay.

The main thing I'm trying to do up front is determine the most likely issues to track down first. My free time is extremely limited to I want to go after the prime culprits first in my process of elimination. If none of those are the issue then I'll dig in to other possibilities as I get time.

KJ
 
Good attitude! Please report back with your findings.

Jeff
PS: Hate to admit it, but we get smarter by learning through other's fixes.
 
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