Tune up problem

[kirkll]

1990 4.3 mercruiser alpha 1 gen 1 , Bluewater Executive Cuddy

Ive been troubleshooting fuel flow issues and have that resolved thanks to another thread here by testing the fuel pump power line to the oil pressure switch while running. I had a loose connection at that switch that was shutting down my fuel pump intermittently….. but….

I’ve still got a edge of roughness to how it’s running, and she doesn’t want to idle very long before dying out. When I set the throttle at about 1000 -1200 rpms it runs smoother, but the rpms will flexuate a bit coming up to 1600 on its own, then back down again, but eventually it starts running rough and dies out.

So I’m thinking I should pop the distributor cap and check out the ignition system ….. Huston we have a problem…. The last time it was tuned up by a shop they put the same old screws holding the cap on, and they are seized up tight. Trying to break a couple of them loose, the slotted heads are wanting to strip out and they won’t budge. So rather than stripping them out, I put some PB blaster on the screws and am letting it set for a day before trying again.

Question: is there an old mechanics trick anyone would like to share getting the screw broke loose other than penetrating oil, and patience? That back screw has me worried because it’s under the transom shelf and I can barely get a std size screw driver in there….

Any suggestions besides busting off the cap and using vise grips would be appreciated. This could get ugly breaking screws off in the distributor. That engine would need to be pulled getting the distributor out.

Thanks, Kirk

 

[Scott Danforth]

Pull the dizzy and work on it on the bench

1990 should have mechanical fuel pump, not electric

 

[kirkll]

The motor on this boat was replaced with a truck motor by the previous owner, so I’m not absolutely certain whether it’s a 1990 motor. But it most certainly has an electric fuel pump. I’ve had a lot of work done in a shop bringing this motor up to marine standards including changing out the starter, putting brass soft plugs in the block, adding a water fuel separator and marine grade fuel pump. But unfortunately the distributor cap screws were not changed out to stainless steel, and now I need to remove the cap without pulling the engine.

I’ve already explained that pulling the distributor itself would not be easily done due to the way the motor is tucked in under the fiberglass bench seat across the transom. Here is a photo.

Any helpful suggestions would be appreciated…. Kirk

 

[nola mike]

if you can't get them out, drill them out and replace with a machine screw/nut