A how to question on checking compression.

R

RandyBC

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When checking compression what is the best way of grounding the distributor before cranking?
 
S

Silly Seville

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Re: A how to question on checking compression.

Huh?

Just remove the lead wire from coil to distributor, or take the purple power wire of the coil positive side post.
 
Scott Danforth

Scott Danforth

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Re: A how to question on checking compression.

just pull the coil wire
 
M

muc

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Re: A how to question on checking compression.

The best way is to pull the emergency tether cord (kill switch lanyard) if your boat has one.
Next best is to disconnect the power to the coil – usually the purple wire to the + side of the coil.
What ever you do DON”T “just pull the coil wire” you will have sparks jumping all over the coil if you do that.
3rd best is to remove the big wire that goes from the coil to the dist. from the dist only and connect that end to ground.

Edit --- if you use the tether cord, make sure you don't have spark when cranking --- some engines will, most won't.
 
Don S

Don S

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Re: A how to question on checking compression.

Even pulling the kill switch doesn't work if you have an electric fuel pump or a points ignition. You would still have power to the coil through the starter solenoid.
Either remove the ignition wires from the plus side of the coil, or remove the coil wire from the distributor cap and put the end of the wire up against a good clean ground. Even an electrical test lead clipped to the end of the wire and the other end on a good ground will work.

On some EFI ignitions, you can remove the ignition fuse or relay.
 
R

RandyBC

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Re: A how to question on checking compression.

Thanks fellas. The kill switch on my boat seems to have been disconnected by the previous owner. It runs without the lanyard attached and flicking the switch makes no difference.

I think I'll use alligator clips on the coil wire to ground.
 
tpenfield

tpenfield

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Re: A how to question on checking compression.

All I do is pop the distributor lead and stick it onto the nearest bolt . . . :rolleyes:

My 'new' MPI engines won't even crank with the kill switches pulled. . . .
 
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