1973 Mercury 650 - General ?'s

avpaulb

Petty Officer 1st Class
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Jun 19, 2011
Messages
298
I found this motor for a very fair price. It is a LONG way from me, so I had one mech question before I take a drive:

The owner says it runs and starts fine at idle, but when you throttle someone has to hold onto the bulb (?) for it to run correctly, otherwise it stalls out.

Any thoughts? Anything else I should look for?
 
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Maxz695

Guest
Re: 1973 Mercury 650 - General ?'s

probably the fuel pump needs a rebuild
 

avpaulb

Petty Officer 1st Class
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Jun 19, 2011
Messages
298
Re: 1973 Mercury 650 - General ?'s

Anything major with that? I'm no mech... but I can figure pretty much anything out. (And I have mech friends)...
 
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Maxz695

Guest
Re: 1973 Mercury 650 - General ?'s

A cave man can do it with the right parts and a little bit of enthusiasm if thats indeed the problem. I strongly suggest you have the compression checked on all cylinders before you take the drive
 

avpaulb

Petty Officer 1st Class
Joined
Jun 19, 2011
Messages
298
Re: 1973 Mercury 650 - General ?'s

A cave man can do it with the right parts and a little bit of enthusiasm if thats indeed the problem. I strongly suggest you have the compression checked on all cylinders before you take the drive

Safe to assume any standard automotive compression tool will work? And I assume there must be a generally accepted method for doing so?
 

ajgraz

Lieutenant Commander
Joined
Mar 1, 2010
Messages
1,858
Re: 1973 Mercury 650 - General ?'s

Standard automotive compression tool is fine. Disconnect fuel line, all plugs out, ground out plug wires, hold throttles all the way open, hook up tester to plug hole, crank it 5 or 6 revolutions or until psi stops climbing on gauge. Make sure LU is on muffs or in a bucket of water to preserve impeller.

EDIT: your motor probably has surface gap plugs, you'll want to find a tester that has a short or "snub" threaded length so it can seal fully but not bang on the piston tops.
 
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