120 Mercruiser 2.5L - No spark

[Mercruiser 120]

Alldodge. Is there a way to test the black wire from negative on the coil to the distributor and screws on the side of the breaker points

 

[alldodge]

Check continuity, remove wire from coil and attach meter probe. Connect other probe to the points, If points are open the meter should read infinity after a few seconds, if closed will read zero ohms

 

[Mercruiser 120]

Check continuity, remove wire from coil and attach meter probe. Connect other probe to the points, If points are open the meter should read infinity after a few seconds, if closed will read zero ohms

Thank you for everything, the tach wire off of the negative on the coil. Starts right up. Sounds great with the new carb rebuild

 

[alldodge]

Ok Tach is shorted out or wire is grounding somewhere. Good to know she's running

 

[Mercruiser 120]

alldodge. Do I set the timing like I always do, 8 degrees BTDC? Or do I have to set base timing? How do I do that

 

[Mercruiser 120]

alldodge. Do I set the timing like I always do, 8 degrees BTDC? Or do I have to set base timing? How do I do that

What is a base timing shunt?

 

[alldodge]

alldodge. Do I set the timing like I always do, 8 degrees BTDC? Or do I have to set base timing? How do I do that

What is a base timing shunt?

There is no base timing mode or shut for your distributor. Just point a shoot to set timing

 

[Mercruiser 120]

There is no base timing mode or shut for your distributor. Just point a shoot to set timing

Alldodge sorry another question
I installed clear gas line from my fuel pump to carb to see what is going on.
It looks like there is air bubbles(big) once every foot at idle at the dock. Idles rough but stays running and better at higher rpm.
Is this a clamp loose?

 

[alldodge]

The bubble shouldn't be the issue with running. Only if there were a lot of bubbles it would effect running.

I couple small bubbles every once in a while I wouldn't think much of. More then that, might be the pump diaphragm, hose fitting or hose clamp

 

[Mercruiser 120]

The bubble shouldn't be the issue with running. Only if there were a lot of bubbles it would effect running.

I couple small bubbles every once in a while I wouldn't think much of. More then that, might be the pump diaphragm, hose fitting or hose clamp

Thank you

 

[Mercruiser 120]

Thank you

Alldodge.
1970 Rochester 2 jet 2cg. The idle mixture screw and the idle adjustment screw. Is screwing in clockwise, leaning it(more air less fuel) or richening it(more fuel less air)

 

[alldodge]

Yes on mixer screws. Going CW on the idle adjustment screw just opens the throttle more

 

[Mercruiser 120]

Yes on mixer screws. Going CW on the idle adjustment screw just opens the throttle more

Alldodge.
I have the 120 going good. After the rebuilt carburetor and the shorting tach wire, it starts up. Just pump and start. Goes faster then it ever has.
I went out set the timing. I bring it back, then into neutral. It will idle(not perfect) then if I leave it, it will slowly get worse, eventually stall out.
Is it my idle mix and idle speed screws need adjustment

 

[alldodge]

Check fuel pump pressure
Need to get a gauge to read 4-7 psi and place between pump and carb. Its either running out of gas due to a bad/weak pump or drawing a vacuum due to antisiphon valve, would be my guess

 

[Mercruiser 120]

Check fuel pump pressure
Need to get a gauge to read 4-7 psi and place between pump and carb. Its either running out of gas due to a bad/weak pump or drawing a vacuum due to antisiphon valve, would be my guess

It was sucking air. I have clear, real gas line from pump to carb. I put a new straw into the tank and sealed the anti-siphon threads. Not a bubble in the line. I bought a vacuum gauge to set the idle screws. When I put the vacuum gauge hose on the manifold spit I can’t get the engine to stay idling well enough(hardly at all) to adjust the idle mixture screws.
I will put the pressure gauge between pump and carb to make sure I’m at least 4 psi.

 

[Mercruiser 120]

It was sucking air. I have clear, real gas line from pump to carb. I put a new straw into the tank and sealed the anti-siphon threads. Not a bubble in the line. I bought a vacuum gauge to set the idle screws. When I put the vacuum gauge hose on the manifold spit I can’t get the engine to stay idling well enough(hardly at all) to adjust the idle mixture screws.
I will put the pressure gauge between pump and carb to make sure I’m at least 4 psi.

Also, if it runs mint once I get it into gear up to WOT, does that mean I have the right pressure coming out of my fuel pump

 

[alldodge]

Also, if it runs mint once I get it into gear up to WOT, does that mean I have the right pressure coming out of my fuel pump

In most cases yes, so long as its not running lean
A motor will run great when running lean. The lean condition will damage the motor. It probably is not running lean but you can do a simple check. Run motor at WOT or close to WOT for a few minutes. Slow down and don't idle much at all and shut motor OFF. Pull a few plugs and see if they are white. White is lean and cream or brown is good

Having new plugs will require running them for a few hours at regular speeds to get them to start showing actual burn mix

 

[Mercruiser 120]

In most cases yes, so long as its not running lean
A motor will run great when running lean. The lean condition will damage the motor. It probably is not running lean but you can do a simple check. Run motor at WOT or close to WOT for a few minutes. Slow down and don't idle much at all and shut motor OFF. Pull a few plugs and see if they are white. White is lean and cream or brown is good

Having new plugs will require running them for a few hours at regular speeds to get them to start showing actual burn mix

Thank you so much. I think I have it perfect. Idling, then going fast, been 3/4 throttle for 20 minutes. I bring the gear shift back and the motor conks out. What am I doing wrong

 

[alldodge]

Does it start right back up easy?

 

[Mercruiser 120]

Does it start right back up easy?

Yep starts up right away and I can giver again