Best way to diagnose vacuum leak??? Reeds?

[cmb1998]

I got my 98 rebuilt 2.5 out today for the first time. I believe I have a vacuum leak somewhere. The idle is erratic (although not very bad) and surges. I also get a puff of smoke out of the carbs when I shut it down and a sound like air escaping from the crank case that lasts 3 - 4 seconds (sounds almost like a mooooooooooooooo cow sound).

I have a new set of Chris Carson reeds in the motor, idle timing is set at 20 (per manual) and it will run just fine, it just surges.

What is the best way to diagnose? Do I need to pull and check the reeds?

[wired247]

Idle timing set at 20? Degrees?

[cmb1998]

Sorry, typo. Crank timing set at 22

[Carter Powell]

If you have an idea where it might be coming from spray a small shot of starting fluid in that area. If you have an air leak it will cause it to rev up just a bit and then settle down again.

Carter Powell

[Dave Strong]

Cranking max Timing? ??

Dave

[cmb1998]

Cranking max Timing? ??

Dave

Cranking max timing is set at 20. Grounded the plugs wires and with plugs out and timing line on #1, turned the starter and set to 22. Set max advance (push timing arm forward and do same procedure) and set to 20. Timing at idle is 20 (boat running at 1200-1400 RPMS)

Any ideas? I am stumped. I spend all afternoon trying to find a vacuum leak, and can't find one anywhere. Checked all the hoses.

Not sure where to go from here?

Boat will idel and run in gear, but at idle it will jump up a few hundred RPMs every few seconds and i can feel the boat surge then running around 2500 RPMs

And advice on next steps?

[Dave Strong]

Way to much idle timing, probably burnt some reeds. Idle timing should be somewhere around 0 - 5 ATDC.

Dave

[Dave Strong]

Can't wrap my head around what you got going on. The trigger can't be moving to have max and idle timing the same. Is the trigger harness hard and allowing the trigger to move freely?

Dave

[flabum1017]

Can't wrap my head around what you got going on. The trigger can't be moving to have max and idle timing the same. Is the trigger harness hard and allowing the trigger to move freely?

Dave

Are you sure you got your numbers right? As stated above, idle timing should be 0 to 5 degrees after top dead center....... ( the timing basically sets the idle speed with the carbs closed )

[cmb1998]

Way to much idle timing, probably burnt some reeds. Idle timing should be somewhere around 0 - 5 ATDC.

Dave

My manual shows what I have it set to? Is this wrong?

[cmb1998]

If I set the timing at cranking speed to 20, and max timing to 22, how do I set the timing at Idle? It must be off, but the other two are right on spec?

[Dave Strong]

There it is right on paper cranking max timing 20deg idle-pickup timing 1-2deg ATDC.

Dave

[cmb1998]

Yep, your right. How do I adjust? With the plugs out the the cranking and max advance timing are perfect.

[Dave Strong]

Set your cranking max timing to the spec at wide open throtle, then set the pickup timing cranking with the throtle arm at idle position.
You have a Mercury manual if start at the begining with verifying that the timing pointer is right, then read carfully and follow the FULL procedure step by step you should be good. Do Not skip a single step, reed twice then check each adustment after made to conferm you are right.


Dave.

[cmb1998]

Thank you very much.

I am sure this is a dumb question, but what is the difference between "Max Timing: Cranking Speed" and "Idle Speed / Pickup Timing"?

I set the cranking speed timing at 22 thinking that was what was needed while cranking, and hence the idle is at the same 22 now.

Thank you again, learning a lot.

Chris