Volvo aq125 stalling at full speed

[nwbayliner1122]

I have a 1985 20' Bayliner with an aq 125 Volvo Penta. The last three times out on the water, my engine has stalled after 15 minutes of running at 3800 RPMs. I always warm it up to temp at the dock (otherwise it won't rev up without stalling) for about 10 minutes. So in total this is happening 20-25 minutes after being started. When it stalls it just completely cuts out without sputtering or misfiring, just goes silent. Afterwards it can't be started for 15 or 20 minutes. I'm guessing this is not a fuel or carburetor problem, so that leaves the ignition/electrical side. Any help would be greatly appreciated on this, thanks.

 

[alldodge]

I have a 1985 20' Bayliner with an aq 125 Volvo Penta. The last three times out on the water, my engine has stalled after 15 minutes of running at 3800 RPMs. I always warm it up to temp at the dock (otherwise it won't rev up without stalling) for about 10 minutes. So in total this is happening 20-25 minutes after being started. When it stalls it just completely cuts out without sputtering or misfiring, just goes silent. Afterwards it can't be started for 15 or 20 minutes. I'm guessing this is not a fuel or carburetor problem, so that leaves the ignition/electrical side. Any help would be greatly appreciated on this, thanks.

:welcome: to iboats

When it does start back up after 15 or 20 minutes does it fire right up or does it sputter back to life?
When it does it check for voltage at the coil. Check to see if your getting spark at the coil wire to the engine block and what the color is.

 

[nwbayliner1122]

It does start right back up like normal, no sputtering when it hits. I'm not sure if I know how to check the voltage at the coil, where does one check this?

 

[alldodge]

It does start right back up like normal, no sputtering when it hits. I'm not sure if I know how to check the voltage at the coil, where does one check this?

Need a volt meter and put the positive probe on the + side of the coil and the negative probe on a clean metal surface of the engine, or negative side of the battery. Check this with the key turned ON. Also touch the coil and see if it is hot, might be over heating

 

[nwbayliner1122]

I will try to measure the voltage, what is the proper voltage? If it is overheating what would you suggest I do, replace the coil?

 

[alldodge]

I will try to measure the voltage, what is the proper voltage? If it is overheating what would you suggest I do, replace the coil?

The voltage should be between 7 and 9 VDC. If the coil is hot then it may be shorting out but let us know what you find and be can do a test. Do you understand how to remove the coil wire and see what kind of spark you get?

 

[dennis461]

Watch the tachometer, if it coasts down with the motor, it is not the points or voltage.
If it drops to zero, then the motor coasts down , it's electrical

 

[nwbayliner1122]

I have not removed a coil wire before so I'm not sure exactly what to be looking for. Also, is there any chance that this could be related to the alternator or voltage regulator? I have noticed that the regulator doesn't kick on until after the engine has been revved up over 3,000 RPM, is this normal? I'm not sure when I am going to have a chance to run these tests, but I am considering just replacing the coil and maybe converting to electronic ignition anyways, advice?

 

[alldodge]

I have not removed a coil wire before so I'm not sure exactly what to be looking for.

The coil wire comes from the coil and goes into the top of the distributer. To do the test you will need someone to help. Pull the coil wire out of the distributer and hold it close to the engine block. Do not touch or get yourself close to the end of the wire. When ready have someone crank over the engine and then look for a spark coming from the end of the coil wire to ground.

Also, is there any chance that this could be related to the alternator or voltage regulator?

No

I have noticed that the regulator doesn't kick on until after the engine has been revved up over 3,000 RPM, is this normal?

Yes this is normal, the alternator in most cases needs some more rpm to start charging. If it was in netural you could give it some more rpm and once it starts charging you can slow it down.

I'm not sure when I am going to have a chance to run these tests, but I am considering just replacing the coil and maybe converting to electronic ignition anyways, advice?

You need to find out what the issue is, sure you could start throwing parts at the problem and sooner or later you might solve it, but it is a bad method. So far as electronic ignition or points they both use a coil. A points setup uses a resistor inline feeding power to the coil, and the electronic coil does not. If you have points you need a coil which requires an external resistor.

If you do the test and there is no spark then it can either be the condenser in the distributer or the coil most likely, just need to find out what the issue is in order to fix

 

[jerryjerry05]

Being that it takes a few minutes to stall??
It could be a coil or a few delivery problem.
The coil how hot does it get? Too hot to touch?
If you can keep your hand on it it's probably not failing.
Replace the condenser. Sometimes they can get hot and fail.
Check the screw that grounds the condenser.
The fuel, the vent line on the tank, it could have wasp nests built up in there.
Allowing for a bit of air to pass but not enough to run.
Try running with the fill cap loose and see if that helps.
The fuel with Ethanol can delaminate the inside of the hoses and cause them to melt and collapse.
Check them for being soft, mushy.