Mercruiser 228 stops running

[ScubaAl]

[FONT=Verdana, Arial, Helvetica][FONT=Verdana, Arial, Helvetica]Update time, after switching out all the electrical components. Today I swapped carbs between motors. After letting the starboard run for around 1hr at 1400rpms I pull the throttle back to idle. Idle was low so the motor died. Now the test, will the beast start. Nope, popped a few times but would not fire up and run. While cranking the motor over I had a timing light on the coil wire. It would only flash now and again, but not consistently. At times it would try to start/run but would die, at these times the timing light did light up. But soon as the motor stop so did the flashing of the timing light. After trying to get the motor to refire up for several minutes I went to do other things for 10 min or so. Upon returning I tried starting the motor again but nothing. Al[/FONT][/FONT]

 

[alldodge]

The distributors are Mallory, I replaced the points with electronic conversion, so distributors are still the original with the conversion.

Been a little side tracked lately. Just re-read the thread a couple times and this comment stands out. You have a Mallory distributor with points and changed to a after market conversion kit. The after market conversion kits are plentiful and are made from the Petronix model "type".

First I don't care for the Petronix or after market Sierra and the like conversions. Main reason is so many of them fail without warring. OK off my soap box.

Suggest swapping the modules from the distributors.

 

[ScubaAl]

Thanks for replying, switched the module between distributors last fall. Didn't help, for no reason except I've switch out or replaced just about everything involving the distributor. I'm now wondering if the distributor might be the problem.

Al

Been a little side tracked lately. Just re-read the thread a couple times and this comment stands out. You have a Mallory distributor with points and changed to a after market conversion kit. The after market conversion kits are plentiful and are made from the Petronix model "type".

First I don't care for the Petronix or after market Sierra and the like conversions. Main reason is so many of them fail without warring. OK off my soap box.

Suggest swapping the modules from the distributors.

 

[alldodge]

Ya need 3 things for a motor to run, air, fuel and spark. Need to find out which ones are not providing their part.


Make sure to remove the tach wire

 

[ScubaAl]

I asked the marina to take a look. Not really expecting much but taking a shoot anyway. Will be a couple of weeks before I get back to the boat.
What does removing the tach do? Also what color should it be?

Thanks, Al

 

[alldodge]

The tach wire connects to the negative side of the coil. If the tach shorts out the coil will never fire. The tach wire is gray

 

[ScubaAl]

Well time for an update. Back in June I asked the marina to look into my problem. Took them until Aug. According to them, they found 2 bad plugs and plug wires. Replaced plugs and wires and said it seemed to now be running fine.
I wasn't able to get up to the boat until yesterday (9/4) I was going to take the boat out for a shake down. But a little voice told me to run it at the dock first. Good thing, same problem as before.
Started and ran for almost 30min but towards the end of the 30min started to act up and finally stalled. Pumping the throttle I could get it to fire, but would die. I did this several times. Then let the boat sit for 30-40min and started again. At first ran fine, but in less then 10min started acting up again and died. Again pumping the throttle I could get it to fire, but died. I did this several times again with the same result.
Now I'm thinking it might be the fuel pump. The motor has the original mechanical pump.

Al

 

[alldodge]

Well don't see how two plugs or plug wires would keep a motor from running, they didn't know what the problem was nor spent the time to find it.

All your post go back to electrical and now your saying that pumping the throttle would get it to fire? You did say if I remember correctly, both motors are feed by the same filter. Hope that is the issue, put a pressure gauge in line with it

 

[ScubaAl]

I'm not a mechanic, just a boat owner trying to get my boat running. So many things lead me to think electrical, so everything was switched with the other motor or just replaced. With the problem still there a person starts thing what else could be the issue.
Early on I replaced all filters, this did not resolve the problem and awhile back switched the carbs between motors. This also did not resolve my problem. Both motors are feed from the same fuel line.
I called the marina today and spoke with the mechanic that worked on the boat. He told me after replacing plugs and wires they let it run for along time with no issue. But was heading right down to the boat and fire it up once again to see if he can replicate the problem.
Don't know, but when I had it running I had it running at around 1000-1200rpm. Maybe the mechanic just had it idling? I'm just wondering if there are internal parts in the fuel pump that could fail under higher rpms equaling more heat.
Again I'm not a mechanic, so end up throwing things out there that might or not be the problem. To say the least, I'm really at my wits end.

Al

 

[alldodge]

While cranking the motor over I had a timing light on the coil wire. It would only flash now and again, but not consistently. At times it would try to start/run but would die, at these times the timing light did light up. But soon as the motor stop so did the flashing of the timing light.

Did some more re-reading and notice this a bit more. You moved the module in the distributor but not the distributor. There are bushings inside the distributor to keep the shaft centered. If there is play in the shaft and heat will cause things to expand. I would suggest swapping distributors and see if it moves. Also check for play in the distributor cam gear

 

[ScubaAl]

Finally got back to the boat for more frustration. Same issue, after running for 30min or so at 1400rpm's the motor stopped. But before it died I had ran a wire from the + side of the battery. When the motor started to stumble I attached this lead to the + side of the coil. When I did this it smoothed out and seemed to run fine. Disconnect this lead and again the motor would start to die. Reattach and again motor smoothed out.
Like in the past when the motor died and I tried cranking over there was no spark from the coil. All the time I'm working on/running the motor I had the timing light on the coil wire.
After the motor died I checked the voltage for pin 5 on the boat side of the harness and it showed 14V or alittle more.
Once the motor had cooled down and I restarted it. This time it only ran for a few minutes before dying. While it was runniing I had my multi-meter on the + and - of the coil. It was reading in the 12.6v area. Once the motor start to stumble again this voltage started to drop until the motor died once again.
With all this in mind, I'm wondering about the resistor wire. Its inside the harness, so don't know how much work it would be to replace.

TIA Al

 

[alldodge]

Have twin motors and everything from one motor was switched with the other and the problem did not change from the original motor. Applying straight 12V to the coil keeps the motor running. The distributor conversion uses a coil with out a resistor wire. Even if the other motor has a resistor wire there appears to be something with it.

Note: when measuring voltage on a coil, positive lead should be on the positive terminal of the coil, the negative lead of the meter should be on engine ground. Attaching it to the negative terminal of the coil is incorrect. The negative coil lead gets turned ON then OFF from the ignition module which causes the coil to fire

 

[ScubaAl]

Note: when measuring voltage on a coil, positive lead should be on the positive terminal of the coil, the negative lead of the meter should be on engine ground.
Yup, that's what I did. Thanks