Intermittently won't start. 1988 V6 225 Looper

Greg_E

Chief Petty Officer
Joined
Feb 17, 2009
Messages
416
One of my engines has been giving me trouble starting. Typically I had the problem when I tried to start the engine after it had been sitting all week and I would want to use it for the weekend.
If I could get it started, would run perfectly and start every time after it was warmed up. I have done some of the checks, found a few things that I thought were the cause of the problem. The frustrating part is when I would put it all back together (still a cold engine) I would hit the key and it would fire up immediately even if it is loaded up with fuel from trying to start it. The next weekend, the same problem would reappear.
Blk/Yel wire is not shorted.
Key switch is good,
I have voltage to the powerpack.
I checked the spark with a Mercotronic spark tester, and to me, the spark looks weak. I've never had much faith in that tool , because I used it in the past, and it would indicate intermittent spark, but when everything was put back together it would run fine.
I did the Ohm test for the charge coils , and with a Fluke meter it reads 835 Ohms pin to pin on both plugs. That is not in spec, but I am not using the recommended meter and apparently the readings can differ depending on the test equipment being used.
Ohms test on the timer base trigger wires appear to be OK.
Tried my spare power pack. No change.
Checked all the connectors for broken pins and anything I felt was suspect has been repaired.
I'm thinking that weak spark might allow the engine to start when everything happens to be just right, and not start if it's not. It seems to flood easily, when it's cold, and once that happens it's all over. If I am able to get it running, it continues to start, I assume because the plugs are warm.
How can I fully test the stator ouput using a standard Fluke meter? The manual references specialized test equipment, and I don't know if the readings I'm seeing are good or bad. Am I on the right track?
I'm 80 miles from the boat, and only have the weekend to work on it, so I need to maximize my efforts. Any help is greatly appreciated.
 

clanton

Rear Admiral
Joined
Jul 9, 2001
Messages
4,876
Re: Intermittently won't start. 1988 V6 225 Looper

Set the meter on the lowest scale that is high enough for the correct spec., then check the ohms. If you are off a 100 0r more, its bad. Your meter should work with DVA adapter to get you the peak voltage readings.
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,392
Re: Intermittently won't start. 1988 V6 225 Looper

You say one of your motors. Do you have 2 matched motors on your outfit ?? If so how does the spark look on the other one ?? or one of your other motors if not a matched pair ?? Like you said it could be the tester. Have you tried another spark tester ??
How are the other basic health items on the motor ??
Compression, fuel and plug condition ??
 

Greg_E

Chief Petty Officer
Joined
Feb 17, 2009
Messages
416
Re: Intermittently won't start. 1988 V6 225 Looper

Set the meter on the lowest scale that is high enough for the correct spec., then check the ohms. If you are off a 100 0r more, its bad. Your meter should work with DVA adapter to get you the peak voltage readings.

The spec is 970 Ohms +/- 100 Ohms when using one of the recommended meter. (Stevens or Mercotronic). I don't have that manual home with me, so I forget which one. Some of the Ohms tests will give different results depending on which meter is used, according to the manual, so I was unsure what I should be seeing when using a Fluke meter. 835 Ohms would be 35 Ohms less than the low side of the spec.

I have a peak reading Fluke meter that I didn't have with me last weekend. Can I use that or do I need the DVA adapter. Where can I get the DVA adapter if I need it?

Yes I have a pair of 225's, but I hesitate to start tearing into that one to compare readings. I just got that one running properly. after having numerous problems with it. (Unrelated to the problem with this engine)
Plugs and plug wires are new. I'll test the compression next time I'm at the boat.
 
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