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Old 04-30-2013, 12:15 AM
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Need Help Troubleshooting No Spark 95 Prostar 205

Boat - 1995 Prostar 205 with the 5.7L, normally this engine is TBI, but the previous owner replaced it with a carb after the system failed (in 2005). No related issues since I purchased it in 2006.

Issue - After de-winterization, boat will not start. I have narrowed it down to no spark. I tested at the plugs and as well as the ignition coil. I used a spark plug tool to check it. Since it was a cheap replacement, I replaced the ignition coil with a new one from the auto parts store, but that still didn't provide any spark. I suppose there is a chance I could have received a bad one, is there any way to verify that?

Safety switch - I believe it checks good. If I fully release the button my perfect pass turns off and my fuel gauge goes to zero. If I replace the lanyard, everything turns on as it should.

Ignition CB on dash - It's not popped.

Battery - One year old and was recently fully charged.

The spark plugs, wires, distributor cap and rotor were replaced at the beginning of last summer. They look great with no corrosion.

Where do I go from here? I have a 12V test light and a multimeter, but I don't know exactly what I am looking for or how to use them in this situation. Is there anywhere else I should be looking?

Thanks for the help!
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  #2  
Old 04-30-2013, 12:22 AM
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Simple question, does it turn over but just not start to run?
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Old 04-30-2013, 07:16 AM
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power to coil?
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Old 04-30-2013, 10:47 AM
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Quote:
Originally Posted by Tristarboarder View Post
Simple question, does it turn over but just not start to run?
Yes, it turns over, but won't start.
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Old 04-30-2013, 10:48 AM
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What is the exact process for determining if I have power? Playing with a multimeter is my weak point. If there is no power, where do we go from there?
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Old 04-30-2013, 11:52 AM
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This is what my ignition coil looks like.

Update - If I remove the four wires going into the coil and I use a 12V light test, I have power going to the purple wire with the key in the run position. Should I have any in the grey wire, (edit, looks like that is for the tach)? The other two wires are red and brown and run to the distributor.

Second update -

With a multimeter, the battery reads 12.25V. In Run, the purple wire reads ~11V, the red and brown both read ~11V. In Start, the red and brown both drop to ~7V. Is this normal?

I am headed to work now, hopefully by the time I get back someone smarter than me will have responded

Last edited by puck_11; 04-30-2013 at 12:59 PM.
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Old 04-30-2013, 04:48 PM
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Two questions first:
Did you actually test for spark by removing a plug? Reconnect the plug wire, ground the plug on the block, and then crank the engine checking for spark directly at the spark plug gap? I'm not sure what you mean by testing with a spark plug tool?

When the TBI was removed, did they use the original distributor or was it was replaced?


Edit:
My TBI is a 95 but they should be the same. If you still have the original distributor the red and the purple wire are connected together inside of the coil. The red wire is the 12V feed to the coil from the MEFI system relay. First, you need to check your battery voltage while the engine is cranking to make sure it isn't dropping to 7V. My 95 had an intermittent "crank and no start" problem that was caused by a bad/dirty ignition switch. When the key was turned to RUN position, I had 12V out on the IGNITION terminal. When the key was turned to the START position, I had 12V out on the START terminal which would get the starter cranking, but I only had 7 or 8V out on the IGNITION terminal. With only 8V I had no spark and no fuel pump.
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Last edited by ahhudgins; 04-30-2013 at 05:15 PM.
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Old 04-30-2013, 06:06 PM
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Quote:
Originally Posted by ahhudgins View Post
Two questions first:
Did you actually test for spark by removing a plug? Reconnect the plug wire, ground the plug on the block, and then crank the engine checking for spark directly at the spark plug gap? I'm not sure what you mean by testing with a spark plug tool?

I tested it by removing the spark plug wire and putting in a spark plug tester tool (as well as doing it with a spare spark plug), grounding it to the block, and looking for a spark. I also checked it coming off of the ignition coil. I did not check all of the spark plugs.

Quote:
Originally Posted by ahhudgins View Post
When the TBI was removed, did they use the original distributor or was it was replaced?

I don't know what was originally on there, but I assume they used the same one. When I replaced the cap and rotor I used the standard GM 5.7L from skidim.


Quote:
Originally Posted by ahhudgins View Post
My TBI is a 95 but they should be the same. If you still have the original distributor the red and the purple wire are connected together inside of the coil. The red wire is the 12V feed to the coil from the MEFI system relay. First, you need to check your battery voltage while the engine is cranking to make sure it isn't dropping to 7V. My 95 had an intermittent "crank and no start" problem that was caused by a bad/dirty ignition switch. When the key was turned to RUN position, I had 12V out on the IGNITION terminal. When the key was turned to the START position, I had 12V out on the START terminal which would get the starter cranking, but I only had 7 or 8V out on the IGNITION terminal. With only 8V I had no spark and no fuel pump.
I will check for that when I get home.
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Old 04-30-2013, 07:43 PM
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Update - I have 12.5V at the battery, once I crank it drops to 11.5V, adding a portable jump kit, it still shows 12.5V with a drop to 11.5V. So I assume the battery is good.

I also measured the purple wire going into the coil, it also drops to ~7V once its cranked. I assume this is why I am not getting a spark, with 7V not being enough voltage to properly work.

So now I need to figure out what is causing such a voltage drop. I measured at the ignition switch as well, again ~12V drops to 7V once cranked. Could this be the culprit, a bad ignition switch? This is another cheap, easy solution, I'll try to hit the store tonight before they close.
Anything else a likely culprit?
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  #10  
Old 05-02-2013, 06:37 PM
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Never believe every thing you read in a book. I looked at my coil and there is no RED wire from the MEFI relay. It is a PURPLE wire from the MEFI relay. Disconnect the GRAY connector from the coil. Connect your (+) meter lead to the PURPLE pin on the connector and connect your (-) lead to ground. With you ignition key in both the run and start (cranking) positions, you should have battery voltage on the PURPLE pin. I checked mine and mine was dropping to 9.8V but so was my battery which is getting old. If your voltage is dropping to 7V but you still have 12V at the battery, you need to follow the PURPLE wire and find the problem. My 95 is 100% TBI so my wire comes from the MEFI relay. I don't know if you still have the relay or if your wire goes back to the IGN terminal on the key. I would check the voltage at the ignition key. That is where my problem was.

The gray wire is to the tach. On the black connector, the pink wire is battery voltage to the distributor (gets voltage from the purple wire when connected). The brown wire is the trigger pulse from the distributor to the coil.
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