95 SN OB GT-40 - no spark
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=33681
Printed Date: May-06-2024 at 7:43pm
Topic: 95 SN OB GT-40 - no spark
Posted By: sherrema
Subject: 95 SN OB GT-40 - no spark
Date Posted: May-25-2014 at 9:28pm
First time poster here - I hope I didn't miss a post that had my situation - I couldn't find it!
I have no spark.
I have the GT-40 service manual and I'm confused between two solutions:
1. Test 3F1-9: measuring between purple/black and ground gives me 5.1V, not exactly battery voltage! So I say no and go on.
2. 3F1-14: take 60-pin connector off ECA. Testing 12.3V between 37/57 and 20/40/60. So, yes. It says repair defective purple/black wire circuit between ECA and coil.
3. OK, but for fun I go back and do 3F1-9. I get 12.3V with the ECA disconnected. If I say yes to 3F1-9 it sends me to 3F1-10. My coil resistance is within spec on both circuits so I go on.
4. 3F1-11: I put my ohmmeter between the gray wire and ground. It's supposed to read infinity but I'm getting +/- 4700 ohms. So now it says repair grounded tachometer lead!
So, do I chase number 2 above or number 4 above? That wiring harness, with all the nice braided tubing, looks like a nightmare!!!
Any advice?
Thanks in advance.
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Replies:
Posted By: lewy2001
Date Posted: May-25-2014 at 11:03pm
Those flow type diagnosis steps can sometimes point you down the wrong path.
I would back track a bit and start from your low voltage of 5.1V at the coil 3F1-9.
It should be 12V or battery voltage go to the circuit diagram 6-10 The 12V is switched from the EEC relay. Check the voltage there at relay terminal 87 and 30 you may need to make up some jumper wires as it is a enclosed water proof connector. This is with the ECM 60 pin connector plugged in as normal.
While you are there check the voltage at 12.5 amp ECC breaker just above the relays they are normally covered with red liquid insulation so make sure you are getting good contact. You may also still have the large fuse in the fusebox item 14 in the diagram check this connection as it is a known problem area for bad connection and it is the power source for the EEC circuit. There is a modification to remove this if it is the problem.
Get back to us when you have checked these steps out. I did not like the sound of how you had 12V when you unplugged the ECM but lets just get the 12V power source circuit checked first. This is basically the same as steps 3F1-4 to 3F1-6 in the manual.
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If you're going through hell, keep going
http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski
<a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta
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Posted By: sherrema
Date Posted: May-26-2014 at 2:12am
lewy2001,
Excellent tips! Here's the run down:
1. The 12.5 amp ECC breaker checks out AOK.
2. The big 50 amp inline fuse checks out fine too.
3. Terminal 30 has the right battery voltage.
4. Terminal 87 has the 5.1V on it!
5. Swapped the two relays around and then I have 12.7V on both sides.
So, I guess the relay is bad and it's somehow allowing partial voltage/current through?
Are these relays available at a Ford dealer or local auto parts store? Also, would you change them both while you're at it?
Again, thanks in advance!
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Posted By: lewy2001
Date Posted: May-26-2014 at 10:50am
Good work on isolating the problem as you found the fuel pump relay and the EEC relay are the same. The relay will have high resistance across the contacts this causes the voltage drop you measured.
The other GT40 http://www.correctcraftfan.com/forum/forum_posts.asp?TID=33651&PID=433762&title=fuel-pumps#433762" rel="nofollow - Fuel Pumps thread going at the moment was just discussing the GT40 relays. As stated it is worth carrying a spare in the boat. They seem to have a decent failure rate.
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If you're going through hell, keep going
http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski
<a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta
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Posted By: Gary S
Date Posted: May-26-2014 at 11:57am
Just ordered mine Mark! I think these same relays are used on the hatch lift also
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95 Nautique Super Sport
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Posted By: sherrema
Date Posted: May-27-2014 at 12:45am
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Ordered 3 from Napa Online today. The local stores had only one in stock and I didn't want to drive to three stores! Will update when installed and test. Thanks
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Posted By: sherrema
Date Posted: June-06-2014 at 7:51pm
Got the three NAPA relays in the other day. Installed two. Put one in the glove box. Started right up!!!
Thanks for all the help!
Scott
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Posted By: Bri892001
Date Posted: June-06-2014 at 10:32pm
Glad that fixed it. So, it was the EEC Relay then?
I try to keep a running tally of these on the:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25584&PN=1&title=poor-mans-gt40-diagnosis" rel="nofollow - Poor Man's gt40 diagnosis thread.
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Posted By: sherrema
Date Posted: June-10-2014 at 10:13pm
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