Author Topic: Diagnosing the 3.7L Ignition Issue.  (Read 33310 times)

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Offline WrenchWench

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #20 on: April 25, 2016, 12:08:40 PM »
Points will usually corrode over the winter to the point where you may not have spark. Unfortunately I belong to the been there, done that club! A little sandpaper in between the points will usually do the trick. Or, throw in a new set for good measure, they're usually cheap. Just make sure the gap is set correctly.

And it's never a bad idea to throw in a new cap and rotor.

Glad you got it figured out!

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Jen ~ 1989 Sierra 160

Offline WrenchWench

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #21 on: April 25, 2016, 12:10:46 PM »
Cool that you got spark! Not you just gotta get that thing to crank faster.  ;)

Yeah...it would appear that the starter is toast.  I was planning to just get this one rebuilt...unless you think the ebay high torque one's would be better?   Would require some wiring changing I think to that additional solenoid...

http://www.ebay.com/itm/NEW-STARTER-Model-270-3-7L-325-390-470-488-MERCRUISER-STERN-DRIVE-1969-1989-/130923916316?hash=item1e7bac6c1c:g:1OwAAOSw9r1WCWlc&vxp=mtr
Is it starter? Or is your battery just low?

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Jen ~ 1989 Sierra 160

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #22 on: April 25, 2016, 12:46:25 PM »
Cool that you got spark! Not you just gotta get that thing to crank faster.  ;)

Yeah...it would appear that the starter is toast.  I was planning to just get this one rebuilt...unless you think the ebay high torque one's would be better?   Would require some wiring changing I think to that additional solenoid...

http://www.ebay.com/itm/NEW-STARTER-Model-270-3-7L-325-390-470-488-MERCRUISER-STERN-DRIVE-1969-1989-/130923916316?hash=item1e7bac6c1c:g:1OwAAOSw9r1WCWlc&vxp=mtr
Is it starter? Or is your battery just low?

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It's the starter...needs to be rebuilt.

Sent using Tapatalk  ~Doran

1990 Sierra 1700

Offline Rosscoe

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #23 on: April 26, 2016, 08:54:43 PM »
If you have a rebuilder near you, I'd go that route and skip the rewiring.
Ross
61 Surflite 1964 90HP Johnson project
67 V163 Bayflite Super Sport  1989 100HP Merc
67 V164 Bayflite 120HP
67 V174 Crestflite Rat Rod
71 V175 Crestflite 350ci -Jet
73 GT 160
84 CVX 17  83 115 Merc
88 CVX-23 350 Mag

Offline Glastronjohn18

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #24 on: April 26, 2016, 09:42:12 PM »
I'd go with the rebuild route. For at least one reason, if you need warranty work you're dealing with a local firm.  At  $119 there is no doubt these are Chinese built, and you get what you pay for. Murphy's law states "any starter failure will always happen the farthest from the dock".
John
'80 CVX 18 - Survivor Class
'78 CVX 18
'76 V 225 -   Bal Harbor
'80 V195XL
'86 CVX 18- And '86 Makes 3

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #25 on: April 26, 2016, 10:52:37 PM »
Yep, there's a good local shop, so it'll be going there.  Been super busy and haven't even touched the motor since my last update.
1990 Sierra 1700

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #26 on: April 30, 2016, 12:20:57 PM »
Well, with a little starter fluid I'm getting it to spit fire out of the exhaust...but seems to be only firing on 1 cylinder.  Going to check all 4 cyl's for spark this weekend.  Not really a lot to do with it until I address the starter.

I have some other priorities right now, so haven't even touched the boat and it's still in MN
1990 Sierra 1700

Offline Plugcheck

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #27 on: April 30, 2016, 02:32:40 PM »
Cap and rotor match up? Coil putting out four sparks per dizzy turn(2x crank)? I just clamp a single plug to the coil output, take off the cap, leave the rotor.  Watch as you crank.  Perform a static timing test with a test light, and check what cylinder the rotor is pointing to.  I thought you were bringing that engine over some day?
Michael
1979 CVZ-18 388 CI Vortec Mouse
1980 CVX-16SS 140 Mercruiser
1979 CVX-16 Johnson 175
2002 Bennington 2275CC 90 Mercury
1985 Intimidator project
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2001 Godfrey Sweetwater pontoon 115 Rude

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #28 on: April 30, 2016, 04:05:53 PM »
I thought you were bringing that engine over some day?

Oh...I am. 

I have spark on all 4 plugs...just kept moving the spark tester from cyl to cyl watching for spark.  I know that cylinder 1 is firing on the 1st position of the dizzy cap.  (The rest of what you said ... um...sure?)   I don't own a timing gun, so can't do anything there.
1990 Sierra 1700

Offline Rich_V174SS

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #29 on: April 30, 2016, 04:47:42 PM »
Firing order on the cap is 1-3-4-2 I believe. That's from the #1 plug wire on the cap going clockwise.
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #30 on: April 30, 2016, 05:25:59 PM »
Yep,  that's all checked and double checked.   The problem is that I'm chasing whatever the PO did to try to get it to fire... so timing could be off,  etc,  etc

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1990 Sierra 1700

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #31 on: July 28, 2016, 02:52:54 PM »
New starter arrived today...hoping to get that mounted & wired up tonight.  Then we'll see how it turns over now and see if I can get it to fire up.
1990 Sierra 1700

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #32 on: July 30, 2016, 11:12:27 AM »
Ok a bit confused on the starter wiring.

My old starter had a block mounted solenoid, most diagrams show a slave solenoid on the block, then a solenoid on the starter itself.  The new starter has a solenoid on it of course.

So, how am I wiring this up?  Is the block mounted one, now my slave solenoid and I'm running new wires to the starter solenoid?

The new starter solenoid has an 'R' which I believe is unused.

« Last Edit: July 30, 2016, 11:15:16 AM by dorelse »
1990 Sierra 1700

Offline Rich_V174SS

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #33 on: July 30, 2016, 12:53:23 PM »
Correct. Take the output from the slave block-mounted solenoid and attach it to the small right-side terminal of the solenoid on the new starter. You may have to change the thickness of the wire or at least crimp a smaller eye onto it.
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline Rich_V174SS

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #34 on: July 30, 2016, 01:44:57 PM »
The main red battery cable goes directly to the new starter, top large terminal just like any other starter.
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #35 on: July 30, 2016, 03:18:00 PM »
Yeah, sounds like what I ended up with is wrong.  I have the slave solenoid daisy chaining power to the starter solenoid. 

I think what you're saying is that I don't need to run battery power through the slave solenoid at all...so long as the yellow/red wire is powering both solenoids to open when I turn the key to start.

Will do.

1990 Sierra 1700

Offline dorelse

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #36 on: July 30, 2016, 03:24:06 PM »
I must have done something right!  She fires up!

I discovered a couple things...the distributor had the plug wires 1/4 turn off, new plugs, new starter.  With a little starting fluid seems to fire up.  I just need gas now.

http://youtu.be/JQwBhBxXqfs
« Last Edit: July 30, 2016, 03:27:34 PM by dorelse »
1990 Sierra 1700

Offline Rich_V174SS

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #37 on: July 30, 2016, 09:51:31 PM »
You've got some of the wiring to the slave solenoid right. I'll have to see how mine is wired but you need battery power to run through the slave for ignition bypass and to kick the solenoid on the starter. The slave is grounded to the engine through its mounting bracket. The yellow/red wire (start) from the harness is correct to the slave and so is the purple/yellow (ignition bypass) so leave those alone. Disconnect the yellow wire you've added from the slave and reconnect it to the right-side large terminal of the slave by itself. The left-side large terminal of the slave should have the larger red/purple power feed from the harness attached to it by itself.

Now, at the starter - Main battery cable, thinner red wire from harness, and orange wire from harness go to the main lug. The small terminal on the right is to have your new yellow wire going to it from the large right-side terminal of the slave.
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline Rich_V174SS

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #38 on: July 30, 2016, 10:11:46 PM »
Here's a better scan of the 3.7 wiring diagram:
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline Rich_V174SS

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Re: Diagnosing the 3.7L Ignition Issue.
« Reply #39 on: July 30, 2016, 10:33:41 PM »
I just looked at your pics again and it looks like the yellow/red wire that is taped up is supposed to be going from the slave to the starter, in place of the new yellow wire you added.
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115