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Follow up to my V6 voltage testing

Sleepwalker

Contributing Member
1986 Crusader V-6 (4.3L) Points & Coil Ignition with ballast resistor.

Hi. So I have a no start situation and I thought I would provide an update on what I’ve found so far, hoping it will help find the problem. Testing is from suggestions here and a couple other sources. Thanks for bearing with me.
· Battery is charged, now approx. 12.4 V
· Carb is getting gas, verified.
· Engine turns over with key in ignition and turned to start
· Weak appearing spark from Coil high tension wire to ground but light in color
· Have replaced coil, points, condenser & rotor
· Plug and Coil wires are almost new and good quality made in the USA, silicone, etc.
· Verified bright test light with points wedged open, key switch on, test lamp to –coil and ground to battery
· Voltage between + coil and battery ground reads 12.4 V with switch on.
· Voltage between – coil and battery ground reads 12.4 V with switch on and points open.
· Voltage between – coil and battery ground reads 12.4 V with switch on, points open, and 2 wires (gray & black) removed from coil terminal. Is this too high? And if so, what does it mean?
· Voltage between – coil and battery ground with points closed, reads 0.2 V with 2 wires (gray & black) reattached and switch on. (Also got 12.4 V with wires disconnected and same connection)
· Disconnected start by-pass wire from ignition coil side of the ballast resistor. Voltage shows 9.7V when starter is engaged and 0 when disengaged. (volt meter grounded to battery ground) Is this a problem?
· Starter engages and cranks engine when solenoid jumped and ignition switch off
· Voltage checked to solenoid relay. The Yel/Red (goes to small terminal in front of relay) from the ignition switch via the neutral safety switch, reads 8.9V when ign switch is turned to start. The two bigger terminals on the relay were hard to tell wire color because they were painted and a pia to reach but one side was hot, 12.4V with the key switch off, did not engage starter on that one! Should I have tested that way too? The other terminal read 10.0 V when the starter was engaged. Do these seem right?

Thanks, Rich
 
Battery seems a bit low for 'fully charged' - may want to load test it.

Voltage between – coil and battery ground reads 12.4 V with switch on, points open, and 2 wires (gray & black) removed from coil terminal. Is this too high? And if so, what does it mean? - it means there is no current flowing thru the coil and its normal.

It seems to me you have a significant voltage drop(s) thru your system...it could be due to a marginal battery &/or one or more bad connections.

the last item suggests its time for a new slave solenoid (or you can use a relay) with over a 2 VDC drop (assuming that is accurate; ie the 12.4VDC on the terminal is present while cranking as well)...

if you have another battery, you could jumper it in exclusively for the ignition system and see what happens with it....
 
Thanks Mark. The battery is a bit suspect as it is getting older. One thing I was wondering. Will load test it. I have cleaned up all the connections that I tested. I do have a slave solenoid on order and will check that cranking voltage on it. I did not do that. If that should drop, what does it mean?
 
If the battery voltage drops under 10 VDC when you crank it, the battery is marginal at best....and its not surprising that you are having ignition concerns.

That's why I prefer doing voltage drop measurements...you can usually find the issue(s) in short order....assuming you have a serviceable battery...
 
Thanks Mark, just got back from NAPA with a new one. Old one was a DieHard and tested good/marginal but it was a 2013, so I knew it was time. I'll recrank and see. Fingers crossed.
 
Hi Mark, new battery did not seem to affect things too much. Testing the large studs on the solenoid relay; on the hot side (12.7 V with key off, ground to battery) when cranking on start reading 10.9 V, up almost 1 V. The other side shows 0.0v key off and 10.8 V when cranking which is also up almost 1 volt. For the hell of it I tried starting it maybe going thru 7 or 8 cycles but nothing. I'm open to suggestions. I guess I'll put the new relay on when it comes and retest.
 
you are losing almost 2 VDC when the starter engages....it should be ~ 10% of that, at max...and you don't need the new relay (though changing it won't hurt. does either end of the cable connecting the battery to the starter get hot when cranking??

You can see if this drop is the root cause of your no start by temporarily jumping another battery to supply the current for the ignition...if you want to...
 
I see, thanks. Did not check the cable to see. Cables are original and probably due, so will do that. Could a bad starter solenoid drop the voltage like that?
 
A bad starter solenoid could do that but that's NOT what I concluding from your posts...I do the math an only get 0.1 VDC drop acrosss the starter's solenoid so I'd suspect something between the battery and the starter; ie the cable...and if you have a switch in that cable, it could be that or the other cable...

you can tell if the cable is the issue by making a voltage drop measurement across the suspect item - cable in this case.
 
HI Mark. I did my voltage drop measurement. At first I thought I was doing something wrong with the real low reading. Any how both cables came in at .4 to.5 volts. I read where .5 is marginal. I plan to order new cables. The negative one is fairly long so I can't get that locally. There is a main on/off switch for the battery, like a Blue Seas. I'm going to have to get into that when I get the new Pos cables, so I can see what that looks like.
 
You want the total voltage drop in the starter circuit under 1.0 VDC....no more than 0.2 VDC drop for any conductor. If you are getting new cables, make sure they are large enough...often, even on new boats, they cut corners on the heavy gauge cables. Not to endorse them, but the prominent'big box marine store' typically has assorted battery cables in bulk and will crimp on decent connectors while you wait...they aren't cheap but you get what you pay for...you want fine strand, tinned strands making up the cable...
 
Thanks. Yes I ordered proper USA made cable, shrinkwrap ends, etc from an outfit in Georgia that I've had good luck with before. I will give a report but don't expect to see them till later next week. I think I'll go ahead and install that relay solenoid anyways and keep the old one on hand. Take care and thanks again.
 
You want the total voltage drop in the starter circuit under 1.0 VDC....no more than 0.2 VDC drop for any conductor. If you are getting new cables, make sure they are large enough...often, even on new boats, they cut corners on the heavy gauge cables. Not to endorse them, but the prominent'big box marine store' typically has assorted battery cables in bulk and will crimp on decent connectors while you wait...they aren't cheap but you get what you pay for...you want fine strand, tinned strands making up the cable...
Hi Mark. Good news. Today we had lift off. Guessing it was the new cables but the other stuff couldn't hurt either. Thanks for all your help. --Rich
 
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