Need help with coil wiring and slave solenoid - diode to starter wire/coil +?

[CamaroMan]

So I replaced my original strter with a PMGR unit, and ran the batt cable straight to the starter bypassing the slave solenoid - since these are prone to failing im not too phased.

Also - the PO had 2 wires connected to the coil +, one is tach and another is prob the power. I have the positive running thru a resistor to the coil (coil states use with external resistor)

Now i did a quick test, when the motor is running, i get about 6v coming from the coil +, I was wondering how to wire up the low power 12v wire that switches the started solenoid on to the coil + (by passing the resistor) during cranking - my only worry is the 6v might cause the starter to perhaps kick in while the motor is running, so im wondering if I can install a 3A 400v diode to avoid any current flowing back to the starter signal wire?

Then im also not sure what else was wired to the slave solenoid, can I just leave it out? The thick red wire that charges the system I have connected to the battery as well - it looks like it was connected to the original slave solenoid on the thick red batt + starter wire..

Im just worried the 6v volt reading form the coil might be just enough to engage starter solenoid? Not a chance I wanna take!

here is a pic clearly showing the idea I have in mind:

http://www.bracketracer.com/howto/ig...ringPoints.jpg

 

[alldodge]

First, what are you working on

The slave solenoid is used to reduce the amount of current need to engage the starter thru the key switch. It can be done without it but no manufacture builds one without using a slave solenoid, hence the reason to continue to use one.

There will be no connection between S and R terminals on the starter, unless power is applied to the S terminal

 

[Bt Doctur]

What are you working on?
The battery cable from the battery does go directly to the starters main post.
You starters solenoid gas 2 small lugs/posts. The inner most one goes to the slave relay . the outermost one goes to the coil IF you are using a points type ignition. Not normally used with electronic ignitions. Save yourself some wiring work, get a coil thats internally resisted to eliminate the resistance wire or ballast resistor
No you cant leave the slave out, ign key start wire to slave, slave powers the starters solenoid

 

[Bt Doctur]

http://ww2.justanswer.com/uploads/JA/jacksparrow1956/2013-04-17_001248_scan0008.jpg

 

[wrench 3]

They use the slave solenoid in the starter system because there can be quite a large voltage drop in the length of wire from the helm. The solenoid on the starter requires a large amount of currant to initially pull in and it is higher when the solenoid is hot. As a result, without the slave solenoid the starter may work when the engine is cold but refuse to engage after a hard run.

 

[achris]

First, what are you working on

The slave solenoid is used to reduce the amount of current need to engage the starter thru the key switch. It can be done without it but no manufacture builds one without using a slave solenoid, hence the reason to continue to use one.

There will be no connection between S and R terminals on the starter, unless power is applied to the S terminal

The 'R' is also sometimes labeled 'I' (ignition)...

Chris.......

 

[CamaroMan]

ok great thanks guys - awesome answers. I am working on a 1974 searay with a 233 ford 351w. Bought it last month and had to replace USCG approved elec components, incl a pmgr starter.

I was under the impression ford used the external solenoid for heat issues which i installed on me chevy with headers. Was wondering if the slave was a second solenoid. I understand the use of the slave then. I will reconnect it then, either way my starter is engaging very well. I have cleaned and soldered every wire and used permatex die electric grease between all connections incl new very heavy duty battery cables.

I will wire the 2nd small pin to the coil (if i have it). I hav seen starters with no 2nd coil pin which is why i asked about popping in a diode

Ill have a look later today and hopefully see the 2nd pin. Yes its points - prestolite original I found brand new on ebay. Works perfectly, dwell at 29 degrees / base at 10 and so far as I cana hear from my wife all in at 28 degrees @ 3000 rpms. Im happy being back 3-4 degrees on a boat anyway.

 

[CamaroMan]

so as it turns out I dont seem to have a 2nd (to coil +) terminal on my starter - only the switch from ignition and heavy battery cable. So I guess ill be adding in a diode 12v+ to the coil for cranking. Will look up for stock wiring on the mercruiser -

 

[alldodge]

You could take it off the slave solenoid

 

[Bt Doctur]

You could get a marine starter, you could change the solenoid for a marine solenoid and you could check to see if you still have a resistor wire in the coil circuit. Cant have a resistor wire and a resistor going to the coil

 

[wrench 3]

I'm with Bt Doctur on the resistor wire. You should have closer to10V at the coil when the engine is running.

 

[CamaroMan]

hi all - i replaced the slave solenoid and rewired everything except the heavy duty batt cable - starts instantly now. Im facing some other issues - i read one wants about 3-3.5 ohms resistance total on a v8 points ignition.

I measured my coil at 1.6, so bought a ballast resistor of 1.4 and 1.6 - I have the 1.6 running now, i think i measured 8volts idling on coil + .. maybe i should try the 1.4 resistor to get 9-10v?

When the motor has run about 45 mins.. it will suddenly stall - and restart instantly 90% of the time.. for some reason the engine temps play a role - heat soke into condensor?

I changed points yesterday before putting boat back on trailer so havent tested it. Now new coil/condensor/dizzy/points. Fuel supply is fine - tested with elec backup pump and same thing..

At least the slave solenoid has the ignition terminal for a 12v boost during starting. However, after shes warmed up she starts harder than when cold..

 

[alldodge]

Could be an issue but since it restarts instantly I wouldn't think so.

Are you using a coil with an internal resistor?

 

[achris]

Could be an issue but since it restarts instantly I wouldn't think so.

Are you using a coil with an internal resistor?

If the coil measured 1.6Ω, I'd say no internal resistor.

When the motor has run about 45 mins.. it will suddenly stall - and restart instantly 90% of the time.. for some reason the engine temps play a role - heat soak into condensor?

When the engine dies, does the tacho just drop dead, straight down to 0, or does it track the engine revs as the engine is dying?

Chris.......

 

[alldodge]

If the coil measured 1.6Ω, I'd say no internal resistor.

Also depends on how accurate his meter is

 

[CamaroMan]

sorry for the confusion - I hooked up my dwell meter incorrectly.. base timing was 16!! PLUS i forgot to readjust timing after changing dwell! reset it all and base at 8 degrees - motor purrs now and starts at the turn of the key.. heck it idles at 400rpm lol (i dont run it there of course but it does). I bought a complete suntune test kit and performed most of the tests - everything passed. Ill buy a new set of points to keep on the boat just in case -

fyi im quite shocked at the consumption of this thing. We filled up and left for catalina last week, spent the night and cruised around half the day fishing, we also went an extra 20 miles return to the backside for a peek.. then headed back to 2 isthmus cove for a swim - then back to San Pedro -

I thought we ran out of fuel and that maybe the new fuel was stuck at half, after pulling the gauge - the tank was half full, exactly as the gauge showed - thats pretty insane.. i still cant believe it. 1974 old V8 chugging a 4000lbs cabin boat around for about 4 hours including mucking around looking for fish, plus the stalling for about 30 mins and we used maybe 20-30 gallons.

Anyway thanks for the comments - I also verified the rpm with the test kit - same as gauge.

The points are showing 9v while running which is perfect - 12v+ at cranking. my garmin striker shows 14.4v at cruise which is also great - im going to install a diode between alternator red to my backup batt and a second diode after that splice to main batt/system so the main batt cant leak over to 2nd batt - that way both get charged when running and there is no crossover unless i flip the isolator switch -