What's a B+ Power Source

[rdc54yty]

I'm installing a GM 3.0L w/Delco Voyager EST ignition system in a boat w/1987 wiring harness that used to be breaker points ignition system. <br /><br />Installation guide says connect coil power wire (purple) and shift interrupt power (also purple after conversion from grounding circuit to +12v circuit) to a non-resistive B+ power source. Could someone explain specifically what's a B+ power source and, for future reference, what does the term B+ mean? I can't find it in the manuals anywhere. <br /><br />Anyway, I connected both coil and shift interrupt to the purple wire coming from the ignition key switch (pin 5 at the plug). I spliced in to the purple wire on switch side of the big plug to avoid resistor wire. Haven't got it started yet because it's blowing the 20 AMP fuse in the red/purple wire at the ignition key switch. Not sure the two are related. Any suggestions?<br /><br />Thanks.

 

[Laddies]

Re: What's a B+ Power Source

A 12 volt positive battery source

 

[tommays]

Re: What's a B+ Power Source

a nother guy here just put in a late model 3.0 in and older boat and he was able to get the boat side of the harness for less than 200 dollars brand new <br /><br />no spliceing or worring about old wires just hook up the key switch and guages and go<br /><br /><br />then you have a whole boat that matches a current wireing diagram and you will be able to service without wondering whats old and new<br /><br /><br />tommays

 

[rdc54yty]

Re: What's a B+ Power Source

Thanks for the B+ info. <br /><br />Sounds like I got a good B+ source wire since pin 5 purple seems to be a switched +12v source. <br /><br />As for the shift interrupt, I rewired the switch to apply +12V to the interrupt input on the new distributor, instead of the grounding circuit the old system used.<br /><br />Now to find the crossed wires...<br /><br />I wondered about a new wiring harness. The current one has been pretty hacked up by previous fixers. Especially under the dash. I think I have to put that on next years "to do" list.

 

[KaGee]

Re: What's a B+ Power Source

"B+" is an electrical/electronic term defining "positive". "B-" means "negative". <br /><br />Blowing your fuse sounds like you have something cross wired. <br /><br />Does your system have a shift interupt module? If it does, most of your electronic mods require a further modification to compensate for that.

 

[rodbolt]

Re: What's a B+ Power Source

keith<br /> there are two methods of shift inturrupt that can be used. one method requires rewirieng the interrupt switch. on the point type motor the interupt shorted the coil primary to ground. on the merc EST system it shunts the module to base timing mode or stalls it. if you have not removed the ground from the point type circuit thats most likly your fuse problem.<br /> your EST kit should have come with a service timing tool. little black connector plug that inserts into the control side of the module with 4 pins. two pins are jumpered and the third is a pigtail.<br />to bypass the resitor wire tie your purple ign feed from the choke purple wire to the EST coil purple wire. you will now have bypassed the resistor wire. tape off the old non used resitor wire. now for the inturrupt. you will take the timing tool. inset it in the siocket on the distributer. run the pigtail to one side of the inturrupt switch. remove any grounds from the switch. run a purple wire from the other side of the switch to the choke purple wire. what will happen now is when the inturrupt switch is activated it will go to base timing. usually 2*btdc or 0*BTDC. if it wont shift from an ingear position to netural you will have to cut the white jumpers at the timing tool and install bullet connector ends on them now when the inturrupt is activated it will cut the ign. with the white wires not cut, to set timing all you have to do is use your fingers and activate the inturrpt switch. if you have to cut the wires you hook them back together(here is where the bullet conneters come in) and then activate the switch. its a simple reliable system.<br /> when your all done setting the service timing, also known as base timing, its imperative to check timing advance. some modules wont advance correctly.

 

[Don S]

Re: What's a B+ Power Source

Just out of curiosity, are you putting this in an OMC or Mercruiser?