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Wiring 1988 5.0

pbrad118

pbrad118

Member
Have a 1988 bayliner trophy with a 5.0 305 chevy that has been rebuilt. i am at the point of wiring it up and i am not getting any fire to the plugs. looking at the wiring diagram their is one part i really don't understand.

coming from the alternator on the wiring diagram are two wires. purple on the bottom and red/purple on the top, then their is a splice and it looks like the red/purple come to the bottom and tie in with the pruple and goes to the + side of the coil. and the purple goes to the top and goes to cable housing connector.

what i really need to know is, do the splice have all three wires coming together as one
i tried to put the wiring diagram up with this post but it would not let me.

thank for any understanding anyone can give me on this matter.
 
Re: Wiring

I assume you have a Mando alternator. The red/purple and purple are both positive feeds. The connection to the alternator is the sense wire which tells the alternator whether to be charging or not. You should also have a big orange or red wire coming off the alternator POS (+) post and connecting to the solenoid battery feed side. In addition the feed to the electric choke (+) should be connected to the alternator ACC post.
 
Re: Wiring

p brad i just wired my chevy 305 a few weeks ago . it was an engine i pulled from another boat and had original wiring harness. that is exactly how mine was too . i had to untie about a half mile of electrical tape to follow the wires to be sure , but , thats how it was so i put it back together the same way.
 
Re: Wiring

One more thing, the red purple and the solid purple, which are both pretty much the same wire, are switched power.
 
Re: Wiring

dimitrimfogal said:
p brad i just wired my chevy 305 a few weeks ago . it was an engine i pulled from another boat and had original wiring harness. that is exactly how mine was too . i had to untie about a half mile of electrical tape to follow the wires to be sure , but , thats how it was so i put it back together the same way.
Click to expand...

so are you saiding that the R/Pu and the two pu wires was splice together after it come off the alternator?
 
Re: Wiring

o2batsea said:
I assume you have a Mando alternator. The red/purple and purple are both positive feeds. The connection to the alternator is the sense wire which tells the alternator whether to be charging or not. You should also have a big orange or red wire coming off the alternator POS (+) post and connecting to the solenoid battery feed side. In addition the feed to the electric choke (+) should be connected to the alternator ACC post.
Click to expand...

the alternator i have has got a red and black wire coming out the back. the black wire is +12 with engine running, and the red is +12 volts always and yes it is a orange wire going to the solenoid.
the alternator is a delco marine 3 wire 105 amp that i got off ebay. It was new and cost only around 80.00

I just dont understand that splice. should all three of them wires be splice together? because i was not getting any fire to my plugs. the way it was. i am useing a HEL electronic distributor and i was told to run a wire from the battery to the distributor and it worked. I got fire. so now i need to fine out how come i have no fire when i have the r/pu wire connected to the distributor. or do i need to buy and new wiring kit.
 
Re: Wiring

ok i just went and looked at mine just to be sure. now keep in mind that this is my first boat , first engine swap , and first time wiring this engine so needless to say i am by no means knowledgeable when it comes to wiring an engine however when i wired it i put it back exactly as it was when removed. the original wiring harness on the 78 305 had the three wired together but where they go to from there on yours may differ from mine. none of them go to dist, i got out my manual and looked and i have a part that is not shown, small electrical part made by prestolite mounted on thermostat housing.the wire from the alt connects to this wich another wire comes out of that to the splice. there is one wire. one comes from voltage regulator . thats two. and both of those connect to the third wire wich on my boat goes to the main plug witch im not sure where that goes from there. the point being none go to the distributor. however the wire that goes to the voltage reg eventualy ends up at the coil. perhaps thats where your problem is.now as i said the wiring diagram in the seloc #3400 is missing some things that are on my boat and i was questioning the same issue but i clearly marked all of the electrical connections on both motors before making the swap and was pretty sure that was how it was supposed to be. i guess i got lucky cause she fired right up.perhaps if you posted a pic one of the experts can better explain for you . if i was not helpful;good luck bud...dimitri,..p.s ill take some pics of mine and post this afternoonbut theyll probably confuse you more cause i swapped a 68 buick300 with 78 chevy 305 and nothing matches on my boat except for the tears in my seats lol
 
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Re: Wiring

http://http://www.selocmarine.com/content/manuals/3404/pdf/340410w151.pdfdimittrimfogal this is my first boat also. I rebuilt the hold engine myself withhelp from youtube and friends. and this site.i have the seloc for my boat also, i just don't understand why all three wires would be splice together as one wire and then going to two diffen wire on the alternator
yes the wire do go to the coil, but now that i am useing a distributor with the coil build on top of the distributor cap, i was thanking that i had to run that wire that was on the coil to the coil on top of distributor that i am using now because it was connected to the + side of the coil.
 
Re: Wiring

well honestly bud i dont know chit about electronic ignition either all i know is that i had the same splice deal on mine and although it didnt make sense to me . i was lucky that it worked for me. so hopefully one of the veterans will post a logical answer to your dilema. pics coming soon
 
Re: Wiring

red/purple wire from splice to coil on OMC is a 2 ohm resistance wire to reduce operating voltage to the coil when running so the coil does not overheat and fail. Never replace it with regular wire, and never shorten it.
During cranking, a purple/black wire off the relay terminal of the starter feeds full 12V to overdrive the coil for a quick start with hotter spark.
The purple wire spliced in further back in the harness where the resistance wire starts usually runs to the ESA module to power it.
 
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