4.3 mercruiser hard starting

[pjnadon]

just a little background boat is 97 model engine 4.3 genx ser# 0k0k191245 I bought the boat with a cracked block so i put a reman long block used the same 2 bbl mercarb and distributor i am assuming its a thunderbolt v. after putting he new motor in the boat was some what hard to start now it takes forever to start or not start at all put a timing light on the coil main wire and try to start it i get some spark and flash from the light then it stops no start
i did the trouble shoot table test and this was the results
battery voltage 11.91
key on 9.4 volts at the + term on the coil
key on 8.6 volts at wht red wire from the module
checked for spark at the coil by striking the wht green wire on a ground and there is spark from the coil
when i put a jumper wire from the battery to the + term on the coil motor starts right away pull the wire and it runs good shut it off try to restart and no go till i put the jumper wire in
question is what do i need to replace to fix this

 

[achris]

Voltage on the + terminal needs to be the same as battery voltage. If it's not, start looking for bad or corroded connections.

Chris

 

[Scott Danforth]

start from the battery and clean every cable connection to the motor and back. by clean, I mean shiny and clean enough your kids can eat off it. then follow the cable to the large circuit breaker and head towards the helm cleaning every connection all the way to the ignition switch.

you have at least one really bad connection.

 

[pjnadon]

i have basicly gone thru every connection i can find cleaned i get 12 volts at the ignition switch going in and coming out on the purple wire at the plug on the engine harness i have still have 11 volts but on the purple wire at the coil and the choke volt drop to 9.
when i look at the wiring diagrams that single purple wire powers a lot of things from dash gauges , coil,ignition module on distributor,choke all the way to the alternator my thinking is that this wire because of the amount of things it has been powering it has been getting weak and losing its conductivity
i think i am going to try and run a separate wire along with the purple wire form the ignition to the coil.

 

[Bondo]

my thinking is that this wire because of the amount of things it has been powering it has been getting weak and losing its conductivity

Ayuh,..... Wires don't work like that,.....

The ends, 'n connections corrode,....
If the casin' is nicked, then corrosion can happen, but wires don't just loose conductivity,.....