Bench testing 140 No Start

[SSTKO81]

I just finished freshening up my '81 merc. 140. reworked head, valves, rebuilt carb, new oil pump. I stabbed the distributor back in and set time to TDC. I've got spark when starting because I shocked the hell out of myself trying to test it.... But the engine seems to only want to fire while I'm cranking on the starter. As soon as I let go of my jumper it quits right then and there. I'm getting a lot of sputtering and a few back fires.
I guess my question is: is there a series of wiring jumps or bypasses I need to make in order to bench test this. I've checked all the wiring diagrams in the seloc manual and everything looks to be correct so at this point I don't know what else to do to make it start. I put my (+) battery cable on the starter, (-) on the block run a (+) jumper to the yellow/red terminal "s" on the slave solenoid, which then makes a click noise, then remote start from that "s" terminal to the Yellow Terminal on the slave solenoid. Crank crank crank, sputter sputter sputter. no dice.
any thoughts?

 

[SSTKO81]

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[alldodge]

I just finished freshening up my '81 merc. 140. reworked head, valves, rebuilt carb, new oil pump. I stabbed the distributor back in and set time to TDC. I've got spark when starting because I shocked the hell out of myself trying to test it.... But the engine seems to only want to fire while I'm cranking on the starter. As soon as I let go of my jumper it quits right then and there. I'm getting a lot of sputtering and a few back fires.
I guess my question is: is there a series of wiring jumps or bypasses I need to make in order to bench test this. I've checked all the wiring diagrams in the seloc manual and everything looks to be correct so at this point I don't know what else to do to make it start. I put my (+) battery cable on the starter, (-) on the block run a (+) jumper to the yellow/red terminal "s" on the slave solenoid, which then makes a click noise, then remote start from that "s" terminal to the Yellow Terminal on the slave solenoid. Crank crank crank, sputter sputter sputter. no dice.
any thoughts?

Your missing your resistance wire coming from the carb connection. There should be a connection which goes from the battery, through the ignition key to the purple wire. The purple wire supplies 12V to the coil constantly through a resistance wire or ballast resistor. The Pur/Yel comes from the starter to the coil which is bypassing the resistor during cranking. Once the engine starts power is removed from the Pur/Yel wire and power continues through the resistance/ballast connection to the coil.


The above wiring is a simplistic diagram only

 

[SSTKO81]

No Title

pics of how its wired.


so I need to run a second hot jumper to my purple wire and it should start?

 

[alldodge]

pics of how its wired.


so I need to run a second hot jumper to my purple wire and it should start?

Not fully seeing how you have it wired I'll provide this. Appears your using the Merc wiring harness which came with the engine. If this is the case, there should be a purple wire connected to the choke. If the wire is there it should be purple, and if this is the case there will be another purple wire which should be connected to the + side of the coil. If the wire is not there, run a wire from the electric choke to the + side of the coil. If none of the previous is there, run a jumper from the battery or cable on the starter to the + side of the coil through a ballast resistor.

If you don't use a resistor with the coil, and you do have points, your coil will get hot a burn up. You can run it for 10 minutes or so, but not long

 

[SSTKO81]

well theres no purple wire going to my choke, as it is a heat-riser style, but i did find the terminal in the merc. harness that runs to the resistance wire. I'll run 12v to there and see what happens. I peeled back all the tape on my wiring harness and found a purple wire that was cut off and cappped running to my alternator. i did my homework and it looks like it was upgraded to a single wire alt. at somepoint and that "exciter" wire is no longer needed(?) even tho it runns right back to the resistance wire ...

 

[Bt Doctur]

" I stabbed the distributor back in and set time to TDC"
Did you mean to say you set the engine on #1 TDC compression and then installed the dist with the rotor pointing to #1 cyl.????????????

 

[Bt Doctur]

 

[SSTKO81]

Did as suggested and ran 12v to my resistor wire and it starts and runs, but it sure is rough. Really have to feather the gas to keep it going. Was back firing a lot but adjusted the points and that really seemed to help. I just can't keep it running long enough now to set time....

 

[SSTKO81]

And I found a Nasty front crank seal leak. FML

 

[SSTKO81]

Just an update to this post! Did get engine to stay running long enough to set time. Turns out my wires were on the distributor in the right firing order, but the wrong terminal.... (dummy) also it has an aftermarket coil that requires 12v rather than the lower voltage required by a factory coil... so that may have played a roll as well. I do still have the oil leak at the front - looks like its from around the crank. Anyone know what the part number for this seal is?