Jlo 400 engine problems

[jpswift1]

Glad to hear the good news, Nate. Those JLO 400 engines are pretty stout. Just take your time and double check all of your connections before you go and open it up. I know sometimes I get too excited and just want to go out and get on it, but I make myself look over everything so a bolt, fuel line, or wire doesn't pop off while I'm flying along and cause a catastrophic failure. Congrats on the project.......its quite an accomplishment, and it certainly does bring a smile to your face when you breathe life back into a vintage machine and get it going again.

[nate52]

well i'm back lol i did get the engine to start up but after i did i realized that i didn't have the 5 wire plug plugged into the engine. the problem i am having now is that when i have this plug plugged into the motor i don't get any spark, unplug and i have spark at both cylinders. i tried a process of eliminating wires one at a time and nothing, it doesn't matter if i have all the wires plugged in or just one of them plugged in i don't get any spark but if i unplug all of them i get spark....i'm so close to getting this thing going and i had to run into another snag, i've racked my brain for what seems like forever and can't figure it out. hopefully one of you genius's on here have some advice for me what do you think Doctor????

Nate

[Don]

You may have a short in the harness or the switch, Nate. The JLO connects the two kill wires together in order to short out the spark, so I'll bet it's in the switch, because even if you take both kill wires to ground on a point-fired JLO you'll usually have fire on one cylinder. 'never really figured out why that is, but I've run into it a lot. I'd pull the plug off the back of the switch and see what happens.
Good luck!

[nate52]

hey don, i've removed all the wires from my switch and test it with the ohm meter and everything seems to be working fine. i then re-connected all the wires except the two kill wires and i still have no spark...? is there anything else it could be?

[Don]

Hmmm. Have you tried disconnecting the harness at both ends and checking for continuity between the two kill wires? The only thing I can think of that would make it act like that is a short circuit somewhere in the harness between the two.

[nate52]

k i'll have to try that tomarrow, it's getting to late here tonight. thanks for the suggestions, i appreciate the help. hopefully they'll help me solve my problem with this engine. much thanks don

Nate

[nate52]

well it was eatin me up, and i can't stop racking my brain to try and figure out what i'm doing wrong and most likely won't be able to get any sleep tonight because of it lol but anyways i was getting tired of going over and over in my mind what the problem could possibly be so i went out to the garage and checked out your suggestions don. the two kill wires between plug-ins ohm just fine and nothing seems to be wrong with them, i also checked the switch again and everything seems to be ohming in the correct order of switch position. today when i was trying to figure out the problem:

1. i first started by disconnecting the two kill wires from the switch, leaving the two wires going to the rectifier and the ground wire hooked up to the engine and had no spark.
2. i disconnected the two wires to the rectifier and the two kill wires, leaving only the ground wire hooked up and still no spark.
3. i disconnected the ground to engine plug and had the rectifier wires and kill wires hooked up and no spark
4. i disconnected the rectifier wires, with ground wire and kill wires still hooked up and no spark
5. i disconnected the rectifier wires, ground wire, kill wires and i had spark

why would i not have spark with any of these wires hooked up to the engine, but when i don't have any of them hooked up i have a great amount of spark?
also why is there a ground in the five wire plug that connects to the motor when the motor is already grounded without this wire? it has a ground cable running from the motor mount to the frame.

Nate

[nate52]

hey guys, i was messing with it again today and finally narrowed it down to the two kill wires. with all the wires hooked up i still have no spark, but if i unhook either one of the two cylinder wires i get spark. i hook them both back up no spark, unhook one of them i get spark....what do i have wrong or am i doing wrong?

[Don]

I'd run jumpers from the two kill terminals on the engine to the two on the ignition switch. See if it works like it's supposed to that way, and if it does, replace the kill wires and you're good to go. There should be nothing else connected to either wire. I hate to diagnose over the net- usually puts somebody else through a whole lot more work than necessary, but that's my best guess. There almost has to be something in the harness; partial short, maybe?

Good luck (again)

[nate52]

hey don, i actually have only one terminal on my switch that these two wires both go too. my machine didn't have a switch when i bought it and the old wiring harness had a 5 prong plug for the old ignition switch. i did some research on the site in which i found a thread listed below describing a switch in which someone used on their attex and hooked it up which i am using now. this switch has a ground terminal, lights terminal, power terminal, starter terminal, and a terminal which the ground is transferred to when the switch is off. it is this terminal that i have both my kill wires running too, could this be a problem?

http://www.6x6world.com/forums/attex...on-switch.html

Nate

also i will check the two kill wires in the wiring harness again.