engine wont crank using start button, unless.....

its been a while since i posted, but im just about finished rebuilding the 83 xj750mk for my dad, but when i press the start button i get nothing, unless i cross a hot wire to the red and white wire on the solenoid.


im pretty sure that ive got all my wires hooked up, the only thing that isnt is the headlight. is there any safety switches i havent thought of to bypass and check, checked the neutral safety, nothing, tried the clutch safety, nothing, even hot wired the start button, nothing and even did the kickstand safety.


any ideas would be appreciated.

 

When all else fails get a continunity light or volt meter and start following backwards until you find power. Something has to be blocking power.

 

Have you checked the connections on the kill switch. In one of the embarrassing times in my life I went crazy changing solenoids and tracing wires on a different bike. After a few hours of pulling my hair out I found that all I had to do was turn the switch back on and the bike started. Not saying that you overlooked that, but you may have a dirty connections in that switch.

 

I'd check the Ignition Fuse.
I always pull the Fuse when I do work to prevent the Engine from being cranked.

Next, comes the Test Light and Meter looking for + 12 V.
But, while you are at it, ... "Tighten-up" the Cylindrical Terminal Ends that Bullet Ends fit into.

Poke around in the "Birds Nest" to see if there is anything dangling you might have not plugged back in.

Check the Main Ground.

 

You can also temporarily unplug the safety relay as a troubleshooting aid. Unplugging it effectively "bypasses" the entire safety system and if it then starts, at least you know where to look.

 

I had the same prob and I took apart the start button and cleaned all the connections, put it back together, and squirted some wd40 into the start button and she cranked great after that.
Tip, do NOT use wd40.. Use That electric sticky stuff. WD is what I had on hand and decided that it was NOT good to use after I remembered it was flammable.
-Chris

 

fitz, just for my records, which one is the safety relay? I know I'll need this in the future :wink:

 

well, i got out my test light, when the ignition is on i get power at both small wires on my solenoid, so i unplugged the connector and had power on the blue/white wire only. but once i push the start button the power goes away, the only time the engine will crank is when i put a hot wire to the red/white wire, should i have power on the red/white wire when i push the start button????

 

All of your power goes away? that seems like it could be a short no? or, it could be the safety system like it has been said before, just cutting power to ground? i dont know much about these bikes, but Electrical, is electrical.

 

Yes, you should have 12V supply on the R/W when the ignition is on. The main reason you wouldn't is if the starter cutout relay is disabling the starter. That's the one that's controlled by the sidestand relay, the neutral switch, and the clutch switch.

 

I have also seen a condition whee the Starter wouldn't turn-over due to the Armature being too contaminated with "Carbon Dust" from the Starter Brushes being worn down.

Rare as it does occur, we should be mindful that it would be a cause. In that case, though, the Starter Button works ... but, ... not every time. And sometimes there is a delay from when the Button is pushed until the Starter Turns.

 

Interesting, but this wouldn't explain why he's not seeing 12V on the R/W wire to the solenoid.

 

I know.
I just want him to be aware of all the Gremlins.
There's also the possibility that the Safety Relay IS NOT a Safety Relay.

They look like identical twins.
But, the Safety Relay is wired differently and if a Generic Relay is used to replace the Safety Relay ... the bike acts like its Haunted!

 

I removed my safety relay and hard wired the R/W wires.Bypassing all of the safety gremlins. Havent had a problem with my bike starting since.

 

i got the bike started by swapping the safety relay with a reguilar relay, but the neutrasl light doesnt come on, and the thing will sart in gear, so i need a new safety relay, but i can get it to ride if neccesary until the part is found.

 

the little black relay under the fuel tank is the safety relay, or is it the one under the side cover, i have seem them listed both ways. its getting very confusing.

 

I ran into this exact problem Friday night putting my 82 Seca back together. When I took off the fuel tank I knocked the safety relay loose. It hangs from the frame just above the carbs.

Plugged it back tight it worked great.

 

Having a Regular Relay in place of the Safety Relay causes some Safety Features to be REVERSED.

++>>> WARNING <<<++

With Ignition Switch ON ... Kill Switch "RUN" ... Bike IN Gear ... Clutch Lever Pulled ... Start Button Pushed ... --> Starter Motor will NOT Operate.

BUT ... ⬅ ⬅ ⬅ And, thats a BIG BUTT !!!

With Ignition Switch ON ... Kill Switch "RUN" ... Bike IN Gear ... Clutch Lever
➤➤➤ RELEASED ⬅ ⬅ ⬅ Start Button PUSHED ... ➤➤➤ STARTER WILL ENGAGE ➤➤➤ CAUSE THE BIKE TO LURCH FORWARD ➤➤ OR START !!!

 

I have got the exact same problems.

Start switch is clean, continuity is good.
Safety Relay clicks when ignition is turned on.
Starter Solenoid Works when bridged.
Battery Voltage is good (12.6v)
Fuse is good.
Engine Kill Switch is good, the safety relay clicks in and out when operated).


All I can think, is that the clutch switch (which has broken off the handle) has got something to do with it. The green nuetral light comes on when ignition is on, and the bike is definately not in gear.

I have disconnected the safety relay, and still nothing.

I do have a wiring diagram, and I note that the start switch has a blue and white wire to the safty relay, and also shows a black wire from the start switch to earth. My switch has only one wire from it, so I was wondering if the earth is through the handlebars?

I really am totally confused with this problem now.......

 

Ive just thought.....

I fitted a new set of black bars. Ive loosened them slightly, wobbled them about a bit, in case the switches are earthed this way, tightened them back up......

Hey Presto, my start switch works again........