Im not getting fire to my 84 vf700...check the test i did does it tell you anything?

I have a 1984 VF700F Interceptor thats been sitting 14yrs...bike has 7k miles on it and im trying to get it started...my problem is im getting no fire except one spark after i let off the start switch...the bike has a new battery, new pulse generators, new main fuse...ive used a test meter and checked everything...tested right....cleaned all the connectors, start switch, kill switch...

ok i talked to a guy here on VFRworld and he recommended i do this:
First thing I usually do is 'pop' the seat and go directly to the ignition units. One is for the front cylinders, the other for the rear. You can do pretty much all your testing (except the ignition coil secondary (spark plug wires and caps) right there. Unplug the ignition unit connectors.

First thing, make sure they're grounded. Do that by checking resistance from the solid green wires to battery ground...you should have a complete connection. Then turn your meter to DCV, check and note the battery voltage. Next, while leaving the probes on the battery, key the ignition, hit the starter button and note how much the DCV drops...Normal would be less than 2 VCD. IE, battery tests 12.7, then when you engage the starter button VDC drops to 10.7. This is your baseline. If your VDC drops excessively, like under 9VDC that could be your problem.

Next put your positive probe on the black/white wire in one of the ignition unit connectors, the negative probe in the solid green on the same connector. Key the switch and check for battery voltage, you should have essentially the same VDC as at your battery...hit the start button and you should also note the same voltage drop. Do the same test in the other ignition unit connector.

You gotta have good voltage to the ignition units. By doing these tests you've established that and eliminated the possibility that the ignition switch, main fuse and especially the emergency kill switch is the problem. Let me know how you turn out.

so heres what i found out:

Ok i did the tests he said to do...the battery tested a 12.66v and dropped down 2v when i hit the start button...i did get resistamce when i checked the GREEN wire in both connectors to the NEG on the battery...in the connector for the cdi boxes putting the POS lead on the BLACK/WHITE wire and the NEG lead on the GREEN wire with key ON i got 12v...hit the start switch it drops to ZERO, let off the start switch back to 12v...no voltage but the motor is cranking...did the same thing on the other connector and same thing..key ON i have voltage, hit the START switch and ZERO voltage but the motor is cranking.....hopefully this will tell you something...let me know if i need to check anything else...thank you very much for your help...this has been driving me nuts!!

has anyone had this problem or know of what could be wrong? what to check?

thanks

 

14 years ???????

YOU have small rodents there in Knoxville??

Small rodents love to, need to chew, and there must be an abundance of types and numbers of them thereabouts.

Wire insulation is commonly gnawed--wheather out of sheer boredom or because it's fun, science has not yet determined--to the point of destruction.

Switch contacts develop corrosion and may not work after long storage.

Unplug EVERY connector plug you can find, inspect for corrosion on contacts (usually is a greenish-white deposit), brush contacts with medium sandpaper, replug and be sure they're locked.

Check the fuses frequently.

Time and the ohmmeter will get it all sorted out, and you might need some more replacements parts.

Honda service manual is the best scource of info.

 

Yep 14 years...ive done all of that 3 times over...replaced the main fuse, pulled all the connectors and cleaned them, used deoxit5 cleaner and dielectric grease...ive tested everything with a analog meter and resistance and voltage checks out right...pulled all the fuses and checked them they were all ok...pulled the start switch off the handlebar and cleaned it out good...im getting 12v to everything with the key ON...i hit the start button and the motor cranks..strong...but i get ZERO voltage to the CDI boxes...with the key ON im getting 12v to the CDI boxes but hit the start button it drops to ZERO...could the start switch be bad? would it send power to the starter but not the CDIs? with it being a dual ignition system it has to be something that controls both sides because both sides are doing the same exact thing...what can go bad that will kill the voltage to the CDIs? start switch, kill switch, R/R, stator, starter relay...ive replaced the pulse generators and gauged them for proper clearance...it has a new battery...puzzling i know.

 

It could be in your kill and or start switch contacts or your ignition sw for the start circuits. There is also a run relay which supplies power to the ignition boxes that used to go bad. It's in the main wire harness up by the coils along the frame. Small rectangular unit plugged into the harness. I would clean all the contacts in the switches and check for power there on the start side. The kill sw could be closed but is acting open because of a dirty contact. Same for the start sw start contacts. If you have power at the switches in both start and run, then the relay could be bad. You might be able to jump the relay for test purposes. I'd have to check the wiring diagram to see if the start circuit goes thur the relay. Do you have a wiring diagram to look at? Not sure if the CDI boxes use the same wires for start and run. That's why you may not be seeing a voltage when you hit start. Back to the wiring diagram for that.

 

Ok heres what has happened so far....

i ran jumpers to the BLK/WH wires in the CDI connectors from the POS terminal on the battery....

i tested it and i was getting 12v

ok..with the jumpers connected i was getting power (lights ON on the dash panel) with the key OFF and the KILL switch ON...flip the KILL switch OFF and no power (lights OFF on the dash panel)...

ok...key ON...kill switch ON...cranked the motor but still the same thing...NO spark while cranking the motor then ONE spark when you let off the start switch....

ok...i used my meter to test voltage with the jumper wires hooked up to the BLK/WH wire...i put the POS lead on the BLK/WH wire and the NEG lead on the GREEN wire in the CDI connector and was getting 12v...hit the start switch and again it dropped down to ZERO volts....with the jumpers connected to the battery still....

hopefully this will tell you something.....

basically its doing exactly the same thing as before running a HOT jumper from the battery to the CDIs

 

Ok part 2 of my mad experiment lol....

ok...so im thinking what if (that always gets you in trouble) i hook a jumper from the NEG battery post to the GREEN wire in the CDI connector to establish ground....

ok...i hooked up the jumpers and turned key ON...kill switch ON and hit the start button...i looked down at the spark plug i had hooked up and grounded and yes...im getting good spark.

ok...so i look backl up and im smokin lol...the jumper wires melting...the connector a little burnt and a GREEN wire in the wiring harness just below where the seat sits is melted..the plastic melted but not burnt into...

ok...so i disconnect the jumpers and i tested the CDI boxes for resistance and they checked fine and i tested the connectors..fine...so i dont think i damaged anything...

im sure it was stupid to do it but hey did i mention im no expert lol...but...for that moment i was getting fire...the plug had a good spark...

so obviously its a ground problem...what should i do next...or should i say right and not fry anything lol...i know where the battery grounds to the engine but where does the wiring harness ground?

hopefully in my dumbness all this will mean something...

 

to add to it...the jumper wires were lite gauge wires..come to think of it maybe way to lite for what i was doing...maybe thats why they melted???

 

I was wrong about the relay location. What I described that's in the harness was the silicone rectifier for the starter solenoid. The main relay is on the left side under the side cover. Here's the wiring diagram Not sure if it's readable/large enough for you.

Now where to start. Let's try here. At the ignition connector when you push the start button you should have connectivity between the black and red wire. 12v at the black= ignition side of key switch. With key on,

At the start switch (rt handle bar) you should have connectivity between the black and black/white wires (at connector). Those are the kill switch wires. also 12v at both. kill sw must be on. w/Key on
Same connector should also have 12v at the Black/red wire. That's the run circuit- w/key on

At the main relay Black/white = 12v to ignition bat side, Red supplies 12v to relay from key switch, Black/Blue =12v to fans

At CDI boxes Black/white = 12v at both when key is on also when start button pushed. The 2/4 box-blue & white/blue is signal from pulse generator at connector, the 1/3 box yel & wh/yel is signal from pulse generator going in to the connector. and at the coils. When you hit start button

I think that's right. If need be I could e-mail the diagram and you can enlarge it on your pc for better viewing. Make sure all your connectors have all the wires pushed in to them and are clean. Good luck.

 

I do have a service manual with the wiring diagram in it...thanks for posting that one....honestly its all greek to me...did you read what i did so far....when i hooked a jumper wire from the NEG battery post to the GREEN wire in the CDI boxes connector I got fire to the plugs....it was a strong spark....but i was having the melt down.....so it seems to me the CDI boxes are not grounded....i dont know where to start to check the grounds for the wiring harness....i pulled the ground for the battery to the engine and cleaned it yesterday....OR...you did read what i posted and i need to test everything you listed????

THANK YOU SO MUCH FOR YOUR HELP!!!!

 

Oh wait!! I just thought of something that happens to those CDI boxes. The connectors in the tail section will get wet and corrode/oxidize. Make sure they are all cleaned and lubed with dielectric grease or something like that. Deoxit comes to mind also. For cleaning and coating electronic switches and connections. Try a music/guitar store.

That green wire is a ground. You will have to trace it backwards to see where it's not making a good connection. They go back to a Green w/yellow leader wire. Look on the wiring diagram for all green and green w/yellow wires. That's the grounding circuit for the bike. So trace your rear harness backwards to the next connector and see what that connection looks like male/female ends. Use a meter to see if you have continuity back to the CDI ground wires from there. If you do, you know that section of harness is good. Then keep going forward to next connector. Just follow the green wires on the diagram for start, run and CDI circuits. Also before doing that. Take a good look at the CDI connectors where the wire goes in to the socket, it may be half/full broken where it is crimped to the contact lug, and in side the socket at the male and females ends for corrosion. All grounds no matter where you find then should be traceable back to the ground at the CDI boxes. Ground is all one circuit. The easiest to trace.

If it got good spark with just hooking to ground. Then that very well could be your problem. Time to go hunting again. This is the fun stuff of electrics.

If that doesn't work then you most likely have to look at all the other I mentioned before. Let us know how you make out.

 

HOLY COW HOW STUPID................

IT RUNS!!!!! you wont believe how STUPID the reason why it wouldnt....my neighbor has been helping me with the bike...when i got it all the rear stuff was removed so he put it all back together....the mistake...well i realized the ground was my problem but its because of what you guys told me to do is how i came to know that....well the ground problem was the ground was HOT...so im thinking its a dead short and it must be touching a hot wire somewhere...well i started unraveling the wiring harness at the rear of the bike tracing the wires...ok the dumb mistake...the main ground connector for the wiring harness was hooked up to a post on the starter relay....yep....that stupid....the main ground was hooked to a HOT....so i unhooked it...grounded it to the frame where it was suppose to be under the seat....and guess what....she fired right up...after sitting 14yrs....i mean barely tap the start button and shes runnin....believe it or not she purred away...sounded great...quiet...no chatter...considering no fuel pump hooked up just gravity feed, the carbs not synced and they do need attention....SHE RUNS!!!! everything seemed to work on it.....its a start...shes gonna be an awesome bike one day....now the fun starts....thanks for helping me everyone...now where to start????

 

"now where to start????" At the beginning of coarse.:smile:

Good deal on the find. Your very lucky nothing electronic got fried like those boxes! It will be nice to hear another GREAT First Gen hits the street.

Go suck on an egg Squirrel man!! I don't want to hear it. :tongue2:

 

Seems like old Hondas--if they were running when parked--come out of prolonged storage easier than almost any other make.

Ride, enjoy, repeat..........,