87 VFR750FH - Died at 70mph wont start

right so ive had a read and am now scratching my head as the workshop manual isnt helping much either..

filled up bike went for ride.. happily crusing at 70 odd mph and >>> boom just died.. as tho kill switch had been hit.. it hadnt.

at the side of the road realised fuel pump wasnt running so jumpered the relay and ran still no fire..

got recovered, cleaned and checked the pump points.. got a new relay.. still no run.. im getting 12v at the pump so all there is good..

however found no spark....

kill switch is fine, checked cleaned terminals

uised contact cleaner to clean all plugs, getting 230 ohm at the pulse generators ( however temprature ousitde was betewwn 1 and -1 c so accounting this in the fact of such low resistance)

not sure how to test the cdi using multimeter..

suggestions ideas ?

perhaps someone in rochester kent uk free this weekend who would help out for a bacon sarnire, brew and petrol money ?

 

Did you check the battery voltage ?? Low voltage means no sparks. No surprize if the problem would be a nother failed charging system !!? Overvoltage or undervoltage from another defective r/r can render inoperative a CDI. Find the one wire (at the CDI plug) that sends power to the box (often brown in colour) and confirm that +12vdc power is getting TO it when key and run switch are both ON. Check that green wire at CDI plug has zero resistance to ground. Other gound connections need checking too.

The fact it stopped so suddenly could have been a clue that it wasn't a fuel pump problem. Even with a dead pump, the bike would run for a few seconds on CHOKE if it were getting sparks and run out of power slowly.

Check smaller fuses and main 30 amp fuse first. Inspect/clean the main plug from ignition switch to the wiring harness, where a bad connection could be hiding.

 

Hi
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Roger

 

it didnt cross my mind at the time about the fuel till afterwards, just noticed no fuel pump running at the side of the road..

thanks for the tips... battery was charged and was using a secondary battery as well to boost it as all the cranking drained it eventually.

i had a r/r over volt bout 4 months ago and have had new r/r and battery since without a problem.. my first port of call was the earthing points this weekend but the CDI wires was were i was unsure as the workshop manual i have covers the newer of the 750f's

all the fuses were good as well first thing i checked, and ive cleaned up all the multiplugs under the right farring (although were pretty clean tbh , but a bit of contact cleaner never hurts)

will keep you updated... thanks

 

Hmm. From your description with the bike suddenly cutting-out, it sounds more like an electrical issue, and I would leave the fuel system well alone for now.

On the 750s there have been a fair few issues eventually traced to bad earthing, and wiring/connectors. Indeed bad enough for someone to design a wiring upgrade (VFRness). So it may be worth spending time giving the wiring a thorough check.

Hopefully someone else can point you in the direction of the imfamous orange connector as it is a known trouble source which is taped inside the loom somewhere.

Remove the side fairings, then with a decent inspection light carefully inspect the wiring loom end to end, disconnecting, cleaning and reinstating connectors and earthing points. Focus on the charging circuit and the starting and CDI wiring. Check for signs of fried or chafed wires especially where the loom is clipped in as vibration can cause insulation to fail and short out circuits. Don't forget to check the fuses beside the battery.

I take it when you had your previous electrical issues you did static and 5k rpm checks on the AC stator output with the RR disconnected. If the stator output is too high or low it can kill the RR and then take out other electrical components - were any of the lights blown?

One last thought does your bike have an alarm / immobiliser - as they can be a real source of grief.

Good luck and let us know how you get on.

 

believe it or not i have been contemplating making a whole new loom but as my daily runner and no alternative means was put aside

on my 3rd RR since owning it (oct) first over charged.. 2nd from new was ok for 3 weeks then dropped voltage when hot my 3rs a 2nd hand one off a suzuki hard wired in has yet to let me down..

ive gone over all the plugs and followed the look for breaks.. as well as contact cleaned everything only 1 plug looked a biut cruddy and thats now clean.. im going to run some earths around the bike to be safe as i know when working cars earthing is a main issue.. so will hopefully solve that

yeah it did but was literally spliced in to the main feed from the starter solonid which i have since reverted due to the alarm packing up.. only immobilasitioon atm is a whacking big chain and disc lock.. however reminded me i never did check the switched live to the alarm as worked ok once i un did the imobilisation..

cheers for the tips

 

Well all earths appear ok. Power fine to the CDI. Coils showing 12v on both pins.

Truly a bit stumped on this one

 

Does it turn over ?

Does that version have a crash tilt kill switch ? disconnect it if it does, as it tell ECU NOT to keep sparking !
Or does it have clutch switch ? bypass it & see if that fixes it.

I assume no spark at plug !? ECU ? It cuts voltage to fire coils. Try leaving a voltmeter attached to coils LV connection & see if they keep dropping to induce the coil ! It the voltage does not vary then the ECU (or is it old CDi on that version?) it not cutting the volts to induce the HT side to spark !

Pull all fuses not required to run the engine, so if there is a short anywhere, it won't interfere with the motor ! If you get it running insert fuses one at a time until it stops, then you will know which circuit is at fault.

Failed wire from/or ignition sensor ?

Best of luck with diagnosing it.

 

Technically, if the engine quit, the pump would stop when the power went off.