Hello, can anybody help?

Does anybody have an opinion on an issue with my bike? It is a 1988 VFR750FJ (RC24) and yesterday it stopped, as though it was going on to reserve. I moved the tap around and it made no difference. I had to get the bike recovered. Today I have confirmed that the fuel pump is functioning and there are sparks. Really strange, anybody got a pearl of wisdom?

 

Does the engine turn over?
I would check the stator the rr and the battery for proper voltage. Good luck

 

No issues with the battery, it turns over brilliantly, there's just no life, not even "trying" to fire. My gut instinct was a fuel supply issue, but no problem with the pump. I wonder if there's anything else that can prevent fuel getting to the engine, upstream of the pump?

 

Did the bike actually shut off or did it just sound start running rough like it was starving for fuel? Is the problem persistent or does it randomly occur? Any signs of rust inside the tank? You really need to check the fuel filter and then open the screws on the carb bowls to see if fuel is indeed getting to the carbs. Also pull a few of the spark plugs to see if they are wet.

Rollin

 

It shut off as though it had run out of fuel (it hadn't) and I haven't had a peep out of it since. This is the first and only time this problem has occured. No issues with the fuel filter, but I have very recently discovered some wetting on the plugs, so perhaps an ignition issue? There is a spark though, although maybe it's weak? What do you think?

 

If you think there is a spark issue, it could be that the battery is getting weak or something wrong with the charging system. How old is the battery on the bike? Can you check if the the carb bowls have fuel in them?

 

No issues with battery or charging system. Fuel supply not an issue. Confusing!

 

Check for leaks in the carb boots since too much air in your air/fuel mixture can also prevent the bike from starting and/or running correctly. If you have verified spark and the plugs are indeed wet it means that you are getting fuel but the fuel mixture is not igniting. This could be due to timing, fouled plugs, improperly gapped plugs, or weak spark caused by dying/defective ignition coils. Seems odd that it happened so suddenly which is often a sign of a failed electrical component.

Rollin

 

Can these bikes be push started or try starting rolling from the top of a hill in neutral and jumping in to gear and release clutch?

 

Yes they can however I would advise popping into second gear instead of first after getting up to adequate speed. A quick test to determine if you carb boots are leaking is to spray a little starting fluid around the boots while trying to start the bike to see if it makes any difference. Just be careful if you try this since you could easily set your bike on fire if you aren't careful and spray too much. By chance did this problem start after a recent fuel fill up?

Rollin

 

Update: The bike hasn't actually started, but it's trying to now. There are some encouraging signs of combustion. Very strange. I think it could be as simple as fouled plugs. I've consulted my (handwritten) service history, and I've done 12,500 miles on the current set. Perhaps a shiny new set will wake her up. Just a bit weird that it went down three miles into a ride like it did, after starting fine. It was -3 when I set off yesterday, I wonder if that could have been a factor in any way. Anyway, thank you all for the many helpful suggestions, by all means keep them coming. I'm not used to reliability issues on this fine machine!

 

Checked all your electrical connections. My old VF400, had a loose coil connection and did the same to me.

 

I did have it running yesterday, seemingly on one cylinder only, so there is life! Next step is to change the plugs and see how we go. Could it be that simple? There are sparks, but they look weakish, and there is fuel. I've just never known old plugs to cause a dramatic on-road breakdown though. I wonder if a foreign body has made it through the fuel filter, caused the breakdown, and my attempts to restart have flooded most of the pots? This is a weird one, for sure.

 

I don't think the fuel fouling of the plugs alone should cause the starting issue. The fouling could be because the RR/battery is not providing the full volts to necessarily burn the fuel(unless it is flooding issue).

Change the plugs which should be relatively cheap/easy fix and if the problem still persists, then you will have to look at the charging system. Keep us posted with the updates and hopefully we can resolve this soon...

 

Update. I think I've cracked it! I have discovered that the water drain from the fuel filler area is blocked. I'm thinking that water has got into the tank as a result. I've manually poured (good) fuel down the carbs, and she's fired up! She stopped again when this fuel had burned off, but does "try" to start. I believe if I drain the carbs and tank, and use fresh fuel, I'll be back in action! Obviously I have cleared the blocked drain. I'll update when I've done this, but many thanks for all the suggestions and advice, it's nice to be among friends!
Rob.

 

Glad to hear the good news......... :thumb:

Cheers
Scub

 

It's just fired up on the "dodgy" fuel and run reasonably, but did stop after a few minutes. I'm certain that a drain of the tank and a refuel will solve this one! Nice to have sussed it, it had me very baffled for a while there! Check your water drains guys! That's my tip of the day!