Problems with my CBR 600 F 1993 - question

Hi Guys,

I won’t annoy you with long details of what the problem is that my bike is manifesting on and off (leaving me stranded sometimes).
I just wanted to ask you, and sorry if it’s a stupid question:

does anyone here know if the CBR 600 F 1993 has a fuel pump or does the fuel literally ‘fall’ in the carbs as soon as I open the fuel tap?

thanks in advance, it’s really important for me to know in order to narrow down what the problem might be…

The existence of this part suggests there is a pump:

I’d say so

thanks guys! then I think / hope this might be the problem.
my mechanic isn’t able to fix it since every time I brought him the bike it was working fine.

in short, sometimes when I start it and it’s cold, the engine goes on. works fine. warms up. then it dies on me suddenly and there is no way of turning it on again. usually had to wait an hour or so. Now it has been for five days stuck in the neighborhood where I work. Tried again today, out of curiosity, same starting procedure as usual and ta dah! it works!

But I can’t have a non reliable bike which leaves me stranded half of the times I use it. It’s a nightmare because the important things (engine and so on) all work perfectly. When she does work…she works like a beauty!

any ideas?

at this point I thought it be a tricky fuel pump…
spark plugs have been recently changed, battery is new and works fine. And I have been riding bikes for more than 10 years and I know it’s not a flooding problem that might be caused by too much choke or something (also because I have never heard about a flooding problem this bad).


thanks guys!

btw I am changing mechanic…

If it runs for a while and then cuts out then it sounds really likely to be fuelling. I’d get a service manual (haynes etc.) and see if that says how to diagnose issues with the fuel pump, but it’ll also be worth removing and cleaning all the bits of the process - the fuel tap in the tank, the pipes to the pump, the pump, the pipe to the carbs and the carbs themselves. How mechanically confident are you?

CBR 600f is fuel injected so it will be a fuel pump and not gravity fed

Injected in 1993? Blimey. No carbs either, then, and so I’ve no idea what’s going on.

Oops got the wrong year
I need to put my glasses on

Fuel filter?

Loose connector at pump , wobbly kill switch … I had a CBR that would cut out when you turned left … then when you straightend up … it would fire up again … … I managed to ride it for a week like that before I gave in traced and fixed it… it was a broken wire behind the ignition .

Has it ever been left to stand for a while, weeks without starting? If so Id be looking at main jets. Also fuel filter, fuel tank breather or kinked fuel hose. Tbh the diaphragm pumps on those things are pretty reliable. IIRC they run off a vacuum hose from the manifold, so check the integrity of that too.

Google cbr fuel pump repair kit for your model, the points on the pumps relay might of gone funny.

This might explain it better

Hey Big Red,

thanks for the reply!

Fuel tap and all those parts have already been looked at and cleaned by my mechanic who wasn’t able to find anything quoting ‘I can’t fix a problem I can’t find’ (since obviously…the bike worked perfectly when I brought to him).

And I am a horrible mechanic…

I do believe in ‘coincidences’ and with my first car I had a similar problem taunting me and it was the fuel pump…

it’s carbs - so much I know for sure :slight_smile:

wobbly kill switch could be a good shout indeed.

it’s really weird how it dies (when it dies). starts normally, fires up well, I start driving it and then it doesn’t even sputter or anything, it just dies completely.

tbh half of this message is too technical for such an amateur as me… :hehe:

before I bought in September it had been standing still for a while, but I spend quite some money on it including new spark plugs, cleaning carbs and balancing them, cleaning fuel tap and a bunch of other things.


however this work is way out of my league…:Whistling: including that i don’t have any kind of shed, garage and only have a basic set of tools that are just good for basic stuff…

but good to know that the parts/part are/is not so expensive!!

Ah, that’s much less likely to be a fuelling issue, then. Generally, with fuel starvation you’d expect to gradually have less and less fuel getting to the cylinders per stroke, and so you’d get a degredation in power over at least several thousand cycles. Something electrical sounds much more likely, and if the killswitches are known to have issues occasionally I’d check that out first. It might be the sort of thing you can find with a multimeter - looking for high-resistance as a sign of a damaged cable - but it’s also possible that it’s a connection that goes from absolutely fine to nothing. You’ve got a load of cylinders and (presumably) separate HT coils so it’s unlikely to be those (since you’d expect them to die fairly individually, and so get a power drop) and is probably, then something further up.

I’d have a look at all the safety switches - kill switch, sidestand switch and neutral switch - and check they seem to operate okay. Do you have a multimeter? Basically, remove the switch, check it’s not obviously knackered (doesn’t wobble all over the place, seems complete) and see if there’s a way of manipulating it into being open when it shouldn’t be. I’ve seen neutral switches hidden under final drive sprocket covers, where they fill with dirt unless properly covered by a rubber boot, so it could be something like that. If you’re feeling really brave, you could try bypassing all the safety switches and see if the problem goes away (they are called ‘safety switches’ for a reason, though…).

besides that I just realized that I replied to everyone without quoting… :pinch:

thanks for the insight! At this point every idea is super helpful!
as I said, unfortunately I really don’t have the skills and tools to do something like this…but good thing to mention it to the mechanic!

I’m not sure how averse you are to mechanical work generally, but it may be worth simply replacing the safety switches as a precursor to employing a mechanic to dig deeper. The switches together are probably somewhere in the £30-£50 region for the pair of neutral & sidestand switches and they’re generally quite easy to replace. The sidestand switch probably has two connectors and one screw holding it on, and the neutral switch often is just one connector and screwed into the side of the engine, needing a socket to get it out. Doing that will at least rule them out.

If you’re going to take it to a mechanic it would be good to be able to somewhat predict how to make the problem happen. Aside from making it easier for the mechanic to find the cause, it’ll make it easier for you to validate that it is actually fixed and start riding it again without fear of the engine cutting out. Things I’d test/take a note of are:

  • How long do you generally ride for before it cuts out? Is it always a small number of minutes, or can it go for ages?
  • If it’s always soon after starting, does it to it if it’s just left to idle?
  • Are there any other electrical oddities? Weird flashing rates on the indicators, sometimes-dim headlight or something?
  • Does the bike start again immediately after it’s cut out? Can you just hit the starter and have it fire up? If not, do you have to do anything to make it start?
  • Can you make it happen while idling? While it’s sat idling on the sidestand flex any visible, reachable bits of cable (from the switchgear etc.) while the bars are straight, and at either full-lock, wobble the sidestand switch, maybe lift the seat and prod anything you can see there.