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CBF 125 Fuel Pump Removed
Blog Date - 14 March 2013
You're supposed to check the fuel pump by initially checking the flow. The idea is to remove the high pressure output line that feeds the injector then measure how much fuel it pumps out in 10 seconds. Surprisingly easy. The fuel pump "primes" for 2 seconds when you switch the bike on so being sure to collect all the fuel that is pumped switch the ignition on and off 5 times! Simples!
According to Haynes there should be at least 27.7ml. In my 5 turns I got enough to fill my 60ml syringe twice, so there's DEFINITELY enough flow. OR at least that's what you'd think. However I'm not entirely convinced by Mr Haynes method. You see having duly noted there's no lack of flow I continued to remove the pump...because I couldn't think of anything else to do. Once removed another half-cup full of fuel tipped out of the pump.
Possibly the offending item...not sure yet and at £250 or more for a new one, I want to be CERTAIN.
This implies that there's a fair old amount of fuel that "lives" within the pump. Sooooooo...I know the pump can pump the fuel but it may not be getting in fast enough. I know when I removed the pump there's no goddam fuel tap and the costly juices flowed freely from the pipe until such times as I rammed it closed with a screwdriver. There nothing blocking the tank. There is however, from what I've read in forums, a filter within the fuel pump. Perhaps this is blocked.
So fuel comes out of the tank OK. The pump can pump the fuel from within it's own reservoir OK. Maybe the filter is before the reservoir and blocking the flow into the reservoir? There is no obvious method to check. Or is there...Maybe I need to get a big jug to catch the fuel and let the pump...pump. If it continues to flow well then the filter is not blocked. Otherwise if the reservoir empties and fuel comes slowly the filter is blocked. Only problem is the pump only pumps for 2 seconds. Ignition on/off quickly every 2 seconds?
I now know my next test.
The space where the fuel pump once was. Surprisingly easy to remove. Note the screwdriver blocking the fuel pipe as there's no fuel tap. BE WARNED. Work in a well ventilated area away from ANY flames or possible sources of ignition. No...really CAREFUL
Reader's Comments
John said :-
Ren. Would it be possible to force petrol the other way (where it comes out, force feed it and see if that could dislodge any sediment). just a thought,
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
Well John if I establish there's a blockage that's a possibility. I sure as hell won't give up on it straight away. It way come to dibbling it with a dibbling stick and see what that brings out.
01/01/2000 00:00:00 UTC
Tom McQ said :-
Ren, there's lots of ways to prevent fluids gushing from a hose prior to disconnecting it, but these little tools are handy... http://www.ebay.com/itm/260923795978
And there's a cheap used one on eBay...
http://www.ebay.co.uk/ctm/Honda-CBF-125-2010-Fuel-Pump-
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
Hi Tom. Yeah I used to be a mechanic so I know of such things. Thing is...I didn't have one handy. Never been quite sure of the merits of crushing a rubber hose like that anyhow...
There's plenty out there second hand. I probably will try a second hand one IF and when I establish it is the pump. My only concern is that I may just be buying someone else's knackered fuel pump too. This one claims 14 days warranty which at least gives me a chance to try it. BUT...if I buy it as a test item and it doesn't work...does that mean I've purchased another bunged up pump or the problem lies elsewhere? With second hand you can't be sure.
Mind you, with brand new you can't always be sure either...
In a perfect world I need to find someone with a fully funtional CBF 125 who's willing to lend me their pump for an hour or two.
01/01/2000 00:00:00 UTC
Norman said :-
The cbf 125 does have a fuel pump problem but it's more down to design and the tank.
The filter in the pump is non-serviceable. The inside of the tank is coated to protect against rust etc. It seems that the problem could be the ethernol content of the fuel degrades the coating forming a waxy substance that finds it in to the filter blocking the flow.
I've not had that problem as far as I know but I did have a lump of waxy substance block the tank outlet preventing the fuel getting to the pump.
The answer seems to be fitting a small inline filter between tank & pump. This can be changed as required.
01/01/2000 00:00:00 UTC
Norman said :-
ps.
Once the pump is blocked it's done for. The fault is usually described as kangaroo hopping. Mine on the other hand was a max speed of 50. After quite a few days of trying to find the fault it ended up getting slower and slower till it stopped after 5 miles. It was then the wax had almost completely block the outlet.
I also had other faults at the time so they were confusing the fault finding.
I am only getting 90mpg and, other than riding style, the only thing left to try is a replacement pump as my theory is as follows.
The pressure regulator that should keep the pressure at 43psi (3 bar) is faulty and the pressure is high. As the injector is fired for a set time the excess pressure is causing too much fuel to enter the cylinder and engine is running a bit rich. Not enough to cause a noticeable problem other than lower than expected mpg.
What do you think?
01/01/2000 00:00:00 UTC
miles said :-
hi
just a question , is there a other pump that one can use as replacement or where can one get parts for the pump
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
Hi Miles
Sorry bud but I'm not aware of a replacement pump. BUT - in my experience many of these parts are taken from other models of motorcycles or even cars! The Honda Africa Twin had issues with it's low pressure pump and that was the same as fitted to Yamaha Fazer FZS 600's and MANY other motorcycles and rumour has it many other cars.
Find part numbers and google them, you might find it's listed for some random lawnmower. Look closely at your pump and then google images of fuel pumps, does one look the same?
I'd love to hear your results :)
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
PS the part number for the fuel pump is 16700KWF952...
01/01/2000 00:00:00 UTC
Sameer said :-
hy there, thanks ,the topic was very helpful as m having same problem and wanted to know if i could replace my cbf 125 2010 fuel pump with some other bike pump if it does works as cbf 125 fuel pump is sealed and once blocked u cant really do anythng, thanks
01/01/2000 00:00:00 UTC
Neil said :-
As for the fuel hose simply just bend it up and put a tie wrap around the base of the hose not tight just so it releases no fuel simples
24/08/2021 00:20:33 UTC
Kaecarter said :-
I’ve got a Honda cbf 125cc, I know nothing, but I have been told that the injector has a module on it that needs remapping to the bike as when starts cold it idles for a minute, cuts off, repeats but then third time starts and when warm no problems?! But I have been told this remapping is £300-£400?? Wtf… can anyone help with advice please
28/01/2024 10:20:30 UTC
Ren - The Ed¹ said :-
The CBF125's fuel injection system is about as simple as it gets. I cannot claim to be an expert but "remapping" doesn't sound right to me at all. If the problem is cold starting my first place to look would be the temperature sensor. Are you getting an "check engine" light at all? The light circled in the image should come on when you switch the bike on, and go off soon after.
29/01/2024 07:56:50 UTC
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