Hi all, I have a 1989 K100 RT, there is no noise from the fuel pump so I've removed the tank and disconnected the 4 pin plug. Can anyone advise how to test the pump and which of the 4 pins for current? Thanks, Jon.

Hi Jon before you go any futher test the 4 pin plug and make sure it is actually working. We see quite a few where the female part of the plug opens up slightly and doesn't conduct and what happens is that you test the pump and all is ok and you check power at the plug with the thing unpluged and it is ok as well then out comes the hair by the handfull.

Thanks Rick, will do, I'll post my results. Jon.

If you get no love from the four-pin connector check also that none of the fuses (left hand side of the bike under side cover, attached to the central electrical box) are loose in their slot. I have had one slip out just enough when going over a bump and it caused all manner of time-delay headaches at the side of the motorway whilst uncaring traffic whipped past and I was late for an appointment. Pressed them all back in and she started up and hi-ho Silver, away.

Hi guys, I tested the 4 pin plug and there's no current on any of the 4 pins. I checked the fuses and they're OK (but still not sure which one relayed to the fuel pump.) I have current on 2 spade connectors on the relay. So now I'm stumped as my electrical knowedge is poor. Can anybody suggest something else to check?

I've never owned or even started a K100 before and I've bought this one as a non-runner, do I need to know anything about the starting proceeding? e.g. you need the clutch in to start or the side stand needs to be up or......

The FI relay closes the contacts a couple of seconds when the starter button is
pressed, then stays closed when the hall sensor signal is present (engine turning).

Measure at the green/white wire on the four pin connector, when pushing the
starter button (only a short touch is needed).

It isn't any sidestand switch on your bike (only Motronic equipped ones), but
neutral must be selected to start (or clutch pulled).

jon ...dont know what you have done to the bike as of yet .....but might be a good idea ...(given you say you bought it as a non runner ) to replace ALL the fuses ....regardless of what they look like .

whilst doing so, inspect and clean with electronic cleaning spray and a toothbrush each and all the fuse carriers . we recomenrd a product called deoxit for this cleanup after all the other stuff is done ( you will find it mentioned all over the site )

hope you learn more about elecricity fundamentals soon ...as you will need the knowledge to restore operations

kbike wrote a really good article a little while ago , which i commend needs a good reading of, for electrical newbys

https://www.k100-forum.com/t725-using-a-test-meter-volts-amps-and-ohms

we find that corrosion in the electrics is a verry common thing ...but be aware that its not a good idea just to start pulling things apart applying the cleaners and hoping that things change.,work methodically on each subsystem and prove that it works or doesnt work before proceeding.

you will be looking for the green/white and the brown coming from the wiring harness side of the tank connection for voltage. insulated aligator type clip leads would be verry handy to have for this and other measurements as we dont want to short anything out .

brown is usually earth on european wiring standards



good luck

Thanks for all that advise guys. I tested the wiring as you suggested Inge K. and I have power on the green and white wire. So now I guess I need to test the pump, is there a way of doing this? Should I remove it from the tank and wire it directly to the battery? This is al very much appreciated BTW.

I would suggest that you first measure if you got power to the terminals on the pump.
The reason why, is that the four pin connector is a known problem source.

If you measure low voltage, you could try to squeese the female connector a bit
tighter with a couple of toothpicks....or similar.
And of course, you could have the same problem at the ground side.
If voltage seems to be OK, your pump is the problem......but you could try to reverse
it....if your lucky you get some debris out of the inlet.

Anyway it also could be a good idea to check the pre filter at the bottom of the pump,
if the pump needs to be changed or not.

Thanks Inge K. I have power at the pump as I removed the filler cap and was able to touch the conection on the pump with the test lamp. Some of the items in the tank look a bit gummed up (the sender unit and the pump locator nuts) I think this may be due to the fuel going stale before I bought the bike. So I think I need to remove the pump and look at the condition of it and give it another test. Assume I undo the nuts round it inside the tank for this?

Motobins got the parts you need.
They got a lot of satisfied customers here on the forum, myself included.

I have not used mototbins but have used www.motorworks.co.uk for scondhand parts and thet were reasonable.

92KK

Morning Jon,

Don't give up on the pump. There are many options available.
PUMP 1

PUMP 2

If you want to get the bike going you can find something here that will not be OEM but will get you out of trouble.

And welcome to the forums

rossco

See what it costs to send it to Melbourne Australia and back if cheap and you can wait for the postage time from & two you I can rebuild your pump and gasket surround for free, just did two on my bikes last month.

Halo

Hi Halo, thanks so much for your kind offer, I might just need to take you up on that. I'll get a price for the postage but i also have a few leads of a couple of second hand complete tanks here so keeping my fingers crossed. Thanks again, Jon.

Hi Jon. Don't despair. You are in the right place to track down a used Peugeot 205 1.9 GTi pump.
I used one that I bought on eBay UK for a tenner in my '89 LT.
Its also made by Bosch and its identical. Apart from the superior alloy mesh on the intake at the bottom of the pump.
Never spend big money unless you have to is the K mantra.
By the way, new Italian made pumps appear on eBay UK regularly for about £60 'buy it now'. I've used one of these too with no problems.

There are many pumps out there that work properly. If it is made to be used on a Bosch FI system from mid 80s to early 90s then it will be ok.
All they have to do is pump the pressure and volume.

Thanks guys, even more information that I would have otherwise never known.

Thats the K100 forum way

Halo