Fuel Pump help please,

Redrooster

Redrooster

Joined
May 9, 2010
Messages
11
Location
Nottingham. UK
Hi,
I would like a little help and advice please on a fuel pump problem I have on my 98 ST1100.

Ok, the bike has been stored unprepared for about 6 months for the first time in it's life !!
I've tried to start it with no luck. The fuel pump is not pumping at all, with the ignition on I have metered between the green earth wire and the brown/black wire and have a reading just over 12V.
Being a carpenter and not an electrician I not sure what other readings I can take if any on the pump?
Should I get any reading from the other brown/red terminal ? at the moment it's 0.00
Is there a simple way of testing the pump if I disconnect the fuel line at the filter and allow it to flow into a container? assuming I can get the pump working !!
I am going to change the fuel and fuel filter but I just need to get the pump working first if possible.
Many thanks for any help you can offer.

Regards

Red
 
6 months parked is no big deal.
I park my Euro bike for 91/2 months of the year and only disconnect the battery. Have done this since 1990.
Both ST1100 and ST1300.
The bikes have never failed to start. Only seldom even needing a jump.
If your fuel pump has failed, this is a issue separate from parking I should think.
 
When my fuel pump failed, I could still get my bike to start and run. It had to be FULL of gas (gravity is your friend) and I needed the choke to get it going. Once started, it would run about 100 miles or more. It GOT ME HOME!

While you have the tupperware off it is pretty easy to check several things.

Pull the hose out of the fuel pump and see if it pumps at all. Really good specs and diagnostice information on Mike Martin's site here:
http://home.insightbb.com/~mmartin36/Disclaimer.htm

The other thing to check right away is the fuel valve function. Fuel filter is right there, too:)

Good luck, let us know...
 
Well it could be a couple of things and like mentioned above, 6 months is not really that long. Without the bike running, when you first turn on the ignition, the pump should momentarily run and then stop

Try jumping the pump directly:

In this pic, the terminal with the + sign on it is the positive wire that goes directly to the pump. Take your seat and the left side cover off and carefully run a wire from the positive battery terminal to the + terminal on the pump. The pump should run

fuelpump.jpg
 
GitSum said:
Well it could be a couple of things and like mentioned above, 6 months is not really that long. Without the bike running, when you first turn on the ignition, the pump should momentarily run and then stop

Try jumping the pump directly:

In this pic, the terminal with the + sign on it is the positive wire that goes directly to the pump. Take your seat and the left side cover off and carefully run a wire from the positive battery terminal to the + terminal on the pump. The pump should run

fuelpump.jpg
Click to expand...

Many thanks.

Please bear with me, I'm a little confused here, with the ignition turned on and the pipe disconnected from the filter nothing at all happens with the pump, completely dead.
So just to be clear, at the moment and relating things to the photograph.
I have a brown/red wire on the + terminal.
I have a brown/black wire on the LOW terminal
I have the green wire on the Grd terminal.

With the ignition on and the multimeter connected to GRD and LOW terminal I get a reading of 12.00 V.
With the ignition on and the multimeter connected to GRD and the + terminal I get a reading of 0.00V. Therefore does this mean I have an electrical problem somewhere else?
I assume if I run a direct supply from the battery to the + terminal leaving the the LOW and GRD connected, it should run?

Many thanks, as I said I'm a carpenter not a sparky, sorry !!

Red
 
Low Terminal - this goes to the low fuel sensor and you should be reading 12v there. This is normal, the sensor (thermistor) actually heats up from the voltage passing through it. If it is submerged in the gas, it cools down enough to not complete the circuit. If it is not in the gas, it warms up enough to complete the circuit and turn on the light

+ Terminal - Your reading of 0 volts is normal with the ignition on and the engine not running - that is why you have to "jump it" to see if the fuel pump is actually defective.

Yes - Leave the Low and Ground connected and run a temporary wire from the + battery to the + terminal. Be carefull if you have the fuel line pulled off because the pump should run. (technically you can jump a wire from the low terminal wire to the + terminal but I prefer to do it from the battery since I have a set of jumper wires)

Report back and we will go from there (you could have a problem with the vacuum operated fuel shutoff valve if the pump is working or the fuel cut off relay or the fuse is blown - 10A:IGN, STARTER, ACG)
 
Hi,
Sincere thanks for the help.

Well, I've just made a jump lead, tried it, and nothing !!

Does this mean the good news is that we've found the problem? but the bad news is that I need a replacement pump?
 
Not even a little spurt? I don't remember the quanitities, but my pump would give a little pump every time I turned the key on.

Dang. I just sold my ST1100 today, the service manual went with it. I'm not sure the possible electrical set up, at all, this doesn't sound like a typical fuel pump failure....
 
Redrooster said:
Hi,
Sincere thanks for the help.

Well, I've just made a jump lead, tried it, and nothing !!

Does this mean the good news is that we've found the problem? but the bad news is that I need a replacement pump?
Click to expand...

Well, unfortunately at this point it sounds like your fuel pump is bad...

Just to double check - If your know your battery is good and you have 12v + going to the + terminal in my pic and the negative from the battery is going to the ground terminal in my pic either the problem is with the fuel pump or the wiring inside the tank - and it is probably the fuel pump

I would try it again and if still doesn't work, think about pulling the fuel pump out. It is pretty simple - unscrew the 6 nuts, disconnect the three wires, you may have to bend up the little tab holding the metal fuel line in place and start lifting straight up. Once it is a couple of inches out you will see a large black hose that connects to a breather pipe directly under the the top of the tank. Pull this hose off sideways (towards the left side of the bike) and you should then be able to pull the fuel pump assembly the rest of the way out. My guess is you had some water in the tank and the pump got fouled up. If you can, pull the the pump and post a pic

I just remembered I made a post about pulling the pump - look at this thread

https://www.st-owners.com/forums/showthread.php?t=77041
 
Redrooster said:
Hi,
I would like a little help and advice please on a fuel pump problem I have on my 98 ST1100.

Ok, the bike has been stored unprepared for about 6 months for the first time in it's life !!
I've tried to start it with no luck. The fuel pump is not pumping at all, with the ignition on I have metered between the green earth wire and the brown/black wire and have a reading just over 12V.
Being a carpenter and not an electrician I not sure what other readings I can take if any on the pump?
Should I get any reading from the other brown/red terminal ? at the moment it's 0.00
Is there a simple way of testing the pump if I disconnect the fuel line at the filter and allow it to flow into a container? assuming I can get the pump working !!
I am going to change the fuel and fuel filter but I just need to get the pump working first if possible.
Many thanks for any help you can offer.

Regards

Red
Click to expand...

I had this problem with my bike only last week. It appeared that the pump had had it but after 3hrs of testing everything I figured out that it was the "fuel cut off relay". It would be worth giving this a check. I can give you details of where to find it and how to test it if you like?
 
As long as you do it right (and it is pretty simple) by jumping the fuel pump - it takes everything else out of the equation. Either the pump will run or it won't
 
One thing I would do before pulling the pump is also run a ground wire directly from the ground (earth) terminal on the pump to the negative terminal on the battery. Then try the jumper wire from the positive battery post to the pump. If you have a bad ground connection, just jumping the postive wire won't fix that. Doing this removes all of the electrical circuits in the bike from the pump and isolates the pump for more accurate testing. If the pump still doesn't work in this mode then I would most likely say that the pump is bad. If it does work in this mode, then the real fun begins.
 
Well guys, I've got the baby running:D

Before I tell you how, I would just like to give a BIG thanks to all of you for your support in trying to sort this one out for me.

After doing all the tests on the pump and together with the advice and experience of you guys, I convinced myself that it needed replacing, so I quickly had a scout around on ebay and I found one from a salvaged bike. I bought it at a very reasonable price of ?32 sterling ( $48 approx) delivered.
In the meantime, today, I drained the tank and pulled the pump. Testing it again on the bench direct from a battery it still did not start.......until.....I gave it a few good taps around the motor and after about the 8th hit it came to life:D
After further testing it continued operating perfectly so it went back in the bike with new fuel in the tank, new fuel filter and it cranked up with no problems at all.
One very happy chappy now, even though I've now got a spare fuel pump assembly being delivered tomorrow !!!

Anyway, the cost of the replacement is relatively cheap and will come in handy if it ever fails again.

Once again guys, many thanks for all your help.

Red
 
I am glad it worked out! That is a good looking ST in great condition

That was going to be my next step - to see if we could coach it back to life. The fuel pump is just a small electric motor with an impeller attached to one end. Sometimes they can get pretty crudded up and you just need to manually "convince" it to start spinning again :)

FuelPump.jpg
 
Glad your up and running again Red sorry I missed your post initially.
I like John would be tempted to give the new to you pump a good cleaning and check then fit that and do the same to your pump and then store it.
Have you just bought the bike? I'm sure I saw that little gem on ebay recently.
 
I wonder if the pump had a small piece of crud jamming it, and the tapping released it? If that's the case, you should be ok.
 
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