UK Monster Owners Club Forum Ľ .: Technical :. Ľ Electrics » 796 fuel pump stopped priming

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Old 05-09-2021, 11:16 AM   #1
jonzi
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796 fuel pump stopped priming

Morning.

Tried to start my bike today and it sounds like the fuel pump is not priming.

Can some one point me in the right direction for troubleshooting it please?

Right now all Iíve done is identify that I canít hear the pump come on when I turn the ignition on.
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Old 05-09-2021, 11:47 AM   #2
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check, and swap the two relays on the side of battery box (sorry about the tank)
if you get nothing at all with them swapped, it’s the relay (the other one is the main relay, so if the efi relay is faulty nothing will work once you switch them)
if you’re really lucky it’s a loose relay, if you’re a bit lucky it’s a £6 relay.
otherwise you need to start looking at the connections and see if the pump is getting 12v
(the connector to the plate under the tank is probably easier to get to than the battery anyway)
how long has it been stood and has the tank been full?
fuel pumps can seize up if left dry and can get gummed up with ‘varnish’ if immersed, bit of a loose/loose i’m afraid
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Old 05-09-2021, 03:19 PM   #3
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I agree with Rob that the most likely (but not the only) possible culprit is the injection relay. It's located on the battery box next to the headlight relay under the tank



As well as trying the relay swap test, you can also check its operation with a multimeter



If the relay fails, I think it should throw up a fault code so check your dash for an "R INJ" message.

If the relay works loose, you'll also see other symptoms such as the dash going blank momentarily and resetting itself. You may also see a "0005 rSW" message very briefly before the dash resets. (Tip: while you're under the tank, secure each relay in place with a cable tie to prevent them working loose in the future.)

Have you had the tank off before? If not, note that the fuel lines are located in a channel moulded into the tank underside and are held in by clips. Make sure the lines are properly seated and secured when you replace the tank.



Also, the wiring connector for the fuel pump lives on top of the rear cylinder - make sure it's properly located as, if it's in the wrong place, it can get crushed and cause problems.



You could check the operation of the fuel pump itself, (to make sure it's not seized), by applying 12V direct to the connector. There are four terminals: two black earths (2 & 4), a brown/white live to the pump (1) from the relay and the remaining pink/yellow (3) is for the low fuel sensor.



Finally, if you completely remove the tank, lubricate the o-rings on the fuel line connectors to protect them from pinching/tearing and to make it easier to push the connectors fully home.
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Old 05-09-2021, 09:25 PM   #4
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Cheers both, ill take a look some time later this week, hopefully it will be a relay, as as far as I remember the last time I tried to remove the fuel lines, they were stuck on.
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Old 05-09-2021, 09:27 PM   #5
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Oh, it had been used recently, a few weeks ago, and it was refuelled, so I am hoping it aint the pump getting varnished or dried up, it's been left longer than this with no problem
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Old 05-09-2021, 10:02 PM   #6
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if a relay’s worked loose, you could strap it (them) into the socket(s) with (a) small tie wrap(s).
vibration aside, i’ve seen push fit connectors gradually unplug themselves, the pins warm up and push the plug out a fraction of a millimetre but they don’t creep back in on cooling, so after months of heat cycles they’ve unplugged enough to fail.
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Old 05-09-2021, 10:48 PM   #7
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You've checked the kill switch of course?

Yes of course you have..
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Old 05-09-2021, 10:52 PM   #8
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Quote:
Originally Posted by Mr Gazza View Post
You've checked the kill switch of course?

Yes of course you have..
The pump still primes even if the kill switch is off, Mr G. (I checked this morning!)
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Old 06-09-2021, 08:22 AM   #9
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Fair dinkum. It doesn't on my SS.
The AA once recovered a non starter combo back home for one of my family, after waiting overnight in the depot. (About 10 miles away!!)
I rocked the kill switch and rode it off the lorry!..
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Old 06-09-2021, 07:19 PM   #10
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Quote:
Originally Posted by Luddite View Post
The pump still primes even if the kill switch is off, Mr G. (I checked this morning!)
The fear and panic, before I had scrolled down and saw this.

Thanks for checking Luddite!

(Thought I will go and check in a minute)

Update: Luddite is of course correct
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Last edited by jonzi; 06-09-2021 at 07:21 PM.. Reason: update
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Old 06-09-2021, 07:34 PM   #11
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c’mon dan, you’d never let us know if it had been the kill switch ;-)
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Old 06-09-2021, 07:46 PM   #12
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How dare you!

It's still not working, so can't be the kill switch.
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Old 08-09-2021, 12:23 PM   #13
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Well, i took the tank covers off, pulled the fuel over flow pipe off the Y joint thing, then I had to turn the ignition on to move the bike (I have a tracker, so didn't want a call), and I heard the fuel pump prime.

Bad news is, I dropped one of the clips that the tank cover screws goes in to. No idea where that is
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Old 08-09-2021, 01:49 PM   #14
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That could be good or bad news!
Sounds to me like you have probably jiggled a dry connection back into contact and now the game will be to find where it is and consolidate the connection. It will probably play up again not long after you get the tank all back together if you don't find it!!

Sorry didn't mean to scare you with the kill switch earlier, sometimes easy to overlook the glaringly simple.
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