Hi All, Not having a fun time at the moment. After struggling to replace the rear wheel bearing on my 996, I eventually get her back together ready for a re-MOT. Headed up to the village to leave it at my local garage, and half way there she cut out! The fuel light was on, and fortunately I'd *just* passed a petrol station (when does that ever happen) and pushed the old girl back for some fuel. Filled up, paid, and went to drive on. Hit the starter and she fired up immediately, but while pushing it back from the pump she cut out. Dead! Would crank forever but not even offering. I'm thinking ... airlock in the system somewhere or crap from the bottom of the tank. You could smell fuel on the exhaust whilst cranking, and the local mechanic came to my rescue with some easy start to see if we could coax her into life. Starting ok on the easy start but would not run on. Pushed it half a mile to the MOT garage. Feck! Passed the MOT as it was a re-test and the mechanic only had to check the wheel bearing. Went back tonight to try and work out what was wrong. Ignition on, could hear the pump whir .... and bike started first time. Didn't last for long though and cut out after a few revs. Lifted the tank, and notice that one of the quick fit fuel connectors had come adrift (White one, not sure if it's send or return). Refitted it and dropped the tank back down. Tried to restart and nothing. On checking I now find that the fuel pump is not priming when the ignition is turned on. You can hear the relay click under the seat, but no pump! Guess that's why she's not running!! Any clues guys? I've checked for loose connectors or rubbed wiring, all looks ok. The pump is obviously not bad as it *was* whirring when I first turned on the ignition. The relay must be good for the same reason. Any help or suggestions appreciated! I'm stumped!! Cheers, Ripface.
You can't rule out the pump nor the relay as either of them could be intermittent. The relay might click but not make contact. Try swapping the relay. Also check that the ECU earth is secure.
as above, plus after trying a new relay it's worth testing to confirm power is getting to the pump and then if necessary even checking pump runs with a separate power supply.
Hi David, As posted, the pump did initially run at the MOT station when I first turned on the ignition ... so power *was* getting there. Will swap out the relay tomorrow and see if that saves the day! Cheers, John.
Check the fuse for the fuel pump relay, the larger amperage of the 2 under the seat (on a 916 anyway). They get hot, especially if the filter isn't changed for a while (or the pump overloading by pumping against a 'dead-end'?). The whole fuse & fuse holder on mine melted into a snotty lump of plastic and although it actually was still working, it wasn't going to be for long.
All good suggestions, thanks for the feedback. I'll be sure to let you all know how I get on ... missing getting out on the old girl in this nice May weather. Cheers, John.
Hi Again, Spent another fruitless hour on the beast! This gets weirder and weirder .... Walked up to 996, insert key, turn ignition. Pump whirs into life for the prime cycle. Ignition off .... and on again 'coz I didn't believe my ears. Pump whirs into life for the prime cycle. Hits the starter and she fires up first go. Rev Rev ... seems ok ... then dies! Ignition off .... and on again .... no priming cycle. No more pump. Checked the fuses and the relay, all good. Relay is clicking, and checked continuity across the feed. All ok. Checked for power at the pump connector, 12v whilst on the priming cycle. 12 while cranking. So I guess the fuel pump has some strange issue, left overnight it seems to work for a while, but then just dies and will not work. Anyone seen this before or have a reasonable rational for this behaviour? Cheers, John.
I have a 10A fuse under my seat of my 916 which when removed doesn't allow pump to run. I have no idea why its there other than it may be to do with data tool veto plus alarm. It doesn't isolate the starter though. Its right by the alarm. Just throwing that out there in case its a straw worth clutching at. BTW to bypass this alarm I can pm the details to anyone interested.
if you can get in to the pump loom, pump side with a test light to check for power especially in conjunction with a multi meter do you need to give it a direct power supply?
Did you actually replace the relay as suggested? Also, ime, fuses can be intact but not making proper contact, so it's worth sliding them in and out a few times to remove any oxidation.
John, a common failure of electric pumps in cars is a motor windings resistance break down when the pump windings get hot and the windings resistance goes beyond its operating range, stalling the electric motor. One reason why it is important to keep the filters clean is the fuel flow cools the motor and dirty filters cause extra back pressure causing an already powerful motor to draw even more power without the fuel flow to cool the extra heat generated. In some applications they can go into melt down when there is a blockage and have been cited as the cause of quite few significant air crashes and vehicle fuel tank explosions. The pump has a 20A fuse and pumps up to 75psi which is an indication of how much power it can take to run (3x as much current as the head and rear lights). You can end up with the motor drawing progressively more power whilst the cooling flow reduces and the motor will give up but a failure of this type will not normally blow the fuse so it is not always that obvious. The speed of its demise can be faster if the tank is nearly empty as there is less fuel at a cooler temperature to cool the motor, the fuel gets warmer as you use the bike. I had a Lancia many years ago which would break down after 20 miles in the summer and only when the temperature outside was over 20c. On one occasion it started missing and I was able to roll down a hill to a petrol station to fill it up and the fault cleared. The maybe 20-30c cooler fuel meant the pump worked. I eventually discovered you could clear the fault by spraying water from a garden hose over the fuel pump casing. It took two years to diagnose it. Similar failures can afflict relays, a lot easier and cheaper to fix
Yes you do, it's the quickest way to rule out the bike's loom/fuse/ECU/relay while you test to see if the fuel pump is in fact the problem.
multimeter and test light allows you to do that Chris without disturbing to much. you can get 12v with a bad connection. put a test light on it and 12v remains chances are the connections are good. open circuit worn brushes or partly seized at consumer.
Hi All, Thanks so much for all the great suggestions. Planning to lift the tank and take it home for more investigation ... don't like taking up space in the MOT garage by working on it there ... although the guys don't seem to mind. Is it best to test the pump in situ, or remove it? With the tank removed I guess there will be no where for the pump to ... well ... err ... pump and I don't want to exacerbate the situation by running it dry. Any suggestions for Ducati 996 fuel pump test scenarios? Cheers, John.
@Old rider Hi, yes ... I swapped the two relays round ... but also tested them for continuity across the feed and both seem to be working fine. Fuses were pulled and tested for continuity, no corrosion evident and they were reseated carefully. Cheers, John.
Test it in situ, take a wire from the battery to pin 1 of the pump connector (Brown white on the loom connector, and you may need to take an earth from pin 2 to the frame to validate the earth. Whilst you in there check that there is a black wire connected to the ecu-frame mounting or thereabouts as it is one of the earths for the back end including the fuel pump
@Denzil the Ducati Thanks Denzil, I'll give that a whirl. I note that there are four wires leading to the pump, I presume the smaller cores are for the low fuel light? Cheers, John.
John the blue one comes from the fuse box (pin 3 at the pump plug), the blue/black one (pin 4)goes to the fuel warning lamp on the dash. The fuel level switch simply completes the circuit when the switch is triggered by low fuel. The circuit earth is from the clocks
