VN fuel pump / fuel supply issues

[Gosling1]

Hi - have had a look at the threads on fuel pumps for the Series 1 - didn't find the answer I was looking for.......

Had a fuel pump die last week - no probs, picked up a Goss pump at Supercrap for $90.

Installed on Friday morning........worked for 2 1/2 days - then failed on Sunday afternoon just gone........

Exchanged the failed pump for a new one today - installed it..............and still no action ! Car cranks over but no pulsing felt through the supply line under the bonnet when ignition turned on....

Checked the fuse & relay - all good. Pulled the pump out and checked continuity of the wiring/plug on the pump assembly - all good. Will be checking the +12v fuel pump supply plug under the car tomorrow to make sure that there is a a good supply voltage........

Is there anything else that could possibly go wrong with the fuel pump or fuel supply that I am missing here ????

Any help / tips appreciated.

 

[VR38]

Nope, pretty much have it covered.

 

[strgas]

don't forget to check the earth return circuit , check electrical connections for correct crimp and tension of the female plugs alignment of the pins etc etc , any loose wires or poor connections which can easily cause a high resistance or poor earth .

Favourite 1st year mistake when installing a new fuel pump was to leave the cap on the discharge port or cocking up the connector from the fuel pump to the outlet pipe . then try to start the engine with zero fuel pressure .

 

[drewVHSS]

Had this issue on my previous stato the final week before the new owner picked it up.
I thought it was the pump, replaced the pump, still no life signs...
For 2 months leading up to the pump not working I kept blowing fuel pump fuses, at least twice a week at random times.
couldn't work it out until I played with the oil sender plug on the engine as it's connected to the fuel pump backup power supply.
Well oil squirted out of the electrical connection whilst turing the engine over..... seems the oil switch was the issue because as soon as I replaced it the fuel pump came to life and it stopped blowing fuel pump fuses.
I should've guessed the oil sender was on it's way out because for 4 months the oil light would come on on startup for around 1-2 minutes of driving despite having plenty of oil on the dipstick and no apparent lifter noise you would expect from a lack of oil.........

 

[wortus]

If you want to check the pump and wiring the first thing I would do is take out the fuel pump relay and check fro +12V on one of the normally open contact in the relay base, this confirms there is power and the fuse is OK. Next bridge the normally open contacts in the relay base. This should supply +12 volts to the pump not just a pulse when you turn the ignition key. If the pump runs then it's probably an issue with the oil sender unit, disconnect the plug from that, work out which 2 wires are for the fuel pump and bridge them out, if it runs it's the sender, if not you have to do some checking of the wiring for damage or corrosion.
You can also get under the car and check the connections are not corroded etc. Another test is to run +12V down to the fuel pump connector and see if the pump runs (don't put it in the earthed side of the connector and make sure you run it from a fuse not straight from the battery). This will confirm an issue with the pump or the circuit.

 

[Gosling1]

thanks for the help :thumbsup: got it sorted late this afternoon. Relay tested fine and getting a solid +12v at the wiring plug for the pump. Fitted pump again - heard the pump working when the ignition was turned on and getting fuel pressure at the line up under the bonnet. Wortus I had a good look at the oil pressure switch and wiring - its a new switch and wiring looked in good nick. I think the power to the fuel pump only goes through the oil switch if the fuel pump relay fails ?? But in any case, no oil spraying out anywhere, I think the oil switch is OK.

Weird things still happening though.....the LPG system on this old girl is a duel-fuel setup. It always starts on fuel, whether the switch is set to LPG or petrol. In this case the switch was set to petrol - and despite the fuel pressure at the inlet line near the firewall - it still wouldn't start. Tried several times.......almost fired but would just not kick over.

I changed the switch to LPG - which still means it starts on petrol and flicks over to LPG at around 1800rpm........and the motor started and run immediately.

NFI what the go is with that, but I will run it past my LPG installer and ask him what the go is. Drove around a bit this arvo, stopped and started the car 1/2 dozen times and all seems to be working 100% now.

 

[wortus]

The fuel pump gets a "pulse" of +12V for a short while when you turn the key on to pressurise the fuel system, this allows the engine to start and the theory is that once the engine starts the oil pressure comes up, closes a contact in the oil pressure switch which then supplies power to the fuel pump. This is to stop the flow of fuel if the engine stops for some reason.
Most LPG converted cars need to start on petrol and switch to gas at some point, usually when up to pperating temperature. If your car starts on fuel only when it's set to LPG then the wiring mods to the factory fuel pump circuit sound sus.
Take out the fuel pump relay and get a short length of wire and pit a male spade on each end and bridge out the pins in the base that correspond to the normally open contacts of the realy, you should hear the fuel pump run continuously with the ignition on, if it doesn't check the added wiring from the LPG installation as it sounds like the problem? if the pump runs continuously see if the car starts, it most likely will.
Can you trace back the LPG wiring to where it is spliced into the factory loom and see if it was done properly?

 

[Gosling1]

OK thanks for the tips - our LPG install has a LPG gas gauge on the lower dash, with a switch to switch between LPG and fuel. Normally - and this has been the case since the install back in 2005 - when the switch is on the LPG setting - the car always starts on fuel and then switches over to gas at a pre-determined rpm point. Ours is set to 1500rpm. For the past 8 or so years - nil issues with this system or the fuel pump....you can flick back to fuel at any time and the car just keeps going.....

I did fit a Series 2 motor to the VN last year - everything has been working OK since the install (LPG and fuel systems)....

I can trace the LPG wiring back into the stock loom, will have a good look at all that and see if any probs with wiring connectors etc.

Won't get a chance to do any of this before the Superbikes trip next week though :beer chug: will have a look when I get back from that.