Fuel pump issues, HELP please :)

[L18M]

One day the fc was working fine, the next day it just won\'t start.
Thought i flooded it but took plugs out and checked them and cleaned them.
Got spark as can feel the heat after trying to crank engine over.

Noticed the fuel pump doesn\'t prime. Checked fuses, all ok. Checked there\'s power going to the fuel pump (took the harness off and put volt meter acros + and -.
Didn\'t try testing pump as didn\'t fancy turning into a human fireball.
Replaced fuel pump with brand new pump and still doesn\'t prime.

Fuel pump is hard wired to the battery via a replay, replaced the relay and still fuel pump does not prime.

Any ideas? :Hammer

[TiddlesRX7]

Sounds like a duff pump or a serious blockage in the fuel filter to me mate.

[the hat]

Remove the fuel pipe from where it exits the filter and simply blow through it back toward the tank too check for blockages

[L18M]

good ideas thanks
umm.. where;s the fuel filter? thought it\'s in a pig of a place to get to like above the rear diff?

I\'ve got a new pump in there and it doesn\'t make a noise when ignition is on. I would of thought the pump would still make a noise even if line is blocked?

[the hat]

The fuel filter is situated on the passenger footwell at the base of the bulkhead it\'s easy too get at

[Prof]

IS it stock ECU?
 
If so you could short out the yellow 2 pin connector near drivers shock tower and the turn the key to ign, the fuel pump should be fully on

[L18M]

Thanks Stuart

Dave, am running ap engine ecu.

[TiddlesRX7]

Whilst you have the fuel filter off. Pop the end of the pipe into a jar and turn the ignition on. You should get some fuel out of the pipe if the pump is working.

Ade

[Prof]

Thanks Stuart
 
Dave, am running ap engine ecu.

Does the AP ECU emulate the fuel pump resistor circuit as well, or just control pump on/off ?
 
Either way - I\'d look to see if you are getting 12V or 0v (which ever way it switches) to the relay from the AP fuel pump output - it\'s probably more likely to be a transistor output that grounds out one side of the relay coil - the other side should be tied via a fuse to the battery+
 
Have you got details of the fuel puimp wiring ?  Or pics even ?

[L18M]

Does the AP ECU emulate the fuel pump resistor circuit as well, or just control pump on/off ?
 
Either way - I\'d look to see if you are getting 12V or 0v (which ever way it switches) to the relay from the AP fuel pump output - it\'s probably more likely to be a transistor output that grounds out one side of the relay coil - the other side should be tied via a fuse to the battery+
 
Have you got details of the fuel puimp wiring ?  Or pics even ?

Not sure about the ECU
No fuses that i can see between the relay and battery or relay and pump.

I think is wired in like this. Just got me thinking, maybe the ecu feed has come loose? if i connect pin 30 to the battery, that should activate the relay and can eliminate the possibility of the ecu / relay being disconnected?

oops 30 should say ecu.
[ATTACH]56045[/ATTACH]

[Prof]

Liam - you really should put a fuse in the circuit :2eek
 
But yes, if the relay coil contact that comes from the ECU has come lose the relay won\'t switch. If the other side of the coil is grounded, then just detach the ECU wire (to avoid messing with it) and try feeding the relay from 12v feed.
 
I have to say, normally the ECU feed will be floating (no voltage) and will be pulled down to ground when it activates, so you should find the relay coil has a 12V on one side of the coil and is pulled low by the ECU the other side.
 
You can connect a small 12v bulb to the ECU wire and then test it against the battery + and battery - contacts - see if it lights when you turn the ignition key which should prime the pump, that will tell you which way the relay should be wired.

[L18M]

Ok thanks dave. will try out in weekend.
What size fuse? the guy who did the wiring didnt put one in.

[L18M]

I\'m back.. with repeated problem

Issue: fuel pump not priming. fuel gauge is dead low (have 1/2 a tank of fuel or there about in there)

Checked:
1) multi meter across +ive and -ive of fuel pump and there is a resistance
2) 30amp relay for fuel pump is working. its clicks on and clicks off.
3) fuel pump earth is good, contact with bare metal
4) i\'ve tried contacting the fuel pump +ive waire direct to batter and still doesn\'t prime (no noise, fuel pump still in tank but being a bosch 044 its quite audible when its running)

Questions:
1) if there is a reading on the multi meter on the fuel pump then fuel pump should be good? what readings are good / bad?
2) why would my fuel gauge drop from mid level to below zero (not sure if the fuel sensor wires have been mess with in past but i\'ve only tinkered with the +ive and -ive wires for the replay, the ones that switches the relay on and off.

Thanks

[Prof]

On the FC, the wiring for the fuel sender takes a negative feed from the pump to that small plate bolted to the top of the fuel tank, which is actually surprisingly well insulated by the rubber gasket it sits on, I had to take a flying earth connection to that plate to enable the sender again when I wired my walbro pump in, as it only came with a wire harness that fed the pump only, and missed that vital earth for the sender.  Try grounding out the plate using a jump lead or test lead and see if your fuel meter starts working  (might need 2 of you ;-) )
 
As for the pump, it sounds like it might have gone partially out of circuit - your resistance check should be a few ohms for a working pump, if it\'s higher I\'d say bad joint or the pump has gone higher resistance and failed.

[Bone]

Fuel pump knackered. Fuel gauge could be the gauge itself, wiring, or sender. Check the earth for the sender isn\'t corroded on top of the fuel tank cover first as it can easily rust up.