Heeeelp fuel pump won't prime :-(
29-09-2009, 05:30 PM
#1
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Heeeelp fuel pump won't prime :-(
To add to all my baffleing electrical problems, my fuel pump won't prime??! J have taken it out and checked the pump and it's ok, seem to be getting 12.6v when turning the key on, am completely lost? Any ideas?
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30-09-2009, 02:49 PM
#11
You're not thick or alone in being confused with this dilema, where you have the necessary voltage but a good working unit doesn't work.
The reason is there is a majorly bad connection, so whilst it can easily read 12.6 or whatever, it can't supply this under load, or a electrical item, the amount a multi meter uses is nothing compared with the pump.
It is more likely to be a bad earth, so you could pull off the connectors and try a substitute live and earth in turn to see which is missing, my money says earth is dodgy.
Missing lugs will NOT stop it from priming first thing in the day, but the prime is a
temp/time related thing so won't do it all the time anyway.
A missing lug will prevent it from running properly, as it will lose the spark for that cylinder.
I would get a bit of thin wire, bare the end about 1" of the wire, and tuck this into the connector plug, and push onto the pump, then connect the other end to earth or live as appropriate, make sure it is a decent earth though, not a cruddy piece of rusty metal!!
tabetha
The reason is there is a majorly bad connection, so whilst it can easily read 12.6 or whatever, it can't supply this under load, or a electrical item, the amount a multi meter uses is nothing compared with the pump.
It is more likely to be a bad earth, so you could pull off the connectors and try a substitute live and earth in turn to see which is missing, my money says earth is dodgy.
Missing lugs will NOT stop it from priming first thing in the day, but the prime is a
temp/time related thing so won't do it all the time anyway.
A missing lug will prevent it from running properly, as it will lose the spark for that cylinder.
I would get a bit of thin wire, bare the end about 1" of the wire, and tuck this into the connector plug, and push onto the pump, then connect the other end to earth or live as appropriate, make sure it is a decent earth though, not a cruddy piece of rusty metal!!
tabetha
30-09-2009, 04:02 PM
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cheers tab! will go have a look now! I will also check all my earths, as this might be the problem to all my electrics.. dont suppose you know where i can get a diagram of the earth points do you?
01-10-2009, 01:12 PM
#13
I don't think there is any piccies to show the earth points, but the ecu earth is on the plenum side on the bolt/nut that holds the throttle cable bracket, it will have 2 or 3(can't remember) ring terminals here under the nut.
The pump is a switched live, from the relay, so it will not hurt at all to put another earth on, although most other stuff is switched by earth, ie injectors.
tabetha
The pump is a switched live, from the relay, so it will not hurt at all to put another earth on, although most other stuff is switched by earth, ie injectors.
tabetha
02-10-2009, 04:31 PM
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Cheers again Tab, gonna have a crack at it tomorrow.. on the off chance that its actually the power, is there anywehre i can get a loom from? guessing ford dont have them anymore...?
03-10-2009, 11:38 AM
#15
If needing new power to the pump just do a rewire, dead easy, can even buy them already done, I don't have any at the mo, but Ryan sells them and his are top notch as well.
tabetha
tabetha
03-10-2009, 02:36 PM
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oh nooooooooo!
well i wired a live to the pump to see if it was the earth at fault and it wasnt. so i thought i would start at the relay and work my way forward, took the lid off the relay and turned key, nothing. tried relay straight from battery, relay clicked like mad... so my money is now on fusebox how about you?!
well i wired a live to the pump to see if it was the earth at fault and it wasnt. so i thought i would start at the relay and work my way forward, took the lid off the relay and turned key, nothing. tried relay straight from battery, relay clicked like mad... so my money is now on fusebox how about you?!
03-10-2009, 03:05 PM
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forgot to mention that we wiggled the relay and the fuel pump primed. and since we did fiddle about with it, it seems to be workin... for now! but not taking it anywhere, until i can diagnose the prob.. is it worth me buying a relay..?
03-10-2009, 05:03 PM
#18
It could be the relay, but first remove the cover of the relay, so you can see the contacts that close to complete the circuit, ie the one that it switches.
Now put relay back in, and press the contacts closed if it works perfectly everytime a new relay will cure it.
tabetha
Now put relay back in, and press the contacts closed if it works perfectly everytime a new relay will cure it.
tabetha
03-10-2009, 07:50 PM
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I took it out today and it wasn't working so I pushed it closed a few times, then connected it straight to the battery and it worked fine and has since, will try it again tomorrow as last time it did this it stopped again after leaving it a few hours. What I don't get is where the 12v came from when we tested it without the pump connected, is it possible for a relay to give up under load? Is this what u were saying to try?
04-10-2009, 02:56 PM
#20
It's entirely possible for the relay to energise and switch as normal, but if there is burning on the contacts, although it will show 12v on a meter it won't deliver any guts so to speak, when you put under load, quiet normal.
If not too badly done they can rescued with DE-OXIT, but it's bloody expensive stuff, especially in quantity, so new relay is cheaper, you could always rig a few lights up to tell you if you lose power either as an output from relay to pump, or as a switching feed to relay from ecu, bit of messing about but tells you what is what if it conks out.
tabetha
If not too badly done they can rescued with DE-OXIT, but it's bloody expensive stuff, especially in quantity, so new relay is cheaper, you could always rig a few lights up to tell you if you lose power either as an output from relay to pump, or as a switching feed to relay from ecu, bit of messing about but tells you what is what if it conks out.
tabetha
08-10-2009, 07:55 AM
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Sorted! After cutting out on the m60 on the way to work yesterday I checked the relay and nothing, swapped for an identical one that was in the fuse box and off I went! Alot cheaper than a fuse box! Thanks all for your help
john
john
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