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From: john hamilton on 24 Jun 2010 10:25
After my car was diagnosed with fuel starvation by recovery, my first
response was to buy a new petrol pump, but have since learnt I'd better
check the pump relay and the actual pump first.

I checked what fuses (1994 Corolla) I can find, that's one by the passenger
foot well
and more under the bonnet but I cannot see a blown one.

I've now got the pump out of the petrol tank. Would the pump be 12volt on a
94 corolla? and could I connect its terminals to a 12volt Halfords trickle
battery charger safely to test if that powers the pump up?

For some reason when I finally found my cheapo voltmeter not used for years,
I find it gives a crazy voltage reading. I must get another voltmeter, does
anyone
recommend a place to buy a cheap one, preferably digital?

As far as testing the relay is concerned is it again alright to again use a
battery charger as a power source? I wonder if this is all getting a bit
beyond me and would a 'mobile call out electrician' really be the way to go?
I can't guess how I could locate a good one (North London) without getting
someone who will charge some enormous amount. Thanks for any advice.



From: Chris Whelan on 24 Jun 2010 11:12
On Thu, 24 Jun 2010 15:25:28 +0100, john hamilton wrote:

> After my car was diagnosed with fuel starvation by recovery, my first
> response was to buy a new petrol pump, but have since learnt I'd better
> check the pump relay and the actual pump first.
>
> I checked what fuses (1994 Corolla) I can find, that's one by the
> passenger foot well
> and more under the bonnet but I cannot see a blown one.
>
> I've now got the pump out of the petrol tank. Would the pump be 12volt
> on a 94 corolla? and could I connect its terminals to a 12volt
> Halfords trickle battery charger safely to test if that powers the pump
> up?
>
> For some reason when I finally found my cheapo voltmeter not used for
> years, I find it gives a crazy voltage reading. I must get another
> voltmeter, does anyone
> recommend a place to buy a cheap one, preferably digital?
>
> As far as testing the relay is concerned is it again alright to again
> use a battery charger as a power source? I wonder if this is all getting
> a bit beyond me and would a 'mobile call out electrician' really be the
> way to go? I can't guess how I could locate a good one (North London)
> without getting someone who will charge some enormous amount.
> Thanks for any advice.

Why not just connect it directly to the battery to see if it runs? (A
trickle charger may not be able to supply enough current.) Use whatever
bits of wire you have laying around; if you're careless, nervous, or
both, make up a lead with an inline fuse. Chance are you could carefully
use jump leads if that's all you have.

Don't run the pump dry for too long.

You can't just power up the relay to test its function; there are
essentially two parts to it. Firstly, the magnet coil. If you can
identify which terminals of the relay are the coil, connecting 12v to
those should make it click, and show that part is probably working.

However, the likeliest failure mode is that the contacts that the
magnetic part operate are worn. You won't be able to check that, at least
without a multi-meter.

Best bet is to try another relay. A generic one is not going to be
expensive. There may be another suitable one on the car that you could
temporarily use, but be sure it is suitable first.

Alternatively, identify which two pins of the relay socket connect to the
switching part. Bridge those with a short bit of wire poked in the holes.
With the ignition on, the pump should then run. If so, the relay or the
supply to the relay coil is the fault.

TBH, if you really are not confident about this sort of stuff, and you
run an older car, AA/RAC cover would at least give you a chance of some
fault diagnosis.

Chris

--
Remove prejudice to reply.
From: Dave Plowman (News) on 24 Jun 2010 13:54
In article <hvvpsv$ju$1(a)news.eternal-september.org>,
john hamilton <bluestar95(a)mail.invalid> wrote:
> After my car was diagnosed with fuel starvation by recovery, my first
> response was to buy a new petrol pump, but have since learnt I'd better
> check the pump relay and the actual pump first.

Do you mean starvation - ie not enough fuel - or none at all?

> I checked what fuses (1994 Corolla) I can find, that's one by the
> passenger foot well and more under the bonnet but I cannot see a blown
> one.

The driver's handbook usually gives details of where the fuses are and
what they do. If there's not a list on the actual fusebox.

> I've now got the pump out of the petrol tank. Would the pump be 12volt
> on a 94 corolla? and could I connect its terminals to a 12volt
> Halfords trickle battery charger safely to test if that powers the pump
> up?

Pumps usually take more current than a trickle charger could provide. But
many battery chargers won't give any output unless connected to a battery
anyway. And aren't suitable as a power supply substitute. So why not just
use the car battery?

> For some reason when I finally found my cheapo voltmeter not used for
> years, I find it gives a crazy voltage reading. I must get another
> voltmeter, does anyone recommend a place to buy a cheap one, preferably
> digital?

Is the internal battery flat? If you switch it to resistance and short the
leads, does it read zero, or near zero? Ebay is full of cheap DVMs and
they're usually ok for simple things. Or Maplin.

> As far as testing the relay is concerned is it again alright to again
> use a battery charger as a power source? I wonder if this is all getting
> a bit beyond me and would a 'mobile call out electrician' really be the
> way to go? I can't guess how I could locate a good one (North London)
> without getting someone who will charge some enormous amount.
> Thanks for any advice.

You can test relays, but it sounds like it may be beyond you. If it is a
standard type, take it to a decent accessory shop and see if they can
supply a spare - should cost about a fiver, so better to eliminate it by
substitution of a new one if possible. If it is a unique type and a
maker's spare is expensive, ask again.

Hear's a mail order source of the common relays:-

http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/relays.php

--
*Hard work has a future payoff. Laziness pays off NOW.

Dave Plowman dave(a)davenoise.co.uk London SW
To e-mail, change noise into sound.
From: Stu on 24 Jun 2010 14:48
On Thu, 24 Jun 2010 15:25:28 +0100, "john hamilton"
<bluestar95(a)mail.invalid> wrote:

>After my car was diagnosed with fuel starvation by recovery, my first
>response was to buy a new petrol pump, but have since learnt I'd better
>check the pump relay and the actual pump first.
>
>I checked what fuses (1994 Corolla) I can find, that's one by the passenger
>foot well
>and more under the bonnet but I cannot see a blown one.
>
>I've now got the pump out of the petrol tank. Would the pump be 12volt on a
>94 corolla? and could I connect its terminals to a 12volt Halfords trickle
>battery charger safely to test if that powers the pump up?
>
>For some reason when I finally found my cheapo voltmeter not used for years,
>I find it gives a crazy voltage reading. I must get another voltmeter, does
>anyone
>recommend a place to buy a cheap one, preferably digital?
>
>As far as testing the relay is concerned is it again alright to again use a
>battery charger as a power source? I wonder if this is all getting a bit
>beyond me and would a 'mobile call out electrician' really be the way to go?
>I can't guess how I could locate a good one (North London) without getting
>someone who will charge some enormous amount. Thanks for any advice.
>
>
All the fuel injected cars I've seen will switch the pump on for a
couple of seconds as you turn the ignition on, to pressurise the
injectors.

This being the case, couldn't you do a simple test of the wiring,
relay & fuse by substituting the fuel pump for a headlight bulb? Flick
the ignition on and if it lights up nice and bright, you have a
healthy power supply to your pump. The other advantage to using a
bulb, besides providing a quick indication, is that it will draw a few
amps of current and prove your connections are good.

Stu
From: Dave Plowman (News) on 24 Jun 2010 18:25
In article <co97265m0seku1tsg0v1i0nmq846gmhai9(a)4ax.com>,
Stu <no(a)spam.com> wrote:
> All the fuel injected cars I've seen will switch the pump on for a
> couple of seconds as you turn the ignition on, to pressurise the
> injectors.

My early Rover with EFI doesn't. Operating the starter does, though.

> This being the case, couldn't you do a simple test of the wiring,
> relay & fuse by substituting the fuel pump for a headlight bulb? Flick
> the ignition on and if it lights up nice and bright, you have a
> healthy power supply to your pump. The other advantage to using a
> bulb, besides providing a quick indication, is that it will draw a few
> amps of current and prove your connections are good.

If it does run the pump when you switch the ignition on you should be able
to hear it - perhaps from outside the car.

--
*I'll try being nicer if you'll try being smarter

Dave Plowman dave(a)davenoise.co.uk London SW
To e-mail, change noise into sound.
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