nikpro
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| posted on 3/5/06 at 10:00 AM |
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Fuel Pump Not running
My mate has an MK Indy that runs a 16ooVX engine using the Vauxhall ECU. The car has been converted to run with R1 carbs but recently it's
developed a problem where the fuel pump runs intermittently. This has got gradually worse and now the pump only occasionally runs as the engine is
cranking and stops as soon as the engine starts and the ignition is released.
Is this likely to be an ECU problem.
I thought of the relay but surely if the pump is running whilst the engine is cranking the relay must be OK?
He didn't build the car and there are about 6 relays under the dash and I can't think how to find the one that controlls the fuel pump.
Is there also likely to be a relay to feed power to the ECU?
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IainB
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| posted on 3/5/06 at 10:17 AM |
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is it a bike pump?
http://s43.photobucket.com/albums/e365/IainB1986/
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DarrenW
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| posted on 3/5/06 at 10:19 AM |
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Can the pump be tested by running a live feed directly to it? This might isolate wether it is a faulty pump or a control fault.
Forgot to ask - does the engine run normally? If it does maybe the pump is getting up to pressure and switching off. Sounds from your description that
after initial starting it doesnt run at all so presumably the engine cuts out.
[Edited on 3/5/06 by DarrenW]
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ned
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| posted on 3/5/06 at 10:24 AM |
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My 2ltr vx has a fuel pump relay which is controlled via a signal from the (aftermarket) ecu.
Don't know if this is the same for the standard ecu but you coul dtry running a fused live direct to the pump which would discount the ecu and
relay or help to pinpoint the problem.
Ned.
doh beat me to it darren, that'll teach me to go and do some work before hitting the submit button 
[Edited on 3/5/06 by ned]
beware, I've got yellow skin
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nikpro
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| posted on 3/5/06 at 10:25 AM |
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The pump is fine, this has been checked and it is the voltage to the pump that drops when the engine is running - it goes from around 13.5v to 0.
The engine runs untill the fuel bowls on the carbs are emptied then dies.
He doesn't fancy running a switched live feed to the pump because if, god forbid, he crashes he could end up with fuel pumping out
everywhere.
[Edited on 3/5/06 by nikpro]
[Edited on 3/5/06 by nikpro]
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ned
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| posted on 3/5/06 at 10:32 AM |
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well its still worth doing to test it imho. you could then look at changing the ecu if that turns out to be the problem. otherwise you can get a
rollover type switch inline with the power feed so if the car goes over the fuel pump power is cut.
Ned.
beware, I've got yellow skin
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graememk
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| posted on 3/5/06 at 10:41 AM |
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i have mine live with a roll over knock switch, as my ecu used to tell the pump to come on and off when it felt like it.
got my switch from ebay 7.50 inc pnp
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DarrenW
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| posted on 3/5/06 at 10:44 AM |
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i didnt mean run a permanent live to it - justa temp one to test the theory out.
As Ned says you could fit an inertia valve / switch jobby if you decide a permanent live is the easiest way to fix the fault as this will cut the
power in a crash.
I have known fuel pump relays to fail before. i located mine in my old Golf as it was very hot. New relay fixed it. I also had a fuel pump fault once
that was caused by an badly fitted immobiliser. The immobiliser should be fitted to the low current side of the fuel pump relay as they can only
handle low current. It was actually spliced into the main feed that caused a major voltage drop and stopped the pump working. It was Ok at first but
slowly got worse. That took a lot of finding.
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britishtrident
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| posted on 3/5/06 at 11:59 AM |
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Some older Rover systems used the oil presure switch to triger the hold on signal for the fuel pump relay. Oil pressure switch would fail and cause
the same symptoms you describe.
[Edited on 3/5/06 by britishtrident]
[Edited on 3/5/06 by britishtrident]
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rusty
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| posted on 3/5/06 at 12:45 PM |
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sounds like the pump relay as it probley has to coils, one to pull it in during cranking and one which the ecu pulls in when it knows the engine has
fired.
Sounds like the coil the ECU pulls in had an intermittant fault and has now totally had it.
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rusty nuts
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| posted on 3/5/06 at 05:46 PM |
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Start the engine and pull the relays out one at a time , wait a few seconds then try next one . Engine will stop when you pull the fuel pump relay
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ned
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| posted on 3/5/06 at 06:14 PM |
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quote:
Originally posted by rusty nuts
Start the engine and pull the relays out one at a time , wait a few seconds then try next one . Engine will stop when you pull the fuel pump relay
erm no it won't as it will have to use the fuel thats in the float chambers first as he's aleady said so wil have to wait 30secs or so
inbetween each one waiting
beware, I've got yellow skin
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Mark18
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| posted on 3/5/06 at 06:18 PM |
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quote:
Originally posted by IainB
is it a bike pump?
Why do you say that? My bike pump doesn't seem to be working.
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omega 24 v6
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| posted on 3/5/06 at 09:12 PM |
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The old v/hall carltons etc were renowned for faulty fuel pump relays. The coils go on them intermitantly as already posted. Also if it's
running the original ecu and pump relay, then the relay will only be pulled in when the engine is turning (cranked or running), so that in the event
of a crash/engine stall fuel does not spew everywhere.
If i can find my old carlton manual I'll have a look see for more info.
The ralay itself will be more recognisable(sp) as it has 6 (if my memory is right) terminals on it and is double the height of a std relay (like some
flasher units).
All of this will only apply if the original gear from thr v/hall was fitted.
Good luck.
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nikpro
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| posted on 3/5/06 at 11:11 PM |
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quote:
Originally posted by omega 24 v6
The old v/hall carltons etc were renowned for faulty fuel pump relays. The coils go on them intermitantly as already posted. Also if it's
running the original ecu and pump relay, then the relay will only be pulled in when the engine is turning (cranked or running), so that in the event
of a crash/engine stall fuel does not spew everywhere.
If i can find my old carlton manual I'll have a look see for more info.
The ralay itself will be more recognisable(sp) as it has 6 (if my memory is right) terminals on it and is double the height of a std relay (like some
flasher units).
All of this will only apply if the original gear from thr v/hall was fitted.
Good luck.
The biggest problem is that it seems to be a right mish-mash in the electrical department. I think it has the Vauxhall engine loom; a loom from a
sierra and anything else the builder felt like putting in there! It's a shame because mechanically it's beautifully put together.
Trying to locate the fuel pump relay is the real problem as it is only running intermitently when the engine cranks and not at all when it fires - it
coughs and splutters on the fuel in the carbs for about 20 secs before dying.
I think we will have to continuity test wires from all the relays to the pump. Unfortunately the wires are one colour in one place; they go into some
loom tape and appear different colours at the other end!! - Bugger.
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rusty nuts
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| posted on 4/5/06 at 05:11 PM |
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Sorry Ned , just reread original post but same thing applies if thee fuel pump runs when cranked remove relays one at a time, crank over and check
pump operation? Also have you checked fuses? could have been wired with a fused pump relay . Check for fuel pump cut off?
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