Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum

Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum (
-   General Technical Chat (
-   -   No pump voltage (

custommoggy 08-25-2012 10:04 AM

No pump voltage
1998 1.8 Mk1 petrol zetec, chopped into a custom car, using all the original harness ecu etc, there is no supply to the fuel pump, all the ecu voltages seem to be correct, I believe pin 53 is supposed to ground the pump relay to complete the circuit? I believe this is not happening, there may be a sensor unplugged somewhere or another issue such as immobilizer? If I hook up the pump to a 12v supply, the car will start and run for a second or two, then stop, the pump is running continuously like this but it shows there's a spark, if I turn the key again it'll start again for a second or two.
Now I believe the fuel regulation is controlled by the ecu so the correct amount of fuel is injected and by running the pump direct from 12v this will just deliver the maximum fuel, thus the car starts, then I suspect the ecu is seeing something it doesn't like and switching off the ignition thus stopping the car, now that bit is just guesswork, any ideas anyone? would it have a spark if either the cam or crank sensor was not connected for example?

I've driven myself mad reading the haynes manual![?|] any help appreciated

whynotthinkwhynot 08-25-2012 10:22 AM

Fuel cut-off switch? Also known as the inertia switch, or maybe what you call the immobilizer. It's designed to cut the fuel pump off in an accident. In US vehicles it's located on the right side kick panel of the vehicle. I'm not sure about RHD vehicles though, so check your owner's manual. To double check this switch: unplug it, use some solid insulated wire to bridge the 2 points on the conncector, try to start car. Do not run the vehicle for very long like this. If you have an accident, are unconscious, and your key is still ON, fuel will still pump. I've seen accidents on other vehicles without this safety feature where the fuel continues to pump out of the vehicle as fast as the pump will do it.

There is also the fuel pump controller which on US cars is located under the RH side rear seat. Lift the seat up, and you'll see the electronic controller there. Unplug and check to be sure you have power to the power supply side with the key On. If you have power there, and not power going out- that might be indicative of your problem. I think you'll find it in the fuel cut-off switch though.

custommoggy 08-25-2012 10:56 AM

If only it was that simple [mecry] not the inertia switch, there's no votage to that either and i've bypassed it, think it's possibly to do with the ecu seeing something elsewhere and not switching on the pump relay, what would result in that? I know the relay is fine, changed it, but the relay is switched on by the ecu or not in this case.

BC_ZX3 08-25-2012 01:11 PM

Is the fuel pump driver module correctly grounded? The ECU regulates fuel pressure by varying the pump duty cycle via the fuel pump driver module. It in effect turns the pump ground on and off very rapidly.

Lots of good operational information/links and wiring schematics here:

custommoggy 08-26-2012 04:20 AM
FPDM? There's no priming, or running, the only way I can get it to start
is to connect 12v directly to the pump, then it starts for a second and dies.
the lead back to the ecu I think is the control lead and it's not doing it's job,
may be a connection missing somewhere else causing the ecu to shut the
fuel pump control off. "I" has a 12v feed and I assume "K" is the control, ie
the ecu grounding K would switch on and off the pump the same way as the
FPDM would if it had one, I'm guessing the ecu is seeing an error elsewhere
and refusing to start the pump.

1turbofocus 08-26-2012 10:09 AM

The US car the 12v+ stays on all the time and its the ground that controls the pump , have you confirmed this with your UK car

There is a fuel pump driver in the ECU , inertia switch , driver module then the fuel pump , there is some fuses throw in there as well

Curious what you did about the PATS , maybe the UK cars dont have this ?


custommoggy 08-26-2012 12:39 PM

it's the same system, as for PATS I used the entire harness, key, column with switch gear, modules etc, not the door locks and I can't tell if the immobilizer is on or off but like I said previously it does start if i pump fuel in but only for a second or 2

custommoggy 08-26-2012 03:47 PM

How would I know if the immobilizer had kicked in? would the car crank?

BC_ZX3 08-26-2012 04:05 PM

Car wouldn't crank if the immobiliser was active.

custommoggy 08-30-2012 11:19 AM

Starting issue,
Turn the key, engine starts but wont tick over, start it and rev and there's a huge delay between throttle and engine revving, in fact if I press th accellerator pedal to the floor it revs on the way back up, here's a video, turn your sound up and you'll see what I mean, mid range is rough and misfiring.

All times are GMT -5. The time now is 06:14 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.