1 step forward - 2 back

[Northern_Paul]

Fitted the dash etc this weekend, took it out for its spin around the block and it stopped. Fuel pump isn't working - but I've been here before - in the past it was intertia switch and more recently electronic relay (both fuel pump and main engine were replaced) I've had bad connections on the pump itself.

I've also had problems with the immobilisor and alarm, I disconnected the immobilisor 3 months ago. Now I'm begining to think that the gemini alarm unit is causing this...................so my question is, does anyone know for sure that a gemini alarm malfunction can stop the fuel pump, or is the fuel pump a seperate circuit and I can fault find without worrying about the alarm???

I had thought that fitting the dash had crushed some wires etc.

[griffter]

Northern_Paul said:

I had thought that fitting the dash had crushed some wires etc.

Check the two blade fuses next to the engine and fuel pump relays - one of these is in line with the fuel pump. You may have another one in the fuse box, too - I do.

Sorry, don't know about the Gemini.

[Ballistic Banana]

I am not sure if it is the case with the Gemini Alarm, but others are fitted to immobilise the Fuel pump but through the ignition feed i think.
This is known to cause some problems with hot starting as the wire from the immobiliser breaksdown and when stopping the car when hot and then trying to re-start it wont... Not always the Fried Starter.

David Beer is the Guru in this field me thinks

BB

[Northern_Paul]

Looked for the in-line fuses and couldn't find them, but I did find some cables cut and twisted together where they might of been.

I hot wired the fuel pump last night and it worked, I'm picking up another 2 relays later today for the fuel and main engine - bosch no. 0332014112 - hope this is right as these are what are already fitted.

If this fails it's a visit from the Auto Electrician to sort out new alarm/immobilisor......sounds expensive.

[wildeep]

If the alarm and immobiliser are separate units and you have disconnected the immobiliser then the alarm shouldnt be interfering with the fuel pump or any other cirucuits, probably something simpler like a dodgy wire, also check the connections where you have bypased the immobiliser.

>> Edited by wildeep on Wednesday 25th August 09:40

[Northern_Paul]

wildeep said:

If the alarm and immobiliser are separate units and you have disconnected the immobiliser then the alarm shouldnt be interfering with the fuel pump or any other cirucuits, probably something simpler like a dodgy wire, also check the connections where you have bypased the immobiliser. >> Edited by wildeep on Wednesday 25th August 09:40

That's what I was hoping to hear, and what I thought - immobiliser was fuel etc, alarm for entry etc. Will check connections again but I'm sure they are o.k. hoping relays fix it as they did last time.

[Northern_Paul]

Replaced the relays, and with investigation it must be the ECU, the fuel relay switches on for a second and then off, I've disconnected the 'load' fuel pump and it still happens.

From the diagram on page 84(2nd edition) heavy current is waiting to come across from the injectors on a brown/orange wire(N/O) on the MAIN relay, the coil has live always on 86 brown (N) and ECU gives 85 blue/red(U/R) the circuit to latch the coil.

When MAIN relay is made heavy current is on the FUEL relay, the ignition switch supplies one side of the coil 86 white/slate(W/S) and the ECU the other 85 blue/purple(U/P), when this is made 87 white/purple supplies the Fuel Pump.

This latches for a second and then switches off, I've took the load off (cut the wires) and it still happens, I think I'm loosing the ECU signal (pin 16)to the coil on 85 blue/purple.

Any budding electrical Einstiens out there can confirm my reading of page 84???

[wildeep]

Sounds like the fuel pump is priming like it does when you just switch the ignition on without starting. I guess the ECU is missing the signal that tells it the engine is running?, not sure where this comes from?. There is a wire that runs from the coil back to the ECU, maybe check that this is connected?.

[Northern_Paul]

wildeep said:

Sounds like the fuel pump is priming like it does when you just switch the ignition on without starting. I guess the ECU is missing the signal that tells it the engine is running?, not sure where this comes from?. There is a wire that runs from the coil back to the ECU, maybe check that this is connected?.

No the fuel pump isn't priming at all - the relay latches for a second (shown on fluke meter) then opens - I never hear the pump. The reason seams to be that pin 16 on ECU is opened and this opens the relay.

>> Edited by Northern_Paul on Wednesday 25th August 19:42

[Northern_Paul]

Just a thought........everything worked fine until I connected up the instruments (the speedo has never been connected in the last 2 years).

So is it just a co-incidence that the ECU has started playing up/broken or has the conection of the speedo caused the ECU to malfunction?? or other instruments.

I know I'm asking a lot here, I'm just interested in a different point of view..............Thanks.

[wildeep]

Looks like the ECU just switches the ground to the relay coil. Maybe try running a wire from pin 85 on the relay to ground and see if it fires the pump up.

[greenv8s]

I'm confused (doesn't take much!).

The fuel pump relay closes but the fuel pump doesn't run? In that case you can ignore the ECU (it has done its job). Either the fuel pump relay isn't receiving 12v from the main power relay, or the output from the fuel pump relay isn't reaching the pump, or the pump is b*ggered. From here on it's a simple matter of following the voltage and seeing where it stops. For instance, is the relay getting 12V? If you bypass all the wiring loom and connect the relay output direct to the pump (via a fuse of course) does the pump work now?

[Northern_Paul]

wildeep said:

Looks like the ECU just switches the ground to the relay coil. Maybe try running a wire from pin 85 on the relay to ground and see if it fires the pump up.

I agree wildeep, been looking at diagram all day at work and had decided to do exactly what you said. Disconnected the wire from 85 (so as not to interfere with the ECU) and ran straight to earth from the relay and the Fuel Pump relay stayed on! Fuel pump didn't run as I'd chopped it last night (disconnected the load), but no problem. Prior to that I disconnected the speedo but it made no difference.

So after connecting the dash on Saturday, driving 400 yds something happened, either the ECU packed up or something new.

What could be happening is that the ECU is sensing a fault and shutting down the Fuel Pump, as the relay works for one second and then the coil earth opens (switching it off) as if the ECU is in control, anyone have any ideas, anyone know about pin 16 on the ECU ................thanks again for the feedback it's very reassuring

[Northern_Paul]

greenv8s said:

I'm confused (doesn't take much!). The fuel pump relay closes but the fuel pump doesn't run? In that case you can ignore the ECU (it has done its job). Either the fuel pump relay isn't receiving 12v from the main power relay, or the output from the fuel pump relay isn't reaching the pump, or the pump is b*ggered. From here on it's a simple matter of following the voltage and seeing where it stops. For instance, is the relay getting 12V? If you bypass all the wiring loom and connect the relay output direct to the pump (via a fuse of course) does the pump work now?

Greenv8s, you are reading it slightly wrong, the relay comes on for a second then off. I've hotwired the pump and it's o.k. etc etc.

I really appreciate your input, please continue NP

[heliox]

Check the two large brown wire connectors behind the dash as they are prone to breaking contact if disturbed,tie wrap together to make sure they dont come loose.

This is where you will find the fault most likely.

h

[GreenV8S]

Northern_Paul said:

Greenv8s, you are reading it slightly wrong, the relay comes on for a second then off. I've hotwired the pump and it's o.k. etc etc.

That sounds like the normal behaviour then. You should find that when you switch the ignition on you get +12v on the power input to the relay and +12v to one side of the coil, the other side of the coil is earthed via the ECU, the relay closes, power goes to the pump, the pump runs. After about 1.5 seconds, if it doesn't detect a spark pulse from the distributor, the ECU will stop earthing the coil, the relay opens, the pump stops. The ECU will take its side of the relay coil low when the engine is turning over i.e. when cranking on the starter or when running.

How does the behaviour you see differ from this?

[Northern_Paul]

Peter

I'm catching your drift, thats excellent...Thank you.

I think the ECU pushes out 12v on the 'coil earth' pin 16 to switch it off... I thought it was a controlled action rather than an ECU failure.

So it's out with the soldiering iron tomorrow night to reconnect all the wires I chopped and work further down the line - inertia switch, all fuses on fuse board, can't find in-line fuses but I will look again, pump and pump earth.

I will look into the 'motor running' feedback from the coil or distributor.
Anything else??

>> Edited by Northern_Paul on Thursday 26th August 21:23

[Northern_Paul]

This is quite refreshing............I also contacted a company called 'carelec' around Southampton via e-mail - they came back with the same as Greenv8s, it was a function not a fault.

They could of got me to send it off and charged for imaginary fix, but instead they came back with advice, like I said refreshing.

www.carelect.demon.co.uk

[Northern_Paul]

Cracked It

Re-soldiered everything I disconnected previously, traced the feed from the relay to the fuel pump and that wasn't as easy as it sounds. The white with purple stripe exits the fuel pump relay and goes behind the dash to a connector where it changes to yellow, yellow to fusebox, yellow out of fusebox to inertia switch, ineria switch to fuel pump.

I had a break in the yellow from fusebox to interia switch and as the were close I chopped and joined them, jobdone fuel pumping engine purring.

Loads and loads of thanks to contributors, I really think you've saved me an expensive trip to the auto electrician.....Thank You.

[GreenV8S]

Congratulations, glad you've got it working in the end. Well done.