New hot wire install not working
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New hot wire install not working
Hi all we have just installed a Hotwire EFI 3.9 into a Range Rover that had flapper we have replaced the harnes.
We've checked there is a live supply and a switched live supply and the 2 earths go to the battery neg. the gearbox inhibit switch is working and putting an earth to the ecu. The problem we have is the fuel pump is not running the relay is getting the switched supply but it isn't getting the earth signal from the ECU.
I know there is a wire from the earth of the coil to say the car is cranking and this is connected. We have tried the ECU on another car and it works.
Will the fuel pump run when just switching on the ignition or do you need a signal from the coil before it will run? Is there something else that can stop the pump ?
Mick
We've checked there is a live supply and a switched live supply and the 2 earths go to the battery neg. the gearbox inhibit switch is working and putting an earth to the ecu. The problem we have is the fuel pump is not running the relay is getting the switched supply but it isn't getting the earth signal from the ECU.
I know there is a wire from the earth of the coil to say the car is cranking and this is connected. We have tried the ECU on another car and it works.
Will the fuel pump run when just switching on the ignition or do you need a signal from the coil before it will run? Is there something else that can stop the pump ?
Mick
- Ian Anderson
- Forum Contributor
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- Joined: Sun Nov 19, 2006 9:46 pm
- Location: Edinburgh
On a CUX14 ecu
Turn ignition on and fuel pump will run for about 3 seconds then turn off
Start cranking and the fuel pump starts up again
There is a wire from distributed to air flow meter that is easy to play verso ok and causes Jon starting
Ian
Turn ignition on and fuel pump will run for about 3 seconds then turn off
Start cranking and the fuel pump starts up again
There is a wire from distributed to air flow meter that is easy to play verso ok and causes Jon starting
Ian
Owner of an "On the Road" GT40 Replica by DAX powered by 3.9Hotwre Efi, worked over by DJ Motors. EFi Working but still does some kangaroo at low revs (Damn the speed limits) In to paint shop 18/03/08.
Re: New hot wire install not working
The pump should run for a couple of seconds when you switch on (without starting) to prime the fuel rail. It stops to prevent flooding if there was a weeping injector, and the ignition left on. Can you hear the relay click, if the pump doesn't run?texpis wrote:Hi all we have just installed a Hotwire EFI 3.9 into a Range Rover that had flapper we have replaced the harnes.
We've checked there is a live supply and a switched live supply and the 2 earths go to the battery neg. the gearbox inhibit switch is working and putting an earth to the ecu. The problem we have is the fuel pump is not running the relay is getting the switched supply but it isn't getting the earth signal from the ECU.
I know there is a wire from the earth of the coil to say the car is cranking and this is connected. We have tried the ECU on another car and it works.
Will the fuel pump run when just switching on the ignition or do you need a signal from the coil before it will run? Is there something else that can stop the pump ?
Mick
Also, are you using the correct relay for the hotwire? It is an odd twin output type, with a series diode to the coil. If the wiring to the relay coil got swapped round, the relay wouldn't operate. As you probably know there are several relay variations that fit the same 5 pin base.
According to my diagram, +12v goes to pin 86 and the coil ground to pin 85.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y
Thanks for the reply Dave I thought that is how the pump worked unfortunately mine isn't doing that. The live comes from the ignition switch to pin 86 and pin 19 on the ECU. The earth which comes from the ECU pin 16.
The relay is the one that came with the engine and loom purchased as a working set. The relay doesn't really matter because I am testing at the relay base for power, I get 12v at the base from the ignition but do not get the earth from the ECU. We know the fuel pump system works because when I earth the relay the pump works.
Mick
The relay is the one that came with the engine and loom purchased as a working set. The relay doesn't really matter because I am testing at the relay base for power, I get 12v at the base from the ignition but do not get the earth from the ECU. We know the fuel pump system works because when I earth the relay the pump works.
Mick
- SimpleSimon
- Knows His Stuff
- Posts: 620
- Joined: Mon Apr 25, 2011 10:36 pm
- Location: East Sussex
Word of warning here those Bosch Hotwire relays are notoriously unreliable so if you have got yours working by cleaning contacts etc I suggest you get a couple of spares they are bespoke for the Lucas system so not any old generic 5 pin relays will do both are identical
TVR Chimaera RV8 Mods & Megasquirt
They are basically a single pole on/off relay with twin output terminals, and a series diode to the coil. You can just about see this in my schematic above.
Vehicle wiring products do one which is suitable - but you'd have to add the diode externally. If the genuine item is a silly price.
The flapper uses a similar relay, but without the diode. Think the diode ones are identified by a red strip.
They don't seem unreliable on the flapper, though.
Vehicle wiring products do one which is suitable - but you'd have to add the diode externally. If the genuine item is a silly price.
The flapper uses a similar relay, but without the diode. Think the diode ones are identified by a red strip.
They don't seem unreliable on the flapper, though.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y
- SimpleSimon
- Knows His Stuff
- Posts: 620
- Joined: Mon Apr 25, 2011 10:36 pm
- Location: East Sussex
The same relay with the diodes was used on BMW'S back in the day too Dave, euro car parts sell a quality alternativeDaveEFI wrote:They are basically a single pole on/off relay with twin output terminals, and a series diode to the coil. You can just about see this in my schematic above.
Vehicle wiring products do one which is suitable - but you'd have to add the diode externally. If the genuine item is a silly price.
The flapper uses a similar relay, but without the diode. Think the diode ones are identified by a red strip.
They don't seem unreliable on the flapper, though.
TVR Chimaera RV8 Mods & Megasquirt