760 Fuel Pump Relay

760Simon · Sep 4th, 2010, 08:39

Good Morning all

I hope you may be able to help, My 1988 760GLE V6 is refusing to start.b I have tracked it down to no power getting to the fuel pump and suspect the relay, the problem I have is that my haynes manual does not tell me were it is and I cant find it. Is there anybody that can piont me the right direction please. By the way if I feed the pump direct from the battery the pump amd the car run fine.

Many thanks for your help.

oldgit63 · Sep 4th, 2010, 10:39

Dont know if it is like the 740 it is in the centre console under ashtray area. But i think other members will be on shortly to give you more guidance.

gpl1968 · Sep 4th, 2010, 13:54

FAQ is your friend.

760Simon · Sep 4th, 2010, 20:06

gpl1968

Many thanks for the help I will have it out tomorrow take it to bits and find out whats going on. Many thanks again to the both off you

Cheers

Oilydad · Sep 4th, 2010, 20:53

You'd be better off buying a new relay.

Take it from someone who's had it happen. If the relay fails (and the engine stops suddenly and instantly) when you've got a big articulated lorry right behind you....£20 or so will suddenly seem a very small amount of money!!

Not a part to try and repair.

760Simon · Sep 6th, 2010, 20:58

Hi All
Just a quick update with some info which might help someone else.
I took the relay apart and inside there are two small relays mounted on a circuit board. The one nearest the base is for the main pump and the other is for the lift pump in the tank. The relay is operated by the ECU when the ignition is turned on, there is a diode on the –ve side of the main pump relay which looks like it is there for two reasons 1 to drop the voltage to the relay by a further 0.7v to stop contact chatter when cranking as coil is only rated at 9v & 2 to stop any possible static spike getting back to the ECU when you turn the car off. After testing the diode I found it was faulty, so I removed it after purchasing a new one from Maplins for the sum of 0.29p fitted the new one and all is well. I hope someone may find this info of some use.
Cheers all.

Sep 4th, 2010, 08:39	#1
760Simon Getting old disgracefully Last Online: Yesterday 23:45 Join Date: Jan 2009 Location: South Essex	760 Fuel Pump Relay Good Morning all I hope you may be able to help, My 1988 760GLE V6 is refusing to start.b I have tracked it down to no power getting to the fuel pump and suspect the relay, the problem I have is that my haynes manual does not tell me were it is and I cant find it. Is there anybody that can piont me the right direction please. By the way if I feed the pump direct from the battery the pump amd the car run fine. Many thanks for your help.

Sep 4th, 2010, 10:39	#2
oldgit63 VOC Member Last Online: May 9th, 2018 14:29 Join Date: Sep 2008 Location: Kidderminster in Worcestershire	760 Dont know if it is like the 740 it is in the centre console under ashtray area. But i think other members will be on shortly to give you more guidance.

Sep 4th, 2010, 13:54	#3
gpl1968 VOC Member Last Online: May 5th, 2024 23:42 Join Date: Jun 2007 Location: Wirral View Photos By: gpl1968	FAQ is your friend. __________________ Gavin 1997 945 CD (B230FK) [RIP: 1991 945 Turbo (B230FT) 1992 945 SE turbo (B200FT)]

Sep 4th, 2010, 20:53	#5
Oilydad Premier Member Last Online: Mar 21st, 2016 21:21 Join Date: Aug 2009 Location: Exeter Devon	You'd be better off buying a new relay. Take it from someone who's had it happen. If the relay fails (and the engine stops suddenly and instantly) when you've got a big articulated lorry right behind you....£20 or so will suddenly seem a very small amount of money!! Not a part to try and repair. __________________ Are We Nearly There Yet! No longer a VOLVO owner, not by choice, but 'cause they don't make proper Volvos any more! Last edited by Oilydad; Sep 4th, 2010 at 21:05.

Sep 4th, 2010, 20:06	#4
760Simon Getting old disgracefully Last Online: Yesterday 23:45 Join Date: Jan 2009 Location: South Essex	gpl1968 Many thanks for the help I will have it out tomorrow take it to bits and find out whats going on. Many thanks again to the both off you Cheers

Sep 6th, 2010, 20:58	#6
760Simon Getting old disgracefully Last Online: Yesterday 23:45 Join Date: Jan 2009 Location: South Essex	Hi All Just a quick update with some info which might help someone else. I took the relay apart and inside there are two small relays mounted on a circuit board. The one nearest the base is for the main pump and the other is for the lift pump in the tank. The relay is operated by the ECU when the ignition is turned on, there is a diode on the –ve side of the main pump relay which looks like it is there for two reasons 1 to drop the voltage to the relay by a further 0.7v to stop contact chatter when cranking as coil is only rated at 9v & 2 to stop any possible static spike getting back to the ECU when you turn the car off. After testing the diode I found it was faulty, so I removed it after purchasing a new one from Maplins for the sum of 0.29p fitted the new one and all is well. I hope someone may find this info of some use. Cheers all.

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