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BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

2004 Defender 90 Td5 CSW Santorini Black

Fuel Pump or Relay?

Looking for some ideas relating to a fault on my Td5 90.

Last Friday I drove up to the Peaks for the weekend. I ragged around a couple of passes before stopping in Holmfirth for lunch. At this point all was fine.

After grabbing lunch I made my way back up to the top of Holme Moss to enjoy said lunch. However, on the way up the 90 wouldn’t rev above 2,500rpm. It was down on power and not particularly happy. Got to the top and plugged in the Nanocom. No faults, MAF fine, coolant temp. fine, injectors fine.

After scoffing lunch and doing some online research I turned on the ignition and noticed something - silence from the fuel pump. In neutral it wasn’t revving as fast as it should and wouldn’t really go beyond 3,000 - 3,500rpm.

I left the 90 parked until Sunday morning for the trip home. Start-up was rough and smokey, but settled after a few short seconds.

I managed to drive at 45-60mph for 60 miles, which got me a way down the M1. After 55-58 miles I noticed I couldn’t maintain power on the flat any more, the engine was sounding spluttery, and I was holding up HGVs. I tried rev matching on the down-change, only to find it wouldn’t rev. When speed fell to 30mph, the alarm bells were ringing - I dived into Trowell services. Here the 90 was rough and barely idling. I attempted to reverse into a parking space and it stalled. After this it refused to start. The AA came and recovered me back to base fairly swiftly, which was a pleasant surprise.

Now, I think I’ve diagnosed this to a fuel pump or relay issue. The glow plug and MIL lights both illuminate correctly, but the pump is totally silent. The relay has never been changed yet the original pump was replaced with a VDO unit as a precautionary measure about 18 months back. I should hope the pump wouldn’t die so soon. Also, there are no fuel leaks.

What do people think? Pump? Relay? Earth?

Could the relay cause this kind of progressive failure? Overall, it happened within the space of 70-80 miles, so perhaps it’s not that progressive . . .

I won’t be with the vehicle until Monday week, so I can’t physically check anything beforehand.

Click image to enlarge Charlie

1949 Series 1 80 (SOLD)
2002 Td5 90 (SOLD)
2008 Freelander 2 (SOLD)

1958 Series 2 88 Pastel Green (2019 LR Legends Best Restored)
1983 V8 110 Limestone (Previously owned by Tom Sheppard MBE)
2004 Td5 90 Santorini Black (Td5INSIDE Powered & Rebuilt by CSK)
2012 Puma 110 Zermatt Silver (Overlanding Build)

Instagram: @BaronDefenders

17th Nov 2022 2:51pm

roel

Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Sounds like the fuel pump to me. I had the same thing after a fuel stop. Also so suddenly. No been able to rev the engine and no power. I could get up to 70 km/hr barely.

My gus would be the pump but you can easily check the relay. Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)

17th Nov 2022 3:57pm

BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

I’ve ordered some relays, so I’ll have spares if nothing else.

Charlie

1949 Series 1 80 (SOLD)
2002 Td5 90 (SOLD)
2008 Freelander 2 (SOLD)

1958 Series 2 88 Pastel Green (2019 LR Legends Best Restored)
1983 V8 110 Limestone (Previously owned by Tom Sheppard MBE)
2004 Td5 90 Santorini Black (Td5INSIDE Powered & Rebuilt by CSK)
2012 Puma 110 Zermatt Silver (Overlanding Build)

Instagram: @BaronDefenders

17th Nov 2022 4:01pm

Martin
Site Admin

Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6604

2015 Defender 90 Puma 2.2 XS CSW Montalcino Red

A relay wouldn't be progressive like that, it's a switch. On or off.

1988 90 Td5 NAS soft top

2015 D90 XS SW

17th Nov 2022 4:10pm

BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

Tank out then.

17th Nov 2022 4:12pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17339

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

^ Not easy on a 90. I'm afraid.

17th Nov 2022 5:57pm

BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

I’ve heard . . . I have a drawer fixed in the back so I can’t just hack a hole into the floor.

I do have the YRM tank cradle fitted, so should be less of a battle. Charlie

1949 Series 1 80 (SOLD)
2002 Td5 90 (SOLD)
2008 Freelander 2 (SOLD)

1958 Series 2 88 Pastel Green (2019 LR Legends Best Restored)
1983 V8 110 Limestone (Previously owned by Tom Sheppard MBE)
2004 Td5 90 Santorini Black (Td5INSIDE Powered & Rebuilt by CSK)
2012 Puma 110 Zermatt Silver (Overlanding Build)

Instagram: @BaronDefenders

17th Nov 2022 6:06pm

andy2111

Member Since: 17 Oct 2021
Location: Kent
Posts: 365

I have had almost identical issues.. You literally could be describing the problems I had/have. Fuel pump not running, issues at those revs etc.

I first had my fuel pump replaced on recommendation from the garage, but my suspicion was this was a red herring. It was as the problem persisted.

I found that by pressing the fuel pump relay after it had failed that I could make the pump squeak as the connection was temporarily restored. I had the relays all rewired ensuring the ends of the wires were trimmed to expose fresh metal

All was good for a couple of months then the truck broke down when my wife was driving it alone. Got it recovered. Wouldn't fire at all and engine management warning light was on. Fixed that by removing/refitting the 30A fuse from under the seat box. As soon as I did that the warning light went out and it started immediately.

So I am now thinking I have an intermittent ECU problem which is fixed when removing the fuse which forces it to restart. There's stuff online about faulty ECUs causing the power dropouts around 2-2500 rpm.

This is as far I I have got. Two problems, one solved by sorting the relay and another still unsolved and waiting to strike another day! Will get the ECU tested next...

17th Nov 2022 6:41pm

BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

Interesting.

I have a suspicion the pump has been slowly dying, as I noticed a while back that it was quieter than usual when first priming. Charlie

1949 Series 1 80 (SOLD)
2002 Td5 90 (SOLD)
2008 Freelander 2 (SOLD)

1958 Series 2 88 Pastel Green (2019 LR Legends Best Restored)
1983 V8 110 Limestone (Previously owned by Tom Sheppard MBE)
2004 Td5 90 Santorini Black (Td5INSIDE Powered & Rebuilt by CSK)
2012 Puma 110 Zermatt Silver (Overlanding Build)

Instagram: @BaronDefenders

17th Nov 2022 7:47pm

458GT

Member Since: 22 Jun 2022
Location: Warwickshire
Posts: 83

Interested to hear how you both get on .... never fun

Just out of interest why is it difficult to change the fuel pump on a 90? When the time comes I can't bring myself to get the floor cut so will just let the (initially willing) garage crack on with it...

17th Nov 2022 10:19pm

BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

Click image to enlarge

Click image to enlarge

I think that answers that then. Charlie

1949 Series 1 80 (SOLD)
2002 Td5 90 (SOLD)
2008 Freelander 2 (SOLD)

1958 Series 2 88 Pastel Green (2019 LR Legends Best Restored)
1983 V8 110 Limestone (Previously owned by Tom Sheppard MBE)
2004 Td5 90 Santorini Black (Td5INSIDE Powered & Rebuilt by CSK)
2012 Puma 110 Zermatt Silver (Overlanding Build)

Instagram: @BaronDefenders

30th Nov 2022 3:10pm

MadTom

Member Since: 10 Sep 2013
Location: Olomouc
Posts: 616

You can remove the plastic cover of relay and watch, if it is switching. And you can also manually press the moving contact of relay, to switch it on. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo

30th Nov 2022 4:14pm

BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

I gave it a push into the connector block and it started working again, so I’ve replaced it for a new one.

All working again.

30th Nov 2022 4:24pm

geobloke

Member Since: 06 Nov 2012
Location: Nottinghamshire
Posts: 4410

At the very least it is worth opening up the cover just to see where the singeing originated. I had to replace all the yellow relays in Miffy. The contacts within the relays had badly eroded over time. Caused the overheating and blackening, plus some irritating running issues.

30th Nov 2022 4:27pm

camelman

Member Since: 27 Feb 2013
Location: Peak District
Posts: 3368

I had similar issues to yours. Replace the injector harness with a sealed unit, cleaned the ECU plugs up and jobs a good un. £50 and half an hour of your time.

HAve you checked the red and the black plugs going into the ECU under the seat for any traces of oil?

30th Nov 2022 4:40pm

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