under bonnet diesel pump gremlins

finbarr saunders · 10th March 2021, 21:32

Hi all, Last week i jumped in the car but she wouldn't start, lifted up the bonnet & I found diesel pump was not working, then while i went to get something to tap the pump with I got back & it was working!, Thinking that the pump was probably on it's way out I fitted a new one, Then today it done the exact same thing, checked pump plug for power & there was nothing on the live side but ground was OK, checked the under bonnet fuse & no power to that either, then as before it suddenly started working & started up fine, Has anyone got any clue where to check next as there is obviously a problem on the live/switched side, Ignition switch perhaps ?,,,,,,cheers.

MacRob · 10th March 2021, 22:59

Quote:

Originally Posted by finbarr saunders

Hi all, Last week i jumped in the car but she wouldn't start, lifted up the bonnet & I found diesel pump was not working, then while i went to get something to tap the pump with I got back & it was working!, Thinking that the pump was probably on it's way out I fitted a new one, Then today it done the exact same thing, checked pump plug for power & there was nothing on the live side but ground was OK, checked the under bonnet fuse & no power to that either, then as before it suddenly started working & started up fine, Has anyone got any clue where to check next as there is obviously a problem on the live/switched side, Ignition switch perhaps ?,,,,,,cheers.

Not an answer but hopefully this will help in your search

trikey · 11th March 2021, 06:37

Have you got a dry plenum,? A wet ecu will cause pump issues.

finbarr saunders · 11th March 2021, 07:32

Quote:

Originally Posted by trikey

Have you got a dry plenum,? A wet ecu will cause pump issues.

Cheers for that, I keep forgetting that the ECU is situated in a stupid place!, will have a look later,,,cheers.

Mike Noc · 11th March 2021, 07:42

Yep could be a faulty ECM. Worth checking or swapping the fuel pump relay over to rule it out - the ECM earths the control side to switch it on so if the relay is good then either a break in the wire going to the ECM, or it has gone for a swim.

trikey · 11th March 2021, 09:05

Lt me know if it’s your ecu that’s suspect, I’m in your area next Sat and can help if you need it.

Sent from my iPhone using Tapatalk

finbarr saunders · 11th March 2021, 10:21

Quote:

Originally Posted by Mike Noc

Yep could be a faulty ECM. Worth checking or swapping the fuel pump relay over to rule it out - the ECM earths the control side to switch it on so if the relay is good then either a break in the wire going to the ECM, or it has gone for a swim.

Ah right it's called an ECM & not ECU, Anyhow I have had it all out this morning & found about 1/2 inch of water in the plenum, 'So I gave it a damn good poking making sure I didn't damage the rubber until the fluid shot out (fnarr fnarr)', Of course it is now behaving itself this morning & starting up first time (typical) which doesn't help matters finding the problem, Maybe the plenum had a partial blockage & has slowly drained away overnight or something?, , , , ,in regards to the relay, is that mounted in the cabin fuse box & is there an identical relay I can swap it over with?., , , ,cheers.

finbarr saunders · 11th March 2021, 10:32

Quote:

Originally Posted by trikey

Lt me know if it’s your ecu that’s suspect, I’m in your area next Sat and can help if you need it.

Sent from my iPhone using Tapatalk

Thanks for the offer & much appreciated, as I have mentioned on another post the damn thing is behaving itself this morning so I really don't know what is going on with it, It done the same thing about 2 years ago after driving through a flood, it kept running ok but when I turned it off & tried to restart it again it done the same thing as now, I ordered a new pump but by the time it arrived the damn thing didn't go wrong after that so I left it, so it seems it could be water related.

BigRuss · 11th March 2021, 11:41

The fuel pump relay is located on top of the passenger compartment fusebox, you can swap it over with one of the same yellow relays from the underbonnet fusebox

Russ

finbarr saunders · 19th March 2021, 11:09

After thinking that this had been sorted it has come back again, car was fine when i parked it up 2 days ago then went to go out this morning & yet again no power to the pump,

, Have pulled out ECM & checked it & all is bone dry, swapped over the relay in the fuse box & still getting nothing, I cant see it being the ignition switch as the stereo comes on when turned to switched live,(I assume they use the same switch contact) Anybody got any other suggestions as this is driving me mad now?

10th March 2021, 21:32	#1
finbarr saunders Avid contributor ROVER 75 Tourer Join Date: Oct 2015 Location: Worksop, Notts Posts: 106 Thanks: 30 Thanked 8 Times in 7 Posts	under bonnet diesel pump gremlins Hi all, Last week i jumped in the car but she wouldn't start, lifted up the bonnet & I found diesel pump was not working, then while i went to get something to tap the pump with I got back & it was working!, Thinking that the pump was probably on it's way out I fitted a new one, Then today it done the exact same thing, checked pump plug for power & there was nothing on the live side but ground was OK, checked the under bonnet fuse & no power to that either, then as before it suddenly started working & started up fine, Has anyone got any clue where to check next as there is obviously a problem on the live/switched side, Ignition switch perhaps ?,,,,,,cheers.

11th March 2021, 06:37	#3
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,760 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Have you got a dry plenum,? A wet ecu will cause pump issues. __________________ Lest we forget..

11th March 2021, 09:05	#6
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,760 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Lt me know if it’s your ecu that’s suspect, I’m in your area next Sat and can help if you need it. Sent from my iPhone using Tapatalk __________________ Lest we forget..

11th March 2021, 11:41	#9
BigRuss Premium Trader 75 CDT Tourer,2.5 Launch Saloon, Omipro MG/Rover (T4) Join Date: Jul 2007 Location: Liversedge, West Yorkshire Posts: 5,405 Thanks: 1,105 Thanked 1,340 Times in 661 Posts	The fuel pump relay is located on top of the passenger compartment fusebox, you can swap it over with one of the same yellow relays from the underbonnet fusebox Russ __________________ Replacement Key Service http://https://the75andztclub.co.uk/...d.php?t=244732 Full T4 Testbook diagnostics available. Diesel ECU repair and replacement. Options enabled or disabled as required. Diesel X-Power 135 and 160bhp, Rover 1.8T 150 to 160 MG 160 V6 to 177 upgrades available P.M. for details.

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11th March 2021, 07:42	#5
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,547 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Yep could be a faulty ECM. Worth checking or swapping the fuel pump relay over to rule it out - the ECM earths the control side to switch it on so if the relay is good then either a break in the wire going to the ECM, or it has gone for a swim.

19th March 2021, 11:09	#10
finbarr saunders Avid contributor ROVER 75 Tourer Join Date: Oct 2015 Location: Worksop, Notts Posts: 106 Thanks: 30 Thanked 8 Times in 7 Posts	After thinking that this had been sorted it has come back again, car was fine when i parked it up 2 days ago then went to go out this morning & yet again no power to the pump, , Have pulled out ECM & checked it & all is bone dry, swapped over the relay in the fuse box & still getting nothing, I cant see it being the ignition switch as the stereo comes on when turned to switched live,(I assume they use the same switch contact) Anybody got any other suggestions as this is driving me mad now?