CDTi not starting

SomersetJeff · 22nd April 2023, 18:12

My 75 Tourer won't start after it's been standing for a few weeks. It has a new battery on it and when I turn the key, it just cranks continually - no sign of it firing.

My initial thought is that it's fuel pump or something to do with the immobiliser. What's the best routine to check out the fuel pumps?

Just adding to this. When I turn the ignition on before starting, I can hear the under bonnet pump humming away but then I hear what sounds like a lot of air going back into the tank which suggests to me there's a leak somewhere, but no signs of diesel.

macafee2 · 22nd April 2023, 19:22

how much fuel have you in the tank?

macafee2

Lee T · 22nd April 2023, 20:08

The air in the tank sound will likely be the valve being exposed by low fuel level and a failed in tank fuel pump. If your fuel is below 1/4 tank the under bonnet pump cannot supply fuel alone. Get the gauge close to half a tank and it should start. Get someone to turn the ignition to pos 2 and listen for the hum of the in tank pump, either by the fuel filler with cap off or ear pressed to rear seatbase drivers side. It will run fine if kept above the 1/4 but will work the UBP harder. Replace the in tank fuel pump with a VDO brand or similar quality, cheapies don't last or provide the correct fuel pressure.

Lee.

Matt_75 · 22nd April 2023, 20:21

Hi Jeff,

I had a similar no-start problem with my diesel a while back. Here's some posts I found useful when diagnosing the problem

Multimeter Tests for fuel pressure and cam sensor signal
https://www.the75andztclub.co.uk/for...ad.php?t=69308
https://www.the75andztclub.co.uk/for...d.php?t=109615

Additional info on pressure sensor voltage
https://www.mg-rover.org/threads/cdt...1/post-5027500

HP Pump Check Valve
https://www.mg-rover.org/threads/75-...p-pump.329789/

The above is useful if you dont have access to diagnostic equipment like T4, pscan or TOAF.

Some other owners also shared some useful info in the thread I created that might be helpful to you too: https://www.the75andztclub.co.uk/for...d.php?t=320259

The immobiliser inhibits the starter motor, so if the engine is turning over, that won't be the cause of your problem.

SomersetJeff · 22nd April 2023, 21:22

Thanks all. I'll start with adding some more diesel as I think it's marginal on quarter full and see what happens.

I've just recently got a TOAF cable and TOAF so might give that a go too.

MyReallyNiceCar · 23rd April 2023, 08:42

Quote:

Originally Posted by SomersetJeff

Thanks all. I'll start with adding some more diesel as I think it's marginal on quarter full and see what happens.

I've just recently got a TOAF cable and TOAF so might give that a go too.

Coming at this from a slightly different angle,
are you sure that you're getting fuel actually delivered to the HP pump.?

The 2 fuel lift pumps are notorious for failing due to their age.

I've recently changed both in mine

The HP pumps can fail
but they are far, far less noted for it
than the LP (lift) pumps are.!

The rule of thumb is that if the in-tank pump has failed
that car will run until you get down to about a quarter of a tank
& at that point
the underbonnet LP pump Won't have enough ooomph to pull the fuel through by itself.

If you put a couple of gallons in it & it runs
it's almost certainly the in-tank pump.

I'd suggest that you replace the underbonnet pump too
as it's the same age as the in-tank one
unless you already know that it Has been renewed.?

Get decent pumps, not cheap ones.!

DMGRS & Rimmers have them in stock
but you can also get quality parts such as Magneti Marelli
on eBay at good prices

Best of luck.

Hope this helps.?

SomersetJeff · 23rd April 2023, 18:33

After an afternoon of diagnostics, I am pretty certain the in-tank pump has given up. Everything else seems fine, but the under bonnet pump seems to be struggling and even with 3/4 of a tank of fuel, it won't start.

Struggling a bit with getting TOAF working but I did get one one set of diagnostic codes including one which was something about pressure being too low during cranking.

I really struggled to get any engine data out of TOAF - kept asking me to confirm the engine type but then didn't scan anything beyond that (apart from the one time). If anyone's a TOAF expert, I'd really appreciate some guidance.

It seems like the best course of action will be to do the in-tank pump and under bonnet pump.

hogweed · 23rd April 2023, 20:06

Quote:

Originally Posted by SomersetJeff

Struggling a bit with getting TOAF working but I did get one one set of diagnostic codes including one which was something about pressure being too low during cranking.

I really struggled to get any engine data out of TOAF - kept asking me to confirm the engine type but then didn't scan anything beyond that (apart from the one time). If anyone's a TOAF expert, I'd really appreciate some guidance.

Sounds a bit odd Jeff - normally TOAF will work or if won't, and when it doesn't it's at the start when you haven't got the USB drivers set up, or the correct COM port assigned... are those OK as far as you know?

Does it diagnose the car's other units (BCU, LSM etc)?

SomersetJeff · 23rd April 2023, 20:29

I thought it was odd. I had problems with the USB drivers from the TOAF website so installed some from a VAG-COM site I saw in another post (something about the TOAF supplied ones not having a hash).

I can connect to the car, do a general scan but whenever I click on "Engine", all I get is a choice of three engine types and then nothing happens after that.

All the other modules seem to scan okay and give me codes if they're present.

This is running on Win10 and I've set it as "Run as Administrator" to avoid any privilege issues.

hogweed · 23rd April 2023, 20:38

Quote:

Originally Posted by SomersetJeff

I thought it was odd. I had problems with the USB drivers from the TOAF website so installed some from a VAG-COM site I saw in another post (something about the TOAF supplied ones not having a hash).

I can connect to the car, do a general scan but whenever I click on "Engine", all I get is a choice of three engine types and then nothing happens after that.

All the other modules seem to scan okay and give me codes if they're present.

This is running on Win10 and I've set it as "Run as Administrator" to avoid any privilege issues.

Hhmmm does seem strange indeed... if it's scanning the other modules OK, I'd assume it's functioning properly

I ran it OK on W10 and W11, and didn't even run as admin.

There are two versions of TOAF - apart from an exploit in the older one which allows you to make key fobs, I'm not aware of any difference - but it just might be worth trying the other?

Maybe Mike (Vitesse) has some cleverer ideas... apart from changing to a Mac

22nd April 2023, 18:12	#1
SomersetJeff Regular poster Rover 75 Tourer Join Date: Jul 2021 Location: North Petherton Posts: 65 Thanks: 0 Thanked 1 Time in 1 Post	CDTi not starting My 75 Tourer won't start after it's been standing for a few weeks. It has a new battery on it and when I turn the key, it just cranks continually - no sign of it firing. My initial thought is that it's fuel pump or something to do with the immobiliser. What's the best routine to check out the fuel pumps? Just adding to this. When I turn the ignition on before starting, I can hear the under bonnet pump humming away but then I hear what sounds like a lot of air going back into the tank which suggests to me there's a leak somewhere, but no signs of diesel. Last edited by SomersetJeff; 22nd April 2023 at 18:16..

22nd April 2023, 20:08	#3
Lee T Gets stuck in MG ZT Join Date: Jul 2014 Location: Liverpool Posts: 870 Thanks: 180 Thanked 248 Times in 189 Posts	The air in the tank sound will likely be the valve being exposed by low fuel level and a failed in tank fuel pump. If your fuel is below 1/4 tank the under bonnet pump cannot supply fuel alone. Get the gauge close to half a tank and it should start. Get someone to turn the ignition to pos 2 and listen for the hum of the in tank pump, either by the fuel filler with cap off or ear pressed to rear seatbase drivers side. It will run fine if kept above the 1/4 but will work the UBP harder. Replace the in tank fuel pump with a VDO brand or similar quality, cheapies don't last or provide the correct fuel pressure. Lee. __________________ [SIGPIC][/SIGPIC]

22nd April 2023, 20:21	#4
Matt_75 Gets stuck in 75 Saloon Join Date: Apr 2022 Location: North Somerset Posts: 587 Thanks: 13 Thanked 20 Times in 8 Posts	Hi Jeff, I had a similar no-start problem with my diesel a while back. Here's some posts I found useful when diagnosing the problem Multimeter Tests for fuel pressure and cam sensor signal https://www.the75andztclub.co.uk/for...ad.php?t=69308 https://www.the75andztclub.co.uk/for...d.php?t=109615 Additional info on pressure sensor voltage https://www.mg-rover.org/threads/cdt...1/post-5027500 HP Pump Check Valve https://www.mg-rover.org/threads/75-...p-pump.329789/ The above is useful if you dont have access to diagnostic equipment like T4, pscan or TOAF. Some other owners also shared some useful info in the thread I created that might be helpful to you too: https://www.the75andztclub.co.uk/for...d.php?t=320259 The immobiliser inhibits the starter motor, so if the engine is turning over, that won't be the cause of your problem. __________________ Matt 2001 Rover 75 Connoisseur SE 2.5 (BRG) 1999 Rover 75 Club 2.5 (Dorchester Red) 1973 Triumph Dolomite (Honeysuckle) Last edited by Matt_75; 23rd April 2023 at 09:00.. Reason: Broken links fixed

22nd April 2023, 19:22	#2
macafee2 This is my second home Rover 75 Saloon & Tourer Join Date: Sep 2012 Location: Lincoln Posts: 14,963 Thanks: 1,630 Thanked 3,032 Times in 2,181 Posts	how much fuel have you in the tank? macafee2

22nd April 2023, 21:22	#5
SomersetJeff Regular poster Rover 75 Tourer Join Date: Jul 2021 Location: North Petherton Posts: 65 Thanks: 0 Thanked 1 Time in 1 Post	Thanks all. I'll start with adding some more diesel as I think it's marginal on quarter full and see what happens. I've just recently got a TOAF cable and TOAF so might give that a go too.

23rd April 2023, 18:33	#7
SomersetJeff Regular poster Rover 75 Tourer Join Date: Jul 2021 Location: North Petherton Posts: 65 Thanks: 0 Thanked 1 Time in 1 Post	After an afternoon of diagnostics, I am pretty certain the in-tank pump has given up. Everything else seems fine, but the under bonnet pump seems to be struggling and even with 3/4 of a tank of fuel, it won't start. Struggling a bit with getting TOAF working but I did get one one set of diagnostic codes including one which was something about pressure being too low during cranking. I really struggled to get any engine data out of TOAF - kept asking me to confirm the engine type but then didn't scan anything beyond that (apart from the one time). If anyone's a TOAF expert, I'd really appreciate some guidance. It seems like the best course of action will be to do the in-tank pump and under bonnet pump.

23rd April 2023, 20:29	#9
SomersetJeff Regular poster Rover 75 Tourer Join Date: Jul 2021 Location: North Petherton Posts: 65 Thanks: 0 Thanked 1 Time in 1 Post	I thought it was odd. I had problems with the USB drivers from the TOAF website so installed some from a VAG-COM site I saw in another post (something about the TOAF supplied ones not having a hash). I can connect to the car, do a general scan but whenever I click on "Engine", all I get is a choice of three engine types and then nothing happens after that. All the other modules seem to scan okay and give me codes if they're present. This is running on Win10 and I've set it as "Run as Administrator" to avoid any privilege issues.