Under bonnet pump

[flapper]

My 51 plate connie se CDT (105k)started losing power on the way home on Tuesday and would not rev, kept dying then picking up , It had less than 1/4 tank fuel but just managed to get to garage silly I know but I only put £20 in which didnt raise the level much. This didnt improve the situation and I struggled home at 20 mph. Once there I tried the priming sequence as I assumed there was air in system.
All I managed to do was to flatten the battery with no sign of car starting and hav'nt managed to get it running apart from a few seconds using easystart.
Ive since topped the tank up to 3/4 full, still no joy. The pump gurgles and runs and sometimes does need a tap with a spanner.
The tank pump may not be working but should'nt the underbonnet pump run the car if fuel leve high enough?
Can someone advise how I can test the underbonnet pump? should fuel flow out if the snap connector on the filter side is removed and the engine cranked over?
Is there any other way of priming?
Any advice would be welcome

Pete

[1gp]

what you will find is , if you know you have had one pump not working , it puts stress on the other pump , and the working pump will also fail ...;) it seems , you now have two dead pumps , if it will not start. one way is remove the fuel line to the injectors and crank over , if you have no fuel coming out , then you may have found the problem . It should pump fuel out at a high rate...

[FrenchMike]

Hi,

UBP and ITP are powered simultaneously during one minute after ignition on.

You'll find thousand treads about fuel pumps on this forum....

Mike

[Mike Noc]

what you will find is , if you know you have had one pump not working , it puts stress on the other pump , and the working pump will also fail ...;) it seems , you now have two dead pumps , if it will not start. one way is remove the fuel line to the injectors and crank over , if you have no fuel coming out , then you may have found the problem . It should pump fuel out at a high rate...

That is the commonly held belief and it's been repeated so many times it's accepted as fact. But I don't think it should be. ;)


When the ITP fails it will give the UBP a bit more work to do, but it doesn't stress it to failure. I've run with a known failed ITP for 20k miles before replacing both pumps and the UBP was still working fine.


The fact is that both pumps will wear out and the ITP's usually go first. This will go unnoticed if the tank doesn't ever get too low on fuel, and the car will run fine on just the UBP. But when it finally gives up the ITP is also found to be dead and then it's assumed the ITP has caused the UBP to fail.



My 51 plate connie se CDT (105k)started losing power on the way home on Tuesday and would not rev, kept dying then picking up , It had less than 1/4 tank fuel but just managed to get to garage silly I know but I only put £20 in which didnt raise the level much. This didnt improve the situation and I struggled home at 20 mph. Once there I tried the priming sequence as I assumed there was air in system.
All I managed to do was to flatten the battery with no sign of car starting and hav'nt managed to get it running apart from a few seconds using easystart.
Ive since topped the tank up to 3/4 full, still no joy. The pump gurgles and runs and sometimes does need a tap with a spanner.
The tank pump may not be working but should'nt the underbonnet pump run the car if fuel leve high enough?
Can someone advise how I can test the underbonnet pump? should fuel flow out if the snap connector on the filter side is removed and the engine cranked over?
Is there any other way of priming?
Any advice would be welcome

Pete

Pete yes take the outlet pipe from the UBP off at the fuel filter and put it in a large jar. Then with key to position 2 (no need to start the engine) you should get a good strong and continuous flow of fuel into the jar. The pumps will turn off after 30 seconds to a minute if the engine isn't started.

You can listen to the ITP through the open fuel filler pipe, again with key to position 2, and it helps to unplug the UBP so all you can hear is the ITP.

From the symptoms you describe if you change both LP pumps that should cure it.

Mike

[Moodster020]

The underbonnet pump should hum like an electricity substation, any other or oscillating sounds then theres something up with it.

Intank pump isnt connected to the underbonnet pump, but if the intank pump isnt working & fuel is below 1/4- then it can have fuel trapped in a pocket in the fuel tank & the UBP sucks air & burns out- gives you the symptoms you described.

Keep it over 1/4 full & the intank pump is redundant.

[flapper]

Thanks Mike
will check out UBP on Saturday.

Pete

[flapper]

Just tested UBP pump as advised by Mike, with tank now 3/4n full pump works ! and is giving a good flow, however car will still not start.
thefollowing things are taking place;

1.every time the ignition is switched on the "glowplugs on" light come on,, as if it was been started for the first time? happens even after 5 minutes of trying to start it (Ive used a lot of easystart could this have caused problems, also doesnt want to run on easystart?

2 the electronic unit in front of the battery(dont know what it is called) buzzes for a while even after ignition switched off?

3 Tried the priming sequence again, no joy just ran the battery down.

Any more tests or checks I can complete?

NB the car was running ok before low fuel caused the initial problem

[COLVERT]

Just tested UBP pump as advised by Mike, with tank now 3/4n full pump works ! and is giving a good flow, however car will still not start.
thefollowing things are taking place;

1.every time the ignition is switched on the "glowplugs on" light come on,, as if it was been started for the first time? happens even after 5 minutes of trying to start it (Ive used a lot of easystart could this have caused problems, also doesnt want to run on easystart?

2 the electronic unit in front of the battery(dont know what it is called) buzzes for a while even after ignition switched off?

3 Tried the priming sequence again, no joy just ran the battery down.

Any more tests or checks I can complete?

NB the car was running ok before low fuel caused the initial problem

Item 3. Priming sequence; what do you mean ??

Do you mean just turning on the ignition and doing nothing else. That shouldn't flatten your battery. The pumps are SELF PRIMING !!

You DON'T need to turn the engine over; as mentioned in a post above.
Easystart is not going to hurt your engine.

Stop worrying about the glow plug light it's just doing what it's supposed to.

Obviously you are not getting any fuel into the engine.

There are, at the stage you're at, several reasons why no fuel.

Not likely to be an injector problem or leakback if you get get it to rev for a couple of seconds with easystart as the higher engine speed will overcome slight leakback.
.
Could be a High Pressure pump problem or one of the fuel line sensors not giving the correct signal to the ECU.

Also a failed cam or crank sensor could be the cause of the engine not starting. Again no signal to the ECU.

As you have managed to flatten your battery several times make sure it is well charged by giving it at least 24 hours on a charger.

I'm sure there will be others along in a minute with several other things you can try. :)


Colvert.:cool:

[James.uk]

If the car wont start on easy start, then you may have an elec fault with either the cam or crank sensor.. :o
...

[flapper]

followed the run out of fuel advice given in haynes, -crank with pedal floored for 10 secs, rest for 5 secs try again.
Know that fuel getting through filter, after that - no idea whether its a fuel, electronic or mechanical issue:shrug:

[Mike Noc]

When you try to start it does the rev counter needle move at all? If no then the crank sensor could be faulty.

If you have a multimeter you can check the HP pressure sensor on the end of the fuel rail - do a search for French Mike's tests.

Give the battery a good charge before trying to start the car again. There have been a few cases of the car immobilising itself when tryiung to start with a flat battery.

You've done the obvious and checked the plenum drains are clear and the ECU hasn't gone for a swim?

Mike

[COLVERT]

If the car wont start on easy start, then you may have an elec fault with either the cam or crank sensor.. :o
...

James. old chap. You don't need a crank or cam sensor with Easystart.

Nor any electricity. The E.S. gets SQUASHED and fires up quite happily on its own. :cool::cool::cool:



Colv. :D

[COLVERT]

followed the run out of fuel advice given in haynes, -crank with pedal floored for 10 secs, rest for 5 secs try again.
Know that fuel getting through filter, after that - no idea whether its a fuel, electronic or mechanical issue:shrug:

You DON'T need to crank the engine with the diesel.

You are going to KILL your battery.

The diesel system is SELF PRIMING. :twonk::flog::poke::target: The first line in the book says it's SELF PRIMING and the next bit tells you to prime it yourself !!!!

Don't trust the book. ( The book says the clutch reservoir is the same as the brakes. Rubbish; the clutch has its own reservoir. ) and so it goes on with that book.