How To test the Diesel High Pressure System

10205 Views 14 Replies 5 Participants Last post by COLVERT, Feb 15, 2012

FrenchMike

Discussion Starter · Sep 24, 2010 (Edited)

2

Hi all,

In case of non starting (preferably hot),Camsensor is generally incriminated.
But we have to know the behaviour of the common rail pressure in order to rule out a possible injector leak back.

Here is a easy way to do it:

YOU NEED:

-a lowcost multimeter (DC 2 volt range)
-one or two alligator clips with pin associated (as already describe somewhere)

PROCEDURE

1 Disconnect the camsensor.
2 Pin throught the insulation of the blue/black wire (the other green/brown
is the ground.
to pick up the fuel rail pressure signal.
3 turn the key position 2 (you must read 0.5 volts)

4 Crank for 4 secondes then release the key.

If you get a chart like the green one,then,you have no significant leak.

Now,you can see the Camsensor side;but before buying one,have a look here:

http://www.forums.mg-rover.org/showthread.php?t=376399

Mike

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1 - 15 of 15 Posts

COLVERT

· #2 · Sep 24, 2010

Merci bien Mike. Tres utile. j'ai fait copie.

Colvert.

:drunk2:

FrenchMike

Discussion Starter · #3 · Sep 24, 2010

COLVERT said:
Merci bien Mike. Tres utile. j'ai fait copie.

Colvert.

:drunk2:

Je vous en prie mon cher ,be welcome

Mike

equidents

· #4 · Sep 24, 2010

FrenchMike said:
Je vous en prie mon cher ,be welcome

Mike

Bain marie! Rodney.

COLVERT

· #5 · Sep 24, 2010

equidents said:
Bain marie! Rodney.

Now come on Rodders !! Merde ! You know more French than that. Pmsl.

:speakenglish:

equidents

· #6 · Sep 24, 2010

COLVERT said:
Now come on Rodders !! Merde ! You know more French than that. Pmsl.

:speakenglish:

Oui! c'est vrai!

Je comprend assez bien mon copain.

:shh:

simcor

· #7 · Sep 25, 2010

????????????????????

Sprechen sie Deutsche???? :rofl:

I can't make head nor tails of this foreign talk!!! :rofl:

Simon

marcus_zt-t

· #8 · Jan 10, 2012

Mike what if the voltage is higher than 1.25v, I did the test and my multimeter was nearer 1.48v.

FrenchMike

Discussion Starter · #9 · Jan 10, 2012

marcus_zt-t said:
Mike what if the voltage is higher than 1.25v, I did the test and my multimeter was nearer 1.48v.

Hi,

What is wrong ? can't start ?
are you sure of your measurement ? how is the falling slope ?
faulty sensor ?
Try starting sensor disconnected .
during cranking,one must get about 9 volts on the camsensor info.

Mike

marcus_zt-t

· #10 · Jan 10, 2012

Hi Mike,

Yeah car won't start just changed in tank pump today and same thing. I had the injectors refurbished about 50k miles ago, problem started with hard starting issues and also a missfire for a upto a minute then car would run perfectly would start when hot but not when cold. I did manage to start it on easy start twice but now once it burns off the car dies, when it does manage to start there is white/blue smoke with the rough idling.

Saw your fuel pressure test for injectors so did it this evening, I have tried disconecting maf, low pressure fuel sensor. The car turns over wants to start but doesn't, rev counter needle does move slightly when cranking.

FrenchMike

Discussion Starter · #11 · Jan 11, 2012

marcus_zt-t said:
Hi Mike,

Yeah car won't start just changed in tank pump today and same thing. I had the injectors refurbished about 50k miles ago, problem started with hard starting issues and also a missfire for a upto a minute then car would run perfectly would start when hot but not when cold. I did manage to start it on easy start twice but now once it burns off the car dies, when it does manage to start there is white/blue smoke with the rough idling.

Saw your fuel pressure test for injectors so did it this evening, I have tried disconecting maf, low pressure fuel sensor. The car turns over wants to start but doesn't, rev counter needle does move slightly when cranking.

Hi,

Your measurement is abnormally high ! do you get 0.5 volt before cranking ?

I 'm afraid you'll have now to do a 'hydraulic' leakback test .

If engine start with easy strart ,looks like a HP pressure leak somewhere.

Good luck

Mike

marcus_zt-t

· #12 · Jan 11, 2012

Voltage is 0.5v before cranking, the engine will not start with easy start most of the time, only if I am lucky.

What I did do was undo over the weekend was undo one injector loom at a time then cranked the car, with injector 1 & 4 disconected and I cranked the car it was exactly the same as when all 4 were connected (nearly fired up), when I disconected 2 & 3 and cranked it over it sounded as if it was just turning over with no sort of trying to fire at all.

I will do another test on the fuel rail sensor this evening and I will do hydraulic leak back test as well.

FrenchMike

Discussion Starter · #13 · Jan 11, 2012

In case of possible faulty HP sensor,disconnect it and try to start.

(on mine,i can start the engine with this sensor disconnected)

marcus_zt-t

· #14 · Feb 12, 2012

Just to wrap up my issues it was the injectors, poor spray patterns. But thanks for all the help.

COLVERT

· #15 · Feb 15, 2012

marcus_zt-t said:
Just to wrap up my issues it was the injectors, poor spray patterns. But thanks for all the help.

Thanks for coming back to tell us. It can help other people if they have a similar problem.

Colvert.

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