806 won't start

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Kman
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806 won't start

Post by Kman »

My 806 2.0 HDi won't start, the engine is turning on the starter so I expected:

1. No fuel is reaching the engine
2. The immobilizer is active from faulty key, sensor etc.

The fuel pump should prime for 2-3 seconds when the ignition is turned on, but I cant hear it (as I normally can) and when I disconnected the fuel line to the filter while turning the ignition on no fuel came. This leads me to suspect a faulty fuel pump (LP in tank). If there is a fault with the immobilizer, would this deactivate the LP as well?

Is it necessary to remove the tank to get to the fuel pump?

Where is the best location to connect to for "force driving" the fuel pump, to rule out faulty relays etc.?

Regards

Kristian
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AndersDK
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Post by AndersDK »

Hej Kristian -

IF there is access to the pump & fuel gauge sender from above, you should find a large plastic cover to be removed from the floor - under the carpeting.
Usually PSA have such an access cover on all models.

As for diagnosing the starting problem I'd try a testlamp on one of the glowplugs.
The glowplugs would also be dead if its an immobiliser issue.
Even if the glow indicator lamp only glimps shortly, the plugs are still active for several seconds to insure the engine starts and to keep down coldstart emissions.

held med det :wink:
Anders (DK) - '90 BX16Image
dieselnutjob
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Post by dieselnutjob »

if the LP pump isn't running then it won't start, it's as simple as that.
you need to see if there is +12V going to the pump
if there is +12V but no pumping then you need a new pump
if there is no +12V you'll need to start investigating the wiring, relays etc
I don't know if the immobiliser (or lack of) will stop the pump running.
BX
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Post by BX »

When the immobiliser disarms the red LED (little red flashing light) on top of the dashboard stops flashing. If it dosn't stop when you turn on the igition you have an immobiliser problem.
Try giving a few solid thumps to the underside of the tank. If that causes the pump to run when you subsequently turn on the igition, You definately have a pump problem. If it dosn't check that there is power to the pump for a few seconds when you turn on the ignition.
To change the pump there is no option other than to drop the tank on the 806, its sisters Synergie (AKA Evasion) & Ulysse or on its brothers Dispatch (AKA jumpy) Scudo or Expert.
Kman
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Post by Kman »

Thanks for your replies.

Turns out the LP pump wasn't the problem, just another symptom, when I connected diagnosis equipment (PP2000) to the car there was no communication with the ECU. I have a spare ECU, but this didn't work either, suggesting there is a problem with the voltage supply.

I suspected the double injection relay (item 1304 in wiring diagrams) to be dead, so I orded a new one. Before this arrived i did another start attempt, and suddenly the car worked again, for no particular reason. I still changed the relay, suspecting that it was prone to go again, and took the car for a spin, no problems.

When I tried to start the car a few hours later it was dead again! (This was also the failure mode last time, no problems during driving) This could indicate bad wiring, a nearly sheared wire etc, however I find it hard to believe that the wiring was OK during the bumpy drive, and then loose contact while parked, for the second time.

The red LED on the dashboard stops while the key is in, confirming the PP2000 which says the immobilizer is fine, however unable to communicate with the ECU.


Kristian
dieselnutjob
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Post by dieselnutjob »

monitor the rail pressure in live data whilst you crank the engine
if you don't get at least 120bar (I think it is) the engine won't start
wheeler
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Post by wheeler »

Just for reference the (factory fit) imobiliser wont stop the low pressure pump in the tank operating, it just stops the injectors opening.
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