Should the fuel pump prime EVERY time the ignition is on or does it only prime if theres not enough pressure in the fuel line?
The reason I'm asking is in addition to my previous post.
When my car doesnt start, the fuel pump doesnt prime when the ignition lights are on BUT when the key is turned again to engage the starter, the fuel pump fires up but the car still doesnt start.
This leads me to believe either a problem with the relays below the ECU or the ECU itself?
Fuel pump priming
Moderator: RichardW
Fuel pump priming
Last edited by SSaxo1978 on 16 Jan 2010, 21:23, edited 1 time in total.
-
spider
- Posts: 3949
- Joined: 05 Jan 2010, 14:28
- Location: Derby.
- My Cars: Soon, I hope...
- x 77
- Contact:
No it should not need priming as a regular thing 
Typically you'd only need to use it after changing the fuel filter or doing any work on the fuel system.
If you find you need to prime it to get it started easily, it points towards air ingress (which can be fun to track down sometimes unfortunately)
Typically you'd only need to use it after changing the fuel filter or doing any work on the fuel system.
If you find you need to prime it to get it started easily, it points towards air ingress (which can be fun to track down sometimes unfortunately)
Andy.
91 205D-Turbo, gone but still missed
02 106D, TUD5B, gone but not really missed apart from the MPG
91 205D-Turbo, gone but still missed
02 106D, TUD5B, gone but not really missed apart from the MPG
-
CitroJim
- A very naughty boy
- Posts: 49658
- Joined: 30 Apr 2005, 23:33
- Location: Paggers
- My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
- x 6204
- Contact:
All injection petrols I've owned have always appeared to prime on first turn of the key regardless.
Priming is not the right word really. What happens is this. Ignition on, fuel pump runs for a second or so to build up pressure in the fuel rail even if the pressure is there already; the excess fuel jusy flows back to the tank.
Fuel pump stops. Injectors energised. Start engine. As soon as the ECU detects the engine running it restarts the pump. Pump then runs continuously until either you stop the engine, it stalls or the intertia switch trips because you've just run into a wall...
This is all controlled by (usually) the double injection relay under direction of the ECU.
Mostly you don't realise the pump is running continuously as you can't hear it very well above the noise of the engine.
The main thing is, after the initial priming burst, the pump won't run again until the engine starts...
Priming is not the right word really. What happens is this. Ignition on, fuel pump runs for a second or so to build up pressure in the fuel rail even if the pressure is there already; the excess fuel jusy flows back to the tank.
Fuel pump stops. Injectors energised. Start engine. As soon as the ECU detects the engine running it restarts the pump. Pump then runs continuously until either you stop the engine, it stalls or the intertia switch trips because you've just run into a wall...
This is all controlled by (usually) the double injection relay under direction of the ECU.
Mostly you don't realise the pump is running continuously as you can't hear it very well above the noise of the engine.
The main thing is, after the initial priming burst, the pump won't run again until the engine starts...
Jim
Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...