Possible Fuel Pump Problem....

[Guest david_l_perry]

Got an odd situation that has just started on my 2B Jag V6 last weekend

 

The car has been running fine for the last 6-12 months, so something must have failed or starting to go faulty in the pump or fuel line system I think.......

 

 

 

 

 

Start up from cold is fine, but after a couple of minutes, its starts to miss as though its running out of fuel, and then eventually cough's splutters and cuts out altogether.

 

It then will not start up again, turns over, but wont ignite as though its run out of fuel.

 

 

If I go back to the car after say an hour. It will start up as normal and then do the same thing as above after a minutes running.

 

 

Plenty of fuel in the tank

 

 

The car has been running perfectly for the last 12ish months on the following set-up:-

 

Fuel tank outlet into Fuel filter

Fuel filter into low pressure lift pump (sat slightly lower than tank)

Low pressure lift pump into ODP Swirl pot

Swirl pot large diameter output into high pressure pump

High pressure pump into Filter into fuel rail

Fuel rail back through pressure regulator

Pressure regulator back to swirl pot

Swirl pot back into fuel tank return

 

 

When it first starts up you can blat the throttle in the garage and it picks up just as normal, but after a minute it simple acts as though its run out of fuel

 

Clearly something has just changed to cause this problem just to start......failed/failing component or something else as its worked perfectly well with this set-up

 

So.....I have been trying to work out what the problem is and struggling

 

This morning I cleaned out the fuel filter (some small bits of crud but nothing significant)

 

I can see and feel that both pumps are working, but have no way of checking the pressure

 

I disconnected the fuel filter at the fuel rail end and fuel was present.

 

I can see fuel is passing from the tank through the first filter and can feel fuel passing through the pipes at the regulator return feed back into the pipe - so clearly the high pressure pump is pushing fuel to the rail. Unfortunately I don't have a pressure gauge on the regulator so cant check if pressure is constant or dropping....

 

 

What I don't understand is why it starts up from cold, and then starts playing up.

 

If it was a failed pump I would have though it would simply not work at all, unless the pump works until it gets a little warm after a minute of running and then stops pushing fuel at the required pressure ???

 

 

Any suggestion from the masses ??

 

Ta

Edited April 2, 2016 by david_l_perry

[steve in stockport]

Do both fuel pumps run when the engine cuts out, ie when it cuts and you go to restart do you hear both pumps priming and pressurising the system?

 

Have you got sparks after the engine has cut out? Could be ignition related rather than fuel

[Guest mower man]

Sucking through a filter is less than ideal ,filter could be collapsing giving the out of fuel symptons or similar to tank not having a breather ,pure guess but worth a look mick

Edited April 2, 2016 by mower man

[Guest david_l_perry]

Cheers Steve. Yes, pumps are still running. Not checked spark yet.

 

I did wonder if it was electrical at first as it started doing this after being sat on my drive in the heavy rain, and wondered if a sensor contact had moisture in it. But if it was electrcal I dont understand why it would start up ok cold every time and then start to cut out. And its long since dried out now.

 

One thing I did check last week was reinstalling the emerald software from my backup, and no change.

 

Suppose one of the temp sensors could be faulty sending duff info reducing the fuel from the ecu.....

[Guest david_l_perry]

Cheers Mick, tank has a breather and its been running fine like this with large diam pre filter for 6-12 months

[Longboarder]

Classic first check is are you using the facet plus bullet pre filter? I have absolute confidence they are a nightmare for funny fuel problems. Next would be disconnect the fuel rail return, lead it into a litre bottle and cycle the ignition several times to see a good spurt/overflow each time. Maybe 20 times? Shouldn't reduce.

Check the fuel tank vent hasn't got blocked somehow. Breathers can block.

 

Nigel

Edited April 2, 2016 by Longboarder

[steve in stockport]

Did the ecu get wet? Can't remember where it is on your car.

Could be an injector fault, I think they all share a common earth back to the ecu, but the drivers are separate. Or the ignition relay that powers the coil drivers.

Try unplugging and refitting the loom connector to the ecu a couple of times to clean up any crud that may have built up on the contacts.

I'm sure someone more knowledgable will have more in depth suggestions than mine.

[Guest david_l_perry]

Ecu is in a dry compartment under the scuttle. Bone dry. Did try swapping injector coil relay and no change.

[knights_templar]

ECU led will go red if it loses crack sensor signal, might be worth watching that when it cuts out, both ignition and fuel pumps will switch off.

[alanrichey]

Can't give an instant answer, and having spent so much time analysing my ECU I am probably biased But what I have found is that for the first couple of minutes the engine is run on default settings. Once it starts to warm up the lambda (O2) sensor starts to work and the ECU then switches to a different mode whereby the fuel/air mix is actively controlled based on the default setting and the lambda sensor output. Unfortunately if the sensor isn't working the ECU should just drop back to the default settings and should not stop the engine from running. And I am assuming you have a lambda sensor fitted ?

[bullfist]

I would have also said:

"Check the fuel tank vent hasn't got blocked somehow. Breathers can block."

I started getting a similar problem last year - not as bad as yours - where mine coughed and spluttered after warming up. After warming up, vacuum in tank starved fuel to engine - was all ok again after resting. Cleared blockage - all good now.

-steve

[Guest david_l_perry]

Well.....after many hours in garage today it all looks to be a faulty Lift pump. Just spotted it was not pumping at all...this morning it was....must have been on its way out, and is now not pumping at all.

 

It makes sense.....after being left for a while, gravity would have filled up the swirl pot....and allowed the engine to start up

 

......Just need to source another lift pump and hopefully all systems go again

 

Cheers chaps

Edited April 2, 2016 by david_l_perry