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MG MGF Technical - Testing Relay Pack

Trying to Fix A Friends MGF.
When Turning the Ignition Key First thing in the Morning, The fuel pump is Not Operating At All or Is Only Operating for a Very Short Time.
Because of This His MG Can take Longer to Start than Normal.
When Started it Performs Fine All Day....
I Suspect The Fuel Pump Relay.
Apart from Testing For Voltage At the Fuel Pump, How is The Best Way of Testing The Relay Pack ? (in Which the Fuel Pump Relay is Housed)
New Relay Pack from Rover Dealer is 62 But I'd Prefer to Check it First For Him, so He Doesn't Waste His Money.....

Hi Perksy

Its quite normal to only hear the fuel pump operate briefly as its my understanding its only priming the system at this stage..once the fuel lines are up to pressure it stops.. this sometimes is less than a second.

Mine does the same...

Maybe you have a defective pump?


PS ..Sorry ! I'm not a mechanic !! I'm sure someone will give a better explanation
Stu Dickens

Another more worrying thought..

Mine started being a bu@@er to start...

Then ran fine all day...

Turned out to have pressure down on two cylinders and just caught it before going into a HGF..

Keep and eye on the water and oil....

I may be barking up the wrong tree but better I warn you and be safe rather than sorry....

Stu Dickens

What is making you suspect the fuel pump Perksy? If the car does actually run, it seems that the fuel pump relay is operating correctly (check the line via the inertial cut off switch).

If you are suspecting fuel delivery, then it might be an idea to check the fuel line pressure. RogerP suggested to me to use an oil pressure gauge to do this (had problems on an aged K-series powered Metro!) taking a Tee-piece off from the fuel line. If too low then either it's the pump as Stu suggests, or it is the fuel pressure regulator...
Rob Bell

My Mates left the car with me for the weekend to have a decent look at.
Rob, the pump doesn't run at all initially and only seems to run when the engine is cranked on the starter.
So i know that the Crank sensor is doing it's job.
It then seems to Prime fine, until the Engine is Cold Again.
(I replaced the Coolant Temperature Sensor for Him Previously)
I'm going to check it in the morning for Power at the Pump and then Back-probe to see how far the Voltage is Getting....
As i understand the Wiring Diagram, the Main relay powers the ECU, the ECU Then Powers the Fuel Pump Relay
The Time the Pump energises for is Set By the Microprosessor in the ECU.
If the Voltage isn't even getting to the Fuel Pump Relay then it isn't looking too good for the ECU...
Unless anybody thinks anything else ???
Any Ideas Welcomed..

This thread was discussed between 15/04/2004 and 16/04/2004

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