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Matt, Engineer
Category: Ford
Satisfied Customers: 21720
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I put a new transmission in my 2002 gt mustang it

Customer Question

i put a new transmission in my 2002 gt mustang it all back together now it runs like crap.rough idle and no power.i've changed every sensor i can.
Submitted: 9 months ago.
Category: Ford
Expert:  Matt replied 9 months ago.


This sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump at the tank.

1st thing to try is to remove the fuel filler cap and then flick the ignition on whilst listening for the brief ‘buzz’ of the pump

If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,

Ideally measure the pressure at the injector rail (should usually be around 3Bar / 45psi +) and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.

You can also get this issue with contaminated fuel , if there’s water or dirt in the tank then either the petrol floats on top of the water or the filter sock on the pump is choked up – so if the other things check out then I’d consider pulling out the fuel pump and cleaning the filter sock

And one other thing to try is to loosen off the fuel filler cap, as there’s a 1 way valve built into the cap to let air into the tank and so prevent a vacuum from being created as the fuel leaves the tank to the engine

If this helps then replace the cap with a new item

Customer: replied 9 months ago.
my check engine light is on and i checked the code and it said fuel volume regulator circuit open.i drove it and it stalls alittle then has power until i stop?
Expert:  Matt replied 9 months ago.


Ok so that backs up the lack of fuel pressure theory

the pump is controlled in relation to the fuel pressure sensor on the injector rail

these sensors have a history of failing so I'd start by replacing that

Customer: replied 9 months ago.
i aleady did that.
Expert:  Matt replied 9 months ago.


in that case I'd get a pressure gauge on the rail to confirm if the fuel rail pressure really is low