Vt v6 auto starts and idles but wont accelerate?

[Shauno96]

hi
so my friends v6 vt s2 auto has suddenly stopped running properly..one second its driving fine and next it starts choking up.

Basically it will start perfect,idle and even rev out in Park and Neutral but once it is put in any gear (i.e D,3,2,1 or reverse) it idles ok but once u try to accelarate in either direction the revs fall and it go's to stall...i barely managed to drive it home 15kms like this as i found if u play with the accelarator pedal a bit while it is struggling it will come good for a bit if u keep it in that spot but mostly it just chokes and barely stay running unless u back off the pedal completely..runs slightly better in 3rd than drive too...also noticed it seems to struggle more on uphills and while under load basically...

:so far i have tested the spark plug leads and coil packs with multimeters and all check out...even replaced leads with spares that tested good too
:replaced the coil packs with working spares i had lying around..
:spark plugs are 3 weeks old and look near new still...electrode was white though...
:replaced fuel filter
:tested fuel pump by having hose to filter in a jar and turned key in car and it sprayed pretty solid..roughly 100ml
:removed air intake and TB and ensured all hose were good and connected..
:replaced TPS and IAC with working spares i had.
:and also did an error code check and only comes up with 12 repeatedly so nothing there...

all i can think of now is maybe a solenoid in the trans but am out of ideas really so any advice to this strange problem would b most appreciated...

cheers

 

[sidecar55]

You need to check the fuel pressure. Very common that the pumps stuff up.

 

[Shauno96]

i also replaced the ignition module that the coil packs bolt and connect to with a working spare as well.....

 

[Shauno96]

when i pulled the fuel pump relay while engine was running to de pressurise etc to do fuel filter..within 2 seconds of me pulling the relay the engine died...i was assuming it would run for a bit b4 dying..made me think fuel problem maybe...

to check fuel pressure i would need a t fitting with fuel pressure guage and connect it inline i assume so will get one tomorrow and see how i go...

 

[Tree cutter]

It does sound like a weak fuel pump. You need to put some sort of a restriction on the fuel hose to let the pump build up pressure when testing, to see if the pump slows down or keeps pumping.

 

[sidecar55]

A good scantool will tell you if the fuel flow is OK as well.

 

[devilly]

if your having to play with the pedal,i would say tps faulty or maybe the connector. remove the connector use a micro flat blade screw driver and make sure the pins are square if they are not pop the metal tabs in place properly.

possibly blocked injectors,just run some injector cleaner through the system add to fuel tank see how it goes.check to see if l/h change anything.

and yes you can get and idea on petrol ratio through your car via pressing holding mode and up arrow then start car release buttons .if you car has this function. click mode until you get to l/h should be around 2.0 l/h liters and hr and leaving it on idles until warms up should get as low as 1.5. drive with it on and work out rpms against l/h.

 

[Nut Kracker]

Squeeze the fuel return hose with some pliers.
If the revs increase it's more than likely its the pump.......or the fuel regulator.

 

[Shauno96]

well all the signs seemed to point to the pump to me,fuel guage was always dodgy, pulled the pump relay while car was off and went to start it and wouldnt even start at all....
So i decided to take a punt and go get a fuel pump from repco..was $200 but that was for the whole assembly (or $144 for just the pump) and installed it.
Once it was installed and primed the lines a few times she started 1st go...took it for a 10km drive...ran like a dream...all fixed!

pretty easy job too...i found if u parked so car is on flat ground but there is a slight downslope from behind the rear wheels and back..dont need to b a big slope, u can just drop the tank straight out...no jacks/jackstands needed...once tank is on ground just angle it out.

So seems the punt paid off and it was the pump coz all is good now...its been driving for 2 days no without a problem so guess its all fixed now...fuel pump it was lol

thanks.