No fuel pump when cranking but ok when Inital set connector bridged
Thread Starter
long live the monster BP
Joined: Nov 2005
Posts: 483
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From: New Zealand
No fuel pump when cranking but ok when Inital set connector bridged
Hi, My fuel pump wont work when i crank the motor over. It works when i jumper the yellow initial set connector plug in the eng bay and turn the key to on but is no go when cranking?
Ive got a haynes manuel and have been trying to work it out but am having dramas.
I have just installed a new motor and everything ran fine 3 weeks ago when we pulled it out. Ive been thru double checking everything and cant work it out. We have started the car with the yellow plug bridged and it ran fine but wont go when its not bridged.
Your suggestions please as this is getting frustrating.
The AFM is definatly plugged in properly!!!
Ive got a haynes manuel and have been trying to work it out but am having dramas.
I have just installed a new motor and everything ran fine 3 weeks ago when we pulled it out. Ive been thru double checking everything and cant work it out. We have started the car with the yellow plug bridged and it ran fine but wont go when its not bridged.
Your suggestions please as this is getting frustrating.
The AFM is definatly plugged in properly!!!
Joined: Dec 2001
Posts: 10,630
Likes: 3
From: NY, MA, MI, OR, TX, and now LA or AZ!
Open the AFM flapper by hand with the ignition to ON and see if it starts running. If it doesn't, inspect the harness/wiring near there, it's possible the wiring to the switch got fubared during reinstall.
Thread Starter
long live the monster BP
Joined: Nov 2005
Posts: 483
Likes: 0
From: New Zealand
SO presuming it runs with the AFM door open, ( cant check till tonight ) what else could it be ? Dosnt the start sequence from the ECU tell the pump to turn on then it switches to the AFM or have i got that wrong and it only uses the AFM
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
When you hold the key to START, the same power from the ignition key that causes the starter solenoid to activate, also goes to the Circuit Opening Relay to cause that relay to pull in and in turn cause the fuel pump to turn on.
IF you look at your circuit opening relay you WILL see a black/white wire in the plug. That is the wire that gets 12v when the key is held to START. On a non turbo its color is black/red. Same function.
The OTHER way to pull in the circuit opening relay is thru the vane in the afm being pulled aft just a few mm and making a switch in the afm which in turn puts a gnd on the circuit opening relay.
IN other words there are two coils in the circuit opening relay that can cause it to pull in. One by putting a gnd on it's coil and the other by putting 12v on the other coil. See FSM wiring diagram of the circuit opening relay.
By the way, the yellow two socket plug does the same thing as the switch in the afm i.e. puts a gnd on the same coil in the circuit opening relay.
IF you look at your circuit opening relay you WILL see a black/white wire in the plug. That is the wire that gets 12v when the key is held to START. On a non turbo its color is black/red. Same function.
The OTHER way to pull in the circuit opening relay is thru the vane in the afm being pulled aft just a few mm and making a switch in the afm which in turn puts a gnd on the circuit opening relay.
IN other words there are two coils in the circuit opening relay that can cause it to pull in. One by putting a gnd on it's coil and the other by putting 12v on the other coil. See FSM wiring diagram of the circuit opening relay.
By the way, the yellow two socket plug does the same thing as the switch in the afm i.e. puts a gnd on the same coil in the circuit opening relay.
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