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Delboy63

New Member

• Jan 25, 2014

• #1

I recentley done a 3.9 serp hotwire convertion and was running lovly wen fuel pump was running constantly on original wiring but not good for safty reason SOOOO i wired the pump up to the fuel pump relay (white /purple i think) now the pump primes when ignition is switched on but nothing when cranking. Ohh and the little wire by the airflow meter to neg side of coil .
Can any 1 shed any light pls
Many thanks del

 

jamesmartin

Well-Known Member

• Jan 25, 2014

• #2

its that little wire going to coil that triggers ecu to switch fuel pump on when cranking ,is there a live feed to coil

 

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Delboy63

New Member

• Jan 25, 2014

• #3

That it iv connected that wire to the negative side of coil.
Ignition live to positive side

On the original 3.5 wiring that runs fuel pump continuously it run like a dream.
But when wired to fuel pump feed it primes and when cranking runs for like 3 secs an dies as the ecu is not giving the fuel pump its feed when cranking .

So to me this indicates that the ecu dont no the engine is turning over from that little wire on the coil .

Dose this sound about right or am i talking rubbish and going wrong somewhere

Cheers del

 

jamesmartin

Well-Known Member

• Jan 25, 2014

• #4

sounds right ,when ignitions switched on pump should run for 4 secs then switch off then come back on as soon as you crank engine ie signal from coil

 

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Delboy63

New Member

• Jan 25, 2014

• #5

Think i may have cheek continuity back to the ecu

Cheers del

 

jamesmartin

Well-Known Member

• Jan 25, 2014

• #6

Delboy63 said:

Think i may have cheek continuity back to the ecu

Cheers del

Click to expand...

you have got wires from amp connected as well

 

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Delboy63

New Member

• Jan 26, 2014

• #7

Yeah there both connected

 

jamesmartin

Well-Known Member

• Jan 26, 2014

• #8

if coils working and ecu does at least switch pump on continuity would be best option

 

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Delboy63

New Member

• Jan 27, 2014

• #9

2day i cheaked the wire from the coil to pin 39 on ecu and i have 6.8oms so i really confused as i was hoping the wire was broken

Any other idears

Cheers del

 

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Delboy63

New Member

• Jan 30, 2014

• #10

Sorted after studding a wiring diagrame found that the switch feed to the coil and main switched feed need to be off the same wire starts on the button now and fuel pump working as it should cheers guys