ColettaMerc

Like the title says I had my computer flashed and vats removed along with the emissions etc for a swap got the engine running today but only if I run power to the fuel pump. The green and white wire that is supposed to turn on the fuel pump relay has no power coming from it when the ignition is turned on I have double and triple checked that it is the correct wire from the harness but nothing. Any Ideas?

Oh and this is a 1998 ls1 ecm,harness and motor.

NoGo

iTrader: (2)

Is the anti-theft light lit on the dash or VATS code being thrown?

ColettaMerc

I have no anti-theft light as this is a swap into a 1951 Merc but when I hook up a code reader to it I have no codes being thrown. Motor seems to run fine so far it just is not giving me a 12 volt output on the fuel pump wire. I dont think Vats is doing it though because wouldn't Vats kill the injectors after a few seconds if I was bypassing it by hot-wiring the pump?

NoGo

iTrader: (2)

VATS should kill the injectors, but I figured I'd ask.

It could be a bad I/O, but I doubt it.
It could be an incorrect flash, but usually that comes with more problems than just the fuel pump.

I suspect a wiring issue with the PCM transplant.

Were you able to have it running on this PCM prior to the flash?

flame

iTrader: (13)

How sure are you everything is out of a 98? The fuel pump green/white on the 98 is pin 37 and 99+ its pin #9 maybe check if pin 9 has voltage.

ColettaMerc

Its defiantly think its a 98 pcm and wiring because I wired everything else for a 98 and the tuner also said the computer was a 98 and the wiring harness has the three wire temp gauge and 2 wire oil pressure sender. Which is only 98 I believe? Also every wiring schematic I have referenced for the 98 seems to match.

ColettaMerc

I personally did not have it running on this pcm before the flash but the guy I bought it from pulled it out of a running 1998 car. Well thats what he told me.

MikeyC

Did you get your issue fixed yet?
From what I understand about PCM's, they usually control the ground side of the relay for the pump circuit as opposed to supplying a 12V source.

flame

iTrader: (13)

PCM controls the ground side for everything except the fuel pump. I guess they don't want the pump running if the wire would get rubbed through and ground out so they trigger it power side.

ColettaMerc

Have not figured it out yet but I just have it run from a separate power source(ignition wire) for now. I am going to try and mess with it tomorrow.

brianfromhawaii

iTrader: (3)

in PCM control of HP tuners i think you can turn the pump on an off.. try turning it on, someone may have commanded it off and it could have stuck? 98 computers are weird.