Code 556 fuel pump primary

[KasperG]

:SNSign: Please try and help me figure this out.
My car has a hard time starting. After a few turns it will fire up, but it will sputter at a real low rpm before it gets better. After that it will idle fine. Maybe within the next minute the idle will jump up and back down again and after that it will run just fine. I ran the codes and got the 556 and 172 wich is "system lean bank 1" Both of the codes could be related to the same cause. I have an idea that it might be the relay. I think this might be it because once the car starts to turn over a few times it will build oil pressure and the fuel pump will supply. But the primary is not priming. My main questing is... Where is this relay and what does it look like. Any of you have photos.. From searching different sites I found out that it might me in the little black box that hangs off of the coolant resarvoir. Is this correct? If so , do you just open the black box and find the realys inside? Any help? please

 

[bill302]

i would start by testing both oxygen sensors. you will need a repair manual you can purchase one from a parts store or check one out from library, test will be in emmissions controls section. you will also need a digital multimeter, wal-mart has them for about $20.these are good tool to own if you own a mustang. you will use them alot. you probably have 1 or possibly 2 bad oxygen sensor.

 

[HISSIN50]

Because it happens only right when you start up a cold motor (right?), I actually would not necessarily think Lambas. The O2's take 30-120 seconds or so to light off, so initially their input is kinda ignored.

The lack of FP priming is not good and could explain prolonged cranking. You can ground a terminal in the self test connector to jump the pump on.
The relay is integral to the CCRM AFAIK (I could be wrong) - one would need a new CCRM if the relay is bad. One can probe the wires for the pump circuit at the CCRM to see what is missing (if the relay does not get proper inputs, it wont prime - it is not necessarily the CCMR's fault).

Good luck.