So my neighbor bought a truck, was running now it cranks no start. Threw a anti-theft code that has been cleared, tried to mate the key back with the truck but the snap on scanner isn't seeing the module needed to do that.

Crank no start. No fuel pressure at the port on the manifold. No pressure to the tank side of the fuel filter.

Suggestions? I know the easy thing is to condemn the fuel pump, but given it had that anti-theft code (I wasn't here when the codes were pulled and cleared) I'm wondering if there is something else we need to troubleshoot before throwing a fuel pump at it.

 

If it’s a security issue, usually the engine will start but then immediately die, accompanied by the indicator light flashing.

Did you happen to check the status of the security code (history or current/active)? A history code is nothing to be concerned about but a current code means the condition is still present. Do you remember what the code was?

You can rule out the functionality of the fuel pump one or two ways:

1) Check for the pump to run for about 2 seconds when the key is turned on. This is easiest by having a helper remove the filler cap and listening while you turn the key (or vice versa).

2) Remove the fuel pump relay and jumper the switch side (pins 30 & 87) to provide direct battery power to the fuel pump. If it works there’s a reason the PCM isn’t turning on the fuel pump which can range from bad fuses to the security system.

Note that on trucks equipped with 2 tanks, there are 2 relays - the primary relay has direct battery power at all times but the secondary relay only receives power when the key is on, so if attempting to test the secondary pump, make sure the key is on.

 

Thats what throws me for a loop. I would think even with security enabled, the fuel pump would power up some. We're getting nothing. Getting a couple of codes b2948 b2961, both related to security, but not the only ones, just the only ones I saved on my phone. I think we've decided the security module is bad. We're going to send it up to my buddys shop this week and let him figure it out. lol

 

Actually the codes both indicate a problem with the pass lock sensor for the ignition key cylinder. Could be the cylinder needs replacement or the wiring to/from the key cylinder is shorted or open - both are common problems for the pass lock system. I’m not sure if that wiring going open would completely shut off fuel pump operation, but if you jumper the relay and the pump kicks on, it’s a likely scenario.

The security system is controlled by the BCM and doesn’t have a standalone module, so replacement would require vehicle and pass lock programming.