adogriam

My son has a 99 3500. It started fine a week ago. Yesterday went to start it and the batteries were dead. Charged the batteries up, and went to start it. The wait to start light came on but keeps flashing will not go out. Checked all the fueses and relays, and they were all good. Do not hear the lift pump come on. Checked to see if it had power when you turn the key on and nothing. Wired the pump direct to the battery and the pump works. Also pulled the heaters off and they worked when wired direct to the battery. Is there a problem with the ECM?
I also checked for codes and there were none. It has a superchip tuner on it. When I tried to go back to factory the tuner did not recognise the truck. Son said the tuner started that a while back after he changed the injector pump.

totalloser

The way most programmers work is they only let you program one truck. That way you can't buy one and tune everybody's truck you know with it. Unfortunately, the tune was probably stored in the ecm in the old pump. You'd have to retrieve the program and reinstall it on the new vp.

As to the lift pump, the pcm controls the lift pump, so something is going wrong between the pump and the pcm. If I had to drive it, I'd be tempted to just wire it to come on with the key in the "on" position. If I understand correctly, the stock setup runs for a period when you first key on, then stops. The time it runs is based on how recently the truck ran or something like that. But once the engine is running the pump runs constantly.

Don't really have a very good idea of what's going on with your problems, but since no one has replied yet I thought I'd give it a shot. Take it with a grain of salt, I'm doing a bit of guessing here.

adogriam

Thanks! We did try hot wiring the pump and it does pump and raises the fuel pressure. Tried stating it and no go. The wait to start light never goes out it just keeps flashing. Did check the fuel heater and both stripe were good. We pulled the ECM, just have not bought a replacement yet.