2000 4.7 broke down after fill up. Cranks but no fire. Fuel pump relay clicks but can't hear pump. Fuel gauge has no indication. I suspected fuel pump/sender so I replaced it with new one. Still same symptoms only with ignition on OD miles flash (no set # of times) and then displays "no bu5". Also, I had no error codes before I replaced pump and now won't read codes at all. I refuse to take this in, I know this is something I can fix at home. Already cost me $650 to get it home and replace the pump so I'm not going to give someplace $100 per hour as well.

 

Your cluster and/or PCM is fu*ked. With no signal from the computer (hence the "no bus" code) nothing electronic (injection, etc.) is going to work...

 

Or you can have the CCD bus shorted out. Sometimes a bad sensor can do this, cam, crank, IAC, MAP, you name it.

The fuel gauge itself is run off the PCM.

Try a cluster test to begin with.

 

I suspected the PCM but didn't want to go there. How do I test the inst. cluster? I will also start testing the sensors. I tested the fuel sender when I pulled it out and it was indeed bad so I thought that would cure things. I will test all the inputs to the PCM before I replace it just to make sure one of them didn't short it out. 181k I guess I can't expect it to live forever. I don't want to get rid of it, they are fantastic trucks. Drives through everything.

 

Here's the self test on the cluster. It may/may not help.

(1) Begin the test with the ignition switch in the Off position.
(2) Depress the trip odometer reset button.
(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On position, but do not start the engine.
(4) Keep the trip odometer reset button depressed for about ten seconds, until CHEC appears in the odometer display, then release the odometer reset button.
(5) A series of three-digit numeric failure messages may appear in the odometer display, depending upon the failure mode. If a failure message appears, see the Instrument Cluster Failure Message chart for the description and proper correction.

Depending on what happened to the fuel sender it may have fried the PCM. All you can really do is isolate various sensors and modules to eliminate them.

 

ok, got the codes. 920, 921, and 999. I assume the 999 is the end code. Inst cluster codes not listed in my manual. Can anyone tell me where I can find them?

 

never mind. both codes are related to PCM crapping out.

 

You may need a new pcm or a rebuilt one. I had the same problems and codes. Ordered a rebuilt one online. Problem was solved . Good luck