catahaula

99 3500 crank it up moved 6ft&quiet. had less than 1/4 tank of fuel ,added 10 gal, still wouldn't crank. Then drain fuel filter for water, nothing! Change fuel filter. Dropped fuel tank and checked it. Checked lift pump, pulled it off and it runs. Check fuses & relays. don't get juice to lift pump. Got one reading, no reading injector pump.

SIXSLUG

Ecm....

Busboy

To check the lift pump you need to "bump" the starter, just click it but not crank it, this will give power for 25 seconds to the lift pump.

SIXSLUG

I agree with Busboy, but if you do not have LP power after all the work listed, you may have the ECM not sending signal to fire the lp...

If you are certain you do not have air in the fuel line and it will not stay running I would get the fault codes checked and post up results..

jrs_dodge_diesel

Yeah, that sounds exactly like when I ran mine out of fuel (completely empty), thanks to a bad fuel sender in my tank.

Any way, you will not get a reading at the lift pump for very long. When you turn the key to on, the LP is turned on for maybe a second or two by the ECM and then shuts off. This happens pretty quick and a digital voltmeter (DVM) may not catch it unless yours has a peak hold function.

If you bump the starter and leave the key in the ON position, the ECM assumes that indicates a failed start and it will activate the LP for 25 seconds to "prime" the fuel system. Priming here means that fuel will be available at the INLET on the VP44 injection pump. The LP will not push fuel through the VP44. The only way to "prime" the VP44, and get the air out of it, is to crank the engine.

When mine ran out of fuel, I put 5 gallons in the tank and gave it a few tries with the bump the key (LP prime cycle) and crank it for ten seconds. I didn't even get a cough or sputter. I ended up cracking open 2 injector lines where they go into the cylinder head, and wrapped a rag around the fittings. I then repeated the prime and crank cycles until I saw fuel at the fittings (didn't take but one or two cycles), and then tightened them up. The next attempt got some sputtering and then it started.

Our engines only need 3 cylinders firing in order to start. Here's some other useful tips:

• Crank for no longer than ten seconds at a time, you can damage the starter if you crank longer than that by it overheating.
• Pause for at least two minutes between crank cycles, this allows the starter cool.
• Don't trust the fuel gauge for more than 500 miles.
• A test light is very handy for short momentary readings.