Engine/Transmission (1998.5 - 2002) 15 second fuel pressure.

[Madman]

I have a '99 2500 4wd on which I just had to replace the ECM (Reman Plug and play from ECM Diesel) and went ahead and replaced the lift pump in the tank. Now I get intermediate fuel pressure when I turn on the key. Sometimes when you turn the key the starter hits and 15 PSI shows on the mechanical fuel gauge, other times it takes 2 or 3 tries for for the pressure to come up. The one thing that works every time is turn turn the key on, wait 15 secs at which time the fuel pump comes on and pressurizes the rail then turn to start.

The only "timed" part of the computer that I know of is the intake air heater could there be a glitch in the new ECM?

Any Ideas?

 

[JR]

The ecm does not supply voltage to the lift pump until after you bump the starter and then it will run for approximately 15 seconds before shutting off (unless you start the truck)

 

[Sticks]

That is not entirely accurate. You get about 1/2 second of lift pump voltage to "prime" the system when you go to key on from off. That is either design, or part of the system checks (like all the lights in the dash come on for a couple seconds).

 

[JR]

OK, yes to be exact you get a split second of voltage when the key is turned on. To be entirely accurate, it is not enough to prime the system, and not enough to build anything over about 1-2psi for a split second assuming the fuel system is already primed. If you've just had the system opened up or have a leak somewhere you won't even see that.

 

[klcammie]

When I first turn on the key the lift pump runs for about 3-4 sec and the gauge shows 20 lbs. then drops to 0. As I turn key to start the fuel pressure goes to about 10 lbs a couple of times as engine rolls over and starts.

 

[Madman]

If I have a leak why would it start on the first "bump of the starter sometimes"? The pump isn't coming on for 15 seconds. I'm going to put a test light on it this morning.

 

[Sticks]

OK, yes to be exact you get a split second of voltage when the key is turned on. To be entirely accurate, it is not enough to prime the system, and not enough to build anything over about 1-2psi for a split second assuming the fuel system is already primed. If you've just had the system opened up or have a leak somewhere you won't even see that.

I don't know about you, but mine will spike up to 7psi then slowly drop down. But then again, I don't have any system leaks.

 

[cerberusiam]

The fuel pump run is timed also. Initially it was something like 5-10 seconds whne you key on and wait for the lights to go out. The VP44 doesn't like that pressure at start up so there is a flash to drop that to 2-3 seconds with the initial key on then the LP won't run again until the engine starts or you go thru several crankng cycles without starting.

Just a key on the pressure should jump to 5-6 psi then bleed down or you could have starting issues. If it jumps to 15 psi and\or holds more the 5 psi for any length of time probbaly should get the ECM flashed for that update.

 

[DLMcpherson]

Did you find out what the problem was?