Engine/Transmission (1998.5 - 2002) pre start buzz

[bandrew]

i have a 02, 3/4, regular cab, 6spd, H. O. and just the other day I noticed while waiting for the "wait to start" light to go out there was no buzz coming for the engine compartment. I think that the buzz was the lift pump? Is it? So i have been listening for it for a while and haven't heard it. Does it mean that my lift pump is shot.

 

[BillGotthelf]

Not necessarily. Sometimes the pump does not turn on with key but will start when engine cranks. I believe this is due to fuel pressure still being present but as fuel is used by injector pump pressure drops and lift pump turns on.

 

[davemac]

What Bill said is true but if it is your lift pump and you continue to drive it you could ruin your injector pump. That`s very expensive. I would suggest that you have your lift pump checked as soon as possible.

 

[Bob Wagner]

try hitting the starter without actually starting the engine. You should hear the pump by "bumping the starter"



HTH

 

[Sixpack]

I think the buzz you hear may have something to do with the grid heaters. My truck makes a slight buzz while the wait to start light is lit but stops when the light go out... Maybe?

 

[pcarlson]

What sixpack said, the colder it is out the relays for the grid heaters buzz. It is temperature dependant and might not do it everyday if its above 15-20 degrees. Mine do it every time after a cold soak even if plugged in. Nothing to worry about though.

 

[David Wheeler]

For what it's worth... . when mine stopped buzzing it signaled to me time to visit my service department. Diagnosis..... dead lift pump. They replaced the pump, buzz immediately returned. So the moral of the story is that our trucks may rattle, but a good "buzz" is good too!



David

 

[WestTN]

buzz

Thre is a little high-pitched whine when the heaters are active. I'm guessing they are driven by a high frequency chopper output from the ECM because DC doesn't make a sound.

The pump makes a lower pitched buz and is very brief. You can hear the pump sound better if you roll the window down, put on your seat belt to stop the chime, and when turn on the key and just bump the starter. When you do this, the pump will run for about 25 seconds. Then you will know if the pump is okay and exactly what it sounds like.

 

[ToolManTimTaylor]

Also with the cold weather we (And you first) have experienced as of late the diesel is quite a bit thicker and the pump will labr more with the colder diesel. That will make the pump buzz more pronounce.

 

[Wiredawg]

You need gauges bad!

Do everthing the other guys said, but you need an fuel pressure gauge and an extra lift pump. Find someone with a mechanical gauge and check it.



Wiredawg.

 

[Eventer]

I think I may have the same problem. I no longer hear the lift pump buzz. I also had a problem earlier today where the engine would not start after changing the fuel filter. I had to unplug and replug the power to the lift pump then all was well.



Is not hearing the lift pump a bad thing? Should I run not walk to the nearest dealer to have it checked. I have almost 91,000 miles and the warranty is about gone.