Maybe sounds silly but.....I don't drive my 2000 7.3 everyday. She only has 93,000 on her. Here is my question .. I think I remember the fuel pump under the cab used to run for a couple seconds when I turned the key to on. I noticed that I don't hear the pump any longer. The truck seems to take more revolutions now to start, used to start right up. But it does start and run ok.

If it runs the pump has to be ok, is there a separate circuit for power when key is turned to ON position maybe?

 

It should run for 20 seconds when the key is turned on, and will continue to run while an RPM signal is detected. You might have to pop your head under the cab to hear it; I can barely hear mine in the cab. If there's any ambient noise, I can't hear the pump at all.

 

Often they will start but not run over 40 mph or so.

You say you used to hear it. I would suggest you use a DVOM w/Low Amp Clamp. If its using more than say 12+ AMPS, replace it. If it starts an maintains 8-11 smooth, don't sweat it.

 

I'm sorry, this must be a typo or I lost track of the flow of the thread.

My head was following the fuel pump, and the sentence implies the fuel pump will actually shut off once nearing OD speed.

 

That 40 mph comment got me, too, Rich.

Perhaps in the context of his recommendations for checking the amperage on the pump, he might be implying that the pump won't put out enough fuel to go more than about 40 mph if there is for some reason a reduced amperage driving the pump's internal pistons (internal short inside the pump motor, corroded/loose wire connection, weak/dying battery, etc.).

 

Pretty sure he meant the engine may start and run if the fuel pump isn't working.

 

Thanks for the replies. Seems like I used to hear it run when waiting on glow plugs. I know it's fine because truck runs fine. Thanks guys

 

just had this issue. cannot believe the truck even ran. pressure gauge was showing ~4psi at most.

pump was ~6 months old. took it back to oh-rye-lees and got a new one. back to a solid 72psi now.

 

Tugly, et-all,

The OP wrote referring to the Fuel Pump:

"If it runs the pump has to be ok, is there a separate circuit for power when key is turned to ON position maybe? "

My response was:

"Often they will start but not run over 40 mph or so" This statement was intended to inform the poster that: "If it runs the pump has to be ok" in NOT a method of accurate troubleshooting; "As Often they will start but not run over 40 mph or so"

Tom

 

Thanks for getting back to me on that. As I read through the replies and revisited the sentence, it started to come through the way you had intended.

You'll notice I didn't assume you would say the pump shuts off... I just stated my GPS coordinates so you guys could lead me out.

 

Which pump (brand) gave you this problem?

 

While this isn't a direct answer to the question:

I did a lot of homework on fuel pumps for the 7.3L when I was powering up. After looking at every pump available on the market that allegedly fits the 7.3L diesel, the OEM is the best performer and most reliable - unless you install fire hoses for injectors. If I had that situation, I'd engineer a dual-OEM system.

I bought my OEM from Riffraff Diesel to get a better price than from the stealership.

 

don't recall the brand- but will update if found.

what was really sad was the pump was clearly stamped "made in the USA".....

 

I noticed you politely side stepped using the OEM brands name, although most of us here know your preferred brand.
I admire you Rich, but on fuel pumps, you and I disagree. I am OK with that. I trust you are too.