Half way through our camping trip pulling our 5th wheel I noticed a pinging/rattle metallic sound from the left side of the engine. The strange part is the sound came and went within a certain RPM range, for example 1700 RPM was the worst and between 1700-2,000 it was hardly noticable, 2,100 an above it picks up again.

If I stopped for fuel or idled or took it real easy for period of time it went away completely, till I start to push again on the highway.....Without the fiver attached I don't have a problem.

There is NO loss of power and it starts right up as usual on first click of the key.

It's an 03 with 58,000 miles so I sort of expect an issue with the lift pump, maybe I just have blinders on and its something else.

Any thoughts?

Thanks

Ron W.

 

Befor mine went out, I had longer starts and a couple times is just died when parked while running. No Noises like you described.

 

Could be your lift pump. If you have a couple dollar's to throw at it I would get a fuel pressure gauge. I know my lift pump is in a different spot than yours (in-tank rather than in the engine bay) but, towing with my stock pump I could see my pressure coming down from about 7.5 to 5 and it would stay there while I was in it for a long period of time. So it kinda makes sense to me that if your lp is on it's last legs that possibly you are supplying enough at normal operating conditions, but not with a decent load.

Not familiar with the sounds so I'm not much help there. I know this though the lp's in the engine bay have been problematic so you might as well get an aftermarket or in-tank lift pump or at the least a fuel pressure gauge. Whether that be a mechanical with an isolator or an electrical. Quad rail pressure with the addition of the fuel pressure kit might be ideal for you.

 

If you can pull a warranty relocate to the tank I would go for it....

One a side note the CP3 doesn't need a LP or positive pressure to run... but it sure helps.

 

I have a similar noise MAYBE from my 2007 5.9. Mine sounds more like clatter from the injectors. Does yours go away as soon as you lift up off the Throttle just slightly?

 

If I lift off the throttle the sound certainly drops off, almost completely.

It's kinda strange why it's so loud only in those ranges, another way to describe the noise , it sounds like the noise you get when your speedometer cable was starting to go (If your old enough to remember).

What I will do before taking it to the dealer is re-program the Bully Dog, maybe back to stock then back to Tow mode.

It's funny I did a search on lift pump failures and read most of the posts and no one mentions any noise associated with their failure, only loss of power and slow starting.

Ron

 

That was my thoughts, don't remember lift pump going out noise... I do not have the Bully etc. All stock.

 

Will it have less power though? I think my 03 is loosing power and am curiuos.
Thanks!

 

The Dmax guys who add LP's do report an increase in power, but how much I do not know.

 

I had no noise or symptoms assocciated w/mine going out.....just died when going down the road.

 

on my 03 when the lp went out it went truck wouldnt run at all. it never made any noise but your noise makes me think that maybe an injector line clamp is loose they will buzz at certain rpm's

 

When the lift pump starts to go it will sputter like its running out of fuel until it totally dies and truck won't start again. Happened to a buddy of mine 2 years ago on his 04.5 when I was with him. He didn't notice any real noticeable symptoms until it was actually about to die.

 

Don't 04.5's still have the engine mounted LP? From what I have read the in tank is a flow thru design, if it fails it will still deliver fuel...

 

i have a 2004.5. when i turn my key forward i can hear the LP buzzing by the rear tank somewhere. I have a quadzilla rail/LP gauge and i always keep it on LP. I usually see 8-9 PSI LP all the time and 7-8 when im driving or pulling. are these numbers good for a stock LP or is mine on its way out?

 

If you really think you have a LP problem then check the fuel filter first. If you haven't changed it yet this year after the winter fuel change over then that can cause the exact same systoms. I would think that yo may have a vlave or injector problem though.