Is A FP Gauge Necessary In The 3rd Gens?

[RJOL]

I've done a search on the 3rd Gen forum and have gotten some info on the new lift (pusher) pump.



I have a 3rd Gen on order and will be adding gauges when it arrives. I will definitely be putting a boost/egt gauge in, but I wonder if I need a FP gauge?



From what I'm reading, if you keep your engine pretty much stock, there shouldn't be a problem with low fuel pressure (like my old 2001 had). Even if the pressure should drop to zero, or you pull a vacuum, the engine may stumble, but recover when the fuel returns.



If all this is correct, is a FP gauge really that necessary? If so... why??

 

[scottmcd]

I'm very interested in what ever info you get on this post... Scott

 

[rbattelle]

A question as old as the 3rd gens themselves.



There are many opinions out there whether a FP gauge is required on the 3rd gen trucks if you're staying stock. There have been instances of stock LP failure on stock trucks, but they are admittedly rare. In my opinion, flow to the CP-3 is more important than pressure (I don't believe the CP-3 needs very much pressure at the inlet to run properly). I think a fuel pressure gauge is a good investment for "peace of mind", if nothing else. If you're remaining stock, I don't think it's really such a necessity as it was for the 2nd gen guys. Just my opinion. Others will disagree, I'm sure.



Now, you've got a 2005 on order, which means your lift pump will be in the tank. No one knows whether this will finally be the "end" of all the LP problems these trucks have had over the years. I suspect it will be the end (gasser in-tank pumps seem very reliable). But that's just my opinion. There's really no way to tell until the 2005 fleet gets a couple years old.



So, I guess it comes down to what you want and what you need for peace of mind.



-Ryan

Disclaimer - no offense intended anywhere in this post... just my opinions!

 

[RJOL]

I guess it comes down to this... If you loose your pump (in the tank for the 05's) can it damage the CP3 injector pump? Other threads have said that the European version of this setup doesn't even come with a fuel pump. The duramax apparently only has a priming button (what's up with that. . ).



With all the problems with the lift pump, on the 2nd Gens, one would hope that they have fixed this problem, but I would hate to end up paying for a new CP3 or other parts, if it isn't fixed. No one has really answered the question of low fuel pressure in the CP3 and if it is critical to lubricating the pump.



The guys with FP gauges have said that the pressure is low, and they can run it down to zero. I don't know if this is on stock trucks, or modified trucks.



If the FP is no longer critical to monitor, then I can't see putting in a gauge just to look at. If not needed I can put a "one hole" mount under the grab handle, and use a Westach EGT/Boost combo. .

 

[lil red cummins]

i put a FP gauge on mine, only because i needed something to fill the 3rd hole in the cubby mount. its interesting to watch. it runs between 3-1/2 and 6. normally around 5. i guess it will come in handy if the lift pump ever goes bad.



jim

 

[Matt400]

I guess it comes down to this... If you loose your pump (in the tank for the 05's) can it damage the CP3 injector pump? Other threads have said that the European version of this setup doesn't even come with a fuel pump. The duramax apparently only has a priming button

One possibility is that if the lift pump were to fail it could cause a restriction as the CP3 trys to pull fuel through a dead pump where as the Euro applications having no lift at all would have much less restriction.



I thought DC put it there to just prime the system in case you ever ran out of fuel making a more consumer friendly application.

 

[RankRam]

It's well worth having a fuel pressure guage just to keep an eye on the condition of your fuel filter.



Sender would need to be mounted post filter of course.

 

[rbattelle]

One possibility is that if the lift pump were to fail it could cause a restriction as the CP3 trys to pull fuel through a dead pump where as the Euro applications having no lift at all would have much less restriction.

I agree. I believe a dead lift pump will kill the CP-3.



-Ryan

 

[RJOL]

I agree. I believe a dead lift pump will kill the CP-3.



-Ryan

Well... If this is absolutely correct... I would install a FP gauge... The question is... "Does anybody really know this as a fact, or is it just an educated guess?" ...

 

[ceaman]

I know from experience that a 03-04. 5 truck with a bad lift pump will not run. If you install a low volume 7 to 9psi universal pump that it will run but wont have enough power to climb a hill.



Im installing a FP guage in the 05 when it comes in!

 

[RJOL]

I know from experience that a 03-04. 5 truck with a bad lift pump will not run. If you install a low volume 7 to 9psi universal pump that it will run but wont have enough power to climb a hill.



Im installing a FP guage in the 05 when it comes in!

Guess I should have been more specific... I was referring to the 05 CTD with the "pusher" pump in the tank...

 

[rbattelle]

The question is... "Does anybody really know this as a fact, or is it just an educated guess?" ...

I'm afraid I can only offer a guess. I don't have the time, money, or equipment to test it.



A better question is: "How is the CP-3 lubricated?" I believe the answer to that question will guide you toward whether a FP gauge is appropriate for you.



-Ryan

Disclaimer: I am not being in any way mean spirited in this post. It contains only my opinions. I encourage all readers to do their own independent research and come to their own conclusions.

 

[RJOL]

... A better question is: "How is the CP-3 lubricated?" I believe the answer to that question will guide you toward whether a FP gauge is appropriate for you.

If the CP3 must have continuos fuel for lubrication, then the addition of a FP gauge may be useful. I just wonder why the European setup, and the duramax setup, don't even come with this option. If the pusher pump, in the 05 CTD, fails, does it restrict the flow of fuel to the CP3?. If not, then the CP3 should be able to draw enough fuel, in stock application, to run the engine, and lubricate itself... Still wondering...

 

[SRadke]

I've got one in my 03. I watch it float up and down as I'm on and off the throttle. With the box up it'll pull down to 0. I DO NOT regret installing it. My $. 02



-Scott

 

[RJOL]

... With the box up it'll pull down to 0. I DO NOT regret installing it... . My $. 02 -Scott

Exactly... And if I added a fueling power modification, I'd install one. Not because your pulling down to zero, but that you may be causing a vacuum...

 

[barbwire]

Maybe you do not need this input, if you are looking for 05 specific, but... ... I believe that if I had a fp guage on my 04, I may have seen the lp going bad before it left my ride dead along side the road, while I waited 2 hrs. for a tow.

The only problem I see is that the fp guages seem to be as prone to failure as the lift pump that they are supposed to monitor. But, one of these days I'll bite the bullet, and take the plunge.

 

[RJOL]

. . Maybe you do not need this input, if you are looking for 05 specific, but... ... I believe that if I had a fp guage on my 04, I may have seen the lp going bad before it left my ride dead along side the road, while I waited 2 hrs. for a tow.

Although I'm mainly interested in the 05 (due to the new pump location) this is still a valid input, as you have the same CP3 injector pump. The only difference is wether the failed lift pump you had restricted the CP3 from getting fuel, when it failed. From your tread, it sounds like it did. If the pusher pump, in the tank of the 05's, restricts fuel flow, if and when it fails, then this will be an issue with this setup also...

 

[barbwire]

I hope you do not have this problem with the new trucks. However if we start hearing about pusher pump failures, I guess that then I would be looking at getting a guage. Till then, maybe, in tank pump is the fix.

 

[scottmcd]

What FP Gauge would you all recommend installing, working with my truck. Going to be ordering the New fuel filter cap from Geno's, that is tapped. TIA... Scott

 

[Matt400]

Personally I like SPA. Very accurate and programmable so you would get a warning lamp at any user selected pressure drawing your attention to the gauge among other features.



While we are still on the subject of a FP gauge on the 3rd gen I noticed in my 2003 factory OE manual it states lift pump pressure spec is a min of 9. 5 lbs. If thats the case wouldn't it be a good idea for those running under that to have them replaced while still under warranty before they get worse?