I am getting PM'd by people looking for info, so here is the complete set of threads to search before contacting me about lift pumps. I started some of these and participated in all of them. Between them is just about everything you probably need to know about lift pumps, for the 3rd gens anyway. Reading between the lines you can figure out what to do with the 2nd gens.

Yes it would be nice if someone wrote a FAQ on this. No I am not going to do it.

Please don't PM me. If you honestly can't find something you need after reading these, post it to the "My CP3 Feed..." thread and I or someone else will answer it.

I'm posting in general diesel because the 2nd gen guys are asking questions too.

I have no affiliation with Ford, Cummins, Dodge, Walbro, Bosch, SwageLock, McMasterCarr, Genos, Holley or this site.

One more thing: it is not harder on a pump to suck fuel than to push it.

Thanks.

It started here:
2 micron filter and pump for my Cummins in Ford ?
https://www.dieseltruckresource.com/...ad.php?t=70118

2 micron stock filter for ISB ?
https://www.dieseltruckresource.com/...ad.php?t=70565

Aftermarket fuel pumps II (Blowing filter lids)
https://www.dieseltruckresource.com/...ad.php?t=73365

I got it running and used it for a few months. I got a PM from a certain member who was having engine trouble and we traced his problem to the Holley lift pump. In response to his problems I started this post.

This post has most of the technical detail in it. It only talks about the CP3, but would be similar for a VP44.
My lift pump/ CP3 feed solution
https://www.dieseltruckresource.com/...ad.php?t=78702



This one got the ball rolling again. I didn't mean to hammer this guy.
Note the CP3 went out before the lift pump did.
Lift pump quit
https://www.dieseltruckresource.com/...ad.php?t=86621

This is so typical.
LIft Pump gone bad? Anyone else!! Need Help!!!!!
https://www.dieseltruckresource.com/...ad.php?t=86652

Lets talk about lift pumps, CP3s, hard starts, knocks, smoke, etc.
https://www.dieseltruckresource.com/...ad.php?t=86643

CP3s are rebuildable.
https://www.dieseltruckresource.com/...ad.php?t=86694

cp3 leak
https://www.dieseltruckresource.com/...ad.php?t=55904

any reason to all the lift pumps dying???
https://www.dieseltruckresource.com/...ad.php?t=86671

Poll: 3rd gen lift pump failures
https://www.dieseltruckresource.com/...ad.php?t=87084

CP3 Replacement after new lift pump
https://www.dieseltruckresource.com/...ad.php?t=86640

Filter Housing Cover
https://www.dieseltruckresource.com/...ad.php?t=87272

In-tank lift pump failures
https://www.dieseltruckresource.com/...ad.php?t=87679

This thread opened the debate up and got people talking about lift pumps.
What is so great about FASS ???
https://www.dieseltruckresource.com/...ad.php?t=87890

It gets ugly:
in-tank lift pumps: truth, myths, speculations, lies.
https://www.dieseltruckresource.com/...ad.php?t=87999

Here is where people should discuss actually putting a Walbro fuel system on their truck. The start of a parts list is here.
Implementing a Walbro fuel system:
https://www.dieseltruckresource.com/...040#post860040

Here is a thread I started on putting a 2 micron Cat filter between the stock 10 micron fuel filter and the CP3:
https://www.dieseltruckresource.com/...485#post862485

 

[QUOTE=Superduty]too.



One more thing: it is not harder on a pump to suck fuel than to push it.


Sorry, the higher the suction pressure, the higher the rate of air coming out of solution and resulting cavitation & chance to lose prime. The suction side under greater than negative pressure allows air to stay in solution. Fill a hypo half full of any solution then sealing the needle end, continue to pull the plunger outward and watch the solution fizz like an alka seltzer.
Additionally, the Bosch VP44 has a relief valve pressure of 15psi. Evidently the engineers designed the VP to receive near and around 15 psi or else the relief pressure would've been set closer to another value.
Otherwise, the Walbro pulsajet carburetors in my chain saw and weed trimmer are pretty good pieces.

 

sorry the load on the pump is the same for the same differential pressure across the pump.

I have yet to see/hear of the internal parts of a fuel lift pump eroded due to cavitation either.

At any reasonable inlet vacuum there is no appreciable difference to the pump. At severe vacuum levels the fuel might start changing from liquid to gas, but prior to that point the pump is just fine with things.

The conditions in a hypodermic needle are not indicative of the internals of a fuel pump. For example the needle inlet on the syringe is severely constricted. The velocity pressure component of the fuel increases, and the absolute pressure drops thus bringing the air out of solution. It is like the orifice on a fuel injector working in reverse.

Fuel pumps are designed so that doesn't happen. For example, the CP3 is used on Duramaxes without a lift pump. And it sucks fuel through the stock filter and sometimes an auxiliary filter without too much difficulty.

For this to happen the area of the inlet must be large so the fuel velocity is low as the fuel enters the pump. If the pump inlet was severely constricted then phase change could be an issue. Pump designers optimize the inlet size of the pump, the velocity at which the fuel moves through the pump prior to being pressurized and the diameter of the line that feeds it so that there isn't a problem.

 

This is like watching a tennis game

 

Superduty, thanks for sharing your lift pump system. It is elegantly simple as well as inexpensive. As I read the threads it just boggles my mind how you can explain it countless times and some people still don't understand how/why it works. Keep at it.

 

agreed......EXCELLENT information - thanks for the effort !

Would be nice if this thread had a sticky on it so it would stay on top.

 

superduty why dont you put a kit together with some instructions and sell this thing. put a nice mark up on it and go from there! i would try it but dont have a truck to put it on yet.

 

I don't have time. And there isn't much to kit.

Why don't you guys put together a group purchase and parts kit and instructions ? You could add a bit of profit into the kits and buy this site some server equipment. Just a thought...

 

I'm seriously looking at doing this. The design and idea are 100%.

The problem with others, Holly, this and that, they want the name. For race cars, weekends, every now and then, those pumps are great. For everyday driving anything with brush's will wear out. It has to in order to work. We run brushless pumps here at work. We work in Biotech, has to be clean, no dust, sanitary, ect. a Vane pump is much better (kinda like the wash pumps on boats, rotary design on seals, pumps up to 30 psi, but will do it forever, no brushes)

I think people dont' look at the insides, and what actually makes it last forever. Nothing last's forever, but longer than shorter is in my book.

Question for you superduty, YOu had two diagrams as to where to mount the pressure relieve valve, before the fuel filter, or after the fuel filter. I agree with the after the fuel filter mount due to pressures. Have you implemented this yet, or are you still running just the green bypass tube? I want to perform that as well if I run the pump.

 

I'm going to be running the bypass with the Swagelok very soon. It takes a couple of weeks to get that darn regulator/checkvalve ...
It'll be worth it in the end. I'll post pics when done.

 

"Question for you superduty, YOu had two diagrams as to where to mount the pressure relieve valve, before the fuel filter, or after the fuel filter. I agree with the after the fuel filter mount due to pressures. Have you implemented this yet, or are you still running just the green bypass tube? I want to perform that as well if I run the pump."


The purpose of the two diagrams was to compare the pressure regulation performance, because a lot of people insisted that a pressure drop at the injection pump was unavoidable. (Thus the need for big lines, etc...) I say if the regulator is put at the injection pump and a proper lift pump is used, there will be no pressure drop at the injection pump.

I am just running the green bypass tube. I might change to the regulator someday.

One more thing while we are at it.

There is the potential for a problem if one just runs the bypass without a regulator. If the lift pump ever quits and there is no regulator in the bypass circuit and if the return line in the fuel tank allows fuel to be sucked from the tank (ie no checkvalve) then it is POSSIBLE for the CP3 to suck UNFILTERED fuel from the tank. This will be entirely prevented by running the Swagelock regulator in the bypass line and will probably be prevented by running a Holley 3 port regulator as well.

I don't worry about this eventuality because

1) I've never seen my Walbro fail
2) I'll put a pressure sensor on my lift pump at some point
3) the Walbro continuously pumps the fuel from the fuel tank through the filter thus after an hour or so the fuel in the tank is clean.

Each to his own though.

 

It's like an expose' or 20/20 episode with John Stossle here.

Whistle blowing on the whole "pusher pump" kit phenom.

If only for the ease of swapping my LP, I am still happy with my Vulcan Relocation and Big Line purchase.

 

I'm beyond fighting with all the experts here. Do whatever you want.

 

No intention of "fighting", but you throw out all of these broad sweeping, "By the way" statements and then expect people not to wonder??

Dumping on other peoples Mod's (or lack there of) is somehow acceptable and in some cases commended when it comes from you.

Obviously your knwoledge of all that pumps is superior to most if not all of us, but the cocky delivery is sometimes a bit much.

 

I've never felt SD's comments to be cocky. Sure he's knowledgable. And he's to the point and matter of fact-ish.... Cocky... I don't think so.
Maybe that's because I agree with him. But if I didn't I certainly wouldn't enter a thread where he's trying to help those who WANT it and start bashing him.
To me, it's like trying to censor someone, kinda like Howard Stern. If you don't like it or agree with it, then don't tune in to it.
There are so many threads about FASS here and on other boards that I wholeheartedly disagree with. Like spending $500+ when you don't need to. But I don't interject on those threads.
With the way some people on this board react to SD (not naming names), I'd be surprised if he sticks around much longer.