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I realize that the LP is a problem for many but after all my research I have found that the LP isnt as bad as many think and it is actually a good pump. The big problem with the fuel system is the size of the fuel lines themselves. Way to small. How many have taken the time to check out the size of their lines? If you think the are all 5/16" you are wrong. I was amazed to find out that on my truck from the fuel tank to LP was 5/16" and from LP to filter housing was 5/16". BUT from my filter housing to the VP there was a section of fuel line that was actually 1/8"!!! Yes that right 1/8". You couldnt breath through that. Now after sharing this I read that some have found this dreaded 1/8" piece to be between the LP and filter housing, too. The only reason anyone came up with was that maybe it was to reduce VP pulses to the LP. Dont know except that the LP cannot survive like this. With this puny factory setup the LP is forced to live its life in the bypass mode which inturn eventually forces the internal bypass check ball to hammer its way against the LP housing and spring untill failure. So by opening the fuel line sizes to a straight 5/16" which is OK or to 3/8" which is better or to 1/2" which is best then that allows the LP to supply the VP with a constant supply of fuel and actually raise pressure readings. I know this sounds totaly against what everyone already has read but it really works. Yes the fuel tank is about even with the LP but try this, take off your fuel line at the LP and tell me that diesel doesnt run all over you. That means that the LP doesnt have to suck like you think.
There has been so much talked and tested about the dreaded LP failures and many have come up with what they feel is the best solution but after all the reading I have done (which equals to many many hours) the stock LP is pleanty good enough to deliver fuel for around, I believe it was, 375 HP with high flow banjos and at least 3/8" fuel lines all the way throughout. Any more power and you need a bigger pump with 1/2" lines and no banjo fittings.
 

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Oh yea I forgot to mention that many have found the vent on their fuel tank to be caped. I guess the assembly line forgot to remove before installation. That causes a major vacumm in the fuel system.
 
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Thanks for the input KATOOM.....by the way welcome ol friend its been a long time! :woot:
 

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Hey Katoom havn't I seen your handle before over on Diesel Ram or DTR???? Sorry didn't mean to steal the thread.,.....:popcorn:
 

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"The big problem with the fuel system is the size of the fuel lines themselves. Way to small."

No. Other pumps will push 75 GPH through them without any problem. Not even breaking a sweat. Ford trucks and gasser vehicle use the same size lines.

The problem is that Dodge and Dodge truck owners keep putting carburetor type pumps (ie pumps rated for maximum pressures of 10-15 PSI) on their trucks, then proceed to run them with loads 15 to 20 PSI (at the pump, 10 to 15 PSI at the lift pump) and then they fail. Do the math !
 

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Superduty said:
No. Other pumps will push 75 GPH through them without any problem. Not even breaking a sweat. Ford trucks and gasser vehicle use the same size lines.

The problem is that Dodge and Dodge truck owners keep putting carburetor type pumps (ie pumps rated for maximum pressures of 10-15 PSI) on their trucks, then proceed to run them with loads 15 to 20 PSI (at the pump, 10 to 15 PSI at the lift pump) and then they fail. Do the math !
Well I dont really understand the "Do the math comment". What math? I'm simply speeking from experience. I guess if you want a mathmatical equation then maybe you didnt read the part about 1/8" fuel lines. I dont recall EVER seeing a fuel line that incredibly small on ANY vehicle before (not even a motorcycle), but I guess since you stated that Ford trucks and gassers (theres a general word) use the same size fuel line then OK you are the man of knowledge. Oh yea, did I already say that what I said works, cause it does. The problem isnt pressure its volume. The VP actually likes the extra fuel for better cooling. And by the way carburated fuel pumps usually dont exceed 7psi. If so then they need to be regulated with a return line at the FP or at the regulator before the pressure drops. Thats funny. Did I say cutting down the pressure before it gets to the carb? Wouldnt that ruin the FP? NO, because the FP wouldnt be running in the bypass mode since it has a return line to keep up the volume. Hey thats something our poor little LP doesnt have untill after the VP. Reason needed for the increased fuel line size to increase volume on the Cummins.
So if in the future you dont speek from experience, not just opinion, then dont be so rude. Thanks
 

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"Well I dont really understand the "Do the math comment". What math? I'm simply speeking from experience."

I was referring to looking at the pressure needs of the system and then selecting a pump accordingly. You want 15 PSI at the VP. The carburetor pump struggles to put that out. Other pumps will make 60-80 PSI like nothing. Why not select a solution that give you a 50 PSI increase (that being a different pump) rather than a 2 PSI increase (a different line) ?

Yes, increasing the size of the fuel line will increase the flow to the injection pump. But if you selected a different pump it would push fuel through those lines without any problem at all.

Increasing the line size allows the barely adequate carburetor pump to get a few more PSI to the VP. Say 15 PSI. Replacing the carburetor pump with an EFI pump like a Walbro would increase the pressure to oh... 60 to 80 PSI without a bypass. It delivers so much fuel that you need to provide it with a relief system to limit the pressure, all with stock lines.

Replacing the line is a band aid. Replacing the pump fixes the problem.

"I guess if you want a mathmatical equation then maybe you didnt read the part about 1/8" fuel lines. I dont recall EVER seeing a fuel line that incredibly small on ANY vehicle before (not even a motorcycle), but I guess since you stated that Ford trucks and gassers (theres a general word) use the same size fuel line then OK you are the man of knowledge."

Fuel lines (being steel tubing) is measured in OD. I am not aware of any lines being 1/8" OD on the supply side.

"Oh yea, did I already say that what I said works, cause it does. The problem isnt pressure its volume. The VP actually likes the extra fuel for better cooling."

OK. Leave the stock lines alone, bolt on a Walbro, put on a bypass and see 70+ GPH right to the VP44 inlet. Now which was a better fix ? The bigger line or the right pump ? There is no way the stock pump will ever move 70 GPH to the VP, bigger lines or not.

"And by the way carburated fuel pumps usually dont exceed 7psi. If so then they need to be regulated with a return line at the FP or at the regulator before the pressure drops. Thats funny. Did I say cutting down the pressure before it gets to the carb? Wouldnt that ruin the FP? NO, because the FP wouldnt be running in the bypass mode since it has a return line to keep up the volume. Hey thats something our poor little LP doesnt have untill after the VP. Reason needed for the increased fuel line size to increase volume on the Cummins."

www.holley.com. Lots of their pumps exceed 7 PSI. Yes, they need to be regulated.

"So if in the future you dont speek from experience, not just opinion, then dont be so rude. Thanks"

You might want to read some of the posts on Walbro fuel pumps.
 

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Superduty, lets not argue this anymore. OK? I dont want to insult anyone anymore than I want to be insulted, but my point was simple, that Cummins installed a ridiculously small ID fuel line (yes, 1/8" ID) to stop VP pulses to the LP. Guessing that the pulses from the VP kill the LP. Not even sure why the LP is attached to the motor. Maybe DC didnt want to have to supply Cummins motors with a FP on the truck so Cummins put one on the engine when it left the factory. (possible warranty issues?) And I dont even know if all year trucks have this line size problem since I've read of others reporting their lines having this small ID block in various locations between the LP and VP and others not having it at all. Ya never really know what the manufactures reasonings are. So again to my point, I know from fact that the stock LP is plenty good enough to deliver fuel to the VP for thousands of miles with no issues as long as its through big enough fuel lines. Its an easy and cheap way to keep the Cummins alive as long as you dont go over 375+ HP. Then yes I totally agree with you, a bigger pump is a must. But by telling everyone they have to spend hundreds of $$$ to assure a happy VP is simply (I feel) an over kill. And not to mention all the research I have found is that the VP doesnt like real high fuel pump head pressure. Something like over 20+ psi (cant remember the exact number) and it may cause problems.
And commenting on what you said about the VP being able to supply itself with fuel, well thats true but its a LP failure backup. This way the truck still runs with a weak LP but it tends to cooks the VP. Thats why the trucks rarely just stop running while tooling down the road, they just dont start again when shut off. The VP cant supply itself with enough fuel with out a FP.

You argue a good point, there needs to be a fix for the VP/LP problems but how extreme you go is up to the wallet of the consumer.

Oh yea, just to let you know for in the future, you dont have to type everything over someone has already said just to show it on your reply. Just click on the quote below the reply you wish to comment on and it will transfer their whole reply on yours, then you can delete what part you dont want. Lots easier.:thumbsup
 
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I tend to agree with Katoom (welcome to the site!).

Biggest single problems as I see it with the stock LP is it's location - down by the tank would be better, then there's Katooms point of the LP constantly working against it's internal bypass, beating it to death. A good EXTERNAL PSI regulator set to about 12 PSI and returning bypassed fuel to the tank would allow plenty of fuel PSI and flow to the VP-44, and greatly reduce stress on the LP.

The Walbro may well be an excellent replacement solution - but without an established track record on OUR trucks, and OUR fuel systems, it remains to be seen if it's actually BETTER or not!

Has ANYONE actually had a Walbro apart to see if it's BUILT any better than a Carter = or is it simply another totally self-contained motor/pump device whose only REAL difference is that it puts out higher PSI?

What's the most miles one of the Walbros has been successfully installed on a Dodge Cummins? I'm not real interested in what one will do in a ricer or a Ford - that's largely apples/oranges - what have they been shown to do on a DODGE?

AND, after we do all the associated fuel system mods to install a Walbro, how much would those SAME mods (fuel regulators, lines, etc.) have done to improve the LP we already have?

No arguments, just my own points and opinions - and IF the Walbro lives up to what's being presented, I might well be one of the first to try one myself - but I need lots more info before that would happen!
 
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"I know from fact that the stock LP is plenty good enough to deliver fuel to the VP for thousands of miles with no issues as long as its through big enough fuel lines."

Other people haven't shared your experience. The stock lift pump still fails.

"Its an easy and cheap way to keep the Cummins alive as long as you dont go over 375+ HP. Then yes I totally agree with you, a bigger pump is a must. But by telling everyone they have to spend hundreds of $$$ to assure a happy VP is simply (I feel) an over kill."

A Walbro sells for $100 on eBay. Less than a new Carter and probably less than a big line kit.

"And not to mention all the research I have found is that the VP doesnt like real high fuel pump head pressure. Something like over 20+ psi (cant remember the exact number) and it may cause problems."

Run a bypass line. 17 PSI at idle, 10 to 13 PSI at WOT. 70 GPH going past the inlet of the VP at all times.

"And commenting on what you said about the VP being able to supply itself with fuel, well thats true but its a LP failure backup. This way the truck still runs with a weak LP but it tends to cooks the VP. Thats why the trucks rarely just stop running while tooling down the road, they just dont start again when shut off. The VP cant supply itself with enough fuel with out a FP."

A CP3 will self feed. A VP will not. I don't recall saying that a VP would self feed. If I did, I am wrong.

"You argue a good point, there needs to be a fix for the VP/LP problems but how extreme you go is up to the wallet of the consumer."

A Walbro is $100. You can buy one on eBay.

"Biggest single problems as I see it with the stock LP is it's location - down by the tank would be better, then there's Katooms point of the LP constantly working against it's internal bypass, beating it to death. A good EXTERNAL PSI regulator set to about 12 PSI and returning bypassed fuel to the tank would allow plenty of fuel PSI and flow to the VP-44, and greatly reduce stress on the LP."

a) The location doesn't have much to do with it, other than a bit more heat and vibration. The stock lift pumps are designed for 10-15 PSI and they are operating at 100% of their design all the time. A Walbro is designed for 80 PSI continuous. At 20 PSI it is operating at 25% of its design load. It will literally last forever doing that.

b) External regulator will make no difference. 12 PSI is 12 PSI whether the regulation is internal or external. I'm not sure which pumps have internal regulators. The Holleys don't. When they make 12 PSI, that is just as much fuel as they can move at that pressure. I suspect the Carter is the same.

"The Walbro may well be an excellent replacement solution - but without an established track record on OUR trucks, and OUR fuel systems, it remains to be seen if it's actually BETTER or not!"

Guess what ? The Cummins is a VERY easy engine to feed. A Cummins needs 30 GPH at 20 PSI. Gassers need 40 to 60 GPH at 60 to 80 PSI ! It is a myth and a fallacy that the Cummins is hard to feed. The only thing easier to feed would be a carburetor.

The problem is that people put carburetor pumps on the Cummins and they aren't powerful enough.

"Has ANYONE actually had a Walbro apart to see if it's BUILT any better than a Carter = or is it simply another totally self-contained motor/pump device whose only REAL difference is that it puts out higher PSI?"

Walbro used to be its own company, back in 2000. And they used to have a cut away picture. It is a stout pump.

"What's the most miles one of the Walbros has been successfully installed on a Dodge Cummins? I'm not real interested in what one will do in a ricer or a Ford - that's largely apples/oranges - what have they been shown to do on a DODGE?"

It is absolutely NOT apples/oranges. Gasoline has much less lubricity, more debris in the fuel and EFI systems operate at a much higher pressure. How long do you think a Carter would last pumping fuel at 80 PSI ?

Ford Diesels need fuel at 60+ PSI. The stock Ford PSD fuel pump is a Bosch and it has an excellent service record. They rarely quit.

I've been running a Walbro since 2000, first feeding my PSD at 70 PSI (for 60,000 miles) and now my Cummins at 25 PSI (at the lift pump). In July it made enough pressure to crack the filter lid, so it is a long way from failing.

"AND, after we do all the associated fuel system mods to install a Walbro, how much would those SAME mods (fuel regulators, lines, etc.) have done to improve the LP we already have?"

The bare minimum mod list is:
- mount the Walbro on the frame
- connect it to the fuel suction line
- put a bypass across the VP or CP3. (No regulator).
- possibly wire it with a relay.

The only thing that I can see helping the stock lift pump is moving it off the engine to a cooler location with less vibration. This doesn't solve the basic problem of the stock lift pump being under powered to supply fuel at the required pressure.
 
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