I cut and pasted this from some diesel engineer's post from like 5 years ago...


For the record,

This whole thing for me started when i read the post about prime loc causing lift pump and the vp44 pump failures.

I found the whole post very interesting, and somewhat confusing, and i must confess i cheated while doing some of my r&d. I hired an engineer to check out the system but wanted to verify his findings before commenting.

I'll be honest with you , i thought this could be a good business opportunity, selling a complete fuel system upgrade.

When the engineer gave me his findings, his findings suported prime loc that pressure has very little meaning without flow.

Obviously i have invested a great amount of money to date in this project, i however believed it would be a good investment at the time.

Much to my chagrin, our testing proved the engineer and prime loc's position.

Based on all our findings, the most effective method is to simply move the oem lift pump closer to the tank and clean up some of the fittings(banjo bolts).

Installing a bigger line to feed the existing oem pump or aftermarket high performance pump at its factory location is a waste of money.

There really was no politically correct way of saying this, i know a lot of people have invested a lot of money.

I am not an expert in fuel systems but i have to conclude as long as your pressure does not drop below 2 psi,you will be ok with the oem system as is.

Next upgrade from there in my opinion would be to move the oem pump closer to the tank.

Keep in mind those of you in cold weather climates, the engine compartment does provide a warm location for your fuel pump to protect the fuel pump from geling.

From there a slightly higher flowing fuel pump located closer to the fuel tank, and once again if cold weather is a factor , the engine compartment is a warmer climate area.

Let me know how you feel about our findings, i am a transmission technician and i am trying to learn about the fuel systems just as you are.

 

so what was the end result....did this diesel engineer ever find the solution...or are you posting saying you might try this out.....

i can understand the idea of moving the stock LP closer...but it would seem to me that, that would cause a "longer push" of fuel to the VP...and cause a "strain" on the LP

if anyone knows the result of the above let me know...i am soon to be purchasing a new truck.....and this is one of the FIRST items on my hit list...

NCA

 

Pumps have an easier time pushing than sucking so it is beneficial to move the pump closer to the tank. This is the idea behind the in tank "update". They also move it into the tank to keep it cool from the fuel. Personally, I would move the pump close to the tank and get a big line kit that also removes the banjo fittings... bigger line and no banjos = flow.

 

What they decided was that all this talk about fuel pressure is basically nonsense, and that too much pressure is bad for the VP$$. They say the pumps push better than they pull, so its best to get the relocation kit. They also say to reduce restrictions, so the big line kit from Vulcan is a good answer to that one.

I find it very interesting, as there is so much written about pumps these days...

 

easier to push than pull...makes sense i dont know why i didnt think of that...i mean when i pull something and i cant get it going what do i usually end up doing....get behind it and push....duhhhhhhhh!!!!!!!!!!

so, is it fair to say that if i find a truck (24v) which either hasnt had LP/VP issues or had either or both replaced.....that i can KEEP the oem, and just relocate it and take away the restrictive lines and fittings which will allow the oem pumps to opperate better.....or

still go after market with FASS or something of that nature.....650 for the Fass is not to bad but what does that gaurentee me...it seems like nada...because the VP can still crap out...right???

ps...skeeter that does 73mph...not bad....24' Walk Around that does 52 in 2-3' swell out in the bay....boat weights 5600lbs....gotta love that....when we going fishing?????lol

 

Yo Nor-cal,
Please do NOT take anything I post as the gospel. I have no personal knowledge to give you that I would stand by. As you continue to read and research, you can form your own opinions, which I encourage you to do.

I bought my truck with 191K on the clock, and have since installed my mods. The cummins is an amazing piece of work and it's power is addictive when enhanced.
I have a stock lift pump, but will soon be moving it to the frame and I'll be installing the Vulcan big-line kit. I think that will be good enough for me, but if I burn up a VP$$ in doing so, then perhaps I will be wrong.. I just don't know it's a crap shoot.

Sounds like you like salt water, I fish bass 99% of the time. The ocean scares me and gets me sick quick!

 

Well I was thinking like ya'll are when I did the vulcan relocation and a new carter pump- and it worked great. Bigger lines, less restrictive fittings and higher pressure = more flow. The problem is that pump crapped out after 10 months, luckily it was under warrenty. So I've come to the conclusion that either you get a mechanical pump or be prepared to replace that electric pump down the road.

If you don't want to get a cam driven pump, the mitusa system is a great alternative and availble through trediesel.com

Watch for a bunch of fass posts below