2500CTD

Ok so since my LP is on the way out, I ran my FP down to 3psi but lifted so I'm not sure exactly how low it will go. After a week of reading the FP threads I'm on the kick that pressure is not really all that important as long as there is ample flow to keep the VP cool, that being said anyone know how to figure out how much GPH a VP needs? I'm looking at a pump that can deliver 140GPH free flow and 120GPH at 6 psi. Even if pressure drops from high HP (not with my truck yet) 120GPH should be plently of fuel flow, given the rest of the fuel system is up to par. Any input?????

Don M

120 GPH is plenty. A high volume like that will make more pressure. The restriction ( the pump and the overflow valve ) is what makes the pressure go up from all the volume trying to go into the pump.

Many pumps that will deliver high volumes at free flow will fall off quickly in flow as the pressure is increased. At all depends on the rotor or gear design.

Don~

2500CTD

So is there a way to lessen the restriction of the overflow valve? I'll look for a chart of the pump and try to post it, it doesn't seem to drop of that quick. Pump Specs

infidel

My understanding is that the stock fuel filter is the main restriction to flow. It starts building a steadily increasing pressure differential from inlet to outlet at 17 gph.

CTD NUT

Remember, all pressure is, is the measured resistance to flow. What the drop in pressure is really telling you is that less fuel is being bypassed to the return line and more is being diverted to the injectors. It is the fuel that runs through the return circuit in the pump that is doing the majority of the cooling and lubricating of the VP44. As return fuel flow drops, so too does the pressure..........pressure is the resistance to flow......less return pressure = less return flow......it is the fuel return flow that is important to keeping the VP44 alive.

JDGnut

Not to jack this thread...

But has anyone adjusted the Charge pressure on a VP44?? Don???
Bryan

Mike D

http://www.jegs.com/cgi-bin/ncommerc...31&prmenbr=361

Here is some good info on the pump I'm running/beta testing. I heard a rumor that a vendor whos product we all know is doing some testing on this pump too. I'll let him let the cat out of the bag.

HOHN

Yeah, but his don't say Edelbrock on them. Edelbrock is pulling a Bully Dog and rebadging.....

jlh

Holiday

A holley black is supposed to be 140 free flow and 120 at 9 psi. Those are the specs with gasoline. They don't have numbers for diesel.

Mike D

You're correct, see my thread https://www.dieseltruckresource.com/...400#post681400

The pump is made by Essex Industries, no secret. I found this pump, because I refused to pay the 600 bone price tag for a "reliable" fuel pump. Tim McDonough (Essex Design Engineer) was nice enough to send me a unit to test. This was a new pump for Essex, so Tim's motivation was to get the word out about the pump and to see if he could help solve our problem. After all that's what engineers do. So far, I'm very pleased with this pump. By the way I'm not saying this will be the perfect pump for everyone or every application. It's been working good for me.

I've talked with "Deep Throat" he is still deciding if he is going to market this pump through his company. I hope he will be nice enough to give me a cut. just joking.

I did the research/leg work for everyone to benefit, was tired of hearing about dead lift pumps and smoked injector pumps. Hopefully, this pump will be a economical way to fix our fuel system problems.

RowJ

The original question (one of them) was...How much fuel flow is needed to cool the VP44?

Anyone Know?

At 80 mph...and 18 mpg....we use (burn) 4.4 gallons per hour! The basic FASS flows 95 gph at 15 psi and works well, but returns a lot to the tank (on it's own). So we know 90+/- gph cools the VP44 well and is more than is needed. But....
-What's the minimum?
-Is this much, or more, harmful without a return line built into the pump?
-How much fuel is consumed at WOT?

RJ

Mike D

Mind you this is pulling from memory, but I think the vp44 requires at least 45 gph.

As far as a return line to the tank from the fuel pump, it would probably cut down on fuel turbulence going to the vp44. The more fuel that is bypassed with a internal bypass, the more chance there is to create turbulence. That's my thinking anyway.

If you look at the cross section picture of the pump in the link above you can see how the interal bypass is set up. http://www.jegs.com/cgi-bin/ncommerc...31&prmenbr=361

HOHN

While I think the Essex pump is a nice unit, I'm just not a fan of internal bypass. Blame the OEM pump, but I think a separate FP regulator with its own bypass is going to be a much better way to go.

The other thing I think about it pumping too much fuel. Even if we have a large bypass regulator, could pumping a TON more volume than you need result in high fuel temps? Do these high temps have a negative effect on lubricity and VP cooling?

I've been thinking about this a lot, as my VP gave its first sign of weakness over with a very brief deadpedal and a 0216 code. Yet, I've upgraded my fuel delivery with a Max Flow setup, always had good FP to the pump, and NEVER tapped the wire on the pump. Supposedly, I "did it all right" with regard to VP durability, yet mine seems to be on the way out.

It only has 40K on it!

So, I'm thinking about WHY DID THE DC ENGINEERS DESIGN SUCH A RESTRICTIVE FUEL DELIVERY SETUP??

Perhaps there was a method to their madness??? Perhaps fuel pressures over 14-15 psi are harmful to the VP? After all, the overflow opens to relieve (or attempt to) pressure over 14psi, right? WHY????

I'm becoming of the opinion that a pretty small pump (<100gph) that's regulated to deliver 12-14 psi all the time is the way to go.


JLH

Mike D

I agree, "Deep Throat" and I talked about the same thing. I've got the test pump set at 8 psi. I think the vp44 uses just what it needs to meet the demand of the engine, the rest is used to cool and lube the vp44 and returned back to the tank. Increased pressure applied to anything will make heat.

With regards to this pumps internal bypass, it's set by manually screwing in the valve/plunger not like the check ball deal in our stock pumps. Buy running a lower psi there should be less strain on the pump itself. You just have to make sure you have enough psi to feed through the lines to the IP at WOT and not suck the lines dry. At my current fueling I don't feel that is a problem.

But if it make you feel good, you can crank the thing up to 15psi.

2500CTD

So would putting a fuel regulator on the inlet of the VP set to say 12psi with its own return line, be a step in the better direction? Another thing, if you have a "big " pump like the one I'm looking at or the Essex pump, runnign it at low PSI should increase the durability/reliablity of the pump. Kinda like what lasts longer, a small 2.0L engine making 300hp or a 7.0L engine making 300hp? The bigger engine can make more power easier than pushing a small engine to th elimits. (This is just an example, I know some small engines can make good power with longiviety.)