Geico266

IMHO it is this back pressure that is causing the problem. In theory, if you add another relief "dump" tube from the regulator to the tank that should cure it right?

Also, when I was looking at Holly regulators I saw two types; A bypass regualtor has a return line for excess fuel, the standard regulator does not. The standard regulator simply "holds" the pressure at what you set it at. But these regulators are only rated at 9 PSI. (I realize the flow-v-PSI thing)

Superduty

"is the Walboro the right pump for this application? Seems to me there should be a pump that has the ability to regulate the flow / PSI to what the application needs and more importantly what it was designed for."

What became obvious to me with seeing their problems is just how wimpy the other pumps are.

If the Walbro 392 is too much for the VP44, one can always select one of its smaller brothers.

I don't think we've got too much pump. We need to spend a bit of time figuring out how to regulate it.

What has me SALIVATING is getting 80 GPH flowing through the VP44. I'd like to see someone put 100K on it then and see how it stands up. The VP44 creates a ton of heat and fuel is the only lubrication it gets. Now that I see how much restriction there is with a real pump (ala Walbro), I wonder how little flow all the other pumps are giving it.

If it was my truck, I'd forget all about the fuel pressure and bypass and just concentrate on getting all the Walbro flow going through the pump itself. I'd pull the VP44 relief form the pump itself and replace it with a Swagelok in the return line.

80 GPH going through the VP44 itself. Now that is what I would call a well supplied fuel pump.

Superduty

Geico: no offense, but weren't you in my Walbro posts last night telling me how great the FASS is you have on order with AUTO45 ?

If so, what are you doing in this post telling us how the Walbro is supposed to work ?

I'm not trying to start a fight here, but please let us get a few things sorted out before pronouncing the Walbro as too big or doesn't have a pressure relief, etc.

Geico266

SD, I love ya man. But I am compelled to ask the question again. On the specific application of a VP-44 are you sure the Walbro 392 pump is the BEST pump for this application? Seems to me this baby puts out too much fuel for this application.

Superduty

Yes, Geico, it is the right pump. If it isn't, Walbro makes a few smaller models.

Maybe for once the VP44s won't be starving for fuel. I'll bet money that the life expectancy of the VP44 goes up with good fuel flow through it.

Weren't all you guys telling me that the Walbro would never hold a candle to the FASS ? And now you are telling me that we've got too much pump !

Geico266

I'm here to help, not hurt. A critical eye from someone who has put 185K miles on an original VP-44 should be advice you take into consideration rather than dismiss off hand. I want what is best for my truck.

Now, let's get back to work.

Why can't we just use the standard Holly regulator and set it at 15 PSI? I would like to remind everyone the Holly regulators are only rated at 9 PSI so we are over specs already.

Superduty

Another truck is running the Holley with a Bosch pump and it doesn't seem to regulate well. The verdict is out on it and the Bosch.

I'm waiting for some flow numbers to see where we are with VP44 requirements and thus regulator requirements.

"A critical eye from someone who has put 185K miles on an original VP-44 should be advice you take into consideration rather than dismiss off hand."

No offense, but you wore out 4 lift pumps without trying anything different and you've since ordered a FASS, because you didn't have time to fool around with the Wabro and the FASS was a complete kit. And you were in the Walbro threads telling me how great they were. And now here you are giving us advice ?

How about we send you a PM when we get this sorted out ?

Geico266

Actually, it is 5 but who's counting. 3 were under warranty.

FASS II wasn't even out when I started looking at alternatives for the LP. I've waited a few months to make sure they get the bugs worked out. I believe the FASS II is a good reliable pump with a 4 year warranty. I need reliabilty.

There is no need to attack me for my decision to buy a FASS. I'm here to help all I can. I have suggested several times to put a concise parts list togeather and I would have installed the Walbro, but with my truck sitting in the drive way (I will NOT run it lower that 10PSI) I need a fix NOW.

Superduty

Your extensive experience is noted. We will vigilantly monitor the fuel pressure.

Better than that, I am hoping someone connects a Walbro full stream to the VP44 and then this business of "proper" fuel pressure will be a thing of the past.

What I didn't realize until this over pressure stuff surfaced was that the relief valve in the VP44 is pretty darn restrictive and at fuel pressures of 5 and 10 PSI at the inlet of the VP44, there isn't much fuel moving through it. Not much fuel = not much cooling and not much lubrication.

I've got a stinking feeling that the combination of the Walbro and the removal of the relief valve thus pumping 60 to 80 GPH through the pump itself will increase its longevity dramatically.

The way it is stock, it doesn't really matter if you have 10 or 15 PSI on the inlet because the relief is so restrictive that not much fuel is moving THROUGH the pump. That is the objective. Move fuel THROUGH the pump. Cool it. Lubricate it.

Do you guys know how thin diesel fuel gets when it gets hot ?

smokin05

hey guys you all are killing me! not one pic! ...i am going under the truck right now w/ a flash light to see if maybe i can help....this is kinda up my line of works....hince the e-mail texasvalveman @ yahoo? lol brb!

Superduty

"I need a fix NOW."

Go to eBay. Order a Walbro. Order a replacement banjo bolt for the return line. Start wrenching.

The pressure on the VP44 inlet is irrelevant. They need FLOW THROUGH the pump.

I thought the two were the same, ala P7100, but I was apparently wrong.

linetrash75

I'm pretty sure the "relief valve" on the side of the VP is nothing more than a check valve. After I replaced my VP, I had 2 of them I took the old one apart and gutted it, too see if I could eliminate gauge chatter. The only difference I could tell was that the engine turned over a little longer before starting. The fuel pressure gauge stayed the exact same @ idle or @ wot. the valve is nothing more than a spring and ball. I believe there is an orafice inside the VP that regulates fuel through the pump, meaning we will only get X amount of fuel through Vp @ given amount of pressure. I also think the swagelock is being over welhmed @ idle, then @wot it is working correctly and you in realality have it set at 4psi. What you might try is setting it up some to see if you can get a higher psi @wot. that would eliminate 1 of 2 possiblities,1 . regulater overflowed at idle, or 2 LP not suppling enough fuel, I suspect it be #1.

Superduty

"After I replaced my VP, I had 2 of them I took the old one apart and gutted it, too see if I could eliminate gauge chatter."

Pictures ?

"the valve is nothing more than a spring and ball. I believe there is an orafice inside the VP that regulates fuel through the pump, meaning we will only get X amount of fuel through Vp @ given amount of pressure."

That is the way the cascade overflow valve is on the CP3. But the CP3 needs to regulate its internal pressures to control its fuel delivery. The VP44 does not.

It would be easy to test the orifice theory. Pull apart the relief valve and run without it and note the pressure. Any chance the spring and ball were restrictive ? The 1/4" Swagelok valve is just a piston and spring. But try to push 60 GPH through it and it becomes an orifice.

Any chance that the orifice is externally available, like a screw in fitting or valve ?

I'd just love to flow a Walbro though a VP44 full blast.

smokin05

the low pressure supply line goes into the filter from the tank pump right?......the return line starts @ the relief valve on the back of the rail...then to the filter I am assuming that’s where excess fuel is flowed back to the tank from the filter ? Help me out here guys.... so before the "new style pump" where is the fuel regulated or does it just fly through the filter back to the tank? Is this done just by voltage reg to the OEM pump in tank to control pressure?


Also the return line regulator idea is not going to work if you ever blow the rail valve...and I hope that never happens you’re going to trash any type of regulator most likely.

How about this? Discharge the aftermarket pump into a true pressure regulating valve one w/ a fairly broad gpm rating then "tee" into the supply line from this reg. valve going to the filter w/a restrictor back to the return line so it’s constantly bleeding off some fuel to prevent a dead head condition on the aftermarket pump?

this still needs input from you all on how the filter works...does it bleed back or is that line just bolted to it....looked like the hollow bolt trick to me ?

linetrash75

No pics, just barely out of stone age here.Yes I would say the releif valve is restrictive, like i said just ball, seat, and spring, the outside diameter of the ball not much less than the inside diameter of valve itself. I did run without it for a day and saw no psi difference, was it actully circulating more fuel I don't know I didn't do a volume test, I might this weekend if I still have the gutted valve.

Jed