Interesting story on failure of VP44's---Basically the failure of the VP is mostly because of Cavitation.When at high rpm the Vain pump in the VP will pull quite a bit of fuel, and the LP can barely keep up, but still can. However when the rpm goes from high to low quickly, the amt of fuel is not there and cavatation is a result and the vp doesnt get enough fuel. Also the 3/8 line is small for the sytem. They also said the electronics where not the problem....btw if there is a lack of fuel to cool the vp over a extended period of time the electronics will suffer from the heat.(I think, but he didnt say that). SO' basically he said anyway you can do it, to keep always a positive pressure of fuel on the system at the VP, and we should not have anyproblems....The pump makes lot of HP on very little fuel,,it circulates tons back to the tank---I believe he said the vp will circulate 100 gallons an hour,,(something like that)) The trick is to get plenty of fuel at the input of the vp with no more than 15 psi, or we may have a oring problem...SO' the relocation is ok---but Im going with 1/2 inch fuel lines and no banjo fittings---this should help a bunch.

stix

 

Have been thinking about running 2 pumps, then add a crossover hose from pressure line to tank bleeding to the air vent hose with a 15 lbs regulator.
Have pump next to tank.

Thant way pressure will be a constant 15 lbs

 

I put in a Draw Straw, FASS HPFP, 1/2"line and fittings from the filter to the IP, so there should not be any more restriction. I thought about 1/2" line when I did the FASS, but figured that this system would provide plenty of flow. I get 15 psi at idle and 13.5 under WOT. Reckon the 1/2" line would be any better. BTW, I completely agree on no banjo fittings.

 

I already have the bulkhead fittings and such that I need.

I'm going gravity fed off the bottom of the tank.... No need for draw straws-- gravity fed is simple. I'll just install a 100micron screen in front of the pump to protect it from little snarfs.

JH

 

My set up works very well.

All 1/2 tubing or hose, Draw Straw, pre-strainer, Walbro 391, Mallory Regulator and no banjo's.

I have it set at 16 psi for idle. Fuel pressure drops down to 13 or 14 psi at WOT.

Jim

 

I know it diesel but gravity feed fuel tanks are a bad thing.. in the case of car acciedents and such, I'm pretty sure that as a mechanic if I do something like that I'd lose my licence.
also with a "normal " fuel pickup, it does not draw fuel from the very bottom of the tank where water/debris hides, as a gravity feed (unless you install a tube up an inch or two) you will be sucking the crap/water directly into your pump, and the very small screen would become plugged very quickly
Just my opinion

 

I hope it doesn't return 100GPH! The factory lift pumps are only rated around 95PGH with no head!
At least if I remember right.


I too have upgraded my fuel system to include the Vulcan Draw Straw, Big Dog fuel kit and 12 valve mechanical pump. I never see less than 37psi at WOT.

My take on fuel line is this. If the pump is near the tank, it should be fed with -8 line. From the pump out, use -6. There is nothing gained going to -8 other than you have more volume to fill. Now, I have -8 all the way to the engine, but that is where my pump is mounted and I am trying to limit the vacuum on the system.

A bypass regulator pre VP/ post filter will also provide cooler fuel, a more consistant fuel charge and provide the fuel pump with a long life.

Dave

 

Is looking for a bypass regulator, where to look to find one.
Would like it to be adjustable

 

I built my own. But, Eric at Vulcan has one ont he shelf that he sends out with some of his kits. Very simple and effective and adjustable.

I am sure he'll have what you need. Tell him I sent ya. That way you'll only pay retail + 10

Dave

 

Valid points. Here's how I address them:

-- I route the plumbing inside the frame rail with some slack in the lines. If an accident deforms the frame, the line will have some slack to take up before it rips out the line and gives you a leak.

-- Tank will be CLEAN before the fitting is installed.

Personally, I WANT the crap and stuff sucked up. I don't want it accumulating in the tank. Now, I'll probably have to go more elaborate on my pre-pump filtering perhaps, but I believe it's "better out than in." (shrek) In my setup, I would have additional filtration on the return line of the FP regulator, so all my fuel in the tank would be continuously filtered, even if the engine's demanded fuel is very low. With this kind of setup, the factory filter would probably last almost forever.

Having seen how much junk hides in the bottom of these tanks, I'd much rather pump it out and filter it than have it accumulate.

It's kinda like a bypass filter for your fuel, similar to how swimming pool filters work. By constant circulation and filtration, the whole thing is kept clean.

JMO

 

Not to be a cynic , But, :
Won't an Uphill or downhill unport the supply port with lower fuel levels?
I thought there was a Baffle/trap to prevent this on the OEM arrangement.

 

There is a quart+/- "cup" in the bottom of the fuel module that catches returned fuel. It's also the location of the fuel pick up tube.... so a bottom tap would require keeping the tank at 1/8 or so full. This is something most members do anyway to stay away from 'hot' fuel, among other reasons. Low fuel light comes on at 10 gal left +/-.
I would not want a bottom tap for drag racing...but see no problem at steady speeds on steep grades. JMO

RJ

 

It would also be pretty easy to sump the tank with one of thoose neat Diesel Innovations sumps, or just a regular Summit/Jegs type sump that gives you AN ports for your fuel lines...

jh

 

I have thought about sump as well. For me, I don't want the lines under the truck. But, a simple skidplate could be fabicated to stop road debris, ect from getting to it.

A race truck would be a no brainer.

But many fuel cells still pull fuel from the top. The pickup is located depending on usage and I have even seem swing type pickup that follow the fuel.

The safety issue of fuel spilling from a truck is very minor in comparison to gasoline. This stuff just doesn't flash the same way.

Since going to the Draw Straw, I have taken a fuel system that would bury a 20" vaccum gauge to one that won't even register a change.

Dave