While moving the truck yesterday, I was reminded it's time for an oil change. And to ready it for the upcoming wheeling season, realized it was time to revisit a couple of other things...

Back in Nov., it dyno'd at 177hp (mods in sig), which IMO isn't bad RWHP considering the sloppy torque converter/slushbox, but it had/has very little smoke at WOT. Doesn't this equate to not enough fuel?

It also has a noticeable "lag" at WOT between 50 & 60mph. Doesn't appear to be RPM related, as it pulls good up to 3rd gear @ 50 where it just goes flat... doesn't miss, skip or anything like that... just like I leveled off the throttle. It hits 60mph and starts pulling good again... almost like it's running out of fuel (even with new filter). Is this the diaphragm LP of unknown age/origin not keeping up (flow &/or pressure) on hard runs? (yes, I know I need to get a gauge on it to properly troubleshoot ) Since the pump is an unknown and (even if replaced) likely to tank/fill the crankcase w/ #2. It appears there's a couple of options:

#1 - The "industrial" piston LP for the VE, but some folks have doubt it will keep the VE supplied @ 15# once the pump is further tweaked?

#2 - A 2nd Gen piston LP is up next, but that requires a bypass regulator to negate the higher output from blowing the VE's seals out... additional expense.

#3 - [where I'm currently leaning] I just saw that PureFlow Tech. has released the "Raptor" high-flow pump w/ a built in pressure regulator (no bypass needed), so I should be able to dial it in for 15# post filter. Not sure about going totally electric though. While it is enticing when swapping filters/priming, I have my doubts! Wouldn't really mind it if (see below), I could easily swap back to the (capped off) OEM LP as an emergency backup (should the electric ever die)...

Was also planning to add a "big line" kit, a) For easier swapping of parts in the field (roadside)/troubleshooting vs. all the steel lines that must be fiddled into position/removed in stages, & b) "easier" plumbing of fuel pressure gauges, both pre & post filter.

Any of these mods should be within my budget. I was planning to run grease, but just happened into reasonable local source for B100, so the budget for grease mods can be "re-appropriated"...

Opinions (with reasoning)...

 

BTW, it appears the Raptor ships WITH a big line kit... so that's a PLUS to this option?

Edit: Comes with JUST the line (1/2" x 15') tank end & filter inlet fittings, so I'd have to source the other fittings elsewhere... Definitely enough hose length though!

 

No pump that is regulated before the filter will be able to able to keep fuel pressure up under load. Might as well run one of those crummy Holley pumps if you aren't going to regulate after the filter.

 

With stock injectors, I see no reason why a 1st gen piston LP won't be enough. No smoke at WOT is a good thing on a truck that works for a living If I were in your position, I'd do a 1st gen piston pump and oversized banjos from Genos. Run the 1/8'' tapped one post filter and get some kind, any kind of FP gauge in there. IMO, you'll be ready to haul for the season, as far as FP goes. As for the driveability, it could be related to the tranny shifting into OD late if FP turns out OK...

 

Wanna, while I'm not an engineer, I have worked with a few different fluid systems...
I'm having a hard time understanding why a pump that'll flow 100gph @70# (way overkill for these trucks IMO) and is regulated to say, 15# post filter, would have any issues keeping up with the demand? In theory, the filter would need to handle more flow & higher pressure (than 15#) for the pump to react to the drop in pressure on the filters output to "keep up". Isn't that what the pumps regulator is designed to do?... Keeping the regulated pressure at a constant regardless of demand?

Outside of a dirty filter... I just don't get it

Good for now, but what if...?

Agreed, I'm just peein' in the breeze until I get some a gauge installed to get some factual numbers...

The "lag" between 50-60mph happens in 3rd with the OD turned off (I don't tow in OD). Once past 60, it's like the switch gets thrown and it's back to pulling hard until it starts de-fueling... IIRC, about 75mph. If the OD is engaged *after* 60mph mark, it pulls until it gets scary handling wise.

 

As long as the regulator is after the filter, the pump won't have any trouble at all keeping up with demand. That Raptor pump you linked to is internally regulated, just like a 1st gen piston pump, a Holley, or a FASS.

With my setup, pressure drop across the filter is 7 psi, that is full flow from the Walbro through a clean FS1221 filter. It's easy to see why a truck with big injectors can suck a 1st gen piston pump or a FASS down under 5 psi under load, the filter is a big restriction. Internally regulated pumps will only put 15 psi (or whatever they are regulated to) into the filter. When flow is high, post filter pressure will drop. My truck runs 15 psi idle/5 psi at full load on the 1st gen piston pump, I lose most of that 10 psi in the filter. If you want to maintain full fuel pressure under load, you need to put your regulator after the filter.

 

Now I see what you mean...

Honestly, the cons you list don't sound like a large hurdle. I don't plan on drag racing, sled pulling, or any other competition type thing... just a decent fuel delivery system. The Raptor seems to be doing a good job for the few that have swapped them in overvalved applications... I believe with all the electronic gadgetry, they require a lot more fuel flow & pressure than we do?

As stated, I plan to start running ASTM grade B100 from a local vendor and figured the diaphragm pump won't live long. Hoping the Raptor was a preemptive swap that would kill several birds with one stone...

So aside from the inherent pressure drop at WOT any thing else to watch for?

I'd like to pre-make, install, & cap a set of hoses so a NEW block mounted LP could be easily swapped should the electric barf on the road (maybe not optimal, but should get me home?)

 

Given your plans, just go with a 1st gen piston pump like Greg said. It's adequate for your needs and nearly bulletproof.

If you want to go electric, I would strongly encourage you to do a Walbro/bypass setup. You can do that a heck of a lot cheaper than the pump you linked to and you WILL have fuel pressure unless the filter is absolutely plugged.