Doubletrouble

That was a very risky test @Tractorman, I appreciate all this info, very interesting. I went ahead and ordered the Raptor 150 as you saw earlier in the thread. I based this on increased potential volume and someone else had stated that a Raptor 100 they had showed signs of pressure drop over a period if time. I will be doing some light mods in the future so planning ahead a little as well but the information you provided does provoke some interesting thoughts. Now in my case, I discovered after the fact that the lift pump failed. It did make it a couple miles to work afterwards so the vp was drawing fuel to some extent. It did not want to run well at all save for maybe at idle. Seemed like once the fuel pedal was pressed it didn't take long for it to starve for fuel, or so it seemed. My hope is that the vp isn't completely toast yet but with your description above comparing that to my situation it sounds like it already fried. Which very well could be the case but, the vp on my truck does appear to possibly be a reman. Judging strictly on the external appearance. The aluminum has a newer, refreshed look to it if that makes sense. That alone is what gives me a slight bit of hope that it may last a little while in order to save the money to get a new reman from a good company. I'm sure there will be other weighing in on your comments above. This conversation could get interesting. There was also another member here that had rigged a bypass for a lift pump as an emergency fix I belive. Just don't remember who it was. We shall see where this goes. Thanks for all the info tractorman. 👍

Correct. I will be doing the relay mod when I install the new pump. I am certain the 150 Raptor pulls more amps than the oem Carter did so to protect the ecm I will be doing @IBMobile'IBMobile's fuel pump relay setup. I will also order the relocation kit with the 1/2" line and a draw straw to be installed as soon as it warms up a bit. I talked to someone at @dieselautopower to see if that pump would be ok drawing through the oem fuel lines for a short time while waiting for warmer weather. They said it should be fine. This is to get the truck back on the road for now and also to see if the vp will be ok for a bit. I'm sure there was wear or damage to the timing piston during the LP failure. Just would like it to last me about 3-6 months so I can replace it. Also a fuel pressure gauge is in the works as well.

This mornings temp. -3F ugh.

No it does not. I don't believe any factory replacement lift pumps have a fuel return line. Maybe the big air dog or fass systems do. I wasn't looking to spend $700 this time around though.

Finally on my way to getting this fixed. I called DAP today and ordered my lift pump. I bought the Raptor 150 that comes with the 1/2" fuel line from the oem filter to the vp. Yhe guy I talked to said it would be fine on the oem fuel lines from the tank for now. Once the weather warms up some I will relocate the pump to the frame and drop the tank for a draw straw and full 1/2" line kit with a pre filter. A fuel pressure gauge will be on that list as well so I can keep an eye on it. Just wanted to update what was going on.

And there are no "dumb" questions here. Ask away, I have learned alot in the past couple years hanging out here reading and asking questions. Great bunch of people here. WELCOME!

The Mopar1973Van? Beauty? (Then you'd have beauty & the beast) Glad to hear it was an easy fix! That would be me

I have an all original 1977 I'll be selling in the spring if your interested. Lol Great bike, just like the harley more and the Honda sits.

That would be awesome

I to am ready for spring. It hasn't been a terribly rough or cold winter but I would really like some seat time on the harley. Things are backing up, my truck is down for now, to cold to want to work on it. I have other things outside that need attention as well. Just don't want to mess with them in the cold either. Also looking forward to camping season, won't be making it to Cali with you all but I am looking forward to some decompression.

To continually filter you would have to go from tank-filter-pressure regulator w/return-vp44. Which would be more work than just installing an airdog that (if I understand it correctly) already does the same thing.

I would think yes, the return type would help to continually clean or polish the fuel. As far as the cavitation, I think that would be from (forgive my layman's terms) the fuel not being able to continually move forward. A 150gph pump moves alot of fuel, that's 10 quarts or 2.5 gallons a minute. There is no way or engines use all this as we already know. The remainder is cycled through as a cooling liquid for the VP. Here's the issue. We run 1/2" line to carry this fuel, the return line is what? 5/16 coming out if the VP? There is a restriction. Which doesn't allow the fuel (150gph) to move fast enough which would create a bit of a jam at the pump impeller which in turn could be the creator of the cavitation. Based on the idea that an impeller in fluid that isn't moving at the same or similar speed as the impeller would cause turbulence and induce a cavitation effect. This is just my theory, I hope I explained it in a way that it makes sense. I have the idea in my head but can't always put them on paper. Or there is the possibility that I'm just full of crap and completely wrong.

The Fass ddrp pumps don't have a return line either. Are those also prone to cavitation? I'm trying to do this on a budget as it's been a little slow at work and so on. But I want to get the best I can for my money. I can't do a full airdog setup though. My thoughts are a replacement pump (fass ddrp, Raptor, or the like) with a pre pump filter (screen/mesh type but spin on) and 1/2" fuel line with draw straw.

@LorenS, that's exactly what I was thinking. I had talked to you before about it. I just couldn't remember who it was I had talked to. Lol I like that's it's short and doesn't hang down below the frame. Also where you mounted the pump looks pretty well protected.

What size are the inlet/outlet on those? I'm wanting to run 1/2" line so will that even work? I have a filter head from a log splitter that I scraped. Could I get a spin on filter for that? Something that isn't super fine but to catch anything that might kill the pump? I could put 1/2" barb fittings on that to easily install the new fuel line onto.

What is the size of the pick up tube in the tank? I'm probably going to have to drain the tank to install a draw straw since it was just filled up. Ugh I assume you want to install them with the tank empty since the bottom if the tank will rise slightly due to the decease in fuel weight correct?

Let's talk gallons per hour, the Fass DDRP I believe is rated at 100gph, there are 2 Raptor pumps, one is rated at 100gph and then 150gph. Which would be the best rout? The Raptor 150 I know has an adjustment for pressure, I believe the 100 does as well. Raptors also claim a lifetime warranty on their website. Are the Raptor pumps superior to the fass? I like the fact that there is a pressure adjustment externally. Which pump will be better suited for my truck. I plan on some light mods later but not much. Is 150gph to much for a stock truck? @JAG1, when I replace the pump I will be doing the relay mod to use battery power for the pump.

I checked for voltage at the plug for the lift pump. Had 12v there so the lift pump has failed suddenly. (Somewhat, really need to get gauges!)

Good point @JAG1, just sucks things like this only seem to happen when it's cold out. Lol The pump that's in it must have just given up suddenly. I checked pressure at idle about 2 weeks ago. It idled at 17psi. Now it's not even turning on. Gonna check for power at the plug in a bit. Waiting for my son to come over to BP the starter while I'm under the truck. 25 seconds isnt enough to get my butt under there to check. Lol

I would say it would be a food one for errands and such but Beast probably gets better milage.

That is what I'd like to do is the 1/2" line kit but, as for now its cold here. My truck don't fit in my garage so I think I'll just replace the pump and leave the lines. When it warms up I'd like to do a draw straw with 1/2" lines. Will a Raptor 150 be ok on a stock truck? Is there a such a thing as to much fuel to the VP? I'm looking at the Raptor 150 at DAP as it also comes with the 1/2" line from filter to VP. It says it mount on the factory bracket on the motor. (Fine for now, change it later to frame mount) Also, in regards to the possibility of the in tank screens being full of goo, should I maybe blow a little compressed air through the line into the tank to clear it?

@Tractorman, the actual milage now is about 163,500. I belive the injection pump may have been replaced at some point just by looking at it. Hard to explain but it looks "newer" than it should if that makes sense.

@IBMobile I knew that but it still irritates me. Lol

Raptor has a factory replacement? I'll have to look. I was intending on doing the LP relay mod. Just seems to make sense to me. Don't know why the factory didn't do that in the first place.

Hey, it's a beater with a heater right? Can't beat the price!