What fuel pressure do you run if you have a gauge?

[Direwolf]

Mitusa pump, idles at 15.5-16. Any throttle and it jumps to 17-18 and never dips below that, even at WOT.

[Texas CTD]

white buffalo, Direwolf,I don't want to take this too far off topic, but what kind of regulator are y'all using, and how is your return line setup?

[white buffalo]

Mine's a spring loaded bypass in the return line. Adding or removing shims or springs, you can adjust pressure by bypassing more or less fuel. My return Y's into the filler neck hose. At my pressures it does bypass a lot of fuel. I don't remember the GPM, but I would think you could do some pretty extensive mods., before needing more fuel. They also make a different pulley setup to overdrive the pump, if you find you need more fuel. Mine is all run through 3/8 fuel line. If run through 1/2 inch with the overdrive setup, this thing would have to move a monstrous amount of fuel. Way more than I'll ever need, I think.

[Texas CTD]

Thanks!I'm using the same kind of regulator you have, and right now it idles at 15 PSI, and under light throttle it'll hit 20 PSI. I can tell the regulator really starts dumping fuel at about 25 PSI. The thing is, if I try to bring down my top end pressure, I have to sacrifice idle pressure. :doh:I have a 3/8" pickup line to the filter, and will soon have a big line kit. My return line is 3/8" down to the frame rail, and then my stock return tee's into the Assassin return, and then I have 1/2" line back to the tank.I'm running my pulley's at a 1:1 ratio, and that is 212 GPH - good for 1,000 HP worth of mods. :D

[Direwolf]

Mine runs the same type of bypass valve. The Mitusa is plumbed a little different though. I run the stock return line back to the tank from the VP. All the regulation is done in a closed loop type systems itch no return line. If the fuel pump pressure exceeds the bypass pressure it is bled back into the supply side of the fuel pump. Mine runs at about 1/2 engine speed, 1:1 must be pumping a ton of fuel!

[Texas CTD]

That's how most people are running their Assassins - 1:1. I started out with a small pulley on the crank, and my idle pressure was too low, but I was using my stock return line at the time, and it was putting back pressure on the whole system, and my pressure would spike.I might just try swapping pulleys again. . .

[Ilikeoldfords]

I got my ad raptor 100 hooked up this weekend. I'm still using my 3/8's line and thinking about switching to 1/2. I idle close to 20 and it drops to about 13 at WOT. Cruising it holds at 16-17. Overall very happy with the pump. A LOT quieter than the old fass and I love having the adjustable regulator too.

[Texas CTD]

I got my ad raptor 100 hooked up this weekend. I'm still using my 3/8's line and thinking about switching to 1/2. I idle close to 20 and it drops to about 13 at WOT. Cruising it holds at 16-17. Overall very happy with the pump. A LOT quieter than the old fass and I love having the adjustable regulator too.

That's still a pretty big drop. . . I switched back to my 12 pitch crank pulley, and get anywhere between 9-12 PSI at idle - that keeps the pressure below 20-21 PSI, except when getting on it hard while shifting, but it still doesn't get very far past 20 PSI.

[Mopar1973Man]

I got my ad raptor 100 hooked up this weekend. I'm still using my 3/8's line and thinking about switching to 1/2. I idle close to 20 and it drops to about 13 at WOT. Cruising it holds at 16-17. Overall very happy with the pump. A LOT quieter than the old fass and I love having the adjustable regulator too.

That's still a pretty big drop. . . I switched back to my 12 pitch crank pulley, and get anywhere between 9-12 PSI at idle - that keeps the pressure below 20-21 PSI, except when getting on it hard while shifting, but it still doesn't get very far past 20 PSI.

I tend to agree I typically only see 2-3 PSI tops so either you got a fuel line restriction or a lift pump that can't keep up.

[Ilikeoldfords]

That's what I was thinking. I have a feeling that the stock hardware is in the tank. How would I tell if I have a draw straw? Everything from the top of the tank to the VP is all 3/8" or bigger. The other thing I was wondering about is the filter I have before the lift pump. It is a Baldwin bf1212. Would that cut the pressure to much?

[2500ctd]

A filter would normally only restrict pressure if its dirty, unless its too small of a filter for the intended fuel flow. Hard to tell whats in the tank without dropping it or trying to see inside at least.I am running a walbro 392 and have been fighting a regulator issue. Found a nice check valve style regulator. Set it at about 17psi at idle and drops a little more then I like at WOT. IIRC stays above 12 at WOT however. I am running a dipricol gauge. Flopping around on the dash for now. Going to go with hopefully an electric gauge in the future. If the project pans out it should be cool. :pray:Oh no snubber just an isolator that I think finally went. Not a big deal, as long as I know what my pressure is.

[GreenRiverCummins]

Hmmm I feel mine is lowish at idle 13-14 at WOT 13 I contacted FASS through Facebook they replied in minutes at 11pm central time was surprised they said "That's a good number but I should do the spring trick to raise it another 1-2 psi and i'm all set" just need to do it. The Truck drive's great aside form the dieing APPS my Diesel repair shop friend hooked it up to a computer and said at WOT it would go from 70% throtle to 5% upto 50% and up and down wouldn't hold a even % As i thought it was a bad VP but he said he was 99% sure it need's a new APPS that the VP was in good shape.

[Mopar1973Man]

Ever since I shimmed and egged shaped the spring on my AirDog 150 pump I've been keeping good high pressures. The only thing I notice so far is I can see how cold my fuel is by how low my fuel pressure drops under load. But once the fuel warms up I'm right near 18-19 at idle and 16-17 at WOT. So I drop a 1-2 PSI roughly the colder fuel gets.

[CUMMINSDIESELPWR]

i need to do the shim and spring thing too, every once in a while the pressure will drop down from 20-22 to 12-14 then clear up. it does this about once or twice a month...

[white buffalo]

Hey, Cumminsdieselpwr, I don't know what gauges you're running. I'm running a mechanical fuel with a needle valve, just cracked open. Sometimes, I get a small piece of trash or something in the needle valve and it will effect my gauge. I just turn the needle knob a little in & out and all is well again. WB

[CUMMINSDIESELPWR]

well bad news, my raptor is on its way out, making bad bearing whine noises and pressure fluctuation from 25-10psi... so screw this i ordered the glacier diesel mechanical fuel pump. i have a stock lift pump ill put in place of the raptor for a primer pump. more to come

[2500ctd]

That sucks if I ever do a cam swap thinking of trying the cam driven fuel pump.

[joecool911]

Just installed a raptor and got rid of the engine mounted lift pump and banjo bolts on filter and VP. Big lines came with the raptor. Added a big line to between filter and VP. Set at 20 idle and goes down to 16 WOT. Nuts holding on lift pump were loose. Didn't even need a socket. 162,000 miles it was time!

[98whitelightnin]

My pressure is always higher the colder it is outside. I did get a new fuel cap because my old one was separating and letting pressure off while driving and now the pressure is down a bit. Don't know for sure that its the new cap but that is the only thing that changed.

[inline]

20-22 at idle 16-18 WOTFuelab Vortex 100gph BDP sump -8 line and Fragola fittings