I just put an adjustable fuel pressure regulator in last night so I had somewhere to get a fuel pressure reading

What pressure should I be seeing? Also I have a Vortech supercharger with a secondary fuel pump for when the boost comes on. Any suggestions for when the second pump comes on?

 

What year is your 460? only reason I ask is just for reference of your secondary pump.

It should be 35ish at idle, 40ish when driving and 0 boost. Assuming you have the fmu, which should be adjustable also, it'll jack up rather quickly with boost. This is not an exact science, but can and should be tuned via a wideband and street trials. I'd set the adjustable fpr to the factory specs (mentioned above) and leave it, then let the fmu do its job.

 

Ok thanks. The truck is a 96

I am seeing 60-65 @ and idle, guess I need to turn it down a bit LOL Kinda burns your eyes

But it idles like it has a big cam

 

Which adjustable fuel pressure regulator did you use?

 

Unless you have some funky pressure switch to activate the secondary pump, it should run key on just like the others.

It's a good idea to have a wideband with your setup as well, if you don't already have one. Then you can play with your fuel pressure to optimize settings, keep the afr safe, and help recognizing problems (which could be fatal, especially with boost) if/as they arise.

 

I have aBBK one

The secondary fuel pump is turned on by a HOBBS switch. When the boost hits a pre-determined level, the second fuel pump turns on.

I also have a boost and A/F gauge as well

 

Oh I see, so you're wondering at what boost level it should kick on...that's dictated by the a/f readings in relation to the fuel press. Your stock pumps are adequate enough to supply well over the 40 psi of a naturally aspirated setup so there is a good buffer between the stock pumps ability and the requirement of the secondary, and it is entirely possible that the stock pumps are good enough by themselves just to put that into perspective.

The fuel pressure will skyrocket under boost, and i mean skyrocket, so as long as your a/f is in check and fuel pressure isn't dropping (indicating the stock pumps aren't being "relied" upon by themselves) then the secondary is kicking on at a good time. The old style setups like you have take some playing with in order to get them optimal, so if you have a situation where a/f increases or fluctuates....you'll need to adjust the Hobbs to kick on the pump for less boost.

Another thing you could do is bypass the Hobbs and see if the pressure regulator can maintain the 35-40 psi with the extra flow....it might sound silly but the less you have to rely on (Hobbs switch) the better in an application such as boost. If indeed you need the secondary to maintain the a/f of 11-12 under full boost, a failed Hobbs can destroy the engine.

 

Before the Fuel pressure gauge and boost gauge I just had the A/F. I NEVER see under 15:1 unless decelerating.
Under acceleration I was seeing 16-20

But right now with the Fuel pressure reading 60+ and the truck sounding like a monster cam and the exhaust so rich it burns your eyes, I need to adjust the fuel regulator before I drive it anywhere. Maybe later today I will have time after I spray a bed liner

 

Wow, what's the wot reading? 15:1? That's no good, looks like you have some playing to do. Wot a/f should be between mid 10's and low 12's. Cruising, it'll be high teens. Under any boost whatsoever it should be down in low teens if not 12. 15 wot is dangerous

 

I would rather have it fat than lean

 

Right, lean is higher ratio, fat is lower. You're lean.

 

15:1 is lean. Very, very lean under boost. Stoichiometric gasoline in air is 14.7:1, under ideal conditions. That means high VE in a gasoline engine, which a basically stock 460 is not, as well as non ethanol fuels (Ethanol stoich. A/F is less than 14.7). When I had a NOVI 2000 on a Dodge 4.7, I used to see 13 psi on the stock bottom end. My tune was safe, and had AFRs in the mid to high 12s. Under boost, with the slightest detonation as a result of being lean...


However, with 65 pounds of fuel pressure, and the truck idling like its running really fat, I would take a look at your A/F meter. I've always used the Innovate LC-1, which is very sensitive to O2 sensor placement, voltage supply, and ground. Very sensitive.

 

Good info, but he's only seeing 60 psi because he just installed his afpr and hasn't dialed it back yet. No doubt the a/f is so low it's burning his eyeballs

 

You need a rising rate FPR that still has normal pressures between vacuum and 0 manifold pressure, then raises the pressure sharply under boost.

The other option too is to do it the correct way and either A. MAF convert it, or B. Swap in a lightning computer and tune that.

 

I have a FMU to raise fuel pressure when needed.

Also a lightning ECM would do nothing for me since it is neither mass air nor boosted