Finally got around to checking my fuel pressure after stretching out my FPR spring. It is running at idle at about 78psi and drops to 60 after I shut it off. Main reason I bumped it up is a had an occasional knock at idle and seems to have cleared that up. So is this too high? BTW I was able to use a gauge off my air compressor and went to Lowes and got the proper fittings in the plumbing dept. I measured at the back of my filter housing. I figure probably not a good idea to leave it hooked up since the pressure gauge is not designed for fuel??????Thanks for any input. I guess I can always take that spring back out and try to compress it a little.

 

It's a little high at idle, but if it's running good and not leaking, I think you're good. Can you check you pressure while driving? Just a hose long enough get somewhere you can see though the windshield.

 

I don't have it set up on a hose, just through the fittings. About how much would it increase? It's not leaking now. I'm kind of thinking about trying to get it around 65-70 at idle????

 

i would not trust a guage of off an air compressor, thats a dry guage, you should be using a liquid filled guage for checking fuel pressure.

 

True on the gauge, probably not that accurate to begin with. You pressure will most likely drop off when driving, not increase. Pump shouldn't change much as far as volume, but fuel demand will.

 

I looked on the internet and looks like the dry gauges should be accurate within 3%. Looks like they add the liquid for vibration dampening and I'm not getting any fluctuating in pressure. So I think I'm in the ballpark but could be wrong.

 

Numerous people have tested numerous fuel pressures on the dyno, and with larger injectors, the best performance is found between 58 and 62psi. I used to have mine on boost reference, set at 50 at idle, and it would add about 1psi for every psi of boost, but if i did that now, i'd probably stall the pump at full throttle

 

So, fuel pressure does increase as throttle increases? I'm not sure why you are banging your head? Maybe, an inside thing? I have stock injectors as far as I know so what would be the best pressure? I know international recommended around 70 but Ford was less.

 

I had an externally regulated fuel system, that did away with the stock fuel regulator system and bowl all together. For stock injectors, i'd keep it at 60-62psi,but thats hard to get by inserting a BB into the thing instead of just turning a bolt and adjusting pressure.

I ran a line from the compressor manifold to the fuel pressure regulator, and it would add a pound of fuel pressure, for a pound of boost. Under no/low load it was 50, get into it and it would get up to 80ish on a WOT run. Now i am guessing 70psi of boost, and aside from keeping the line on the regulator, 130psi would stall the pump easily.

 

did mine just like that but hooked into the map line after the ITP OBA...that way it only climbs 22 to 25 PSI....

 

Wow!!!! Sounds like you have a case of pms. I guess I will have to get that spring tweaked just right. IIRC there was one on ebay that increased the pressure but don't remember to what. I'll have to check that out. Thanks for the inputs from all.

 

Yes, probably a pretty extreme one, but its fun, most of the time. Thats a good idea about tapping into the regulated side of the map sensor!

 

I always ran mine at 62 psi. IMO, too much pressure, and it could induce fuel aeration by forcing the fuel through the small orifices in the head. Remember that all the fuel pressure is doing is refilling the injectors. I think there's a point of diminishing returns with the fuel pressure on a 7.3.