Fuel pressure

[Sphinxmunkey]

When isn't there a ? about fuel pressure...

Anyway, I finally rigged some pieces to make a 1/8npt adapter into the shrader (sp?) valve fitting to adapt my old fuel pressure gauges empty hole (and remove that busted pos)

And put the new sending unit on (electric ftw)

So, I put it in and MHM strange, 55psi fuel pressure, that CAN'T be right.

So I adjusted the FPR, brought it down to ~40 with the vac line off, put the vac line on it and it dropped it down to ~35 at idle (1000 rpm) and will go up to 40-44 at 0+ pressure.

Just wondering if this is correct, and I don't hear any detonation but I'm not sure how keen my ear would be to it if it were there...

But the car idles smoother and at ~850-950 now instead of ~1000 and surging from 600-1400...

So, I feel it was the right move, but the car seems to lack a little something, idk. Maybe just me paranoid I'm leaning it out.

And it use to leave black spots on the ground from the exhaust if I revved it on pavement, now I don't believe it does... so it was hella rich all this time and the other gauge lied to me and this cheap ass ebay gauge is accurate?

I'm still figuring it out, leave your .02 ... BEEP.

[Blacksheep]

Can u smell fuel around the tail pipes?

whats the pressure at on WOT?

It would be great if u had a wideband, then we could really see whats goin on with it. We could even get it pretty close to a good "tune"

[Sphinxmunkey]

Working on a wideband, just fishing for any input right now...

And answer me this... what modified non egr 5.0 DOESN'T smell like fuel... LOL

none I've had hahaha

[Notch93]

How much is done to your motor? Because 38-39 lbs without the vac line on is the stock setting.

[Blacksheep]

yea i think 55 is around what u want. better to run it just a tad rich than lean her out and POP. there she goes.....

[SVTSkip]

55 is WAAAAY too rich !!! I dont know your combo, but even with an all forged custom built motor with good heads/intake/.544 cam, LT's and all the goodies I'm only needing 39psi with the vacuum disconnected, and my A/F is 12.8-12.9 all the way across the tach on the dyno, so it's plenty fat at 32 total timing and Autolite 3924's...

It IS normal that the pressure dropped after you reinstalled the vacuum source...

[Sphinxmunkey]

55 is WAAAAY too rich !!! I dont know your combo, but even with an all forged custom built motor with good heads/intake/.544 cam, LT's and all the goodies I'm only needing 39psi with the vacuum disconnected, and my A/F is 12.8-12.9 all the way across the tach on the dyno, so it's plenty fat at 32 total timing and Autolite 3924's...

It IS normal that the pressure dropped after you reinstalled the vacuum source...

That's what I wanted to hear, thanks for your input :thumbsup1:

Its a stock block, svo head, 42# injector and a little positive pressure.

The gauge I was running said 40psi at idle and went up to ~50 under pedal or boost or 0 pressure... I plugged this gauge up and it read 55 idle and 55 with the vacuum off as well, now its at 35 idle and goes up to 40-43ish with the pedal down.

I'll pull the plugs and check them after a few days and see if they turned white or melted off just to be safe... lol

[Stable]

Pressure drop is correct at idle. In the computer there is different fuel injector slopes that adjust the pusle width of the injector based off of RPM...There is a low setting and a high setting