I need to check my fuel pressure before I start tearing into the top part my TPI.
I have never checked the fuel pressure .
How do I check it? I went and bought the fuel pressure gauge from AutoZone.


I know theres an article around here somewhere but i cant find it....thanks



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wishmister@yahoo.com

1987 White IROC-Z
305 TPI LB9
700-R4 auto tranny
87,000 miles
Very Clean car
Performance Resource Chip
Flowmaster Muffler
Throttle Body Coolant bypass
TPIS air Foil
K&N's
Gutted air box
Accel 8.0 plug wires
Moroso Super Coil
Blue Streak Cap and Rotor
AC Delco Rapidfire plugs
Mobil 1 15/50 Synthetic motor oil
Mobil 1 synthetic Trans fluid.

 

On the back of the passenger side fuel rail, there is a threaded fitting, it may have a cap on it, it may not. Screw the fuel pressure gauge onto the rail and turn th key "on". Then turn the key off, and hit the release button on the guage (this will bleed the air out of the gauge) then hit the key again (waiting at least 10 seconds for the ECM to power down) and record your readings. This will be your MAX pressure. Then start the car up and record your readings, this is your MIN pressure (with vacuum applied).

Your MIN pressure is what you normally drive around with.

Your MAX pressure is what is used at WOT or heavy load conditions.

Typical specs are: No Vac (MAX) 45psi
Vac (MIN) 35psi

Make sense?

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'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
JET AFPR,
Ported Plenum,
TB Coolant Bypass,
SSM SFC,
Boxed LCAs,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
KYB Shocks

'97 Bonneville SSE

 

Ok I did what you said and heres what I got.

*Turned key on and got a 41 psi reading.
*Turned key off, hit the release button on the gauge. Then turned key to "on" again, waited 10 secs. and got a 41 psi reading again.
Then turn car on and the pressure dropped to 36 psi.

This was all with that vaccum hose attached to the pressure regulator.Did I do it right or should I remove the hose off the regulator?


Im going to put a Holley AFPR on this week.
Should I reset it to 41 or go up to 45 or 48...?


thanks




[This message has been edited by Wishmaster's87IROC (edited November 19, 2000).]

 

When you disconnect the vacuum hose it probably should go back to 41 (or darn close). Give it a try.

As for adjusting your fuel pressure, start with you stock pressure and then try bumping it up a couple of psi and see if you can feel a difference. If you have anyway of verifying it (drag strip or G-Tech), do a 1/4 mile run. Then keep bumping it up 1 psi until you either see a decrease or no increase in WOT performance.

You may wish to play with it still, because even though it may be optimized for WOT, it may not be what you prefer for normal driving. I found 44-45 psi for the best WOT performance and 47-48 psi for best normal/part throttle performance. The higher fuel pressure gave me better throttle response and fuel economy. The 45 psi was best for WOT but my part throttle wasn't as crisp and my fuel economy dropped 2 mpgs. I found 46 psi gave me the compromise I preferred.

But those are MY best fuel pressure settings. Every engine is different, even if equiped the same. You have to find YOUR BEST SETTINGS. It might be higher or lower.

 

i have an 88 vin 8 l98 iroc motor swapped in my 83 chevrolet malibu classic station wagon... don't laugh..

anyway i did a fuel pressure test and looked on the board here to check my results...
when turning key forward got 41

start car w/ vac. got 34 consistant... is that good?
pulled off vac. got 41..
when vac connected, and i throttle it up fuel pressure drops a few
also is that normal.. i am not a total noob just more used to carbs

any help would be greatly appreciated