Fuel Pressure Question

[steveissteven]

Okay, I have a 1993 Ford Explorer Sport

My question is does anyone know what the correct fuel pressure should be at idle with and without vacuum?

Hanes manual indicates 30-45 psi with vacuum applied

At idle with vaccum applied I get a reading of 31psi
(Actually it is really about 30 and 1/2 psi)

On the low side if you ask me.

Anyone know what it really should be?

I am told that the correct pressure should really be between 35-45 psi

Is hanes wrong?

What gives?

 

[mrboyle]

Is the engine running properly?
If the fuel pressure at idle is slighty lower than spec it is fine, as long as the engine is running properly. If it is higher than spec at idle, or if it drops below spec under load you have a problem.

 

[steveissteven]

Thanks for the input.

How am I able to check pressure under load?

Do you have to drive the vehicle with the pressure gauge attatched?

The fuel pressure gauge only has about a two foot section of hose. How would I drive the vehicle and read the gauge?

Suggestions?


And yes the motor seems to idle perfect. No check engine light and no codes. Accelerates smoothly and evenly up until the point you really gas it. When accelerator pedal goes beyond 2/3 of the way to the floor, engine looses power (hence not enough fuel delivery).

While driving (I have an automatic tranny) no matter how much gas pedal I give it, RPM's will never go beyond 3000. It doesn't REDLINE till 5500... so what gives?

Any clue or is this NORMAL?

 

[mrboyle]

The only way to check fuel pressure under load is to drive it with the guage hooked up. The easiest way to do this is to hook the guage under the windshield wiper (make sure you can read it from the driver's seat) carefully close the hood making sure you don't pinch the hose, then take it for a spin (find a road with little traffic). Watch the pressure for any signs of significant drop. You may also want to try this with the pressure regulator unhooked to see if there is any difference in the two readings. If there is a fuel pressure drop I would suspect (in this order) fuel filter or the fuel pump/pickup. If there is no drop in pressure you may have a problem with air flow (clogged filter, bad MAS or TPS)