For a 1987 F150 4.9L manual, what are the fuel pressure and vaccum pressure specifications. I am fight very poor throttle response which becomes a bucking when accelerating.

Throttle plates have been cleaned, IAC is cleaned, most sensors have been replaced and/or checked, EGR valve is not leaking. Have sprayed brake clean around the intake system trying to find a vaccum leak without success.

These are the fuel pressure readings I recorded:
Key on, engine off 30 psi

1000 rpm idle 48 psi

Engine drops down to 700 rpm idle 52 psi

Open up throttle plates (engine doesn't accelerate) 58 psi

Key off after running, 56 psi

thanks for your help
Kevin

 

The KOEO is the only low reading . The fuel pressure should be 40 to 60 Psi at 2000 Rpms . Idle the engine , remove the vacuum line to the fuel prssure regualtor , the pressure should max out at 60 psi . Also check the regulator for signs of fuel leakage when you remove its vacuum hose . I assume you replaced the fuel filter ?

 

Hey Paul,
You sound fairly knowledgeable about fuel systems... I have a 1995 460 (7.5) and am interested in upping my fuel pressure a just a bit. I have a Mallory adjustable regulator and an Autometer electronic fuel pressure gauge... How and where would you place these parts for the best control and most accurate readings. Any suggestions? Thankx in advance..

Mike
95 F350 Dually

 

[font size="1" color="#FF0000"]LAST EDITED ON 02-Mar-01 AT 04:33 PM (EST)[/font][p]

I put a permanent fuel pressure guage on mine, and yep, it ran best at 55psig with the stock injectors.

Eddie

 

 

Eddie, Can you send me pictures of the connection point (regulator and Fuel pressure sending unit)? You could post, send to me email (meshaffer at mindspring.com) or send me a url where they are located... It would help me a bunch!

Paul, You got and opinion or suggestion(s) for me?

Anyone else have any ideas or gotcdhas?

Mike
95 F350 Dually

 

I really dont have any exp with aftermarket or adjustable fuel system setups . Seems to me as long as everything is installed correctly just experiment with it until you get the results that best suit your needs .