ranger7ltr
Explorer Addict
- Joined
- November 17, 2001
- Messages
- 1,303
- Reaction score
- 29
- City, State
- Great State of Texas
- Year, Model & Trim Level
- 1999 Sport
I have a 99 Explorer Sport that has had some fuel delivery issues since I got it..I finally installed an electric fuel pressure gauge to monitor what is happening..
At start-up, the fuel system primes to 65 or 70 psi...Start the engine and the pressure stays right there... There is very little pressure change...Start to drive and as I accelerate harder I can see the pressure drop and the more I open the throttle, the lower the fuel pressure gets..
If I hold the throttle open, the pressure will start to cycle from 70 down to 0 and then come back to 70!!! If I back off the throttle as the pressure drops, fuel pressure will stop dropping, hold at the current level and then start to climb back to static pressures...
Correct me if I am wrong but this truck has the mechanical returnless system which is supposed to keep the pressure at 65 or 70 psi...I am seeing no change in fuel pump voltage at the interia switch wiring to the pump...And since I do see proper pressures, I can rule out the tank mounted regulator I believe...
I have replaced the pump, strainer on the pump, system filter under the truck, and installed a fuel pressure gauge...I am about to drop the tank and see if there is a layer of crap in there to stop the pump from being supplied with fuel during running conditions...
Tank is half full right now so amount of fuel should not be a problem...This vehicle sat for at least 2 years with fuel in it and I drained that mess out before starting it up but I wonder if there could be a fuel starvation issue with a new pump and old tank...
http://www.aa1car.com/library/returnless_efi.htm
Any ideas? Comments? Am I missing something?
At start-up, the fuel system primes to 65 or 70 psi...Start the engine and the pressure stays right there... There is very little pressure change...Start to drive and as I accelerate harder I can see the pressure drop and the more I open the throttle, the lower the fuel pressure gets..
If I hold the throttle open, the pressure will start to cycle from 70 down to 0 and then come back to 70!!! If I back off the throttle as the pressure drops, fuel pressure will stop dropping, hold at the current level and then start to climb back to static pressures...
Correct me if I am wrong but this truck has the mechanical returnless system which is supposed to keep the pressure at 65 or 70 psi...I am seeing no change in fuel pump voltage at the interia switch wiring to the pump...And since I do see proper pressures, I can rule out the tank mounted regulator I believe...
I have replaced the pump, strainer on the pump, system filter under the truck, and installed a fuel pressure gauge...I am about to drop the tank and see if there is a layer of crap in there to stop the pump from being supplied with fuel during running conditions...
Tank is half full right now so amount of fuel should not be a problem...This vehicle sat for at least 2 years with fuel in it and I drained that mess out before starting it up but I wonder if there could be a fuel starvation issue with a new pump and old tank...
http://www.aa1car.com/library/returnless_efi.htm
Any ideas? Comments? Am I missing something?