EvilTheCat
Active Member
- Joined
- December 6, 2011
- Messages
- 88
- Reaction score
- 3
- City, State
- Lincoln NE
- Year, Model & Trim Level
- '97 Explorer
So I used to be fairly active here when I got my explorer years ago, but stopped getting on because I fixed everything and modded enough stuff to make her suit my needs. However, lately she's been running like ****.
RIG:
I have a 97 Explorer Sport with the pushrod 4.0L OHV and a 5 speed manual.
PROBLEMS:
Hesitation, or maybe a misfire, when ascending hills or when throttle is applied more than half way, at highway speed or taking off from a dead stop. No hard starts really and it usually idles smooth and steady. No Check Engine light on either.
STUFF DONE:
*Started by putting in new plugs and wires, and also a fuel filter. No improvement noticed. The plugs were not too bad. A little light colored, so maybe slightly lean burning, but none fouled. Replaced with NGK platinum plugs (not gapped as per plug instructions)
*Coil pack spark and resistance checked.
*Injector cleaner added to 1 full tank of gas suspecting a clogged injector... what a waste of money.
*Seafoam down the intake through the brake booster, MAF sensor cleaned, and IAC valve cleaned at the same time. Smoked like mad, what a hoot tearing through the neighborhood! Some improvement noticed. The hesitation seemed to occur less frequently and at closer to 3/4 throttle now. Plus my exhaust doesn't stink anymore! I love seafoam!
FUEL PRESSURE TEST:
I rented a gauge from O'reily's to test my fuel pressure to see if maybe my pump or fuel pressure regulator is failing. From 0 psi on a cold engine it slowly climbed to about 25 psi once started. Seriously took about 10 seconds to climb to that. Revving engine resulted in zero change to pressure. Taped the gauge to my antenna and drove around to see where the pressure was when the hesitation occurred. The pressure would hover around 28 psi while driving, but would climb to nearly 40 psi at WOT. I shut off the truck and went to go pee and get another beer. The pressure didn't drop a single pound in 5 minutes. Then I drained all the pressure off and just turned on the key. It jumped right up to 25 psi again. I then unhooked the vacuum line to the FPR and plugged the hose with a .22 shell I found on the floor of my truck which is a perfect fit by the way. It fired right up and the pressure quickly rose to about 38 to 40 psi. I went for another drive and it ran about the same, but the pressure never fell below the 38 psi mark.
I guess my question is what does it all mean? Is the Fuel Pressure Regulator bad? The fuel pump seems to be able to maintain 38 psi when the FPR is open. Am I missing something on the fuel pressure test? This is the first time I've done it. Usually I can tell when my pump is bad. It just stops. Any other suggestions for things to check? I've read somewhere that the Crankshaft Position Sensor can go bad and not send a signal to the ignition when it's supposed to causing a misfire. Anybody heard of this happening? Any way to test it? I'm getting tired of messing with it, because winter is nearly here and I don't have a garage to work in.
RIG:
I have a 97 Explorer Sport with the pushrod 4.0L OHV and a 5 speed manual.
PROBLEMS:
Hesitation, or maybe a misfire, when ascending hills or when throttle is applied more than half way, at highway speed or taking off from a dead stop. No hard starts really and it usually idles smooth and steady. No Check Engine light on either.
STUFF DONE:
*Started by putting in new plugs and wires, and also a fuel filter. No improvement noticed. The plugs were not too bad. A little light colored, so maybe slightly lean burning, but none fouled. Replaced with NGK platinum plugs (not gapped as per plug instructions)
*Coil pack spark and resistance checked.
*Injector cleaner added to 1 full tank of gas suspecting a clogged injector... what a waste of money.
*Seafoam down the intake through the brake booster, MAF sensor cleaned, and IAC valve cleaned at the same time. Smoked like mad, what a hoot tearing through the neighborhood! Some improvement noticed. The hesitation seemed to occur less frequently and at closer to 3/4 throttle now. Plus my exhaust doesn't stink anymore! I love seafoam!
FUEL PRESSURE TEST:
I rented a gauge from O'reily's to test my fuel pressure to see if maybe my pump or fuel pressure regulator is failing. From 0 psi on a cold engine it slowly climbed to about 25 psi once started. Seriously took about 10 seconds to climb to that. Revving engine resulted in zero change to pressure. Taped the gauge to my antenna and drove around to see where the pressure was when the hesitation occurred. The pressure would hover around 28 psi while driving, but would climb to nearly 40 psi at WOT. I shut off the truck and went to go pee and get another beer. The pressure didn't drop a single pound in 5 minutes. Then I drained all the pressure off and just turned on the key. It jumped right up to 25 psi again. I then unhooked the vacuum line to the FPR and plugged the hose with a .22 shell I found on the floor of my truck which is a perfect fit by the way. It fired right up and the pressure quickly rose to about 38 to 40 psi. I went for another drive and it ran about the same, but the pressure never fell below the 38 psi mark.
I guess my question is what does it all mean? Is the Fuel Pressure Regulator bad? The fuel pump seems to be able to maintain 38 psi when the FPR is open. Am I missing something on the fuel pressure test? This is the first time I've done it. Usually I can tell when my pump is bad. It just stops. Any other suggestions for things to check? I've read somewhere that the Crankshaft Position Sensor can go bad and not send a signal to the ignition when it's supposed to causing a misfire. Anybody heard of this happening? Any way to test it? I'm getting tired of messing with it, because winter is nearly here and I don't have a garage to work in.