Hello all. Just rescued a 1992 F-150 4x4 302 auto from a guy I work with. Truck is in ok shape, little rust on the body. Frame is really rusty. But the reason I'm writing is I got a problem. Did a major tune up on it. New plugs, cap and rotor, wires, fuel filter, air filter, trans. filter and fluid, transfer case fluid change, and both axles have fresh lube. Also greased the joints in the chasis. Now, I go out to start it up. No go. I put $10 in the rear tank when I drove it home. It still reads 1/4 on the rear. I can hear the pump cycle for 1-2 seconds like it should then shuts off. I say OK. Maybe the guage for the tank is off. So I put 1-2 gallons in the front. It cycles the same. Still won't start. I hold the pedal to the floor while cranking and It starts! Runs rough, wants to die. I switch to the rear. Same deal. Pedal to the floor, rough running. I pull the codes from the EEC. I get: 116(ECT out of range), 118(ECT greater than 4.6v), 327(DPFE or EVP below min. voltage), 328(EVP below min. voltage), 332(EGR valve opening not detected), 334(EVP above closed limit of 0.67), 556(Fuel pump circuit failure), 634(Trans. manual lever position sensor out of self test.) All these codes came from Key On Engine Off. So, I put on a fuel pressure test guage. Select front pump, short pin #6 and #2. I get 32-35 psi with key off. I un-hook ground and pressure drops to 0. I set the switch to the rear tank. I get 40 psi and un-hook the ground, pressure drops to 0. SO, my qustions are: 1; Are my pumps bad? I know the front is weak but are both shot? 2: I plan on changing the Engine Coolant Sensor. IF the error codes say it's out of range, I should go ahead and replace it correct? 3: Code 556(Fuel Pump Circut Failure) If the pumps are cycling like they should, am I just getting this code because the engine isn't running or because the pumps are going bad? 4: Code 634(Trans. Manual Level Position Sensor) Can this sensor be adjusted? If so, where is it located and how do I adjust it? (My trans is an E4OD by the way.) Also SHould I or can I clean the EGR valve when I replace the EGR valve position sensor? I love all the advice on this site. I check on here regularly for info on my 77 F-150 and found all kinds of interesting stuff for it. If anyone wants any additional info on my problems, I'll be happy and try to give anymore info that you require. Also, pics are apreciated. I work better when I can see what it is I am about to break or have all ready broken.

 

With all of those codes I would check the 5-Volt ref voltage first.
Does not sound good for the PCM.

The fuel pump code is from the shorting of pins 2 & 6 and was in the continuos memory part of the test.

 

Subford, thanks for the reply. Ok, time for me to start asking questions. 1st What's 5-Volt ref voltage? Is it a test of some sort and how do I check it? And 2nd what's the PCM, where is it located and is it expensive? If you can give a picture or drawing of it, that would be great. I'm still kinda wondering about the fuel pressure test. After I remove the short between the pins, the pressure should hold for a bit shouldn't it? Mine drops as soon as the wire is pulled.

 

EDIT: Got an update. Not 100% sure but got the truck to start. I got an exhaust leak on the pass side. Sounds like it's coming from the tube that's on the bottom of the EGR valve. The sheathing that protects it is all black and burnt. I can fell a little exhaust pressure from around the blacken part. I gotta take it foo to see how bad it is.

 

When you short pin 2 to pin 6 of the Test (VIP/DLC) Connector the key needs to be on to check the fuel pressure.

If the pressure drops to zero as soon as you turn the key off or removing the shorting jumper then you have either a bad check valve in a fuel delivery module, a bad injector or a bad fuel pressure regulator.

To check the 5 Volt Reference Voltage use a DVOM with the key on between the VREF (5V Ref.) and the SIG RTN.
You can find these test points at the TPS and EVP plugs.

Yes the PCM can be expensive and the PCM contains the 5-Volt regulator for the 5V Ref voltage.

PCM - Powertrain Control Module
FPR - Fuel Pressure Regulator
TPS - Throttle Position Sensor
EVP - EGR Valve Position sensor
EGR - Exhaust Gas Recirculation system
SIG RTN - Signal Return circuit
VREF - Voltage Reference (EEC supplied voltage = 5 volts)
DVOM - Digital Volt/Ohm Meter

 

Thanks again for replying. I will do the 5 volt test Friday. I found my exhaust leak yesterday. My EGR tube broke. I took it into work and re-welded it. Friday I am picking up the ECT, EVP and Fuel Press. Reg. along with a new intake gasket set. I'll post what I find out from the test. Where is the fuel delivery module located and can I tear it apart and try cleaning it? Quick qquestion though. If my 5v tests passes, is it still possible that the PCM is bad? First time delving into Fuel injection. My '77 is carbd so I know a little bit more about that setup. If it don't run, I usually only gotta check for 3 things. Then I know where to go from there. They just don't build them like that no more.

 

If the 5 Volts is bad then your ECT & EVP sensors are more than likely good.
The fuel delivery module is located inside the fuel tanks.
It is possible of course to have good 5 Volts and the PCM is still bad.
They do not go out very often and if the 5 Volts is OK and the pumps time out then it is more than likely OK.