I am not as familure with this truck as i am with the one in my sig. So i dont know the common problems that go with codes. Thought maybe you guys would have some suggestions to problems that are normal with these codes.

Truck is a 94 Reg Cab Flare Side 4x4 5.8l/E40D

It has the fuel pump bypassed with a switch to turn it on manually. I will be looking into why they did this later. Probably the reason for one or more of the codes.

Fast code
542 - fuel pump secondary
332- egr flow low
172-ego lean

Slow code

542




Like i said some reason the fuel pump is bypassed from the key start. It has a manual switch. I will be looking into the factory wires to see if i have contenuity back to the fuel pump. They ran a wire all the way to the rear from the battery and have a switch inline to shut it off. Very wierd

Egr low is either the egr tube is pluged or rusted out. or the egr valve is bad i figured. Any other solutions?

 

You did not say what kind of codes these were.
It would help to know if they were KOEO, CM or KOER codes.
I have no idea what you mean by Fast code or Slow code.

DTC 172 The right or rear HO2 Sensor indicates system is running lean.

The 332 code has nothing to with flow.
================================================== =================
DTC 332 in Key On Engine Running (KOER) indicates the EVP sensor input did not change after the EVR solenoid was instructed by the Powertrain Control Module (PCM) to open the EGR valve.

Possible causes:
--Vacuum hose leaks.
--Icing.
--Obstructed vacuum hose.
--Obstructed EVR solenoid filter.
--Damaged EVR solenoid.
--Damaged EVP sensor.
--Damaged EGR valve.

Continuous Memory (CM) DTC 332 indicates the EGR valve did not open with the engine stabilized and the EVR solenoid duty cycle present sometime during vehicle operation.

Possible causes:
--Obstructed or cracked hose to EGR valve.
--Icing.
--Damaged EGR valve.
--Damaged EVR solenoid harness.
================================================== =================
DTC 542 Key On Engine Off (KOEO) indicates that one of the following has occurred:

No Start:
--Inertia Fuel Shutoff (IFS) switch not reset or electrically open.
--Open circuit between the fuel pump and FPM circuit connection to the power-to-pump circuit.
--Poor fuel pump ground.
--Fuel pump electrically open.

Engine Starts:
--Fuel pump secondary circuit short to power.
--Fuel pump relay contacts always closed.
--Open in FPM circuit between PCM and connection to the power-to-pump circuit.
--Left/front HO2S short to power (dual HO2S applications).
--Damaged Powertrain Control Module (PCM).

A Continuous Memory DTC 542 indicates that one of the following intermittent conditions has occurred:

--Fuel pump circuit activated when PCM expected circuit to be off (i.e., fuel system test or prime procedure).
--Inertia fuel shutoff switch tripped, then reset.
--Open circuit in or between the fuel pump and FPM circuit at the PCM (refer to «Schematic»).
--Poor fuel pump ground.
--FPM or power-to-pump circuit short to power.
--Fuel pump relay contacts stuck closed.
--Left/Front HO2S circuit short to power (with/dual HO2S).
--Engine stall due to excessive load.

NOTE:
For trucks with dual fuel tanks, perform Key On Engine Off (KOEO) Self-Test twice, once with the front tank selected and once with the rear tank selected. If KOEO DTC 111 and Continuous DTC 542 is present both times, continue with this test (intermittent concern). If KOEO DTC 542 is present in only one test, refer to the Fuel/Engine Group of the Service Manual to check for open circuit between select switch and suspect pump circuit ground.

 

Thanks for the help, hopefully i can get some time monday to look at it and report back. My guess is the guy that had it before me, probably wrecked it or somethign and tripped the fuel inertia shut off and didnt know how to re enable the fuel pump. So he just bypassed it. Im hoping that its that simple.

Where is the inertia fuel pump switch on these trucks. I now its by my passenger side right kick panel on my 99.

Thanks again

+ rep

 

The inertia fuel pump switch is in the same place on these also.
Passenger side right kick panel.


/

 

Only have code 172 now. Truck idles rough like its missing at first startup. And after 10min the check engine light comes on. Its when the truck goes to closed loop is when th check engine light comes on i think.

 

I would start by looking for any vacuum leaks. You may be able to hear it hiss if it is a larger leak. If not, try spraying something like silicone spray around any vacuum lines/fittings/junctions and listen for the motor to pick up in RPM's.

 

No vacuum leaks, already checked all the lines.

 

^ How about any intake gaskets/fittings? Any exhaust leaks around the manifolds? Fuel delivery issues?

Do the '94's have a O2 senor after each exhaust manifold, or just one where the two pipes merge?

 

It has just one o2 sensor. No exhaust leaks i can tell. Fuel pressure is 39 engine off, 32 engine running.

 

You could use a OBD-I code reader to run a cylinder balence test. It will indicate if one or more cylinders are not up to par( as in may the fuel injectors are dirty.)

With only one O2 senor, you can't narrow down which bank is running lean. Is 32 PSI within spec?

 

Yes on the psi.

IM not sure how you can check cylinders with OBD1.

I replaced the MAF sensor, still get a CEL. after 10 min or so.

 

MAF or MAP? ...just asking, two different things. I knew Ford started using MAF on the light duty trucks with the 5.0L engines in 1994, I was not aware the 5.8L equipped trucks went to MAF in that year too.

 

No its the Map sensor. My bad

 

The manual that came with my OBD-I code reader describes how to do it. I don't know if it will help or not, just throwing the idea out there....

If your fuel pressure is in check, try running back-to-back bottles of fuel system cleaner if nothing else. Worst case, you burn $10-12.

Also check the exhaust manifold bolts. I found a loose one on mine this summer when I was changing spark plugs.

Edit- I just looked at my OBD-1 manual. It defines code 172 as "HEGO senor fault/lean." Could that mean that the problem is the O2 senor? I had a bad vacuum leak on my car, and it was throwing 189. Seems like you should be getting codes along the lines of 179, 181, 188 or 189 if a good senor was detecting a rich/lean condition... I could be mistaken though. How old is the O2 senor?

 

The cylinder balance test will only work on the SFI MASS trucks.
He has a MAP sensor so he can not run the test as his truck would be bank injected.

For the 172:
Possible Causes:

-- Fuel injectors.
-- HO2S.
-- Secondary Air Injection (AIR) system.
-- PCV/Hose.
-- Vacuum.
-- CANP.
-- MAP sensor.
-- Electronic Ignition Coil Failure.