94 explorer problem

[jshg46]

i have 94 explorer with 4.0 liter that died on us at the gas pump the other day and hasnt been right since,i have got the truck to start back up but its losing power going down the road at the same time its going into a bad misfire but funny part is it will not do this all the time mainly when its a strain on the truck like at idle you will hear it start missing and it might clear up for a few minute but its alot more noticable if you put it in gear or go down the road if you arent careful it will stall out on you .
things ive done so far
drained gas tank thought it may have been bad gas
truck has new motorcraft platnuim plugs and wires
new fuel filter
cleaned MAF
Cleaned vaccume tree
and diagnostic machine tells me nothing except code 542 secondary fuel
ive changed out the fuel relay didnt help
but truck also has valve chatter when this happens ,sometimes knocking noise reminds me of timing issue

 

[sncwfo99]

I'm not sure if this will help but I would check the crank position sensor.

 

[jeisbell]

Could your timing chain be on it's way out?

 

[jeisbell]

Sorry, forgot to add this too, but I found that the medium grade gas and occasional cleaner addative helps get rid of the clatter and dramatically boosts power. Also look into a K&N air filter.
Best of luck!

 

[Runnin'OnEmpty]

jshg, code 542 is "Fuel pump circuit open connection - Electronic Control Assembly (ECA) to motor ground".

The way I read this, you have a bad ground connection somewhere. I would first check the ECM ground, and any other grounding wires you can find in the engine compartment. It could also be the fuel pump circuit ground.

Good luck.

 

[MrShorty]

I'm going to assume that 542 is a continuous memory code. It would suggest that the cause for you bad running is an intermittent break in the fuel pump circuit. A possible course of action:
1) Clear the code (disconnect the STI during the KOEO test rather than disconnect the battery. You just want the computer to forget the 542 rather than forget everything it's ever known). Drive it and rerun the KOEO test to see if the 542 resurfaces. The idea is that you just want to see if this code is an old code unrelated to the current problem or if it seems to come back when the engine acts up.
2) Recognizing that the problem could be intermittent enough to not be noticed immediately, go through the fuel pump circuit (Get a wiring diagram!) and see if you can find any loose connections or other breaks/shorts in the circuit.
3) If the circuit checks out, but the 542 continues to resurface, you may have to rig up a more advanced means of monitoring the fuel pump circuit until you find the fault (ammeter or something like that).
Good luck.

 

[Opera House]

To simplify it more, that code means the circuit is open after the relay. It could be the inertia impact switch under the carpet on the passenger side, the tanl electrical connector, the pump is bad because of a stick brush, or the ground return for the pump circuit. I would unplug the inertia switch first and reconnect since it may have a poor contact from moisture. Also try pressing the reset switch. Banging on the gas tank can someimes get the pump to restart. This is not a fix, but will verify it is the pump that is bad. You can use any 12V lamp to verify power at the tank connector (two larger wires). Just remember that it will only come on for 3 seconds, so have a helper.

 

[jshg46]

thanks but i think you on the wrong track i noticed this afternoone it has black smoke coming out of tail pipe

 

[liqhx2]

i've seen this before bad fuel pressure regulator check it see if it's pushing fuel into your vacum system just disconect the vacum line running to the fpr and see if fuel is spitting out while the motor is runing

 

[Opera House]

Unless you did something to create the 542 code, it means something. If you have a current meter, pull the pump fuse and meaure the the current there. I'm thinking intermitant pump with low fuel pressure.

 

[shifty1]

This seems to be a problem with the '94's.
When its stalled out, check for spark. Mine was dying intermittently, turned out to be the EEC relay. Try switching your Fuel relay and or EEC relay with one of the others (Blower motor relay etc).