'93 sport 4x4 no start condition- code 542 pulled

[e39dream]

hi guys- I've been trying to get my truck going after parking it for the summer. It was running a little rough when I parked it, but not too bad. Now there is no fuel pump whine. I did the following test from my chiltons and I could hear the relay clicking but no fuel pump whine. put in new relay, same test results.

so then I find this great community and after searching and reading around for a few sessions I research the eec testing a little more, I didn't quite understand it. Long story short I managed to confirm the codes 542(fuel pump secondary circuit failure, pcm to ground) 3 times and am curious if anyone can shed some light as to what to look at. I'm guessing drop the tank and put in a new pump, but if it's something easier or less expensive that would be great. I also was curious about where to obtain the special tool should I need to remove fuel cell. thank you for any input. Any thoughts?

 

[MrShorty]

How far through the diagnostic chart did you get? I'm guessing A1 resulted in a NO, so you go on to A2. I'm guessing that result in a No, so go to A6. what did you get for the result to A6: inertia switch check?

Alternatively, you could just get a voltmeter and a wiring diagram and step through the fuel pump circuit. Where the voltage drops is where the problem will be.

 

[e39dream]

I did check to see that the intertia switch was not tripped. I don't have a voltmeter- I guess I could run to radio shack and get one. time to start opening the wallet

 

[e39dream]

you know- when I first started diagnosing the problem I found a dead weasel under the hood and had to fix the wires he had chewed on the heater blower. I wonder if he gnawed my fuel pump harness off. I guess that would be a cheap fix- not really easy. Can you take the tank down without disconnecting the gas lines? Like as if to check the wiring? Go ahead and laugh, I have pics of the decayed weasel.

 

[marragtop]

On the inertia switch, make sure the connector is tight on the bottom of the switch. It's a long shot, but an easy check.

 

[jammin636]

hey i just recently had this problem when putting my x on the road for this winter. i also had no pump whine and pulled code 542. dont go out and buy a pump just yet. i did that and found that i didnt even need to later.

the solution that i found was referbishing the fuel pump connector. u shouldnt have to drop the tank or anything to do this, its a pain. i checked my connector before also but didnt think it was bad so i moved on. make sure u check it close. look for any corrosion. i found that one wire had actually disintegrated but all others were fine. i took that wire out and spliced it together with the corresponding wire on the other side. fuel pump primed problem solved. it should be up near the frame near the tank.

 

[e39dream]

thanks jammin636, I'm going to have a look at that in just a little while before I do anything else- my frame and other parts down there are pretty rusty and corroded. I also have this feeling I might run into more chewed wiring from the rodent I mentioned above. I will be sure to update my progress.

 

[e39dream]

well I've spent the last two days inspecting wiring and it's getting aggravating. I have decided yesterday to go ahead and drop the tank as when I was feeling around for the wires on top of the tank I pulled out a half handful of broken nut shells and animal bedding. That damned weasel crawled up there and gnawed my wires, I know it. Dropping the tank plate on this rusty old POS has taken me 2 sessions so far, I'd say I've got about 8 hours into removing 5 or 6 bolts so far. And it's still hanging there after I gave up today. This thing is so rusty everything is breaking in two, stripping or needing a breaker bar on the ratchet. I'm currently stuck on a strap bolt thats about 1/2" in diameter and ford thought it best to use their famous "clip-nut" to hold it on- needless to say I've got a fastener thats just spinning and spinning. I tried to cut the head off it with a cutoff disc but guess what- the tool can't reach because the driveshaft and muffler heat sheild is in the way. I tried to drill it out but the angle is all wrong. I hate this truck. If it doesnt come apart tomorrow I'll likely take a sawzall to the tank strap- I just don't care anymore.

 

[e39dream]

lunchtime update.

I decided since the thing didn't want to come apart maybe it was telling me something, so I made a homemade test light from a length of wire and a turn signal bulb from my other car (spare of course). I then disconnected the fuel pump harness and tested the black and red wires while key on, it lights up for one second or so, then lights again if you crank the engine over. so theres power all the way to the harness, nice.

A good sign but now I'm back to dropping the rusted in place tank. I am still on the same bolt as yesterday (last one on the skid plate, of course)and have busted my knucle open pretty badly, after that I knew it was lunch time, lol. I want to cut this truck bad but the sawzall wont fit up in there either.

wish me luck

 

[e39dream]

Well I finally got the tank plate and fuel tank down this morning. Much to my surprise the wiring was perfect from the harness by the rear shock all the way to the pump. The fuel lines are another story- they both were so rusted they broke off at the fuel pump the moment the tank moved. Great. I'll be buying a fuel pump afterall, and then some.

here you can see the fuel lines as they run along the frame. The rusted one went to a different rubber hose to the tank besides the two pump lines, I'm thinking it's a vent or return line. Anyone know where that line goes up under the hood? I'm looking to replace it as well. this is getting expensive quick- the whole truck is worth like 500 bucks.

this is where the lines snapped- lucky me.

another shot- I can't wait until I try to remove the actual pump- look how rusted that locking ring setup is.

the fuel filler inlet is even rusted out- WTF?

lastly I thought I'd share my most heart racing event today. I needed to lift the truck higher than the non adjustable jack stands I have to slide the tank out- this is after the bottle jack fell over and the truck shifted about a foot(note tool bag was resting right up agaisnt rear tire) only to fall on some house bricks which barely managed to catch. I have pulled out the tank, and put the rear tire back on and lowered the truck. My friend will be trailering the truck to his shop where we can continue this fix on a car lift and with air tools.

What started as a simple diagnosis almost killed me becasue I thought I'd go ahead and do the work here real quick rather than waiting until my friend has the chance to tow it. lesson learned- and yes the jack in question was the stock bottle jack. The truck is parked on a slight incline which I believe helped it lose balance.


So I'm looking at a new fuel pump, 1 new line, ford fuel line tool and probably 15 trips to the parts store for whatever else rusts away in the meantime. I wanted to put shocks on this thing this year, but if it keeps this up I'll junk the darn thing.

 

[MrShorty]

The rusted one went to a different rubber hose to the tank besides the two pump lines, I'm thinking it's a vent or return line. Anyone know where that line goes up under the hood? I'm looking to replace it as well.

There are three hoses going from the tank under the hood.

Fuel feed goes to the fuel filter and on to the fuel rail
Fuel return goes from the fuel pressure regulator back to the tank
and EVAP line which goes to the charcoal cannister and eventually to the intake. Reduces emissions due to evaporation of fuel in tank.

 

[e39dream]

thank you sir!