Explorer Won't Start, No Spark...

[runasoft]

is the small wire on the battery cable corroded and or grounding out somewhere?

There is a tiny bit of a white substance on the negative battery cable. I believe this is to be considered corrosion correct?

For some reason I don't feel that the actual short is at the ignition or throughout the engine bay... I'm pretty sure it is the actual cables but I can't be sure about that either. It's pretty dificult to get my hands into the crevices which the battery cables reside

- Rudy

 

[cainfan4u]

sounds like a short in the cables and/or wiring to distb. box to me id check all the wiring from the battery to the box.remove filter box for easier access

 

[runasoft]

sounds like a short in the cables and/or wiring to distb. box to me id check all the wiring from the battery to the box.remove filter box for easier access

Yea, that's exactly what I'm doing right now. I am going to tear that truck apart looking for that short tho. I'm going to go remove as much as possible to see if I can get to the bottom of this short.. It's blowing a 30amp fuse and from what I understand the short should be pretty obvious as thats a pretty big fuse to be blowing.

I need to find the short tho because buying fuses to test it out is getting very expensive. The price for that 30 amp fuse is 1.99 and over 5 fuses it starts adding up LOL...

- Rudy

 

[Longjohn119]

There is a lot of stuff tied to that fuse, it feeds the EEC directly (Before the EEC relay) but it also feeds the EEC relay which in turn feeds the AC and fuel pump relay coils, two pins on the EEC (37,57) Power to the MAF, power to the fuel injectors, canister purge, camshaft position, EGR vacuum regulator solenoid, torque converter lockup and 3-4 shify solenoids, IAC valve ... A short anywhere here could cause a fuse to blow ...

First thing I would do is remove pin 1 (yellow wire) from the EEC and put a multimeter in series with the wire and pin 1 on the EEC, set it for DC current and monitor the current (If your meter has a high/low memory use it) This will tell you for sure whether it's the EEC that's bad ... if the current there is OK then it's somewhere in the rest of the circuit after the EEC relay (red wires) ...

You could also try removing pin 1 from the EEC and putting your amp inline fuse (use a 25 amp) there and see if it get's blown ... if it does then you have a bad EEC, if it doesn't them you have a problem after the EEC relay ....

As far as I can tell none of this circuit goes to the dash so tearing it apart is just wasting your time .... if does however go to the computer which is mounted on the passenger side by the floor, and you'll need to access it there to get to pin 1 wire on the EEC ...

 

[runasoft]

There is a lot of stuff tied to that fuse, it feeds the EEC directly (Before the EEC relay) but it also feeds the EEC relay which in turn feeds the AC and fuel pump relay coils, two pins on the EEC (37,57) Power to the MAF, power to the fuel injectors, canister purge, camshaft position, EGR vacuum regulator solenoid, torque converter lockup and 3-4 shify solenoids, IAC valve ... A short anywhere here could cause a fuse to blow ...

First thing I would do is remove pin 1 (yellow wire) from the EEC and put a multimeter in series with the wire and pin 1 on the EEC, set it for DC current and monitor the current (If your meter has a high/low memory use it) This will tell you for sure whether it's the EEC that's bad ... if the current there is OK then it's somewhere in the rest of the circuit after the EEC relay (red wires) ...

You could also try removing pin 1 from the EEC and putting your amp inline fuse (use a 25 amp) there and see if it get's blown ... if it does then you have a bad EEC, if it doesn't them you have a problem after the EEC relay ....

As far as I can tell none of this circuit goes to the dash so tearing it apart is just wasting your time .... if does however go to the computer which is mounted on the passenger side by the floor, and you'll need to access it there to get to pin 1 wire on the EEC ...

My EEC is fine... I have 2 different EEC's and they both do the exact same thing. I know the EEC isn't causing the surge of power.

As far as I know, the Lime Green wire is run throughout the entire engine bay straight into the Distrbution Fuse Box under the hood. I have verified this visually as well as through the wiring diagram I have.

Right now I'm at a point to where if I put in a new 30amp fuse and turn the key foward all the relays will kick on properly but the fuse will blow...

I will try to rewire the EEC relay yellow wire and see what happens...

- Rudy

 

[kclyki02]

I'm having the same problem as the OP. We tried a new EEC and that wasnt it. New fuel pump, filters and relays. No dice. This is starting to drive me and my mechanic up a wall. Anyone got any ideas?

 

[MrShorty]

Among the first things I would do in a no start situation:
1) Check to see if the fuel pump is running and the fuel rail has pressure.
2) Check to see if the spark plugs have spark.
3) Pull codes from the computer (some no-starts will leave clues here).

 

[kclyki02]

Fuel pump runs when the relay is jumpered but not with the relay. Seems to be a problem with Pin 22, it goes from a weak ground to a strong positive, when it should be a negative. Its not grounding the relay so its not triggering that to turn on the fuel pump. When jumpered, the new pump is putting out 40 psi.

 

[MrShorty]

When does it go from weak ground to strong positive? How are you measuring these voltages (where are the leads)? With positive lead on pin 22 and negative lead to ground you should see:

0 V KOEO
0 V for a second or two after turning the key on, then +12 V
0 V when attempting to start the engine.

If the problem is, as you suspect, at pin 22, then check to make sure the computer has power and that the computer has good grounds.

Have you made any attempt to check spark or pull codes?

 

[kclyki02]

Basically, the fuel relay is showing up positive on both sides and not triggering it. Running a ground from the battery to the relay will turn the fuel pump on but then theres no spark. No codes. Ideas?

 

[MrShorty]

No codes at all or all pass codes? No fuel and no spark (and no codes at all, if that's the case) together point to a problem with the main computer wiring. Does the computer have power where it should? Does the computer have good grounds?

 

[pj8847]

runasoft,

Just a theory here, so humor me...

the fuse in question obviously powers the PCM, so when it goes, your not going to be able to pull codes. It also feeds the AC system, including the WOT relay for the AC compressor.

After mulling over the diagrams I have at my disposal, It's obviously a hard short, seeing the fuse blows so fast. You already tried a different PCM, with no change, that rules out a bad PCM, you have a new fuel pump, which works when the relay is jumped, so that circuit is fine, the relays themselves you already replaced, so we know those to be ok.

You said the truck will run for a few seconds until the fuse blows correct?

Lets try and eliminate the highest load on that circuit, the AC system.

Try this and see if the fuse still blows. Remove the WOT relay for the compressor, and unplug the compressor clutch and the pressure switch, and make sure the climate controls inside the truck are all off. Then try a new fuse and see what happens. If the truck starts and runs, and the fuse doesn't blow, start replacing/plugging in what was removed, one by one, starting with the WOT relay.

If after all this, you still are faced with the fuse blowing, then you'll have to look at the wiring for the MAF, canister purge soleniod, injectors, torque conv. clutch solenoid, 3 - 4 shift solenoid, cam sensor, EVR solenoid, ignition control module and the IAC, as they are all supplied by the same feed, as mentioned already.

Note: you can do this with every single sensor/relay that is fed by this circuit as well, unplug whatever connectors are present and turn the ignition on, if the fuse doesn't blow, start reconnecting them one at a time, may be the quickest way to locate what may be causing the short. if the fuse STILL blows with nothing plugged in that is fed off of the circuit, then you have some serious wire tracing to do.

 

[kclyki02]

Update:

After 600 bucks, a new fuel pump and fuel filter, it turns out I had two ground wires that were toast. A ground from the computer to the frame, and a ground that was triggering the fuel intertia switch when the relay was trying to trigger. Chalk this one up to old wiring.