wont start when it is wet out

[jamesapost]

i have a 92 explorer 4x4 5 speed. it has over 300,000 miles on it. My problem is when ever it rains or it is humid out the truck runs like **** or in todays case it just wont start. it has power, it will turn over but it wont fire up it will just sit there and turn over. im thinking somthing has to be shorted out or there is a senser of some sort that is bad but at this point i have no idea!!! pleas help me!!!


Hear is a list of electrical parts that i have replaced in the last year, alternator, battery, fuel pump, computer, plugs, coil pack, spark plug wires. i even got a few sensors from the salvage yard and put them on to see if my parts were bad then put my original parts back on the truck, mass air flow sensor, tpi,

 

[MrShorty]

Where it's intermittent, the first thing I'd probably do would be to pull codes from the computer. Some causes of a no start like that will leave clues in the computer's memory that might point you to a resolution.

Apart from that, I would have a fuel pressure gauge handy and a spark checker of some kind and, the next time it won't start, check for fuel and spark.

 

[jamesapost]

get this, so it wouldnt start this morning and i went in and rote the 1st post and went back out to the truck about 1 hour after it wouldnt start and tryed it again and it started up and ran fine like there was nothing wrong.... i have a pocket scanner and i got a 522 which the book says trany not in park for the test. but this is cus my explorer is a 5 speed! and a 111 which is all OK. i caled the guy i got the truck from and he told me the to do the same thing you put in the post about the fuel presure gage, and a can if starting fluid in the truck to test if its got spark and fuel!!!

 

[92exp4x4]

Were they new parts or junk yard parts? This may be the difference. I am not at all condemning junk yard parts, but you may have inherited other problems with them. Chances are they are good though.

You may want to examine or change the ignition module. Its possible that moisture is messing with it. If this unit is not working you get no fire. But I would think you would see a code. Intermittent problems suck.

 

[swetrid]

Definitely ignition system concern.

 

[FIND]

Sounds like a bad fuel pump relay. Try swapping it with another of your relays.

 

[jamesapost]

brand new parts= computer, fuel pump, and relay, battery, alternater, plugs, wires, and coil pack,
junk yard parts= mas airflow senser, and tpi senser, and ideal air controler, but all i did was use these junk yard parts for testing and i put my original parts back on the truck.
corect me if im wrong but is the crank position sensor on the harmonic balancer at the front, botem of the engien? could the moister be afecting this senser?

 

[FIND]

brand new parts= computer, fuel pump, and relay, battery, alternater, plugs, wires, and coil pack,
junk yard parts= mas airflow senser, and tpi senser, and ideal air controler, but all i did was use these junk yard parts for testing and i put my original parts back on the truck.
corect me if im wrong but is the crank position sensor on the harmonic balancer at the front, botem of the engien? could the moister be afecting this senser?

I did not realize you got a new fuel pump relay from your first post. I'm sorry, I am pretty drunk right now, otherwise I would give you some more, but maybe tomorrow.

 

[MrShorty]

CKP is certainly a possibility. I would expect a fault in the CKP to trigger a CM 211 or 212 or similar code, which you didn't report, so I don't think it is likely in this case. PCM waits to see the PIP/TACH signal (generated by the CKP) before it decides to close the fuel pump relay. If the fuel pump is running while you are trying to start it, I would expect the CKP is fine.

 

[jamesapost]

i dont know what any of the abbreviations you used, (CKP) (CM) (PIP?TACH) pleas explane what this is to help me understand. thank you for all your help everyone.

 

[MrShorty]

sorry

CKP=CranKshaft Position sensor
PCM=Powertrain Control Module (aka, "the computer")
PIP=Profile Ignition Pickup -- A signal generated by the CKP (a basic Hall effect sensor) and Ignition Control Module (ICM) that tells the computer how fast the engine is turning and "where" TDC (Top Dead Center #1) is.
TACH=TACHometer signal - tells the computer how fast the engine is spinning.
CM=Continuous Memory - see my notes on pulling EEC-IV codes for a description of the types of codes the computer outputs.

 

[huntman58]

Even with a new relay I would still swap them around just to check. Do not know about you but threw the years I have gotten a few bad new parts mostly the electrical ones. Any hoot that’s what I would do as its free fast and easy just to make sure.

 

[jamesapost]

im going to try to get a CKP on Monday or Tuesday and put it on but i wont know if this fixes it till it rains hard again.

 

[zoeysdad]

My 98 Ranger, acts like battery is dead, 1yr old battery, tested Alternator, sometimes it needs a jump, but today, i gave it a moment turned on the headlights and she fired up. Had some corrossion earlier on battery cable terminals. Could those need replaced? noticed more an issue when wet.