1991 Bronco 5.0 302 e4od.
Truck drives perfect in sunny dry weather but when it rains or moisture is in the air my truck shuts off while idling or driving. There is no consistent time when it happens. I drove it Saturday and Sunday with no problems and it rained Monday morning while I was driving and it stalls for a sec then shuts completely off. So what is getting wet guys? Thanks

 

The first thing I would check is to make sure to check that your distributor cap isn't cracked and is completely sealed. If moisture is getting inside your cap your engine could stall and won't want to start.

 

Ask the truck. Pull Codes (KOEO and KOER diagnostics tests). You could chase the possibilities for months and throw money and time at it for just as long. Anything that is enough to cause the engine to stall will trigger fault Codes.

 

I will pull codes as soon as I get time. I have a manual for the truck to show me how. I'm not replacing or changing any parts because the truck runs perfect until something gets wet. So I just need to find out what is actually getting wet. Distributor cap looks fine TFI module looks fine main brain on the firewall looks fine and all relays look good. So I'm very determined to figure this out. Thanks everyone for your help! I'm a real true ford person

 

When it dies how soon after can you restart it? Does it die over and over again?

 

Hey there, so I've got another question for you. Have you checked out the area where the Inertia Switch is located? If that little sucker gets wet it will short out and cause it to die. I had an 88 ranger once that had coolant leaking on it, I threw time and money at it before discovering the wet carpet and putting the puzzle together. If the area around it gets wet when it rains maybe you've got a leak from a rust hole or something and it's shorting? Food for thought.

 

I have checked the area of the inertia switch. It's located between the emergency brake and the foot brake. I have noticed the door seal molding and the carpet at the door seal is wet. The water is coming in through the alignment holes for the black door seal as they have rusted out bigger holes! My truck isn't perfect but I love to drive it. Thanks I will double check that area

 

ok guys! I tested KOEO codes cause i dont have a meter at the moment for KOER codes. SO....
codes:
327=DPFE circuit voltage below 0.2v
565= canister purge circuit fail

what do these mean? Thanks for all the help

 

Code 327 - EVP voltage low (The Bronco uses an EVP (EGR Valve Position) sensor not a DPFE (Digital Pressure Feedback EGR) sensor but the same Code is triggered for this low voltage fault for both sensor types). If received during the KOEO test indicates that the voltage returned to the ECM (computer) from the EVP sensor was below expected voltage sometime during the last 40 operations of the engine.

Troubleshooting involves making certain that the EGR valve is indeed actually moving when vacuum is applied. If you have a vacuum pump, you can apply a minimum of 14 Hg vacuum to the EGR valve at the hose barb and then release it quickly. Listen carefully and you should be able to hear the EGR valve snap shut when the vacuum is released. If not, apply vacuum again and release it quickly. A few times like this and a stuck EGR valve should free itself. In the event the EGR valve does not move in this manner, consider replacing it. If the valve does free itself or is not stuck, run a KOER test and verify that Code 327 is still present. If so, replace the EVP sensor mounted to the top of the EGR valve. If not, check the wiring harness between the EVP sensor and the ECM along with the vacuum supply line from the EVR to the EGR valve.

Code 565 - Indicates the the CANP (Canister Purge) solenoid circuit has failed. This is either a result of the purge solenoid failing or a break in the wiring between the purge solenoid and the ECM. If you want to test the solenoid itself, you can take a resistance reading between the terminals. A functioning solenoid will have a resistance reading between 40 and 90 ohms. If the reading is NOT within this rang, replace the solenoid. The solenoid is located near the charcoal canister and has two vacuum lines and one electrical connector running to it.