Vacuum leak found in ‘96 EB 5.0 Bronco

[goffprof]

My ‘96 EB Bronco recently began having problems with hard start, rough idle, and stalling only on startup. It triggered the Check Engine light and codes P0171 and P0174. I read several BroncoZone tech posts that helped me track down the cause to a vacuum leak in a white (plastic?) vacuum line to the “blend door actuator”. A section of the white vacuum line outside the plastic loom in the engine compartment had deteriorated and had a hole in it.

I cut the factory black tape off the plastic loom, cut out about a foot of the bad vacuum line section and rerouted the remainder back to the door actuator. That immediately fixed the hard start, rough idle problem. I’ll replace the complete vacuum line soon. I still have to clear the 2 codes with my Maxiscan MS310 OBDII scanner as there may be another issue. I’d appreciate any advice on possible other causes for having both the P0171 and P0174 (lean - Bank 1&2) codes.

Here are before and after photos of the white vacuum line leak problem and the temporary fix.

 

[johnnyreb]

Glad you found it. I found 2 on mine this morning.

 

[goffprof]

Glad you found it. I found 2 on mine this morning.

Where was the other leak in your Bronco? I’m also looking for 2 rubber 90-degree elbows for my replacement charcoal canister.

 

[johnnyreb]

Tet Green Sales out of Ohio. They have a huge inventory of New--old stock and used parts. Type in the address bar--GREEN SALES and watch the videos also. . They are fast and polite service --THEY HAVE PEOPLE ANSWERING THEIR PHONES---NONE OF THIS ROBOT CRAP.

 

[96XLT]

The white vacuum line only has vacuum when the HVAC is set to MAX AC and OFF. The white vacuum line runs through the firewall back to the HVAC controls. The vacuum motor on the HVAC in the second photo controls the recirculate/fresh air door. You should think about replacing all of your vacuum lines, rubber or silicone are what most people on the forums use. This post has vacuum diagrams that should help and this is a good vacuum line replacement post. Note: the lines that connect to the carbon canister must be fuel resistant as they s-u-c-k in fuel vapor from the gas tank. Good luck with the repairs!