Well you may remember my 2004 fx4 repair last month that I posted on this site.
I helped a friend out replacing plugs and boots, cleaning TB, new front brakes everything and several front end components. When I was done that truck ran bad ***. I just got a call tonight that the truck barely runs. So I headed over to look at it in the pouring rain thinking a vacuum line was off. No such luck. I could not find anything apparent during my inspection.
Here is whats going on
Check engine light on
ABS light on
brake pedal feels like manual brakes meaning you have to stand on them to get her to stop
VERY rough idle and stalls when coming to a stop.
Smooths out at 3000 RPM


Here is the original post of repairs last month. GeeeeWhiz
https://www.ford-trucks.com/forums/1...r-my-head.html



Now I did what I could do with a flashlight and raincoat...LOL
I told her not to drive it for now and I would come back during the day with tools.
Any ideas where to start? I know I know....What kinda question is that?
It seems like a vacuum leak but I have done no diagnostic work other than an under the hood visual inspection.


My big fear is that now I am married to this truck...I just wanted to help her out LOL

 

Big vacuum leak.

 

sure sounds like it. what did you check last night on the system? just visual inspection?

 

With the pouring rain I only did a visual to make sure no vacuum lines came off from my previous work. I plan on starting out with reading the code stored in the pcm and remove and inspect vacuum line from break booster. I would think it would be something simplistic but Im no mechanic so I will muddle my way thru it. The day before it ran great. No abs light and no check engine light and no rough idle. BIG vacuum leak is right guys LOL Maybe the booster diaphragm? I will update this thread to completion as I always do....

 

Here's my wild and crazy guess. Her FDM finally died from all the water. Check that out as soon as you have a chance.

 

Well I'm guessing that's front wheel drive module? We have had crazy amounts of water w rain and melting snow and iced up storm sewers. I will google it. Interesting. Thanks so much guy.

 

Lol ok I said I'm not a mechanic. Fuel delivery module located on the drivers side rear axle. Nice. Can I go with a Dorman replacement or should I go w oem if this is found to be bad?

 

The Dorman has the stand offs(to prevent corrosion) and should be fine. Rain may be the big clue here. Check for a third brake light leak, water can make it into the electrical connections and cause problems. Check ground straps and battery. That's all I got. Hope its something easy.

 

Maybe the fuel but almost certainly a vacuum leak - maybe a hard old brake booster vacuum line broke.

 

I'm not a mechanic but a tinker is for sure.

someone said the Dorman brand is fine, I like the idea it has its own standoffs and that is good.

Good luck and my fingers are crossed for you.

 

We usually call it the Fuel Pump Driver Module but you are not having the symptoms for it. It causes failure to start and can be intermittent. Once the engine starts everything is normal until it dies. However, if the aluminum base is heavily corroded, you may as well replace it.

 

I agree with 1saxman. Your symptoms are classic vacuum leak, not FPDM.

 

Well they are out of town so the truck is locked up. Guess Im on hold till I can get a look at her Saturday. I will update then. Ive never been someones personal mechanic...LOL

 

Codes are po171 and po 174. The vac line going to the break booster has no vacuum. It turns to metal and goes behind the engine. Anyone know where it goes?

 

Well I suspect the brake booster line has come off the intake port nipple. I sprayed carb cleaner back there and the motor raced. I read you have to lower engine or raise cab. Lol are they kidding. I could not see it from below or above. Here I thought it was downhill from here after the spark plug feasco. Any tips or tricks for this repair guys? Thanks