Gman422

Hello fellow F150 owners! First I want to say thank you for letting me join the forum! I'm looking for a little help with my '91 F150 5.0 2wd.

The truck starts and runs ok, but will occasionally stall or bog when accelerating. I have 2 codes. This is the EEC code reader that displays 2-digit check engine codes.

Code 51 for a coolant issue- I installed a new coolant temp sensor because it wasn't showing any reading on the dash. Now it reads but seems low.

Code 22 for the MAP sensor. I replaced the map sensor with a new unit. I pulled the black vacuum line and it has strong suction.

I have also replaced other parts including the TPS, air idle control valve.

I purchased the truck not running, so I'm slowly bringing her back to life, but I can't seem to get the stalling issue figured out.

Any and all help is appreciated. Thank you!

Steve83

Codes do NOT mean to replace parts. Don't pick a word or part name out of a code definition - read, understand, & post the COMPLETE definition for each code number. Code readers for EEC-IV vehicles are notoriously UNreliable - you should learn to read codes with a jumper wire because it will never lie to you. Click this & read the whole caption:


(phone app link)

The ECT which the EEC monitors has nothing to do with the temperature gauge, which is driven by the temperature sender.


(phone app link)

You should put the original parts back on - they're generally MUCH more reliable than any new replacement parts. When you replace a part, post the brand, PN, source, and the reason you changed it (the diagnosis that led to its replacement, and the test that it failed). Make sure the replacement part passes the same test the original failed.

For us to help, we need to know EVERYTHING about the truck, and we need to see it each time we read your posts, so put it all into your signature so you don't have to retype it, and we don't have to look back through your posts:


(phone app link)

If you don't already have one, get a Haynes manual as this caption describes:


(phone app link)

When you have one, read it.

You should also put a fuel pressure gauge on it so you can see it while driving (but don't let it distract you):


(phone app link)

Gman422

Thanks for the reply, Steve83.

Code 22 says: orc Manifold Absolute Pressure (MAP) sensor out of Self-Test range.

Code 51 says: oc ECT indicated -40�C (-40�F)/circuit open

I did do the test with the jumper wire as you mentioned.

I included the vehicle sticker as well.
I'll work on getting the Haynes manual and fuel pressuee gauge. Any other help or suggestions is appreciated.

Steve83

I suggest you decode that label, and collect all the truck's OTHER details, and put it all into your signature. A photo of the label isn't necessary.