OK guys, Bought me an older f150 for a working truck, 1991 4x4 5.8 automatic.. I have done a good bit of wrenching, but all on carb engines. Trying to do some of this myself because I really don't want to take a 3k truck to my mechanic and double what I have in the thing. So, got the brakes finished up this weekend along with the Neutral safety switch and that got my backups lights and trailer harness connector back working properly to disengage trailer brakes in reverse. Have a steering pump to tackle soon as it is leaking like crazy. However, one concern is that the right side of the engine runs hotter than the left. Also sounds like a exhaust leak on that side that I need to tackle. When I start looking at all these sensors and EGR things and vacuum things, I get lost quick. I had a wire just hanging loose too, What is this from? Would any of this cause my right side to run lean to run up the heat? The red and black wires in the picture were laying up against the vertical pipe and had melted to it also. Any feedback will be appreciated.

 

Those are not wires - they're vacuum lines. Refer to the vacuum map on the VECI label (usually on the air cleaner, or on the hood above the master cylinder) and replace them with color-matched ~3mmIDx9mmOD silicone. Read this page & follow the links on it:

(click this text)


Wires have Copper strands inside. To ID a wire, peel back the harness wrap to expose the original (clean) colors, and look them up on this & the NEXT several pages:

(click this text)


Before you spend any money on the PS pump, read this page:

(click this text)


You should put ALL the truck's details & history (as much as you know) into your signature so it shows with each post, as this page explains:

(click this text)


Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Put your location (nearest city) in your profile & upload an avatar of the truck. The more pics you post of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now.

 

 

If those OEM vacuum lines need replacing, you likely will not find replacements. I replaced all my plastic lines with standard rubber vacuum lines of the proper size. There's no need to replace them with color coded plastic.

 

Great info and videos Bean.

Steve, thanks for all the links and files. I went down the rabbit hole reading all that and was late heading to work today, but oh well. December is slow. I guess I will just pull old Rusty in the garage and start making a list. I also found some black soot stripes coming out of the manifolds that I need to deal with also. I sure hope that is the leak I am hearing. Or not. Might be easier to weld up a hole in the exhaust. Hopefully if. I. get all of this stuff back the way it is supposed to be I can feel the power that I feel like the 5.8 should have. A few decades ago I had an 85 Lariat with 5.0 and my memory is that it had a lot more power than this 5.8 seems to have. Of course it was not 30+ years old either.

Any other info you might want to share would be awesome. Thanks again for a great starting point.

 

Hey gents. Follow up info. I just pulled the codes and the following codes are what kicked out. Mass air flow sensor OOR, Intake air sensor temp OOR, EGR not operating, coolant temp sensor OOR. Each of these codes kicked out twice. I did disconnect the negative terminal this weekend when changing out the Neutral Safety switch. So, does that mean all of these codes. kicked just. sense I changed that out? Would all the broken and missing vacuum lines cause some of these?

By the way, I think these are the right codes. I found another chart online with different information. The codes that kicked out were 21, 26, 24, and 33.

thanks again. guys. I am trying to get a game plan in place for this weekend.

 

This one has only the codes that apply to these trucks, and the correct definition for each:

(click this text)


The NEXT 2 pages are printable. I recommend laminating them back-to-back and keeping it in the truck, or in the shop manual.

 

On ce again, thank you Steve. I went and ran the truck down the road to get everything up to operating temperature and ran the engine on test and it only kicked out codes 33 and 44 this time. Hopefully that will be more accurate. I will have to dig in to this EGR valve and AIR thing and figure them out. Hopefully just repairing those broken vacuum lines will make a difference.

 

33 is the EGR vacuum regulator and 44 is the Thermactor aka TAB & TAD solenoids...

Both share one common wire and thats wire #37/57 12v VPower referrence coming off of the EEC/fuelpump relay............Thats where I think your issues are.........

What is also shared by that 12v referrence circuit is the Idle air controller (IAC)motor............

If you have bad vacuum lines like I see I would replace them ....You can get new lines and ends from your local autoparts store...

On your header panel/core support youll find a couple ground wires...

Clean them good and replace then reset the ECU by pulling the battery and touchn both cables together then get in truck turn on headlights press brake pedal and turn ignition key for 30 seconds to a minute to completely drain the memory.




Good Luck

 

appreciate you Cam. Question. Since both the black and red vacuum lines are completely broken going into the coffee can, and the black goes to both the tab and tad, should I focus on vacuum lines first before chasing down the electrical or is this pretty much definitely electrical. I have new vacuum lines being delivered Tuesday and didn’t know if it would be worth just waiting to fix that first.

thanks