My air pump locked up. So I removed the pully and installed a shorter belt. Truck is back up and running. But what effects, both long term and short term, can I expect from doing this? Will I get increased horsepower? will the air pump get clogged? Several people suggested removing the air pump and using a shorter belt, but is removing the pully enough or do I have to remove the air pump and couple the air hoses together? I'm really a novice at the auto repair so any advise would def. be useful. thanks!

 

Been there.. got the T-shirt.

OK. what will happen? The truck will start to run lean, loose power, ping and hesitate under any load at all, and generally make you unhappy.
Why? Because the ECU is calibrated to see the air from that air pump at the O2 sensor under normal operating conditions. When that air supply is removed from the picture, the O2 reads a righ mixture and cuts back the injectors to compensate.
There are either 1 or 2 vacuum actuated Thermactor valves on the truck, depending on year. If you bypass these and put all the air from the pump into the heads, the motor runs really rich. So there is always some air that bypasses the heads and is vented to atmosphere or routed to the cats.
Run it for a while and look at your plugs, they will tell the story.

 

I knew something not good would be a result of removing that pully... it was too easy.

So, What are my options to fix the problem, do I have to replace the air pump, or is there another easier/cheeper way to bypass it with out hurting the truck (and maybe increase it's power). I'm going to try it out for a bit and, like you said, and check the plugs. But after that I'm not sure what to do. Guess this is where i need to toss my haynes and get a chiltons....

'92 F-250 XLT 5.8 4X4

 

Do either of you have the 2 air lines going to the large bulbuous cat? I need to know which one is in the front of the cat, and which one is at the middle. I put a custom SS system from the heads to the tailpipe, True duals with 2 cats, but in moving from another house the stock air tubes got thrown away, and it is tough to figure out from the diagrams in the ford shop manual which one goes where.
I'd be very grateful for any help in this,

Thanks,
Bob

 

Oh, and Giant, toss 'em all and go to helminc.com and get the real shop manuals. My bud was up at the parts place years ago, trying to get some part or other, and either it didn't exist, or some other prob. The counterman said "obviously you are looking at a Chiltons' manual." That has been a catch phrase with us ever since.

 

The air lines going to the cats ar not "entirely" necessary for good operation. The valves route air to the cat/cats at cold startup to help emissions, but once up to operating temp it's switched to the heads. I did not reconnect the cat air lines on my '90 after installing a complete custom exhaust, and the truck has run fine for 6 years and easily passes emissions tests.
BiggreenGiant.. I think you'll have to replace the air pump.. you will actually loose power and performance without it. The single best way to get more from the Windsor truck engines is to replace the cam. The stock bump sticks are really holding back the motor. And don't wory about the computer. The speed density 5.0 mustangs have no problem with a cam much more agressive than that found in the trucks. You are limited in valve lift to under .500" I believe due to the flat top pistons and no valve reliefs, but an RV grind works very well, like what was found in the carbed 351HO motor from 1980 and up.

 

Thanks for the info, I'm planning on pulling out the air pump and replacing it tomorrow. Are there any fluids I need to worry about when pulling this thing off?

 

Thanks, Conanski. Good info. I have the cats with the inlet tubes bought already, so I think I will hook them up. I didn't get the emission shop manual, I see now why: it's over $300 on helm. So, still, if anyone has the info on which pipe is which I would appreciate it.
I think I will start a thread with this question, then maybe I will have more chance of getting it answered.

Thanx!

Bob

 

What year is the truck? Both of my F150s had a single air supply to the stock cat so I can't say I have ever seen what you describe.

 

It is a '93 F250HD, over 8500lb.
There is a giant sized cat right in the middle of the truck, sticking down enough that I was always worried to take it off road for fear it would get ripped right off. I couldn't believe that they designed an exhaust system for a 4x4 that had something like that. There are 2 lines coming to it, one in the front of the cat, and one at the middle. I had never seen anything like that monstrosity either.
When I made the custom system, I had to go with 2 seperate cats, they are aftermarket with 1 tube on each. I plan to put split lines to the front end of the cat, and also to the air input tubes at the middle of the cats. Should look interesting. And, I managed to tuck them up in there to avoid the ground clearance problem if I do happen to go off road.
The system is shown in my Ford shop manual, but not how it hooks up. the tubing just goes forward, and that is all they have in the pictures.
I have the vacuum diagrams, and they refer to something about air pump line 'A" and "B". I might just go with logic and assume "A" would be the front one and "B" the middle. But, who knows??

 

Surely there's a way to trick the computer into knowing that there is never any air injection going on and keep it from doing the things described above?

 

Sounds like there are 2 seperate feeds for the cat then. Do these come from seperate control valves fed from the air pump? Or is there simply a Y up behind the engine somewhere? ( I doubt it but gotta ask). If there are seperate control valves, are they controlled from the same solenoid or seperate ones? Obviously if they have comon control.. it won't matter which one you connect where. You would also have the option of eliminating one line and simplifying the plumbing mess.

 

I think a programmable computer or piggyback module are the only ways to do that. Replacing the air pump is certainly cheaper.

 

Removing the AIR system will not cause the engine to run lean, nor rich. The computer sends air to the heads when the engine is cold to help light off the first cat faster. It then diverts the air to the downstream cat once the engine is warm (controlled by the TAD solenoid), and in some instances, it just dumps the air to the atmosphere without injecting any into the exhaust at all (TAB solenoid). The computer may monitor the O2 sensor in self-test mode to see that the thermactor system is working, but it does not look for a lean mixture while driving.

The injection line to the cylinder heads on my truck is disconnected (rusted out check valve) and my truck runs just the same as it did when the line was connected. I can hear (and feel) the air from the air pump when the engine is cold, and it does go away once the engine is warm.

You can fool the computer into thinking that the TAD and TAB solenoids are still in place by wiring a resistor in place of the solenoids. This has been discussed in the past, but I can't recall what size resistor to use.

 

Yeah, that's where the "A" and "B" come in. It's partially shown on the vacuum diagram, addressing the solenoids that control each one. So they do activate at different times.