I have seen several videos that say you can by by-pass the smog pump by removing the pully and getting a shorter serpentine belt. If this is done, what would it do as far as the check engine light, etc? Would it effect the engine performance? (good or bad)
I have a check engine light and my mechanic said it was the smog pump and did not really mean anything so not to worry (famous last words)
Thanks

 

A code for why the engine light is lit is important.

Chances are, if it is smog related, the O2 sensor is probably indicating the fuel mixture is incorrect.

Could be the smog pump is not pushing air into the exhaust. Could be the motor is rich or lean. Could be a clogged catalytic converter.

So post up the codes and somebody can maybe provide better information.
As for full removal, no the check engine light will not go off because you've removed the emissions component. I'm not sure what "bypassing" the smog pump means, unless you simply mean "what belt do I use if I want to not include the smog pump". Which of course will not accomplish the goal of clearing the trouble code.
I don't know that it will 'affect' performance however it will not run correctly if the O2 sensor is continually telling the computer that the fuel metering is incorrect. The smog pump/air pump on the 90's vehicle was there to put air into the exhaust system so it didn't spit out as many noxious gasses polluting the air.


If you come back for addition help -please specify what you are working on.

The people would like to know the model year and engine as a bare minimum. I'm guessing you posted in the correct category (pre-1997) but that's not always a true assumption here on the forum.
Bonus info would be things like if you have stock exhaust or modified, still have a cat installed?
I guess at the end of the day, the smog pump may not even be the issue here.

 

Sounds like your mechanic doesn't know what he's talking about, or he's giving you a shorthand explanation. Read this page:

(click this text)


Deleting or disabling emissions controls makes a vehicle illegal to operate on public roads or lands, regardless of local inspections or enforcement. And just because it's not inspected or enforced today, that doesn't mean it won't be tomorrow. Maintenance is cheaper than repair, so try to keep everything working the way Ford designed it to.

 

Thanks to all the info. I checked on the cost of a new pump ($250.00 avg)...Not too sure I want to spend that much and then most likely pay as much for the labor. As soon as time allows I plan on hooking my OBD1 scanner up and check the codes myself and see what pops up! (Hopefully this week-end)
However to answer your question as to the vehicle, it is:
1991 Ford F-150 XLT Lariet
Std cab----Short WB
5.0 engine----True dual exhaust with cats
Auto trans
2WD

 

Put ALL the truck's details into your signature so they appear with each post, and we don't have to dig back looking for them.

(click this text)


There is no sensor on the air pump, so the air pump can't turn on the CEL. And when an air pump stops working, it STOPS. The pulley doesn't turn any more. So it burns the belt off in a few seconds. It doesn't sound like yours did that, so the pump is NOT likely ruined, and so, doesn't need to be replaced at any price. But a good used pump can be had for ~$20~50 at most junkyards, if you can't repair the original.

(click this text)


So AGAIN: figure out what's wrong first. Then decide how best to fix it. But butchering the truck and making it illegal to drive is NOT the best way.

 

I totally agree that removing anything the Ford engineers put on a vehicle is a no-no. That was not my intent when I originally ask about deleting the smog pump. I just wanted to see if anyone could shed a little light on the subject, And as always you guys came thru with flying colors. I had hoped to spend a little time on the old truck this week-end but as my Dad used to say" Life gets in the way of the best laid plans" and life got in the way again. I will try the scanner a little later and see if I can pin point the issue.
Thanks a million to all of you who have commented....It is appreciated

 

It can be done. IDK about the CEL though. I deleted the smog pump, EGR, and all the related bs from the passenger fender on my 92 notchback 5.0L. Prob the biggest mechanical thing to account for it the catalytic converter. The factory cats require the air pump... idk what would happen if the smog pump wasnt there. I would make sure you have pipes with no cats or high flow cats that dont require smog air. I ran my mustang without cats, but if I were to build one again and street drive it....I would def put catted pipes on there.

 

Looking for a smog pump for a 91 Ford f150 XLT lariat extended cab 4 wheel drive 5.8 l.