1991 3F-E De-Smog Performed

spdwaver

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Key words: 3f-e desmog 1991 desmog 1992 desmog bypass smog pump bypass belt part number desmog using bb's bb's in vacuum lines

I followed JollyGreen's thread de-smog procedure in placing BB's in the vacuum lines, and re-routing of the two lines closest to the cab. As far as I can tell, I followed JollyGreen's method without deviating.

In this thread, I am going to go in a little more detail through illustrations for those who need every visual detail. The following text was taken from JollyGreen's thread, for reference.

"I just put BB's into the vac lines on all the EGR stuff and put the air pump bypass belt on it to test an idle problem I was having and my 80 idles 10 times better now. I obviously have a vacuum leak somewhere. I will find it and plan on putting the smog stuff back.

The unexpected side effect was I went from 10.8 MPG on my first 2 tanks to 15.3 MPG verified on 2 tanks just from doing this alone!

I didn't notice much of a power change but there is a huge increase in torque.

All of the egr vacuum lines over on the drivers side of the motor, I put BB's in the line to block it off and put a shorter belt than normally goes to the smog pump so it bypassed the smog pump "by not having a belt on it. Gates TR22525 replacement belt."


First and second image:

Blue lines - These lines represent those packed with a BB on one end.
Green lines - These lines represent re-routing (looped).

Third image:

BB is placed into the line (blue). Also note the detail on the vacuum line retaining clips, showing which lines are blocked and which are re-routed (looped).
bb_schematic.jpg
bb_reroute.jpg
bb_inside.jpg
 
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spdwaver

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Now I will illustrate the layout of the new belt, along with the method used to remove the old belt and replace with the shorter belt.

Smog Pump Bypass:

First image:

I used item number 22525 from NAPA.

Second image:

Using a 14MM box wrench, loosen the nut on the adjustment slot and on the stationary side (both marked yellow). Once loose, push down on the power steering pump to make some slack in the belt.

While pressing down on the power steering pump, remove the belt from the pullies.


Third image:

To remove the belt from the vehicle, I pulled the belt from in front of the fan, between the fan and radiator; it is kind of tricky, but a simple task with a clutch fan. :banana:
napa_22525.jpg
bb_psbolts.jpg
bb_fan.jpg
 

spdwaver

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Any gains??

The only gain I have noticed so far would be the smoothness, and the fact that I can accelerate - up hill.

It really does run much smoother during idle and while driving, which tells me that the 71 code I was throwing has been temporarily resolved.
 

spdwaver

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Great write up spdwaver, Hoping you find your MPG's up. My 92 would love to see more mpg's.

I am hoping that mileage will get better, but I say specifically how this mod will play a part in that.
 

spdwaver

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Time to put the 35's back on :D

Funny you should say that, because I was thinking the same. Only this time, I would rather go skinnier on the tires.
 

spdwaver

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I wanted to add one more detail:

To tighten the new belt once it has been put into place, use a bar (or crow bar like I used), and place it as a leverage point on the AC pump, as shown in the image below.
IMG_0207.jpg
 
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wow.....the BB procedure seems a little complicated when you can simply disable the system by finding the source of the vacuum used for the system..which happens to be the 2 small ports on the top of the TB. Just pull off these lines, cap them off and your done...no more vacuum available to open the egr valve.
The system gets its relatively low vacuum from these 2 ports.

Just trace back the 2 lines from the modulator that are heading away from the egr valve and you will find that they trace back to the 2 ports on the TB.

I am sure the BB method will work but I think my method is just a little more simple and cuts the vacuum off at the source. Then all the vacuum line are simply there as decoration and can be left or removed it doesn't matter.
 

Fergie

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wow.....the BB procedure seems a little complicated when you can simply disable the system by finding the source of the vacuum used for the system..which happens to be the 2 small ports on the top of the TB. Just pull off these lines, cap them off and your done...no more vacuum available to open the egr valve.
The system gets its relatively low vacuum from these 2 ports.

Just trace back the 2 lines from the modulator that are heading away from the egr valve and you will find that they trace back to the 2 ports on the TB.

I am sure the BB method will work but I think my method is just a little more simple and cuts the vacuum off at the source. Then all the vacuum line are simply there as decoration and can be left or removed it doesn't matter.

What about the smog pump then? Belt is still on and turning it...no?
 

Lka1988

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wow.....the BB procedure seems a little complicated when you can simply disable the system by finding the source of the vacuum used for the system..which happens to be the 2 small ports on the top of the TB. Just pull off these lines, cap them off and your done...no more vacuum available to open the egr valve.
The system gets its relatively low vacuum from these 2 ports.

Just trace back the 2 lines from the modulator that are heading away from the egr valve and you will find that they trace back to the 2 ports on the TB.

I am sure the BB method will work but I think my method is just a little more simple and cuts the vacuum off at the source. Then all the vacuum line are simply there as decoration and can be left or removed it doesn't matter.

For those of us who live in an emissions-controlled area, the BB method is more stealthy. And you only change out the belt for the longer one once a year. :D
 

spdwaver

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For those of us who live in an emissions-controlled area, the BB method is more stealthy. And you only change out the belt for the longer one once a year. :D

Has anyone smogged their 3F-E after performing this mod (taking into account that the old belt is put back on the smog pump)?

I would be interested in knowing just how temporary this might be.
 
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What about the smog pump then? Belt is still on and turning it...no?

smog pump is another system......I was just refering to the EGR disable method only.

For those of us who live in an emissions-controlled area, the BB method is more stealthy. And you only change out the belt for the longer one once a year. :D

In Vancouver we have to pass a 4 minute dyno test under load where they bring the truck up to 90 KPH.....if your truck isn't in top shape emissions wise .. you ain't passing. This is how I got to know my egr system inside and out....(long story)

I left everything in place for the 2 year testing...I just have to hook back up the 2 lines to the TB....10 seconds..done.

I was just sharing another option thats all.
 
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Couldn't help myself, Had to do it. Of course telling the wife she may get better MPG's and more power was a plus. Anyway, truck seems to idle better and run better as it does on cooler days. I'll keep track of MPG's and report back.
Belt was about 20 bucks and fits perfectly . Thanks Jollygreen and Spdwaver for their write-ups.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
It's been 2 1/2 years and no change in fuel mileage. Truck idles extremely smooth since this modification and seems to run better in the hot summer months. No EGR=True cold air induction.
 
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spdwaver

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I guess that the next step will be to document our collective mileage to see if there is any real savings from this mod alone.
 

Eicca

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Just To clarify, are there any BBs in either of the green lines?
 

spdwaver

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Just To clarify, are there any BBs in either of the green lines?

I am glad that you asked; there are BBs in the line, which I questioned only afterward. I placed the BBs in the lines as per your illustration (area circled in red), the last step I did was to loop the lines.

Should I remove those BBs in the looped sections?
 

spdwaver

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The looped section on the motor is the only one that needs to be looped.
It should not have a BB in it.

If that is the only section to be looped, then what is done with the ends that are no longer connected? This is where I was unsure from your instructions, so I went ahead and looped the side opposite the motor (thus keeping the vacuum line in place for future replacement).

I will remove the BB immediately, and thanks for pointing that out. :cheers:
 

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