I recently replaced the timing chain on my 87 d-150 318. This included removal of the smog pump that hadn't worked in years. The truck seems to stumble during accelaration and idles worse than before. I put caps on the hard lines that run from the exhaust manifolds. I have since replaced the computer, carburetor, plugs, wires, cap and rotor chasing this problem. The motor is in time. I'm pretty sure I have no vacuum leaks. I'm quickly running out of money, any advice would be greatly appreciated.

 

First I must mention it is ILLEGAL to remove or render inoperative an emission control component...

suggestions:
get an eng vacuum gauge -post vacuum reading.. ck for vac leaks -spray carb or brake clean at suspected leak areas, an rpm change would indicate a leak- carb base gskt, vac lines, manifold, if applicable ck EGR be sure it seats ... ign wires are routed correctly (crossfire) ...eng is reaching correct temp?...carb adjustments?...

 

* in certain states

 

Twitchr: how does this help bpcarman with the issue?
anyway a common laymans mistake, many are unaware of. Not fixing AIR and removing AIR are different issues. wink wink


Sec. 203. (a) -
(3)(A) for any person to remove or render inoperative any
device or element of design installed on or in a motor
vehicle or motor vehicle engine in compliance with regula-
tions under this title prior to its sale and delivery to the
ultimate purchaser, or for any person knowingly to remove or
render inoperative any such device or element of design
after such sale and delivery to the ultimate purchaser; or
Sec. 203. (a) -
http://www.epa.gov/air/caa/caa203.txt

 

I believe if you check it is against federal law to tamper with or remove emission controls.

 

Twitchr"s comment seems to be a common misconception that appears to be routed in weather a state actively enforces the federal emissions laws. Make no mistake about it removing or disabling emissions equipment is illegal even if it is overlooked in some states.

 

for those who don't really give a $hit about about the legality.... back to the question.

is it possible that you have a vac leak or other problem unrelated to your smog pump removal. smog pump injects air into the exhaust for emissions reduction, and should have no real impact on how the engine runs. here's the first couple of links that came up on a search...

i'd start by labeling, and then temporarily capping off every vac line from the carb/tb and intake and taking a short road/driveway test to see if you get any improvement. if so - continue to test each vac line. if not - then its not vac related, so move on. one of the vac lines might prevent the transmission from shifting, so let that be the first one you add back.

a buddy of mine has an 87'ish dodge. we capped off a couple of useless vac leaks on his and it ran good for another 10 years. we used the procedure above. start by capping them all and find that it runs good. add them back one at a time until you find one that adversely affects the way it runs. then either leave it capped or fix it. beware you may find multiple leaks.

http://www.smogtips.com/air.cfm
http://www.thirdgen.org/techboard/te...smog-pump.html

 

First off, thanks for all the legal advice. I live in Alabama, emissions tests here are kinda like 7up and caffeine, never had it, never will. That being said, I can put my hand over the throat of the carburetor and the engine dies, quickly. This leads me away from the vacuum leak theory which was btw, my first guess and may still be the problem. I will try the vacuum line test and post the results. I hope that's my problem, as vacuum hose is way cheaper than everything else I've spent. Thanks for all the advice.

 

deleting the smog pump wont cause that issue (as long as the vacuum lines were plugged). the only thing i can think of is it messes with the o2 sensor but i didnt have that problem.

i just wanted to ad that i remain emissions complaint because i have to take my truck into a shop and have it checked every two years in order to have plates on it. im forced to worry about being street legal (which i why i only removed the belt of my pump so i can put it back on come e-test date)

 

does it go to sorta want to stall when you step on the gas? did you do the timing youself?