Emission Test
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Emission Test
I have a 84 F-150 with the 300 six and a single barrel Carter carburetor. I am having trouble getting the emissions to pass. That is, the hydrocarbons almost fail and CO is twice as high as allowed. I have already done all the easy fixes. New filters, plugs etc... These attempts lowered the CO but not enough for Utah. Does anyone know a site for advise on the carburetor? Any other ideas about getting the CO down?
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Emission Test
Utah tests at two speeds 15 mph and 25 mph:
I will just give you the 25 mph testing. 15 mph only done with first attempt
Originally the following results were recorded. That is, prior to any attempts at replacement of parts etc.
Hydrocarbons - 192 (limit 320)
CO - 6.37 (limit 2.5)
NOx 367 (limit 2200)
After replacing air filter etc and regapping the plugs
Hydrocarbons - 206
CO - 4.62
NOx - 557
Note that this motor has points installed instead of electronic ignition.
I will just give you the 25 mph testing. 15 mph only done with first attempt
Originally the following results were recorded. That is, prior to any attempts at replacement of parts etc.
Hydrocarbons - 192 (limit 320)
CO - 6.37 (limit 2.5)
NOx 367 (limit 2200)
After replacing air filter etc and regapping the plugs
Hydrocarbons - 206
CO - 4.62
NOx - 557
Note that this motor has points installed instead of electronic ignition.
Hotshot
Joined: Oct 2002
Posts: 18,488
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From: The Big, Oregon
Emission Test
It looks like the truck is running rich. How does it run temperaturewise? Make sure that the engine is coming up to full operating temperature before it gets tested, and that the thermostat is functioning correctly. Also make sure the choke opens all the way. The truck should have a catlytic converter on it as well- if that's not working or gone, that should be replaced.
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Emission Test
The truck runs at normal temperature. That is, during a recent road trip ran at middle guage in 90+ outside temperature at highway speeds. The converter is still in place how can you tell if the converter is still functioning? Also how can I tell if the choke is full open?
Posting Guru
Joined: Dec 2002
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From: peoria, az
Emission Test
What kind of readings are these? Are they PPM or GPM or something else? Just wondering because the NOX seems high. Especially a 2200 limit, uor limits are only like 400 but that'sGPM in which case I would look at the EGR.
That sure is dumping a lot of fuel in there at a cruise though. I would say it looks like time to rebuild that carb. Did you pass the "idle test"?
That sure is dumping a lot of fuel in there at a cruise though. I would say it looks like time to rebuild that carb. Did you pass the "idle test"?
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Emission Test
Utah does not have an idle test. The tests are conducted at 15 mph and 25 mph. The units for NOx and hydrocarbons are in ppm. All other test units are %. I would concur about rebuilding the carburetor. I do not have access to a shop manual; is there another source for a detailed description of maintenance on a Carter carburetor? Just found out that this vehicle at one time was using LPG for fuel. Since I inherited the thing and where it use to be driven did not require emissions could the problem be an incompelte switch back to gas?
Last edited by tshaw; Sep 15, 2003 at 11:44 AM.
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