1991 FJ80 Just Failed Smog. No CEL

Joined
Jan 4, 2021
Messages
7
Location
Durham
Hi everyone, first post here. Trying to keep our trusty old FJ80 alive. We've put in some work trying to make her reasonably reliable again. I feel like we're close!

I'm running out of good info sources for the little gremlins that keep popping up, hoping someone out there might have good knowledge on how to smooth out a few issues. 235k mi great compression, 0 ring ridge. (may have been rebuilt)

Other than intermittently turning over and not starting for mysterious reasons, It now runs a little rough at idle, sniffs dirty (barely) at 3000 rpm and has no CEL when key is on run (not started). This caused it to fail smog today. It passed a year ago.
Also has no tachometer function.

Has rebuilt cylinder head,
new injectors,
distributor,
fuel pump,
alternator,
plugs,
wires,
radiator,
igniter, (suspect)
fuel relay, (also suspect) ((Think I need a higher amperage unit))
new CARB catalytic converters

Runs a little rough at idle, sniffs dirty (barely) at 3000 rpm and has no CEL when key is on run (not started).
Also has no tachometer function.

Any advice is greatly appreciated.
 

ppc

M Go Blue
Joined
Aug 18, 2003
Messages
3,883
Location
Nashville, TN
If the vehicle does run and the CEL is not illuminated before starting with the key in the run position the most likely that bulb is burnt out.

With rough running at idle a vacuum leak is the most likely issue. Make sure the large intake hose is not cracked on the underside allowing unmetered air into the engine.

Intermittent starting could be failing fusible links. Cheap to replace and should be done as regular maintenance

Do not mess with the screws on airflow meter attached to the air cleaner or you will want to slit your wrists.
 
Last edited:
Joined
Mar 14, 2008
Messages
1,244
There are a ton of issues that can cause your problems.

Sniffs dirty is pretty vague. Like, HC too high? CO too high? NOX too high? All of the above? They all have different root causes. Just because you put new parts on, doesn't mean they were good parts. The Quality Control here lately has left a lot to be desired on some parts. What's the condition of the engine oil? If it's contaminated with unburnt gasoline, from lots of short trips and sitting a lot, that will absolutely kill your attempts to smog.

If the oil is fresh and all the plugs and wires check out good, start with vacuum leaks and exhaust leaks. If you have either, things go astray pretty quick. There are tons of threads on here about passing smog. With a good tune, good compression and hot Cats, you shouldn't have too many problems with smogging it.
 
Joined
Jan 4, 2021
Messages
7
Location
Durham
If the vehicle does run and the CEL is not illuminated before starting with the key in the run position the most likely that bulb is burnt out.

With rough running at idle a vacuum leak is the most likely issue. Make sure the large intake hose is not cracked on the underside allowing unmetered air into the engine.

Intermittent starting could be failing fusible links. Cheap to replace and should be done as regular maintenance

Do not mess with the screws on airflow meter attached to the air cleaner or you will want to slit your wrists.
Intake hose was replaced about 10 years ago... I'll check it. I will also check the fusable link. A burned out check engine light bulb sounds very laborious to replace...hope it's relatively doable -- can't believe I'm failing an inspection because the CEL isn't coming on! Thanks!
 
Joined
Jan 4, 2021
Messages
7
Location
Durham
There are a ton of issues that can cause your problems.

Sniffs dirty is pretty vague. Like, HC too high? CO too high? NOX too high? All of the above? They all have different root causes. Just because you put new parts on, doesn't mean they were good parts. The Quality Control here lately has left a lot to be desired on some parts. What's the condition of the engine oil? If it's contaminated with unburnt gasoline, from lots of short trips and sitting a lot, that will absolutely kill your attempts to smog.

If the oil is fresh and all the plugs and wires check out good, start with vacuum leaks and exhaust leaks. If you have either, things go astray pretty quick. There are tons of threads on here about passing smog. With a good tune, good compression and hot Cats, you shouldn't have too many problems with smogging it.
Thanks for the reply. CO% Too high. It's 1.38 and allowable is 1.00. The ignitor is from a questionable source. Might be why the tach doesn't work??
I hear you. My trust is getting low with new parts and I can only trust the local mechanics so much.
Everything else I installed was at least OEM and/or the best quality I could find. Oil is clean, haven't checked the new plugs yet.

Thanks!
 
Joined
Mar 14, 2008
Messages
1,244
Even if the oil looks clean, smell it. If you can smell gas, it's gotta go, if you are fighting HC numbers. Sometimes, you can plug the PVC hose internally with a stick, so it can't pull the fuel vapors out of the crankcase and foul up your test, if they don't check to see if it's operational. Here, we just have a visual, you can get away with it. In adding air to get the HC to come down, I have found it usually makes the CO too high, so you could have a vacuum leak that is causing your CO level to be too high. If that is not it, check the temp on your CATS to see if they are getting hot. If the inlet temp is higher than the outlet, checked with a heat gun, your CATS aren't lighting off. They can be plugged, or not getting what they need mixture wise to get hot.
 
Joined
Jan 4, 2021
Messages
7
Location
Durham
Thanks for the insight.

I found and replaced a crusted up vacuum line and de-gunked the EFI throttle valve, things I thought my late mechanic would have taken care of..
It fires up way quicker stronger with no more misfire. Should pass now.
New oil for sure due to it running rough and dirty for a few trips to town.
The CEL check failure turned out to be a dead bulb.
Now just have to fix the tachometer, receive my plethora of new bulbs and try again.
California smog laws are a bit silly. :meh:
 
Joined
Sep 25, 2014
Messages
1,957
Location
Gilbert, AZ
If you do not pass again I would check the VAF with a volt meter and check the resistance of the VAF. The resistance (OHMs) will vary based off the temperature of the unit itself. How do I know, I tested two that I have (one room temp, the other heated from under hood temps) the resistance measured was different between the two, ambient temperature with effect the resistance too.

Also I would check out O2 sensors as well. Not sure what the FSM calls for on the earlier models but my 94 the FSM calls for 5-6.5 OHMs.
 
Joined
Nov 26, 2015
Messages
210
Location
San Diego, California
Hi, Does an antique truck still have to pass smog?
In California anything gasoline after 76 has to pass both sniffer and visual smog for the model + year of the engine, including a visual inspection.
The visual is to prevent engine swaps or smog mods unless you register the swap or mod with the state, and they give you a new sticker for the smog shop to do a visual based on the engine or mod you put in.

Late model cars a bit tricky, you don't have to get them sniffed until they're a certain age or something like that? I don't have any newish cars.
 

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