NorCalJeep

Just got a Comanche on CL and didn't pass smog. What do you know? Was wondering where i should start. I seaformed out the throttle body, cleaned IAC, and put new vacuum harness.

87 I6
It was 2wd but converted to 4x4 and swapped an ax15

cruiser54

My Tips 1 through 5. And maybe 27.

New NGK plugs, wires and cap and rotor with brass terminals.

A can of BG44K in a full tank of gas. Run down to 1/3 tank. Fill with gas. Run down to 1/4 tank before refilling.

A set of Volvo 746 injectors wouldn't hurt either. Contact Programbo here on CF to get a set.

Bugout4x4

Volvo 746 injectors? Do they squirt leaner? After what I have observed with my plugs on this 97 I am curious if it could even stand running any leaner? lol.

Do some run richer than others? if so, this a great reference!

NorCalJeep

Thanks cruiser. I'll order some stuff today and do your steps.

cruiser54

It doesn't work that way....

The 746 Volvo injectors have 4 squirters versus one squirter like the stock ones. Better atomization of fuel.

cruiser54

Great plan.

NorCalJeep

Oh, what is the fuel evap that it failed on

cruiser54

Rotted hoses at the evap cannister?

Bugout4x4

Thank you for explaining this difference, I learned something here and it makes good sense now. Appreciate it!

Metmknice

How much fuel did you have in your tank? I've had, and also seen others, that had less than 1/4 tank fail evap.

An alternative to BG44, is the Amsoil Performance Improver. Cheaper and works good.

NorCalJeep

Yah, i only had about 1/4 on gas at the time

Bugout4x4

After some thought about your issue here I have to suggest something to check. If you know for sure you have no vacuum leaks at the front like Lines or Canister you might want to check the rear. Maybe a leaky line on the way to the Tank or where it connects to the Tank, A leaky "Roll over Valve" or Grommet, A leak at the Vent or Fill Hose or even just a bad Fuel Cap.

I can't count how many Check Engine Lights I have put out by tightening or replacing the Fuel Cap. It could be just enough of a leak to show up on the Emissions Equipment but not enough to trip the Engine light.

cruiser54

He has no CEL anyway as it's a Renix, but going over all those vent lines and tightening the cap are great ideas. Hence, my original suggestion about the hoses near the evap cannister. They're always porous and mushy.

Bugout4x4

Absolutely, You are on track with the fact that EVAP issues are almost always a Vacuum leak. Of course I meant CEL in General not being Vehicle specific with this very common problem. I have to remind myself quite often that there are two ends of every Vehicle when there is an EVAP issue

Thanks for pointing out the Renix system! (Still learning about these.)