99 civic d16y8 obd1 conversion. Last two times I filled up I was near empty, put in close to 11 gallons, and the car started but it ran really rough. Had to keep feathering it, and it was blowing out a lot of black smoke. After like a minute it went away until the next time I filled up.

Seems like common sense to not fill it up all the way for now. I assume it's a problem with the evap system / canister...possibly raw gas getting in there or something. I converted to obd1 and some of that stuff is probably not working properly anymore.

I was thinking about removing the purge solenoid (or whole evap system for that matter) because I dont think the obd1 ECU is controlling it, so gas is just accumulating in the canister under the hood. Or I might just remove it all... what do you think?

 

Possible problem with the EVAP valve inside the tank.

 

There's a couple write-ups on the bypass for it...it's pretty simple...and you're probably right...I doubt it's working with the obd1 conversion. It's all good though...it will clean up the bay a good bit though. EVAP canister is a pretty big piece. I'm in for answers on this though because I'm about to convert to obd1 on my y8 and plan on bypassing evap.

 

RonJ - Is this operated by the ECU? Coincidence it started right after converting to obd1?

Twofaced - Do you have a link to the writeup for the proper bypass?

Side note, the motor is turbo, but all factory vacuum lines and everything are unmodified. Thanks guys.

 

The purge valve in the engine bay is controlled by the OBD1 ECU, which uses coolant temp as the only input.

In contrast, the EVAP ORVR valve on the tank and the two-way valve are controlled by fuel tank pressure.

I'm thinking that you are overfilling the gas tank (possibly due to ORVR system problem), and this is allowing liquid gas to be sucked directly into the canister.

 

https://honda-tech.com/forums/acura-integra-type-r-8/how-evap-removal-step-step-pics-info-769705/

 

IIRC, the purge valve for obd1 is only functioned just after starting the car, and in obd2 it cycles at different times / driving conditions. Therefore, I may have already had a problem with the ORVR valve but didn't notice. Now that I have obd1, all the fuel that dumped into the canister after filling up is dumping into the motor via vacuum line on the purge solenoid just after start up.