So, story in short: I purchased an OBD1 ECU w/crome chip from the great guys at rywire.com. I was running great for a week and then went to fill up the tank. When I went to start the car, the rpms stumbled and wouldn't start. After repeat attempts with the same problem, I swapped in the stock ECU and the car started right up. After getting home and testing the chipped ECU with the same result, I swapped the ECU again for the stock and again everything was great!

Figuring that it was obviously the board (ECU) or chip, I sent it back for an exchange. I received the new part a few days ago and swapped in the new chipped ECU. Everything ran great for a week and then went to fill up on gas. Again, the car quickly died! I swapped in the stock ECU and the car fired right up.

So to clear a few things up:

2000 Civic Si (stock)
93 octane gas
No prior check engine lights (even checked codes on both obd1-2 and nothing came up)
Same result on two different parts after filling up gas tank

I'm completely at a loss. Could the level of the tank have something to do with it!?

Any help would be greatly appreciated. Thanks

 

I know this may sound weird, but disconnect the EVAP Purge Solenoid and see if it continues.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by a1320addict &raquo;</TD></TR><TR><TD CLASS="quote">I know this may sound weird, but disconnect the EVAP Purge Solenoid and see if it continues.</TD></TR></TABLE>

Huh, I could definitely try this. Would this be bad to leave unplugged?

 

Not at all....I had a similar issue years ago with my car, unplugging it cleared it up for some reason. LMK

 

Could this also clear up infrequent start up stumbles like the OP is talking about? It happens every so often, and there are never constant similarities.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by neoc03 &raquo;</TD></TR><TR><TD CLASS="quote">Could this also clear up infrequent start up stumbles like the OP is talking about? It happens every so often, and there are never constant similarities.</TD></TR></TABLE>

It's possible. Assuming you understand how the EVAP Purge system works, it makes sense. Especially factoring in the OP's description of the issue happening during fill-up.

One thing to do as well is ensure the fuel system is fully primed before starting the car, (wait for the CEL to turn off).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by a1320addict &raquo;</TD></TR><TR><TD CLASS="quote">One thing to do as well is ensure the fuel system is fully primed before starting the car, (wait for the CEL to turn off).</TD></TR></TABLE>

Always did this as a pet-peive*...lol

Going to try this tomorrow, so am I unplugging to reset it or unplugging for good?

 

Just leave it unplugged, make sure to secure the clip away from anything that could damage it.

Let me know how you make out

 

Will do. Thanks for all your help.

 

Ok, so where is the solenoid? lol I know where the canister and hoses are, but can't seem to find the solenoid?

 

Ok, I plugged the chipped ECU back with the jumper harness without unplugging the evap solenoid and the car started right up. Obviously affected when I fill up, I still need to locate the solenoid and try unplugging it next time I fill up.

Any ideas why this occurs?

After looking at two different diagrams and having no help from my Haynes manual, I think it may be bolted to the fuel rail:

Here is two different diagrams:





And here is mine:

What I think is canister (left) to evap solenoid (right)


Another shot of the proposed evap solenoid:

 

About to fill her up again....

 

did u solve this problem?