Just did the SPFI conversion on the Brat. Drove it a bit yesterday, all seemed fine. This morning I just drove it, and it started misfiring. Got worse as I drove it more, and then I stopped the car, it started dumping gas out of the charcoal canister.

 

Misrouted hoses? Some solenoid bad? Plugged line somewhere?

I would say you've got the fuel and vapor lines hook up wrong. You'll need someone who's done the swap or an FSM to get them right.

Addition: Apparently gas is being siphoned out of the tank by the canister line right now. The line that goes under the intake manifold, and hooks up to the rear most line on the 3 line bracket that bolts to the thermostat housing. It's been dropping gas for at least an hour now, as I just walked out to the car and saw it dumping it.

 

edit: Ok, I just opened the gas cap; it hissed at me and stopped dumping gas out of the canister.

Edited March 21, 201115 yr by Speedwagon

Sounds like you have the return line or feed line crossed with the canister/vapor line. The canister line stops at the top of the tank and does not have contact with the gas at all. If I remember correctly, only the feed line drops into the gas.

Well, I thought I had everything hooked up correctly, and I went over it a few times. This didn't happen when I drove it at night, same distance. It was only during the day, when it was sunny and warm out, that this happened.

 

I have the feed line(it was going to the carb filter inlet) going to the front most port on the manifold. I have the return line going to the rear most(and upper) port on the manifold. The line that was going to the vapor port on the carb filter(top port) ran off to the right of the brake booster, so I presumed that to be the vapor return, which is what connects to the charcoal canister, via the under-the-manifold hardline, and up to the 3rd line on the canister(#1 being the large one directly in front of the vacuum line).

Edited March 22, 201115 yr by Speedwagon