Disclaimer: I am stupid...

I am having an issue with a possibly contaminated tank of E85 right now. I was hard-wiring and modding the relief valve on my Walbro with an *almost* empty tank of E85 and had some problems with the pump. Because I was working on the fuel pump, almost completely empty and I was being stupid and lazy at 4am (I HATE how awkward and hard installing the pump ring and fittings is!) I didn't completely seal the fuel tank at the pump because I thought it would just be for the night or so, so I just had the fuel pump sitting in the tank but not bolted down/not totally sealed. Life got hectic all of a sudden and I left it like that for about 10-15 days.

Today I fixed my pump issue, poured in 5 gal of new E85, started the car, and it smells totally wrong and is idling a only very slightly rough when I give it a tiny rev. My first thought was that it seemed to be running very rich which I know could result from hard wiring and punching a Walbro, but there was a distinct smell in the exhaust I didn't recognize and I didn;t think the rewire would make a big difference at idle. Since I hadn't anticipated leaving the car like that for so long I didn't "pickle" the injectors/system with gasolinebut I don't think a week or two is long enough to rust injectors is it?

I was about to install my wideband and a Eth% analyzer after I resolved the pump issue I was working on, so I don't have any % data on it.

Is two weeks with a "loose lid" on probably less than 1gal. E85 in a closed garage in SF the last week or two enough to ruin the whole 5 gal I added to the 1> gal. that was sitting for a few weeks? I was hoping the fresh fuel would make its way through in a few minutes but I guess that might not be the case.

Should I:
a- add more new E85 and try to idle/gently drive this tank off?
b- drain the whole tank again and start fresh?

Did I jeopardize the whole system by idling it for about 4 minutes like that?

 

In my opinion- there was not enough absorption to be the issue. If you feel better-drain it and start over-but I do not think this is the issue. How did the new E85 smell/look? Did you at some point use an additive?

If you are running a fine screen or filter you can look at- take a look there before draining the tank.

This could be fuel pressure/excess fuel/or too little fuel related?

 

I never put any additive or stabilizer in it, I think I'm going to add some Ethanol stabilizer tomorrrow. had already closed off the tank without really looking at it. Before I fixed the problem it was normal looking and clear. The exhaust was a little thicker looking but it was hard to tell because it was a little bit cold and humid, but it definitely smelled strong, acrid, a bit "spicy" like maybe 10% as strong as nitromethane. It smelled vaguely familiar like some kind of fruit, I almost want to say the bitter rind of a grapefruit as strange as that sounds. I have never smelled an E85 car running really rich before either though.