I recently pulled my 90 formula 305 tpi five speed out of the garage after about a 9month hibernation. I put it away with low gas in the tank and I only started it a couple of times in those nine months. When I pulled it out the first thing I did was go to the gas station put some fuel system cleaner in it and fill the tank. I drove it about 20 miles and everything seemed hunky dorey. The next day after some stop and go turn it off turn it on driving it started running badly like it was running out of gas or not getting good spark. I thought maybe a clogged fuel filter so I replaced it. Cranked it up and everything seemed ok, but the same scenario occured. So then I thought maybe there was condensation in the tank so I put some heet(fuel dryer) in it and the same thing happened, run fine for a little while then start running badly. Does anyone have any idea what could be the problem?

 

Maybe some trash and junk from the old gas is getting sucked up and clogging the sock on the pump. The stop and go traffic and fuel system cleaner may have broke loose crap stuck to the sides and bottom of the tank. That is my only guess, other than an injector going out.

 

Hello birdflu!!

Next time that you store the car for a long period of time, fill the tank right full, oxygen makes the fuel oxidize, which then makes it break down, causing all types of crappy issues like you got now!!



I stored my car for "6 years" with a full tank of super unleaded, and no fuel stabilizer!! After the 6 years, all I did to get her started was put in a fresh battery, and turn the key!! She started up after those 6 years with a fresh battery like she was brand new!! I warmed her up for about 5 minutes, drove to the highway (about 4 miles), took her up to 60 mph for 15 miles, and returned to town!! Once back in to town, I went through the smog check, and presto, a "PASS" with 6 year old gas!!



Best of luck with your problem, I believe that 89_IROC-Z28 has the answer!!

 

It also wouldnt hurt to get a fuel pressure gauge on the output line, fuel pumps can be real finicky.

 

Thanks guys for your input. I am trying to avoid dropping the tank. As we all know that's no walk in the park on these cars. I figured a full tank of fresh gas would dilute any "funky" gas that was in the tank. When I replaced the filter the leakage that I got seemed pretty crud free,so maybe it is something clogging the"sock" or an injector. The intermittent nature of the problem is what's baffling, you would think a clog is always clogged, but maybe the pump itself is flaking out. I was thinking about disconnecting the fuel line @ the filter putting a hose on it and turning on the pump to drain the tank/check pump operation. Is this feasible,is it too much pressure will I burn up the pump when it gets low.

 

Hello birdflu!!

Just leave a couple of gallons of gas in the tank if your worried about burning up the pump!! Fill it with good gas, and go driving!!!

Remember, dropping the tank, might become necessary to fix any pump/sock filter problem!!