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Bad Gas - In The Car, Not Me!


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Got a tank of bad gas, now SGT is running like crap! Tried dry-gas and octane booster and ran as many as 30 gallons of new fuel. Car runs ok until the supercharger kicks in, then backfires and loss of power. Reflashed tune, changed fuel filter, no change and no codes!

 

Any thoughts?

 

Sam

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Backfire should have left some sort of code, I would be clueless too. Though you do not explained the "bad gas" thought, perhaps there is something else wrong that arises at the same time the gas issue came to mind? If this was my problem, I would pull some spark plugs and evaluate from there. A shortcut to this would be to peek at #1 and #8 first, they reside at two opposite ends of the fuel rails. If nothing seems out of sorts, pull the remainder. Careful with the electrodes, you are just looking, nothing else. Check your observations against known results?

 

I had something a little like this a while back, thought it was possibly bad gas then too. Turned out to be the MAF, a dead spyder's resting spot. Blew everything out and reassembled, problem did not return. No codes then either, just blocked air path to the sensor...Unless I fixed something else by accident. I still cannot explain what it was.

 

Good luck with this, let us know what you think when it's over.

 

Y'all be safe.

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LuLu,

 

Good points, I just pulled the plugs and they all look pretty decent, electrodes actually look a little black, like it was running rich, but all in all no issue there.

 

So, you also mentioned that there could be a secondary issue besides the bad gas, which just happened to come up at the same time. Definitely bad gas, as two GT500s with me experienced the same problems, difference being they cleared up and mine didn't! So, my latest theory, based on a conversation with one of my GT500 companions, (thanks Jim!), is the fuel pump. I have the GT500 dual pumps, and I think one of the control modules or one of the pumps went south. I had a spare tire laying in the trunk and it appears the floor gave way and allowed it to rest on one of the modules. Just a theory, but a real possibility. I just have to figure out how to test each component!

 

Sam

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Well problem solved! It was the spare tire causing the issue! Rather than putting the spare in the well where it belongs, I laid it on the floor of the trunk. Thin, paperboard that Ford uses couldn't support the weight, and with the car movement, it dropped into the well and rested on one of the fuel control modules and associated wiring, causing the loss of one of the pumps. I could still drive the car, just couldn't jump on it, or it would backfire and stutter.

 

Lesson learned!

 

Sam

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