Someone stole gas from me and now my engine runs weird?

[Dustin Jackson]

Hello gentlemen, in the middle of the night on the 4th of July someone stole gas from my Tahoe while it was parked in my driveway. I went to leave for work the next day and discovered my gas cap on my rear tire.

I put the gas cap back on the Tahoe and drove to work. On my way home from work I filled up with 91 at my usual gas station, but ever since then the motor has idled a little rough and on the freeway my Tahoe has a little shimmy like an unbalanced tire or slight misfire.

I just redid my front brakes the day before my gas was stolen so I am going pull my front tires back off and inspect all mating surfaces but I have this paranoid/OCD feeling in the back of my mind that the stealing of the gas caused something to happen with either the EVAP system or they got dirt in my tank. OR the gas station just switched to summer fuel here in California. Either way my motor isn't running as smoothly as it did a few weeks ago.

Today I filled up another tank of gas and the Tahoe had a very notable rough idle immediately after starting it from filling it with gas.

Along with having my property violated! My Tahoe isn't running as well as it used to and I want to see if there is anything I can check on, I am hoping these are just the early stages of a EVAP failure. I have had a history of not being able to fill up the gas tank in one go, the pump always clicks so I have to hold the nozzle at a special angle to get to a full tank.

Lesson learned, locking my Tahoe every night and installing security camera.

Anything you guys can think of or am I just paranoid?

This is how I found my tahoe:

 

[B-train]

That totally sucks. I'm not sure if they would actually be able to get any gas out with a siphon on these trucks, but I've never tried either.

I'd do an inspection underneath to see if they knocked anything loose in their attempt

 

[Dustin Jackson]

That totally sucks. I'm not sure if they would actually be able to get any gas out with a siphon on these trucks, but I've never tried either.

I'd do an inspection underneath to see if they knocked anything loose in their attempt

Is there anything in the fuel filler neck between the tank and the hole that they could of knocked around or damaged?

 

[j91z28d1]

did you notice fuel missing? maybe they put something in the tank messing up your fuel pressure?

 

[intheburbs]

Virtually impossible to steal gas out of the tank.

Much more likely that something was put into the tank.

I'd start with running some good fuel injector cleaner, like BG 44K, and see if that helps. Then, I'd do other "tune-up" items - air filter, spark plugs, etc.

 

[Dustin Jackson]

did you notice fuel missing? maybe they put something in the tank messing up your fuel pressure?

Was already out of gas so and my gas gauge is very lazy so impossible to tell if anything was added or taken away unless it was by the 10s of gallons

 

[Dustin Jackson]

Virtually impossible to steal gas out of the tank.

Much more likely that something was put into the tank.

I'd start with running some good fuel injector cleaner, like BG 44K, and see if that helps. Then, I'd do other "tune-up" items - air filter, spark plugs, etc.

I’ll try some fuel injector cleaner or sea foam. No need to replace those other parts, the motor was halfway rebuilt last summer and ran perfectly fine as recent as I can remember. I pay very close attention to my truck any time I drive it

 

[B-train]

Is there anything in the fuel filler neck between the tank and the hole that they could of knocked around or damaged?

I don't think so, unless they went underneath and messed with the vent or something. I was under the impression that most new tanks had some sort of blocking device that prevented siphoning.

After reading further, I would agree that something was PUT into the tank. Maybe sugar, piss, etc. People are idiots.....

 

[OR VietVet]

Any CEL? You already knew you had evap system problems? My guess is that they tried, could not get fuel and dumped something in there but maybe damaged this too:

More Information for SPECTRA PREMIUM FN779

If you do the try to address the evap system do the entire system. If they dumped something, it could be in the entire system. Sucks.

IMO, if I caught someone doing that, pulling fuel out or dumping something in....I will hurt them.....badly. I need to work on my bat swing anyway.

 

[Dustin Jackson]

@OR VietVet No check engine lights and yes I had pre-existing fuel filling problems.

I inspecting under the Tahoe near the filling neck and nothing was tampered with. The Tahoe was completely unlocked but it doesn't look like they opened the doors because all my stuff was inside. I am hoping they just attempted to steal gas and left empty handed but here we are

If something was dumped down the filler neck would it go straight to the tank or would it hit the EVAP system first?

 

[swathdiver]

Except for that pretty bride, you haven't been having much good luck lately my friend!

First of all, get yourself the proper gas cap. It ought to be yellow, a GT295/20915990.

Then consider running a couple of tanks of E85 to clean out whatever might have gotten in there.

As you know, clicking while fueling can be a number of things, the purge or vent valve, vapor canister or lines corroded or full of charcoal pellets.

 

[Dustin Jackson]

@swathdiver I keep telling myself that eventually things will settle down, right now our biggest struggle is taking care of our disabled 3.5 year old. Wifes job let her go because of all the time she would take off work to take him to his appointments and therapies so we are working on coasting by financially until we can get some IHSS income assistance for all the time she has to spend taking care of him but we keep getting denied. Feel liking I'm hanging onto the "American dream" by the skin of our teeth, I am more well off than everyone I know yet we are still basically living paycheck to paycheck. I don't know how any of my friends or family are ever going to get a house of their own.

Looks like there is a E85 gas station in my town, I'll use that next few tanks of gas. Do I need the yellow gas cap to run E85?

 

[swathdiver]

@swathdiver I keep telling myself that eventually things will settle down, right now our biggest struggle is taking care of our disabled 3.5 year old. Wifes job let her go because of all the time she would take off work to take him to his appointments and therapies so we are working on coasting by financially until we can get some IHSS income assistance for all the time she has to spend taking care of him but we keep getting denied. Feel liking I'm hanging onto the "American dream" by the skin of our teeth, I am more well off than everyone I know yet we are still basically living paycheck to paycheck. I don't know how any of my friends or family are ever going to get a house of their own.

Looks like there is a E85 gas station in my town, I'll use that next few tanks of gas. Do I need the yellow gas cap to run E85?

I don't know for sure, it's probably to designate the truck as FlexFuel. Hmm, I seem to remember people having rough idles with black caps on FlexFuel cars, this was years ago and I do not trust my memory. @gooffeyguy @iamdub @PG01

 

[Fless]

The only difference I can think of in the caps would be the color and the gasket material. The black cap might have a gasket that is not resistive to the E85, and might decay over time. But that's just conjecture on my part and if the gasket on yours is in good shape now, running E85 in the short term shouldn't cause any problems. Long term you may want to get the yellow cap for it, or run with the black cap and see what happens. The only job that cap has is to seal that filler neck.

If they put something in the tank it's not going to affect the evap system, at least not right away. It would be more fuel contamination than anything. But not knowing if they did add something, it's hard to tell if that's the case.

 

[Just Fishing]

I love my security cameras.
I also learned about motorcycle dash cams.
they have this little center box/dvr and can have several cameras!

I picked up one for my Jeep.
depending how it does, I might get another one to help cover the different views.
Main thing I like is I can keep it low key and prevent someone from breaking into the vehicle to steal it.

 

[Jimmyy]

Gas cap hack: hit a gas station or 2 and ask if they found your yellow gas cap. Most stations have a box full of gas caps.

 

[Dustin Jackson]

What would you guys do in this situation?

I'd like to think that they didn't put anything into the tank, there was plenty of items in my Tahoe they didn't steal so if they wanted to be malicious they could have and there was no evidence near or around the fuel fill hole that they tried to put anything in it. I hope it was just a tweaker looking for gas.

 

[OR VietVet]

You need to get a fuel sample and see what is floating in there or if it is cloudy or discolored. Then start the diagnosis for your running problems.

 

[Dustin Jackson]

@OR VietVet I am about 2 tanks of gas into this situation, would a fuel sample still be viable? Also how do you take a fuel sample?

 

[Just Fishing]

Have a tech2?

Might not hurt to look at fuel system data if you do.