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Wrong gas can!

My stepson ran his Buick out of gas this afternoon. He came home to grab a gas can and mistakenly took the fuel mixed for the lawnmower. He put about a gallon of the mixture in the tank and then about 4 gallons of regular in over top of it. The car is sputtering terribly now and will turn over but is acting like it is out of gas. What should we do next? If we wait for awhile will it settle or mix? Should we keep trying to start it or get it towed to a mechanic? I am not much of a car person and any response is appreciated! Yes, we did have a talk about running the tank so low…

It is more likely that running out of gas damaged the fuel pump than the 2 stroke mixture is causing the problem.

I don’t think the mix is the problem…Running modern cars out of gasoline allows their fuel pump to overspeed (run dry) and perhaps damage themselves…

The 4 ounces or so of 2-cycle oil that was included in that gasoline for the lawnmower is unlikely to be causing problems for the car’s engine–especially if it has already been diluted with 4 additional gallons of gas. Years ago, many of us added 4 ounces or so of “top oil” to a tank of gas in order to help lubricate valves and eliminate pre-ignition.

If this engine is running very poorly at this point, I would be more likely to blame poor general maintenance or a damaged fuel pump. rather than the gasoline.

You may want to change the fuel filter, you may have sucked up some junk from the bottom of the fuel tank. If not the others may be dead on with the fuel pump damage.

Thank you all for the input! Is there a test that I can do myself to determine wether or not it is the fuel pump that isn’t functioning?

I agree. Either the gas was very old or tank had sediment that clogged the filter or the low gas level lead to other problems. The 2 stroke mixture is seldom a problem in cars. Modern two stroke oil is meant to integrate with gasoline. It does not interfere with the combustion in a two stroke motor…why should it interfere with a fuel injected 4 stroke. Try a fuel system cleaner first in case the gas was contaminated then take it to a mechanic if that doesn’t work. Let’s assume by now you have filled the tank with fresh gasoline as well and checked or changed the fuel filter.

On the “Fuel Rail”, that’s the fuel manifold that feeds all the injectors, you will find a test fitting from which fuel pressure can be checked, usually with a common tire gauge…

You did not state what year and model of Buick is involved but there should be a test plug for the fuel pump.
If this is a 96 or newer model there may be a tiny wire (possibly red) near the firewall on the passenger side with a small black plastic connector on it.
A test wire can be run from the positive side of the battery to that plug and it will energize the fuel pump.
This is for test purposes only and should not be left like this.

Earlier models should have a pump test connector also and it should be in the plug where diagnostic codes are pulled. This can be jumped to make the pump run and as the other, should not be left connected.

I’m in agreement that the gasoline itself is not the cause of the problem. Maybe the original problem was not running out of gas at all?

ok4450 beat me to it. It’s possible the problem wasn’t running out of gas, but rather an issue that presented itself just as the tank was at 1/16th or whatever. Whatever the problem turns out to be, it’s not likely that adding 1 gallon of mixed gas and 4 gallons of regular gas will have any effect on how the engine runs.

I’d not recommend trying to check your fuel pressure with a tire pressure gauge. I don’t know the specs on this car, but the fuel will be under something between 30-60psi of pressure. A basic fuel pressure gauge is not very expensive and actually screws onto the port and seals up. With a tire pressure gauge there’s a good chance that you’ll just spray yourself with fuel. You also can’t really get a read with the car running.

Either way, checking fuel pressure is next. If the pressure is good, then its likely the fuel causing the problem. How old was that mix?

You didn’t say what exactly is in the lawnmower can. What?

The first thing I’d try if this happend to me, and the lawnmower can was just a 16:1 mixture of gasoline to 2-cycle-oil is to fill the tank all the way to the top with fresh fuel, let it sit overnight to mix up with the other gas, and see if that helps. Doing this will dilute any of the 2 cycle oil from the first mistake considerably.

If that doesn’t fix it, it could be any of a half-dozen things. Dealing with fuel problems is complicated and dangerous. Unless you are the handi-man type with a lot of experience fixing cars, I’d take it to a pro. He can easily (but not cheaply!) and safely clean out the tank, test the fuel pump, fuel filter, plugs, cat converter, etc.

The car is a 2001 Buick century. The fuel mixture put in was 16:1 and a few months ( 4-5 ) old. It is awesome to get all of your responses and I totally appreciate it!

With 4 extra gallons of fresh gas I don’t think your problem has anything to do with the 2 cycle mix. I’ve poured left over weed eater mix in my tank more than once with no problems. When you turn the ignition key to the on position can you hear the fuel pump kick on and run for 1-2 seconds? If not the fuel pump has probably worn out, if you can I’d suggest first checking the fuel pressure to see if the pump is actually putting out the required pressure.

cigroller April 15 I'd not recommend trying to check your fuel pressure with a tire pressure gauge. I don't know the specs on this car, but the fuel will be under something between 30-60psi of pressure. A basic fuel pressure gauge is not very expensive and actually screws onto the port and seals up. With a tire pressure gauge there's a good chance that you'll just spray yourself with fuel. You also can't really get a read with the car running.

A tire pressure gauge should be able to handle pressures over 100 psi. Using a tire pressure gauge on a tire there’s a good chance you’ll let air out of the tire. LIfe is full of risks.

A $10 tire pressure gauge screws on.

Why would the car be running if you have to muck around with a little red wire on the firewall with a black connector on it that’s there specifically for testing the fuel pump?

littlemouse, I have been ignoring you successfully for weeks. Usually your comments are just ridiculous but mostly harmless.

In this case, you’re being ridiculous about working with gasoline - toxic and explosive. 1) Telling the casual passerby to go poking around their fuel rail with a tire pressure gauge is a terrible idea. 2) You cannot do an adequate check of fuel pressure just using “the little red wire.” KOEO static fuel pressure is the first thing to know - but only the first.

Now, littlemouse, if you must go back to posting your mostly worthless quips then do so, but please stay in the realm of “mostly harmless.”

Amen cigroller! I would never let littlemouse touch my car, or any of my clients! Fuel pressure guages were invented for a reason… DUHHhhhh… Thanks to cigroller for some solid advice! Careful out there, life DOESN’T have to be risky, with the right tools. LOL

DC Auto
You can rest easy.
That post from “littlemouse” on 4/16 appears to have been his last post.

After many of us pointed out his almost total lack of automotive technical knowledge and his apparent cause celebre of “needling” others on the board, it appears that he finally got the hint, and departed for greener pastures.