Car won't easily start after adding gas
Thread Starter
Junior Member
Joined: Dec 2020
Posts: 31
Likes: 7
S550
Car won't easily start after adding gas
2010 S550. Car has many problems but this is a strange one. When I add gas, either fill up or a few gallons, press start and it will turn over and either not start or stall right away. And then if I do nothing, it will go hours before it starts meaning every minute I press start until it starts three hours later.
Now, to get it to start, one foot on brake and other on gas pedal. Almost flooring the gas pedal, after two or three button pushes it will VROOOM start up. Always nice to get strange looks for revving car at the pumps. It will run rough, even stall but generally it will run. And then the rest of the time it is fine, stats with one push and no gas pedal.
A person suggested I keep the gas cap off after adding gas. To add to it, I took off gas cap, drove somewhere, was out of car for only a minute, started car, drove to gas station, added gas, and it wouldn't start. Go home and parked with gas cap still off, an hour later wouldn't start. Put the cap back on, has started fine each time (after the first VROOOM method).
Now, to get it to start, one foot on brake and other on gas pedal. Almost flooring the gas pedal, after two or three button pushes it will VROOOM start up. Always nice to get strange looks for revving car at the pumps. It will run rough, even stall but generally it will run. And then the rest of the time it is fine, stats with one push and no gas pedal.
A person suggested I keep the gas cap off after adding gas. To add to it, I took off gas cap, drove somewhere, was out of car for only a minute, started car, drove to gas station, added gas, and it wouldn't start. Go home and parked with gas cap still off, an hour later wouldn't start. Put the cap back on, has started fine each time (after the first VROOOM method).
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Joined: Dec 2018
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From: Washington, DC
2007 S600, 2007 Chrysler 300 SRT8, 2000 C5 Corvette, 2017 Mustang GT, 2023 300C, and a 2019 Lincoln
Hard to know with no codes provided but it sure sounds like a crankshaft position sensor to me. Typically they are OK when totally cold; but when warmed up and you stop for gas, it fails to start until it cools down again. Cheap enough part. Good luck.
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Joined: Oct 2010
Posts: 5,141
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
2010 S550. Car has many problems but this is a strange one. When I add gas, either fill up or a few gallons, press start and it will turn over and either not start or stall right away. And then if I do nothing, it will go hours before it starts meaning every minute I press start until it starts three hours later.
Now, to get it to start, one foot on brake and other on gas pedal. Almost flooring the gas pedal, after two or three button pushes it will VROOOM start up. Always nice to get strange looks for revving car at the pumps. It will run rough, even stall but generally it will run. And then the rest of the time it is fine, stats with one push and no gas pedal.
A person suggested I keep the gas cap off after adding gas. To add to it, I took off gas cap, drove somewhere, was out of car for only a minute, started car, drove to gas station, added gas, and it wouldn't start. Go home and parked with gas cap still off, an hour later wouldn't start. Put the cap back on, has started fine each time (after the first VROOOM method).
Now, to get it to start, one foot on brake and other on gas pedal. Almost flooring the gas pedal, after two or three button pushes it will VROOOM start up. Always nice to get strange looks for revving car at the pumps. It will run rough, even stall but generally it will run. And then the rest of the time it is fine, stats with one push and no gas pedal.
A person suggested I keep the gas cap off after adding gas. To add to it, I took off gas cap, drove somewhere, was out of car for only a minute, started car, drove to gas station, added gas, and it wouldn't start. Go home and parked with gas cap still off, an hour later wouldn't start. Put the cap back on, has started fine each time (after the first VROOOM method).
The next day the dealer said it started fine for them but they also told me the car needed an update in the engine control module as the car would flood the engine during some cold days. I live in Louisiana so we don't really have that cold days but it was a cooler morning when this problem appeared.
The dealer said that the car would have started for me if I had held the gas pedal down while starting it and this caught my eye in your post as you can start it holding gas down. Your problem and and "fix" fit what I had happen so you may have the same issue.
Is it cold outside when this happens?
