Tip & How-To about Chevrolet Cavalier

How to identify vaporlock.

Car running rough? Stalls at strange times but after a few minutes restarts? Could be vaporlock.

Vaporlock is more and more common these days as the fuels change and older cars are running on more and more ethanol. They simply weren't designed to run this fuel, originally.

So the easy way to tell if it's vaporlock is pop the hood once its stalled and pour some nonflammable fluid on the fuel lines. This cools them down and helps it restart. This is a temporary fix. A more permanent one is to get a heat shield installed on the fuel lines.

Technical Explanation: Vaporlock is the fuel boiling and the car does not properly measure it out then so the engine starves of fuel and stalls. The residual engine heat can keep it this way for many minutes.

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2000 Pontiac Montana LWB, after a long drive and the engine is in normal operating temperature, if I turn the car off, intermittently the engine will crank, but will not fire or will fire for about 5 seconds and stall out and currently I need to wait about 10-15 mins for the engine to cool down and then starting is no problem. This problem is occurring more often now,maybe because of the summer temps. Not sure if this has anything to do with it, but when low on fuel in the tank, the fuel gauge will show false readings( FULL when almost EMPTY, but problem can occur even if tank is fairly full). What can the problem be?


It could be a vapor lock issue. Vapor lock is typical in older vehicles. With the invention of fuel injection vapor lock has been minimized. What causes a vaporlock is underhood tempatures causing the fuel in the lines near the engine to evaporate causing a vaporlock. Now once the engine cools down, it will condense back into a liquid eliminating the problem. Fuel injection uses a lot more pressure than the old carburators did. One thing you can do is try replacing the three most important fuel system parts. The fuel filter, the fuel pump relay and the fuel pump. You need good steady pressure to push the vaporlock out of the lines. If one of these three parts is malfunctioning then it will allow the system to vaporlock. As for the gusage readings, taht could be just a bad sending unit.

Aug 21, 2009 | 2000 Pontiac Montana

2 Answers

1994 Cadillac De Ville acts like vaporlock


change fuel filter and check fuel pressure.sound like low fuel pressure problems.

Jun 07, 2009 | 1994 Cadillac DeVille

1 Answer

Car runs for a few minutes then dies.


it seem that your car making a vaporlock in the fuel system so you might check you line which expose to heat like the piping exhaust check for leaks.

Dec 17, 2008 | 1995 Honda Accord

1 Answer

Fuel temperature is 280F. (We live in Arizona) Vaporlock seems to be the problem. Any recomendations...


try installing an aftermarket electric fuel pump. vaporlock problem on an 86 Ramcharger went away. 360 engine w/4 bbl.

Jul 22, 2008 | 1986 Dodge Ramcharger

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