Vapor Lock

Maintenance/Repairs
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21

I’m still not a fan of the vapor lock theory. Given the circumstances behind the problem with the Mazda 6 I’d be inclined to think that it may be more of an intermittent fuel pump failure or possibly something to do with the secondary ignition instead. If the fuel filter has not been changed on a regular basis then the pump would be even more suspect.
It’s also possible that the car could have been running hotter than normal due to altitude and the ECT sensor could have been thrown out of whack.

Recommendations by a tow truck driver to add diesel to the gas tank does not rate very high on the technical scale in my opinion and a scan of the car for any codes would be preferable.

Currently in OK we’re in one of the occassional super hot spells with about 10 days now of 100+ temps, with most in the 108-110 range, and I have yet to see a vehicle on the side of the road suffering from vapor lock, nor have I heard anyone complaining about it. Not even during prior hot summers.

My condolences for being stranded in Limon; the armpit of the Earth in my opinion.
:frowning:

22

Take a look at http://www.epa.gov/obd/warranties.htm#1{/url]

23

I am well informed about what parts are covered out to 8yrs 80K and what parts are only covered to 2yrs 24,000. The only thing out to 8yrs 80k are the ECU and the Cat (if the car is properly maintained)all other parts are limited to 2 years 24,000

24

I think it’s likely an electronic component that’s failing in the high heat. The main problem is some testing needs to be done while it’s malfunctioning. My first check would be for spark at the spark plugs. It’s really a two person job to do this. You could do some research on how to do this. Next time if you’re alone and you call for a tow the driver might help you do the test. A bad ignition module, coil or crank/cam position sensor can kill the spark due to heat.

25

I have a tendency to let my tank run low before filling up but driving across Western Kansas and Eastern Colorado, not too low! I am pretty confident that the first time it happened in 2005, I had about 3/4 tank at least. I’ll have my husband point out the fuel rails to me. This is all very interesting. Thank you for the input!

26

You will probaly end up paying for the scan-if it turns up nothing unusual-Kevin

27

Most of the time ,a lot of these gremlins are electrical,Diesel fuel sounds like a witchdoctor cure to me(take the hood off ,maybe it will run cooler-vapor doesnt pump very well)-Kevin

28

I’m experiencing what might be vapor lock with my 88 Toyota Corolla, which runs fine for awhile then burps and dies.My Toyota is not fuel injected, so vapor lock is still on the possible list, right?

I live in the desert, where 110 degrees is average at this time of year, and at an altitude of like 100 feet above sea level. It was running fine at the beginning of the summer. I took it to higher, cooler temps (9000 ft/68 degrees) for the last two months. Going down a bumpy gravel road, the muffler fell off, so we had that replaced. About this time, it started to run rough, and we thought it was the altitude, so we didn’t drive much until we got back home.

At home, we filled the gas tank and within 10 miles of driving, it started sputtering and dying. We stopped at an auto parts store, got some supplies, then it wouldn’t start and we had to be towed home. My husband changed the spark plugs, rotor, dist. cap & wires…this usually does the trick (bought the car new; he changes all that whenever it begins to run rough, which happens about every two or three years)(the car has over 200,000 miles). Unfortunately,after changing all that, although the engine sounds great and has lots of pep, it still burps and dies suddenly after going around file miles.

The first time we couldn’t get it started and had to get it towed,my husband checked the fuel filter and there didn’t appear to be any gas coming into the line, so he began wondering if the fuel pump was not working. He changed the fuel filter, and when he did, he tried the pump…it was pumping what seemed to be a good amount of gas. Still, the way it just burps and dies,or sometimes burps and then catches, it seems like it’s running out of gas.

So…how do you pressure test a fuel pump?

29

change the air filter

30

It’s time to do some tests. Start with a clean fuel filter, and perform fuel pressure tests: engine hot with engine under load.
Next, since the engine computer controls fuel flow based on information it gets from sensors, those sensors need to be checked for accuracy. Check the MAF/IAT (Mass Air Flow/ Intake Air Temperature) sensor; and the Barometric Pressure Sensor. Or, can someone think of a way of getting the information without doing the checks?
Simply, replace the fuel pump relay, since it can’t be checked for intermittent failures.

31

If this engine has a carburator, a fuel delivery problem shows up as stumble-jerky die. If you have experienced running out of gas, that is the feeling you would get except protracted. Vapor lock will feel like you are out of gas and the engine will not restart until cool again. One trick is to pour cold water on the fuel pump and fuel line to the pump inside the engine compartment.

There are two tests to do on a engine mounted fuel pump. The first is volume test where you disconnect the fuel line after the pump and allow the fuel to flow into a container (do it safely because you need to crank the engine). The amount should be more than the minimum specified. The next test is to connect a low pressure fuel gauge to that line and again crank the engine to see what the pressure is. Anything above 5 psi should be good enough but check the specifications. Also the pressure should hold steady for five minutes after the cranking stops.

If there is a fuel filter on the suction side of the pump make sure that has as little restriction as possible. Also make sure the suction fuel lines from the tank to the pump are air tight. Lightly pressurize the tank and look for leaks and seeps at rusty spots on the hard line. If air is getting into the suction line, the pump will vapor lock easier. Check how close exhaust components come to the line and place insulation on any part of the fuel line that comes close to the exhaust system. If there isn’t a fuel filter on the suction side consider adding one as any debris that makes it to the fuel pump valves can cause intermittant pumping loss.

Hope that helps. Get back to us with results and progess reports.

32

You must all be flatlanders like me. We just came back from Colorado and our 2006 Chev.Malibu Vaper locked out side the Eisenhower tunnel at 11,000 ft. The highway Dep.
has workers there 24-7> The worker that towed us off said right away. It was vaper lock
and just wait 15 min.to cool off.He told us he had just pulled a brand new Rangrover 20 min. before. It was over 100 deg. in Denver that day he said it was very common to vaper lock up there and that he had towed at lest 20 cars that day. When they cooled off they were good to go.