Does This Sound Like Vapor Lock to You?

[Hollowman]

I've had a similar no-start issue twice in the last week and a half. The engine will crank but not fire. Its different from slow or cold starts because there is no indication of fuel getting to the cylinders, it just turns dry. The solution was the same in both cases but I cant rule out coincidence. After the third attempt to light it off, I open the hood, crack the bleeder valve on the top of the fuel filter bracket for just a second, close it and try to start it again. Each time I barely touch the key and it fires right up. I'm wondering if this is a vapor lock issue, as in each instance the truck had been sitting in the sun and was warmer than usual. I changed out the fuel filter the other day and followed the bleeding instructions as closely as possible and it performed fine after the change so I assumed that was the problem until today, when I encountered the issue for the second time. Once again, the truck was in the sun and warm, I tried to start it three times without even a hiccup, then I opened the hood, cracked the bleeder, closed her up and turned the key and it lit before I could even let go. Could there be a bubble between the top of the filter and the injection pump that I overlooked?

Thank You Gentlemen,

Hollowman

 

[91W350]

Sounds like an air leak in the fuel system, since that bleeder is the highest point, good place to have a bleeder by the way, it makes short work of getting the air out. I fought a couple of those leaks and they can be frustrating. Glen

 

[Milbikes]

I have heard of vapor lock when gasoline gets hot enough to vaporize in the lines, but diesel has a much higher vaporization temp, and is probably not going to cause vapor lock like gasoline would.

On a side note, I have an old zero turn mower that always ran good in the heat until they started adding ethanol to the gasoline. It got vapor lock so fast and so often, I had to re-route the fuel line away from the original location under the fan housing. Another reason to hate the "ethanol as a better fuel" myth.