vapor locking with fuel injection

[Big Red Ranger]

my truck is vapor locking on me when it is hot out. It is fuel injected. Dose any one know what the problem could be.

 

[Mark_88]

My Tempo would crap out in hot weather...the fuel pump in the tank was the problem...but not sure what you mean exactly by vapour locking...are you not getting fuel to the engine bay or is it simply not burning the fuel effectively?

 

[Big Red Ranger]

it wont even get to the fuel rail

 

[Kenneth S]

The 88 ranger 2.3 has two electric fuel pumps, a low pressure one in the tank, and the high pressure one mounted on the frame, when it get's hot and quits running check to see if the frame mounted pump is hot, if it is, either cool it off with water from either a water hose, or a large squirt bottle (like what's used for dish washing soap) the water will cool it off, and if it works again you found your problem. I would be willing to bet that's your problem.

 

[Mark_88]

it wont even get to the fuel rail

Try disconnecting the line from the pump on the rail (if it's not too hot) and turn the key (run a hose into a bucket if possible)...if you're not getting fuel to that point, then it could be the in-tank pump...but if it works then you may have a plugged fuel filter (or is it behind the pump???)...

Have you changed the filter recently or ever?

 

[Big Red Ranger]

ihave replaced my fuel filter in the last 2 months

 

[Joepoppa1]

fuel injected vehicles can't vapor lock since the fuel under pressure. like they said, it sounds like it may be a pump issue.

 

[87Ranger4me]

My 87 Ranger 2.9L is doing the exact same thing, in fact it stranded me in the middle of nowhere yesterday in 100 degree + weather. I have replaced both fuel filters, they were both really dirty. So you think it could be the frame rail pump as opposed to the in tank one?

 

[Kenneth S]

The pump that's in the tank usually lasts longer because the fuel keeps it cool (which is why the later models have the high pressure pump in the tank). The reason I suggest to check the frame mounted pump first is because it's alot easier to change if it's the culprit.
BTW During the summer, or a hot day it is better not let gas go below a 1/4 of a tank because the in tank pump starts to loose the cooling it gets from being in the gas thus shortening it's life.

 

[87Ranger4me]

Hey, thanks Ken, I will give it a try. The only bad part is I have to drive around on a hot day and get stranded to see if it works or not. I'm a little gun shy right now because it has quit 4 times now and every time right after I had replaced some part to fix the problem. Oh well, I guess there really isn't any better way to see if it's fixed other that to drive it.

 

[john hennessy]

vapor locking in fuel injected motors is far more common than you think, anyone who says that f/i engines don't vapor lock is completely WRONG.

first off, fuel injection systems due to safety issues have a much reduced pressure than they used to have, if you look at the pressures in older fi cars it was around 60 - 90 psi, it is now common to have 40 - 45 psi in the system when it is running.

the above and the non use of summer or winter blends in hot regions, substituting them for a sort of average blend will boil in the fuel line given sufficient ambient temperature, with half a tank of gas and an outside temp of 110 degrees i have experienced vapor lock, i measured the temp of the bottom of the gas tank, it was 159 degrees and a hissing oozing noise could be heard from inside the gas tank even with the filler cap removed so the noise was not any form of pressure relief valve in the tank or purge system, it was not the fuel pump running either as it had completed the prime cycle with the key on engine off.

the above was exasperated by driving the vehicle at a constant highway speed for 100 miles give or take 20 miles, thus having a small amount of fuel passing through the injectors and most fuel being retuned to the tank.

if the vehicle was left for ten minutes, then it would fire up but die almost immediatly, however with the hood open it would fire up and continue to run.

the ignition system was in as new condition and the engine temp was below 200 degrees and the ac was off.

the above was a "return" system.

another example was a non return single line system which are becomming more and more common, on this system by depressing the test port on the fuel rail vapors would vent and if you continued until raw fuel came out, then the vehicle would start, clearly "vapor lock", i have had this occure on Ford, Chevrolet and Chrysler vehicles so no common parts here, the only common things were the fuel and the ambient temp.

some manufacturers are aware of the problem, and have devised a solution in the form of a fuel cooler connected to the ac, Jaguar and Mercedes come to mind, chrysler have increased their fuel pressure to help eliminate the fault as have other manufacturers, unfortunately, people with older cars who live in the south west are out of luck unless they can find a way of cooling the fuel or raising the pressure but with the modular design of fuel pump/regulators it will not be easy.

an additional regulator and gauge could be fitted in the return line of a return system and even in a returnless system like the later rangers, it could be added in the return line between the filter and tank but this would need an aftermarket regulator and gauge, but systems with a return built into the fuel module it is not easy at all.

 

[tomw]

Get some wooden clothespins. Ha. Old 'cure' for vapor lock was to put the pins on the fuel line under the hood between the pump and the carburetor.
Two solutions come to mind. If you can get some sheet metal and cut it into a series of fins and then clamp that on the fuel line, it would dissipate more heat. Second would be to get a fan and blow air on the affected fuel line or rail.
Back in the late 1980's the F150 with the straight six had little flapper fans located somewhere around the intake manifold to cool, I guess, the injectors. I think it was the 1st EFI six, but don't know for sure.
I am getting vapor lock on my lawn tractor, on the pressure side of the fuel pump feeding the carb. I can hear/feel the fuel boiling after I shut it down. Runs good for 20 minutes until heated up, then starts to miss and chug. I think I'll take the cover off next time to see if it makes a difference. Some of the fuel in the gas cans develops a LOT of pressure, depending on where I bought it, while another can will have a lot less vapor pressure right next to the 1st can.
tom

 

[Mikel89us]

You can buy an aftermarket regulator, install it before the rail, and block he return line on the rail. If you do this, the gas will not get hot in the tank from soaking up engine heat before going back to the tank.

 

[tomw]

mike89 said: "If you do this, the gas will not get hot in the tank from soaking up engine heat before going back to the tank."

True, but the fuel that IS left in the rail, un-returned to the tank, will get to absorb all ALL the heat that would be dissipated over the multiple gallons in the tank. So, instead of trying to heat 10 gallons by 1degree F, you are trying to heat 1/2 CUP of fuel and it will go up a LOT more than 1 degree F as there is so little to be heated.
Kinda like heating a gallon of water for sphagetti vs heating 1 cup of water for instant. Which takes longer?
Maybe leave the return functional would be my suggestion. But I am not an engineer.
tom

 

[Mikel89us]

True it does take longer, but, if you have cool fuel always getting to the rail, the rail itself will stay cooler. If you are always driving long distances the fuel in the tank will get hot. Then you are sending hot fuel to a hot rail. This is partly why new cars all use a return less system