Truck stalling in Hot Weather, any suggestions??

[JoetheMobster]

Well, my truck seems to be very unhappy with the 30+ deg C weather we're getting here, and my truck stalls after a stint of driving. When the day cools down, I have no problems, but in the heat it stalls. I've let the truck idle for periods of time, and never had it stall on me, but if that sun's shining, the truck keeps stalling on me after about 1/2 hour of driving.

After a stall, I have no problems starting it up again, and if I drive it in 1st, or second while keeping on the gas, it seems to be fine. When I hit third though, and the rev's are low, that's when the stall seems to come.

When I switch the fuel over to CNG, it's like riding a MAD rodeo bull, in all gears

Any suggestions? The air filter might need a changing, but it's not too horrible. I should change the spark plugs, they're in need! Thing is, would this fix anything? Remember, the truck runs great in cooler weather (late afternoon, 5ish) but at midday, it's growly!

[JoetheMobster]

I was also wondering about the following picture. You will see the end of the air filter canister is set so that it's sucking in the nice HOT air from the engine, and the sun beaming down on the hood. Would this be half of my problem?

[1968 C-10Cowboy]

Sounds like vapor lock to me......I could be wrong though

[Super Chevy]

sounds like vaperlock to me too,thats when the gas gets hot and turns to vaper in the lines...

[busterwivell]

I agree. Look at your fuel line routing. I'll bet you are close to a heat source and causes a vapor lock in extreme heat.

[JoetheMobster]

Hey, thanks for the replys guys, I'll have to check that out! There's nothing worse than having this happen to you while you're driving down the highway!

This might be a memory for some of you out there, it sure as heck was for me! (pic below)

[O'l Buck]

fuel pump might just be getting weak, dad's 67 used to act that way 'till I changed the fuel pump for him.

[jku72]

The best solution I have done is wrap the fuel lines in the engine compartment with insulation, the keep the heat out. While I used aluminum foil, perhaps a more beautiful material could be used. This vapor lock is common, but also you might check the fuel filter, as it will give similar symptoms if dirty, and almost nobody ever checks them, including me. The fuel pump weakness idea is possible, but I myself think vapor lock, and or a dirty fuel filter are prime suspects.

[SWINGSAX68]

my brothers '87 honda civic makes a Popping sound when given gas....like.....Pop pop pop pop...then it goes, but once you stop at a light for a while it does it again, could it be vapor lock also???just wondering....how about a wet distributer. We changed one of the 3 fuel filters....DAMN FOREIGN CARS!!!!

[Longhorn Man]

A vehicle wit fuel injection will practicly never suffer from vapor lock. The electric fuel pump pumps about twice what the engine will normally use. THe rest is taken back to the tank. The high pressures in that system raises the boiling point, and the higher speed the fuel runs lessens the time spent in the lines.
As for the fuel filter idea, while it is very possable, it is not likely. Normally a fuel delivery problem will show up in the higher RPMs before the lower ones. Shifting to 3rd drops the RPMs (as we al know) and then it stalls...I say check your fuel lines, and see how close it is to the exhaust. See if it is touching the engine up front...probably the head, intake or even valve cover.
If you feel froggy, try re routing the fuel line outside the frame rail (I'm doing this with the Longhorn) and about 2 inches from the engine as it comes up the side of it. When you secure it to the frame use the clamps with the black rubber insolaters. Not only reduces vibes, bit does not transfer heat as well as metal.
Some thing that also works, i discovered this past spring, my 190 degree thermostat was keeping the engine at about 200. I was getting vapor lock like mad. When I installed my 160 degree one, all my vapor lock troubles went away.