Vapor Lock?

[Harleroy]

Yesterday I was coming home from about a 20 mile drive, had the A/C on and the outside temp was about 75 degrees. I was running about 65 -70 mph and when I let off the gas to take an exit, the truck started sputtering and eventually died. It would crank but wouldn't start. I coasted to a stop in a shopping center, called for a ride home and got a different truck to tow my Ranger home. When we got it home, it started right up. I drove it this morning and it's running fine.
This has happened to me on two other occasions but the temp was over 100 then. On those two other times, I let the truck set several hours and came back and it started right up.
I'm thinking it's vaporlock. Does anyone else have this problem? If so, what's the cure? How do I avoid this happening or how do I get the engine running without waiting several hours?

 

[Psychopete]

Vapor lock is more common with older engines with low pressure mechanical fuel pumps. The higher pressure in the EFI system and the fuel pump location make it really kind of rare for this fuel system to vapor lock.

There is a more common problem with TFI modules located on the back of the distributor what will quit functioning when it gets too hot.

If you're loosing spark, I would take a closer look at the TFI module. They can be tested by an auto parts store, or even googleing information on diagnosing TFI-IV systems will give you things to check on the TFI with a digital multimeter.

Have you had any CELs present, and have you tried to pull codes to see what's out there?

You might take a flat head screw driver (to move the intake tube) and a can of starting fluid (to sparingly spray into the upper intake) with you next time. If it doesn't start up breifly, IMO it's probably not getting any spark (classic symptoms of a bad TFI).

Pete

 

[Harleroy]

I haven't had any CELs. A few weeks ago, I was driving it and when I'd push the clutch in to come to a stop, the engine would die. It always started back up right away. I got it home nad checked for codes and there was none. I probed the TPS to check for voltage and when I was finished, it started up and idled fine.
I'll check into the TFI module.
Thanks,
Leroy

 

[dixie281]

Howdy, new here but not to Ford trucks. I'm having a vapor lock problem too, and was googling for other people having the same issue. Came across this post and I couldn't help but sign up to help a fellow Ford truck owner out lol...

I've had my Bronco II (with 2.9L v6) for about 5 weeks now, and twice it has vapor locked on me. My solution to this is to bleed the vapor/air out from the fuel rail using the service/test port. All I do is get a piece of wire (always wire and stuff layin in the bed of my trucks lol) and ground the fuel pump test pin on the EEC self-test connector under the hood. I don't have a picture of it, but google can help you with that. This forces both fuel pumps to run continuously, for as long as you have the ignition switch in the RUN position.

Now that we have fuel flow, all that's left is to take a small pointed object like a ballpoint pen, screwdriver, or the nearest twig on the ground, and *lightly* press the valve down on the fuel rail port. If you mash it all the way you'll get showered in fuel and possibly start a fire if your engine is still hot. Just press down on it real easy til you hear air bleeding out, and once the fuel starts coming pretty steady, release the valve and crank the engine. If it doesn't start after a few seconds, bleed it again. After a few bleeds, it will come back to life. Once it's running go ahead and take the ground wire off the EEC self-test connector and close everything up, you're ready to roll.

This has gotten me back on the road twice now in the short time I've owned this truck, and yes, this happened both times in the middle of the afternoon in 90+ degree weather. The first time was kind of my fault, I had the truck parked across a ditch to work under it and check the fuel strainers, and didn't fill the canister back up with fuel before trying to start the engines. Died on me after a few seconds, which is when I thought of the vapor lock theory. Today it did it again, pulling out of my realtor's parking lot. Was runnin fine, I pulled in there, left about 15 minutes later, and it had NO power. Eventually it died, and I bled it a few times and she fired right back up.

Good luck to you, hope this helps you out.

EDIT: damn, sorry I didn't see that this post was from 08, all I read was the first part of the date and just assumed it was this year...lmao!!

 

[sdmaria]

Howdy, new here but not to Ford trucks. I'm having a vapor lock problem too, and was googling for other people having the same issue. Came across this post and I couldn't help but sign up to help a fellow Ford truck owner out lol...

I've had my Bronco II (with 2.9L v6) for about 5 weeks now, and twice it has vapor locked on me. My solution to this is to bleed the vapor/air out from the fuel rail using the service/test port. All I do is get a piece of wire (always wire and stuff layin in the bed of my trucks lol) and ground the fuel pump test pin on the EEC self-test connector under the hood. I don't have a picture of it, but google can help you with that. This forces both fuel pumps to run continuously, for as long as you have the ignition switch in the RUN position.

Now that we have fuel flow, all that's left is to take a small pointed object like a ballpoint pen, screwdriver, or the nearest twig on the ground, and *lightly* press the valve down on the fuel rail port. If you mash it all the way you'll get showered in fuel and possibly start a fire if your engine is still hot. Just press down on it real easy til you hear air bleeding out, and once the fuel starts coming pretty steady, release the valve and crank the engine. If it doesn't start after a few seconds, bleed it again. After a few bleeds, it will come back to life. Once it's running go ahead and take the ground wire off the EEC self-test connector and close everything up, you're ready to roll.

This has gotten me back on the road twice now in the short time I've owned this truck, and yes, this happened both times in the middle of the afternoon in 90+ degree weather. The first time was kind of my fault, I had the truck parked across a ditch to work under it and check the fuel strainers, and didn't fill the canister back up with fuel before trying to start the engines. Died on me after a few seconds, which is when I thought of the vapor lock theory. Today it did it again, pulling out of my realtor's parking lot. Was runnin fine, I pulled in there, left about 15 minutes later, and it had NO power. Eventually it died, and I bled it a few times and she fired right back up.

Good luck to you, hope this helps you out.

EDIT: damn, sorry I didn't see that this post was from 08, all I read was the first part of the date and just assumed it was this year...lmao!!

I'm glad you posted this even though it was a "late reply" because I needed this info in 2023.