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I have two issues that have been nagging at me lately. First is this damn problem I seem to have with vapor lock. At least that's what I assume it is. As some may know my truck's engine has an industrial engine in place of the original. This engine's fuel pump location puts the pump pretty close to the exhaust manifold pipe. I wrapped the pipe with heat resistant material, and also used some heat shielding on the fuel line going into the carb. I still get what appears to be vapor lock which I notice as fuel disappearing from the inline filter as soon as I shut the engine down on a hot day, and the engine not wanting to start right away right afterwards. And also the filter material inside the glass body sucks in like when a kid sucks air out of a soda bottle when engine is shut off. What the heck is causing this if its not vapor lock? I'm going to make a metal shroud for the fuel pump this weekend in the hopes that will take care of the heat problem. Any advice appreciated.

Second issue is one that involves antifreeze exiting the over flow tube. Ever since I installed my heater, I notice a small amount of anti-freeze will come out of the overflow tube when the engine is run for a while. Its not much, maybe 1/2 an ounce(a guess), but I notice the frame member underneath the radiator is wet from this over flow. This never occured before the heater install. Is this simply that I added too much AF when I installed the heater and refilled the radiator? I filled to the correct height in the radiator, or so I thought. Again, any advice appreciated.

Could the vaporlock issue be negative pressure from the fuel system? I've seen cars with vented tanks which become clogged and then the system can no longer pull fuel against the vacuum. A truck with fording equipment blows pressure into the system to keep out water and thus provides positive pressure.

Yours could be partially blocked. A true vapor lock should be a positive pressure event which fills the line with gas vapor.

The next time this happens, remove the gas cap and see if it "breathes" as pressure is drawn in to equalize.

Or it could be that you haven't fed the squirrel lately.

refit1701;

I have given thought to what you say. I actually checked the fording valve in the fuel cap, which is in the open position. I didn't see fuel rushing back into the line after I removed the cap yesterday. I did notice the fuel bubbling as an old coffee pot would while the truck was idling, and I also notice a little sediment in the filter material. Looks like rust from the tank. Maybe there is a blockage someplace.

Ah, it may be a blockage then, as you say. If there is a vacuum being produced, something is blocked either way with the fuel pump acting as a vacuum pump.

I hope you find it!

Yeah i may pull the sender out of the tank tonight to check. Last time I had sediment in the filter, I was sucking fumes and the truck rna out of gas on the side of the road. The gauge says I have about 3/4ths of a tank, but it can't be trusted. Isn't disgnosing the vacuum cause but will tell me if the sender is accurate or lying its arse off again.

Do you have a heat shield over the fuel pump? sometimes a simple solution can solve a big problem!

GERALDO wrote:Do you have a heat shield over the fuel pump? sometimes a simple solution can solve a big problem!

Yes, I made a shield to fit over the pump since my truck did not have one, and the fuel pump is located in a weird spot. Only drove it once since installing and haven't really had time to notice whether it made a difference for not.

Nickathome wrote:

GERALDO wrote:Do you have a heat shield over the fuel pump? sometimes a simple solution can solve a big problem!

Yes, I made a shield to fit over the pump since my truck did not have one, and the fuel pump is located in a weird spot. Only drove it once since installing and haven't really had time to notice whether it made a difference for not.

"the fuel pump is located in a weird spot"

I think the shield on the exhaust is a good idea, but I also think you need one fabricated for the top of the fuel pump it self as a great deal of heat comes off the the exhaust manifold also. the original fuel pump has the heat shield on top! to keep the heat from comming down on top of the pump. geraldo

GERALDO wrote:I think the shield on the exhaust is a good idea, but I also think you need one fabricated for the top of the fuel pump it self as a great deal of heat comes off the the exhaust manifold also. the original fuel pump has the heat shield on top! to keep the heat from comming down on top of the pump. geraldo

Reckon you might have one in stock for sale at Aberdeen next spring?

NO I only deal in OEM PARTS !!

GERALDO wrote:I think the shield on the exhaust is a good idea, but I also think you need one fabricated for the top of the fuel pump it self as a great deal of heat comes off the the exhaust manifold also. the original fuel pump has the heat shield on top! to keep the heat from comming down on top of the pump. geraldo

one m37 i had had a heat shield that bolted on one of the manifold studs and sat right over the pump. as a matter of a fact i blasted it and painted it yesterday.

Hmm, the shield I made only covers the sides of the pump next to the downtube of the exhaust. As you can see in the picture of my engine Carter provided, the fuel pump is in a weird spot on this engine. I did not make anything to cover the top of the pump. I could remove the shield and weld a piece on. That will be my next adventure.

In the photo you can see one of the bolt locations just in front of the pump. Luckily I had another threaded hole behind the pump as well, so that's where I bolted the shield I made. I'll have to take a photo of the shield in place.

What condition is your motor in? My motor was running fine although it was pretty tired and burned oil. Then I started having trouble with vapor lock. I tried everything to try to cure it, but nothing worked. At the same time I noticed my oil pressure was a little lower. Then all of a sudden, I had a rod bearing go bad and that pretty much ruined the motor. I didn't realize it until it was too late, the probable reason for the vapor lock was that rod bearing was going bad and letting oil blow by and reducing the oil pressure, which in turn was reducing the cooling ability. This made the motor run hotter which caused the vapor lock. This may all be irrelevant for you if your motor is in good condition, but I wish I would have caught my problem sooner. Now I am in the process of replacing the motor.

All sorts of issues could be in play, if you haven't run a compression check, by all means do so. It will answer several questions & really get you in the know concerning engine condition. It will either let you know serious concerns are lurking or give you real peace of mind that your engine is good to go. Only takes a few minutes to do it.