ok granted it is hot here in Boise Idaho. But my 1989 f-250 460, 5spd, 4x4 keeps choking out. I was told that it was vaporlocking. What all causes vaporlock. Also when I switch tanks it dies. What do I check for the tanks? Sick and tired of guessing. What do i do? I am so overwhelmed. Somebody help please

 

Hi there 91FordBaja and welcome to FTE! I've never had that problem myself, must be lucky!
From what I understand.. Heat plays a large part. I've heard of guys moving their fuel lines, after they've insulated them, away from All sources of heat. Be it the exhaust, running under the cab and bed to re-routing the fuel lines away from headers, even stock manifolds.
Your 89' has a canister also that may be plugged or it's usefulness has expired. Some are fairly inexpensive, but you should use the same type that you are running now. It's mostly layers of charcoal that filters the return gases back to the fuel tank and to be burned off in the engine.
Some of the time, it's caused by a return line or vent that has collapsed near the tank or between tanks.

One of our Forum users, posted last week about this and was hauling a trailer when it happened to him. He removed his gas cap- v-e-r-y slowly and could actually hear the fuel boiling in the front tank!

I hope this has helped in some way. Somone will come along shortly to give you some other in-sites or experience in this matter.

OK Guys, he said Please, so lets get to work!!! Talk with you later....

 

Like scooter29 said, vaporlock is caused by heat. The fuel in the fuel lines boils into a vapor and the vapor "locks" the engine up since it cannot be pumped or injected into the engine. It sounds like you have some other issue at hand if you switch tanks and then the truck dies. I would go get a fuel pressure guage and see if you are getting the right pressure to your fuel rail. Then check to make sure all 3 pumps are working properly. There is one in each tank and another on the frame rail after the tank switching unit located in the drivers side frame rail. Check the fuel filter on the fram erail as well, could be clogged up, restricting your fuel supply. Good Luck!

 

I have never heard of an EFI engine vapor locking. Carbed engines can (I've had it happen). It usually happens when you shut down hot and the fuel lines heat soak for a bit and then you try and start up. An EFI engine has fuel constantly passing to AND from the engine while the engine is running so I doubt it could get hot enough. Our engines had a problem with fuel pressure regulation and I believe there was a service bulletin out on it. Check fuel pressure in the fuel loop. There's a fuel pressure regulator that is a common fault. Mine had the same problems by a previous owner and that was the culprit.

 

Thanks rabidranger and drool! I've only heard of FI vapor lock senario's, never seen it, yet. Lots of good ideas coming in! I am under the assumption that 91FordBaja had done a pressure test and was looking for other options. Hopfully he can check out the ideas we have given him already, before the flood of responces start coming in! HEE HEE! Talk with you guys later....

 

yeah it did it again today. I haven't checked fuel pressure yet, but will do immediately. When it locked up on my, I turned the key on to get pressure into the fuel rail, and then bledd off the pressure through the schrader valve. Dang it was scalding hot. I got it running after 20 min. and drove home. On the way home it was wanting to do it again, but I just kept my foot pumping the gas. It tries to die at 30-40mph and then is okay. Also when I put my foot all the way to the floor it tries do die. My temp gauge runs at N on normal. Could it be that I have a bad ect sensor, and I'm overheating? I mean the fuel rail is on top of the engine so could it be getting hat that way? When I bleed the fuel off of the schrader valve, I get more air than fuel. What if it happened at night when it was cool? Could there be something I'm missing? Hey thanks alot for the quick responses. I appreciate it. You guys are awesome

 

More air than fuel??
That has me scratching my head..

The first thing to do is get the fuel pressure tested I have a feeling it will be fine, maybe more hopeful than anything though.

If the fuel pressure pans out okay then I would start checking for codes.

What I have found on mine when it acts up like that when the motor gets good and warm, is the Ignition Module is going out. A very common problem with these trucks. Not saying this is your problem for sure but something to consider if the wires/plugs/cap and rotor are all in good shape.

Good luck!

 

Hey guys! I've never have ripped one of these fuel pumps apart. Anyone else have? I've also considered the pressure regulator. Is that a diaphram type? I know we just throw these things away, since they aren't serviceable, but someone must know. With air being pumped with the fuel.... Could the transfer pump be operating at the rear tank and just pumping air, instead of fuel? I mean, could there be a short somewhere, thats making this senario happen? Don't fret, we'll beat this thing! Well, we'll fix it anyways... Talk with you guys soon!

 

The fuel pumps won't pump air, but a pinhole in the lines will allow air to get in.

 

The regulator is a spring piston type affair. It's a throw away. I was looking at my service manual last night on this subject (briefly) and apparently there's low pressure pumps on the tanks and the pump that pressurizes the fuel loop is on the chassis. It's the high pressure one. This could be a problem too I suppose.

It sure sounds like you have a fuel pressure problem of some sort but that's just my opinion.

 

Check that all the pumps are working, use the haynes manual to do this. They have a good test procedure. If any of the pumps are bad, replace them, If both in-tank pumps are bad, the high pressure pump can still syphon gas out of the tank that had the the good pump last (even if the pump is not running). But without a pump to turn the selector valve, only one tank will operate correctly, Also check your fuel level when this happens. If the tank your running on is less than a 1/2 tank when it dies, you may have a weak pump or the gas is recircluating in the tanks not going to the engine, because the selctor valve may not turn completely and enable it to pump directly to the return line,
(had this happen on a 87 w/dual tanks and 300cid-6.) Fill the tank back up and see how long you can go before it dies.

 

Great stuff!! Is there a way to save all this stuff to my computer?
I'm running out of ink! HEE HEE! Talk with you guys later....

 

hey sorry it took so long to back to you I injured my back and have been out of service. First off I would like to thank everyone for all there support in trying to help me fix my problem. This weekend I was able to finally work on the truck. I attempted to drive it and the problem was worse. However, I found out that the smog pump was siezed up, so I replaced it. I pulled codes and got 33 which is the EGR valve. The fuel pressure checked out, but I replaced the high pressure fuel pump anyway. I replaced the fuel pressure regulator, the fuel pump relay, and the vent line from the tanks to the carbon canisters. The vent line was plugged completly to the "Y". Could the EGR valve be the problem now? It still bucks like crazy then dies. When I try to open up the throttle the whole way it bucks badly. Could it be the dual function resevoir? I'm getting sick and tired of getting towed around behind a chevy all the time. Thanks again

 

Ya' know, my experience with Ford pik'em'ups is very limited, but it sounds an awful lot like a !@#$%$%^% cat. You can try pulling the O2 sensor out ahead of the cat, firing it up, and seeing if it runs more gooder. Just mho.

 

Hey there 91FordBaja! Glad you're feeling better! I had back surgery in Jan., But thats anothe r Forum!
The EGR's function is to bring in exhaust gasses into the intake manifold. All EGR's operate on a vacuum.... There are different types of controls to turn the EGR valve on and off.

An important note: From the Chiltons Repair Manual;
All EGR systems are designed to cut off exhaust recirculation when the engine is cold, at idle, or under Hard Accelleration. If the EGR valve is stuck open, the engine won't idle.

Different tests can be performed to check the operation of the EGR. If you have an inspection mirror, thats the quickest. See if it operates under accelleration. A manual vacuum gauge hooked up to the EGR port. It should hold the vauum at 3-5hg.

Hope this helps. We'll keep trying not to spend your money!
Talk with you later....