Hi all,

I have a 1988 F-450 with the FI 460 engine. It suffers from vapor lock when I shut it off for maybe 5-10 minutes. It is so bad that I sometimes crank my battery down and wonder if I will have to need a tow. If it sits longer, like 1/2 hour, then no problems.

It has those amber colored plastic fuel lines with an unusual type of quick release couplers that the factory used, and the fuel lines are covered with an insulating material and then aluminum foil. Looks like it should work but it doesn't. And I live in Washington State with usually cool temperatures and even so it vapor locks all the time.

Anyone experience this? How did you solve it?

I also want to toss the catalytic convertor since the truck no longer requires emission testing. I am sure the cat is plugged up (and very expensive) and I would like to replace it with a "test pipe" if I can find one. If not, I will fab one myself. Anyone know of a test pipe available for this vehicle?

Thanks for the help.

Randy

 

Super unlikely your truck is suffering from vapor lock.

I'd verify that you still have spark and injector pulses when it does its no start thing.

 

I had an 88 Bronco II that did the same thing. I thought it was vapor lock at first too, the problem started in the summer here (95+ degree heat, 1000% humidity sometimes) and was similar to yours. After driving a bit, I'd shut down and then she would crank, fire, and idle just fine. And idle as long as I wanted her to, for that matter. The problem would usually happen after refueling so one time after buying gas I just let her idle in front of the pump so at least I could break down somewhere shady, but it just kept running. But hit the gas and drive a few feet... HA, not happening. Engine would die and refuse to fire until I let it set there and cool for ~30-45 minutes. I figured vapor lock because every time this happened, I didn't smell any fuel vapors in the exhaust, so I figured it wasn't getting any fuel. Didn't have any tools with me to check for spark because I had sold a lot of them to try and pay my rent on time and at least keep my house (didn't make it). I was broke back then going thru a divorce, so there went my wife and stepkids, and she also managed to "lose" my 1 year old German Shepherd, and so when the truck started acting up I was just like "hey whatever, add it to my list of "...

So long story short, I believe what was really happening was either the PIP or ICM was getting hot (heat soaking after shutdown) and since the computer can't fire the injectors without the PIP signal, I had no fuel. When it cooled down the signal would come back, and I'd be on my way.

I really think that's what the problem was now that I understand how it all works, but never got the chance to actually verify this before the engine and then the transmission took a dump. That truck was my daily driver but I beat the ever-lovin' tar out of it in the mud too.

Oh and something else I learned... no matter what happens, NEVER sell tools or guns to pay bills! You'll miss them later on... or at least I did.

For your exhaust, don't bother looking for a test pipe. Go to NAPA, they sell exhaust pipe in 10ft sections (AutoZone and the others only sell like 1ft long sections) and cut a piece to fit. Clamp or weld it in and be done with it.

I'm trying to remember how the exhaust is on 460 trucks, does it bend to clear the crossmember right after the cat?

 

It's simply not possible to vapor lock the EFI fuel system since it is a return type system that is constantly circulating a high volume of fuel between the tank and engine.
The 1/2 hour cool down required before the engine will refire is a classic signature of the TFI heat failure problem and the reason it was moved from the distributor on early models to the fender on later models. So change it out with another but try to find a used or NOS MotorCraft module because aftermarket modules have a terribly high early failure and DOA rate.

 

Pip in the distributor was the culprit on my 97 f350 460

 

Problem with the 460 exhaust of this year is that two pipes go into the CAT and only one exits. So if I pull the CAT out I will be faced with making a transition piece which I would rather not do because I have a ton of other things I need to get done. But I may have to I guess.

Randy

 

What means PIP and TFI? I bought what I call an ignition module that fits to the side of the dist. but have not installed it yet. It is an Accel module so maybe it isn't total crap?

Randy

 

Run dual mufflers. Have the muffler shop weld them together and put some extra hangers to support the weight

 

The pip is the pick up in the distributor

 

The PIP is a module inside the distributor that tells the computer which cylinder is at top dead center. The TFI is the module on the side of the distributor. It controls the ignition coil, and sends the PIP signal to the computer.

I'm not 100% about 460 distributors, but some distributors require complete disassembly to change the PIP unit, so its often easier to just get a new distributor.

Try the TFI module you bought first, and see how that works.

 

Here's how I did mine.

 

Here's how I did mine.

 

My last truck don't blast me but it was an 03 Chevy 2500hd ccsb 4x4 lt 8.1l 12/10 lift on 38's. Dual flow master 2 chambers welded together true dual exhaust. The only thing I wish they did with the exhaust was put in an x or h pipe to

 

The way I gutted my cat and have 2-in-2-out kinda works like a X pipe.

 

Well, what I have going is a really large single muffler intended for a motor home, right behind the Cat. I think maybe the muffler is a Turbomax and it seems to flow well. But at any rate, it is large so I was hoping to retain it since it is pretty new. But I have read that the 460 responds well to large diameter dual exhaust, and headers, but I am not sure that tossing the big muffler out and doing dual would net me that much? This is a flatbed dump and it can haul a lot of weight but the gas mileage is terrible, like 7 MPG. And it pulls pretty weak for the famous 460. I am really disappointed. I could do dual exhaust with smaller mufflers and scrap my investment but is it worth it?

Also, is the stock air cleaner setup all that great? Could I net some significant HP with an aftermarket unit? This engine needs a transfusion or something. It is factory new with only 30k miles on it.

Thanks,

Randy