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tylerbrowner

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Jul 15, 2019
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Hi I have a 1989 ford econoline 350. It has the 460 engine. I am on vacation and have serious engine problems. When I'm running down the highway it will run good for awhile then begin to surge and eventually die. This morning when it was cooler out side it ran great for 4 hours. Now that is 97 degrees outside it dosent hardly want to run at all. We have changed both fuel pumps and filter. We also changed and relocated the grey ignition module. Hopefully as it cools down tonight we can make it to a shop. Any ideas of what the problem could be?
 
Your problem might be Vapor lock.  The 460 engines are known for having that problem.

I had one and I eventually changed the exhaust system for headers.  Others have added heat deflectors around the exhaust near the heads.

Edit:  Great minds think alike...lol
 
I think vapor lock is a possibility. I'm stranded on a gravel road. in the middle of nowhere. I think I'm going to pull the hood off and see if it will get enough cooling while going down the interstate. Worth a try anyway.
 
Welp made it another 15 miles and now stranded on another gravel road. Guess im waiting till it cools down. Thanks for the welcome and the help.
 
Does gas line antifreeze help to prevent this. Believe I read this somewhere.  Although you may be in the south and would be hard to find any.


Bill
 
What might help possibly would be to wrap the fuel line in the area of the exhaust with some foil wrap to help protect it and somewhat insulate it from the heat.

The long term possible solution is to either make sure that you have heat sheilds in place and or install headers that run cooler and do not retain the heat like the factory exhaust manifolds.  Sometimes a booster fuel pump in line along the frame rail can increase the fuel pressure and help prevent vapor lock.

You also probably have a return line to the gas tank.  Make sure that it is not bent or restricted.
 
I had a similar problem with a ?92 460.  It was a clogged catalytic converter.

Hope your problem is only vaporlock.
 
Carb or EFI? I forget the exact changover in the different engines and models. It was around that timeframe. If it's a carb, I'm going with the vapor lock crowd. You mentioned two pumps, An in tank electric and a mechanical on the engine? Something else?
 
My moterhome is efi. We went to a shop in Colorado springs to check fuel pressures and found that it only had 20psi. We replaced the fuel regulator which was bad and it instantly made it idle much smoother. Thinking we had fixed the problem we headed towards Denver to get on i70 to start climbing mountains. After 2 or 3 hours of driving in and out of heavy traffic we broke down again. After 15mins of waiting on the sholder of an interstate I started it up and it ran like notheing ever happened. I drove to a friends house in Denver not willing to take the chance on driving up the mountins and being stranded. We have replaced the boost pump, the fuel filter, ignition module and fuel regulator. The in tank fuel pump is only a couple months old and has seen very few miles. It is very hard to diagnose because by the time we get to checking for spark or fuel it has fixed itself for another 30min to a couple of hours of driving. It definitely gets worse the warmer it gets outside. I need to get running right I have a 14hour drive home to southern Missouri. At least here in denver I have many more resources than the middle of no where Kansas.
 
I going to look into it being a catalytic converter. We started getting a pretty strong sulfer smell driving today. And it wasent from the propane.
 
Here are a couple of suggestions.

You have a schrader valve on the fuel rail on top of the intake manifold.  It looks like the valve on the A/C line that is used to refill Freon or newer refridgerant, is easy to unscrew the cap and install an inexpensive screw on pressure gauge so that you can see what your fuel pressure is at a glance.  That may be somewhat redundant because you probably can tell just by how it is running.

Another possibility is that you may have bad gas, water in the gas, something intermittantly clogging the pickup sock filter in the gas tank or a restricted fuel line.

Or you still might have a problem with exhaust heat causing your gas to boil and vaporize and not get much fuel thru the metal gas line that feeds the engine and goes right by the exhaust manifold.
 
Do you have an IR gun?  You can shoot the entire exhaust system and see blockages based on temperature. 

That's how I first saw an IR gun in use many years ago. Was at a muffler shop and the guy was under the car using it to find a blockage. 
 
tylerbrowner said:
I going to look into it being a catalytic converter. We started getting a pretty strong sulfer smell driving today. And it wasent from the propane.
Click to expand...

I am not saying that I am certain that the Cat convertor is not the problem,  However, you do know that when they checked your fuel pressure it was low at 20 psi.  I think that the problem is a fuel delivery problem of some sort and not a back pressure issue with the cat.

The screw on fuel pressure gauge will give you an instant verification of low fuel pressure and should not be too expensive.

https://www.ebay.com/itm/Fuel-Rail-Pressure-Gauge-Kit-with-Ford-Service-Port-Schrader-Valve-Adapter/301827212389?hash=item46464dc465:g:s3AAAOSwcgNZDMRO

You can get them at most auto parts store,  I put the link in to show you what they look like.

You can just leave it on all the time without any problem.  I have one on my Mustang all the time.

I would warn you that a muffler shop will love to sell you a new cat for lots of money.

The sulfer smell might be coming from the hot water heater, (rotten egg smell).  Try running hot water and see if you smell rotten eggs.

Good Luck, you will get there eventually.
 
I need to look it up, but I don't think the EFI models had two fuel pumps. Someone may have been trying to fix an issue and added one? Fuel pressure gauge is a must at this point. It'll tell you right away if you have a fuel system issue.
 
100% echo Huey's ideas. Sounds very much like fuel delivery.

Don't get hung up on it being the pump - it *could* be a blocked filter, clogged fuel line, pinched fuel line, or bad electrical supply (relay, etc.). I would not rule out the possibility that the replaced fuel pump fixed nothing, and it just happened to be coincident that you had 20psi before and (I'm guessing) ~45psi after... it could just be whatever was marginal recovered while the work was getting done. I had a Suburban that suffered a similar problem and it ended up being a short run of rubber fuel line back by the fuel filter that had swollen shut... I fought it for months!

Installing a fuel pressure gauge is definitely the first step, since it will capture everything associated with fuel delivery and let you know if you're still getting an "intermittent 20psi problem."

BTW, I'm assuming "EFI" in this case means port fuel injection, and not throttle body injection. GM stuck with TBI for a while, but I *think* Ford's stint with their throttle body injection (CFI was it?) didn't last long.
 
Try removing the fuel cap to let air into the tank in case the tank is developing a vacuum from a plugged vapor recovery carbon canister.
 
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