VAPOR LOCK

[TOMMY47]

I'm experiencing what I believe is vapor lock in my 1990 E350 Class C.
Happens when I climbing hills, especially when it's hot out. I can see the engine temp gauge rise and start looking for a wide part of the shoulder of the road. 10 minutes of cooling down and I'm on my way again.
In looking on line for cures for VL, I have not seen any that involve changing the thermostat out for one in the 180 degree range. Not sure, but I probably have one in the 190-195 range. The engine is always running right in the middle of the temp gauge until I start up a hill.
Wouldn't having a lower thermostat result in lower heat transfer to the gas line/forward fuel pump, thus preventing VL??
Any other suggestions would also be appreciated.

[mchero]

Thanks for the update TOMMY47. Great ifo. for others having the same issue.

[time2roll]

:B

[TOMMY47]

Good news, so far. Drove up I25 from Colorado Springs through Denver to Loveland.
Had a few long hills where I was in 2nd gear with the engine whining away and the temp gauge creeping up--No issues at all. Later at a traffic light in Loveland the temp spiked real high--again, no issues.
So far, it looks like the reflective tape shielding is doing its job.

[TOMMY47]

Well, I don't have the expertise to start dismantling things 1500 miles from home, so I am not pulling filters now. I did wrap the fuel lines with a metal reflective tape that is supposed to prevent 90% of the heat from reaching the lines. Tomorrow, I'll find out.

[93Cobra2771]

j-d wrote:
Does that filter look like one of the ones in this pic? Proabably the uppoer one?




...snip...T-Bird, with early TBI, did not have a Mass Air Flow Sensor. It did have an Air Charge Temp Sensor in one branch of the Intake Manifold. It's a Thermistor, and a Cold Engine caused a High Resistance, which increased the Pulse Time to the Injectors, like Choking a Cold Engine. This was happening on the road, and the car would slow down, sometimes stop, in a cloud of black smoke. So rich it couldn't keep running. Not saying this is happening to you now, but it's a condition I ran into that sapped the engine's power.

Tbird didn't have MAF, but did have a MAP sensor with its speed density system. The ACT alone is not enough to throw serious fueling issues like what you are talking about. ACT is a "modifier" for existing fuel/spark tables and can only sway things a little each way...

Irregardless, I do agree with your comments about the fuel filter and it's ability to flow air when blowing through it. It was probably gummed up pretty heavily...

[da_bees]

ReelTime wrote:
Tommy,
There was no overflow radiator tank on my unit and the water level in the radiator was (with the radiator cap removed, engine cold) around 2 inches from the top when full. The radiator itself was the expansion tank for that year model.

The "expansion tank" subject appears to have various opinions and different set ups on various vehicles.
Any cooling system benifits from haveing an expansion tank more accuratly called a coolant recovery system. It's possible that aftermarket body prep/rv vendors fail to reinstall the tank when thier work is complete. In any event you should make certain one is used even on older vehicles and stationary engines. If yours doesn't have a tank or has a tank where coolant level doesn't rise when hot and fall when cool,check the radiator cap. The cap must have a gasket rather than metal to metal where it contacts the filler neck. For best preformance,the tank should mount near level with radiator cap and of course be connected by leak proof hose. The tank automaticly purges air (same as manual proceedure explained above by Simplygib) on every heat cool cycle. Just add water if tank is less than 25% full when cool.
The benifit is less pump cavitation,no air bubbles insulating between liquid coolant and metal of engine and radiator which henders heat transfer.
I don't think this is the issue with Tommy's rig but is simply a link in the chain of cooling events that some might not be aware of.
However,I believe the overheating should be addressed first. The lose of power may very well clear up becaues we know a hot engine doesn't perform well.

[YC_1]

Since you found the filter below the driver did you replace it?

Take it off and try to blow through it. Those filters were supposed to last 100K miles per the manual but mine was blocked with 11K miles. The big issue was not mileage but years. Most folks don't put many miles on an rv and they can get plugged just like carbs due to fuel varnishing.

I chased the same problem for a couple of years before the in tank fuel pump finally really started acting up and I had to replace it. Found that fuel filter plugged so bad I couldn't blow through it.

Hot days, hard pulls, both would cause vapor lock symptoms.

[j-d]

Does that filter look like one of the ones in this pic? Proabably the uppoer one?



The upper is "early model" like our 84 TBird and 97 Aerostar use. The lower one is from our 02 E450. Just as a note, either will replace the other, but the connections are different. Lower to replace Upper is OK, but Upper won't allow access to the disconnect tool (shown at right) once it's installed in a newer vehicle.

I took one of the old-type filters off the T-Bird and about couldn't blow through it. Red in the Face and enough air came out to blow a few bubbles. Tried a new one at the auto supply and I easily blew dust around on the floor. I can't prove it but I believe a restriced filter can wear down a fuel pump.

T-Bird, with early TBI, did not have a Mass Air Flow Sensor. It did have an Air Charge Temp Sensor in one branch of the Intake Manifold. It's a Thermistor, and a Cold Engine caused a High Resistance, which increased the Pulse Time to the Injectors, like Choking a Cold Engine. This was happening on the road, and the car would slow down, sometimes stop, in a cloud of black smoke. So rich it couldn't keep running. Not saying this is happening to you now, but it's a condition I ran into that sapped the engine's power.

[Krusty]

If that canister does not have a filter installed in it, there should be a dip tube in its place that reaches down near the bottom of the canister. Make sure the dip tube is in place, or it will have a tough time drawing fuel up.

[time2roll]

TOMMY47 wrote:
Also noticed that the last foot or so of fuel line was pretty close to the engine. Someone put about 1 inch of heat reflective tape on the line near the engine. I'll get enough reflective tape to cover that whole area and see what happens.

I would wrap this entire portion of the fuel line with some type of foam. Maybe some foam insulating wrap for a copper water pipe.

[ReelTime]

Tommy, It was just a canister type fuel filter mounted to the rail, no electrical wires at all. Only a gas line from the tank and a return(by-pass) line back to the tank. The "O" ring gasket is all I used out of the fuel filter I bought. The old one was mashed flat and if it leaks fuel the engine mounted pump could just be pulling in just enough air to cause fuel starvation?

93 cobra is spot on the only sure way is a short term fuel pressure monitoring system.

There was no overflow radiator tank on my unit and the water level in the radiator was (with the radiator cap removed, engine cold) around 2 inches from the top when full. The radiator itself was the expansion tank for that year model.

The fan has a temperature activated clutch but when cold the fan would turn a little when cold but not free-wheel.


Remember this is from only my experience with that motor and I am by no means an expert but if it helps that is good.

[ReelTime]

Tommy,
If I am right in my assumption that that small tank actually acts as a "reserve" fuel supply when the engine is in high demand you will need a larger fuel filter than a stock one. Remember the carburetors of that time required 4 or 5 pounds of pressure versus the 40 + pounds of pressure that fuel injection engine requires. I had two fuel pumps one in the single 40 gallon gas tank the other at the engine. I replaced the one in the tank.

And do not over-think the "running hot' thing, use something other than the gauge to determine what hot is. Been their done that more than once according to my wife.:)

[93Cobra2771]

The guesswork of whether fuel filters and fuel pumps are faulty would be solved by checking the fuel pressure - a remote gauge setup so you can watch fuel pressure during the event would be ideal.

I figured it was early EFI 460 but didn't know for sure.

Find the spec for your fuel pressure and watch it. If it starts dropping under load then you will know it is a fuel supply issue.

Reel time is probably spot on with his experience, but it never hurts to verify before throwing parts at it.

[TOMMY47]

Reel time --crawled underneath near the driver's door. Found the pump and what looks like a fuel filter, not in a black case, just connected directly to the line. Also noticed that the last foot or so of fuel line was pretty close to the engine. Someone put about 1 inch of heat reflective tape on the line near the engine. I'll get enough reflective tape to cover that whole area and see what happens.
Also checked the radiator as well as could be done. Not a whole lot of junk there. Would using a power washer be SAFE and a viable way of cleaning it out?
Not necessarily full pressure up close but from a distance.
Turned the radiator fan. It did not spin but was moveable.