thomboz

I have a 2000 Express with v6, 140,000 miles, when the outside air gets over 90 degrees the motor stops. It might start for a minute or two and perhaps drive a mile or so, but it won't really go anywhere till the outside air gets below 90 degrees.
Its been doing this for 20,000 miles, I live in NorCal coast, so its not a problem unless I travel inland. I'm a carpenter and occasionally work it hard pulling trailers, etc... I've had it checked out by the shop with the best rep in town, they say it diagnostics fine. It shows no sign of overheating, and will restart for a moment with starter fluid, so it seems to not be an ignition problem. I do have a slight coolant leak (a quart of coolant every 1000 miles) that I'm trying to track down, but I keep the rad full and also the coolant reservoir.
I'm heading to Prescott in a few weeks to move Mom into a care facility and would like to be able to drive in the daytime.
Any help is appreciated.
ThomBoz

SWHouston

I think you have a Fuel Percolation problem...

I'm not sure just how much you know about cars, so...
Percolation is where part of the Fuel Line, is so close to something hot like a Manifold, that the heat is boiling the Fuel in the Line.

Also if you have a Heat Riser running through the Intake Manifold, if one of the Exhaust Pipe sides is restricted, that can cause the Carb to overheat (usually happens to older V8's so I'm not sure that it applies to your V6)

So...
You need to do a visual, all the way from the Tank to the Carb. If the Fuel Line is anywhere close to the Exhaust Pipe, you should re-route it some way.
This could have happened if the Line was replaced for some reason, and not routed properly, or possibly bent. But, the Engine Compartment is more likely, look and see if the line is bent or close to an Exhaust Manifold, just check it all.

Now to fix...
I don't know what fuel pressure your engine has, but, they make Flexible Fuel Line that will take those higher pressures. I'm not saying that you can't buy a piece of Metal Line and re-route it, but using the Flex Line is a LOT easier, and it dissipates heat better than metal. Plus, you can really get creative in the Route, with Flex.

thomboz

Thanks SWHouston,
Is fuel percolation the same as vapor lock? I'm 60 so I remember vapor lock, but I thought with 70psi of fuel pressure that couldn't happen? I've replaced a couple fuel pumps, the alternator, spark plugs, and power steering pump... so I'm a little familiar with my van.
I actually cut a hole in the van floor and installed a 'trap door' so I can now change a fuel pump in a matter of minutes.
ThomBoz

SWHouston

Thom,

HA HA HA, now that's what I call creativity ! (the trap door)

But yes, Vapor Lock is the same as Percolation, save that it's slanted toward what happens in the Carburetor, where as Percolation could occur anywhere.

If I can assume, that this does not happen in cooler months (winter), then I maintain that it is a Percolation problem.

I had this problem with an 80 Cadillac once:
I just bought 20 Ft of Flex Gas Line and some Airplane Clamps, and routed the Line outside the Frame as moved forward, came in the far left side of the Engine Compartment, and high up toward the Hood, and over to get to the Carb. I just cut the Metal Line just outside the Tank, and right before the Carb, and clamped the Flex onto the metal Tubing. Used Plastic Tie-Wraps to attach the Flex along the way. And yes, I bought too much Flex, but I didn't want to have any reason to pull it into a sharp bend and restrict the flow, or be forced to come anywhere close to anything hot. Just got it as far away from anything hot as I could.

Now, if I'm right about this...
It'll probably cost you just under $40 to "try" this.

But, I just can't think of anything else that would cause the problem.

S.W.