This is a strange problem that has been going on for 4 years now. It’s a little long and please don’t think I’ve lost my marbles. Here goes…

In the spring of the year (prior to May 1st), when we get a very warm day (70 or above) my 95 Econoline will not run 10 miles before it quits. I’ve talk to the local Ford shop and they tell me it is due to the ‘winter blend of gas’. ‘Let your van sit for a while then go fill up with gas’. Whenever the local stations switch over to the summer blend of gas my problems go away.

From all my research I’ve found out that the winter blend has a higher vapor pressure and the summer blend has a lower one. I’m sure there are other differences but the vapor pressure thing is the biggest.

Anyway, it starts out just missing real bad and some times will back fire. It really acts like its not getting any gas. If I leave it sit for about an hour, it starts right up and runs fine. It runs fine in the morning when it’s cool outside. Nobody seems to have a good answer. The Ford guys tell me it happens a lot but very few people I talk to has heard of this problem.

Has anyone got any ideas? I really need some help
95 Econoline
5.0 HO w/mass air

 

I would replace the ignition control module, also check for vacuum leaks. I do agree that the fuel has something to do with it, but I have never had a problem. It runs a little rough on the warmer days but never wants to stall.

 

Hi
Welcome to FTE

Does it seem to do it on all brands or just one specific brand ?
I had a toyota van that would not hot restart. The alcohol in the gas was giving it fits. Have you done any other repairs to it?

 

pfogal - I never thought about those 2 ideas. However, if I had a problem with either of the things you mentioned looks like my van wouldn't run right year round. My problems only occur in the spring. At times I think the van is vapor locking.

gasman - It doesn't really matter what brand of gas or what octane I run. The problem only occurs before May 1st on hot days or at least until I get a tank full of summer blend gas.

 

A drastic temperature change will do all kinds of wired thing tro electronics, I.E. going from 40 at 6 in the morning to 65 at 8, It creates moisture for one and if there is any moisture in the electronics it can cause problems. I would at least have them checked.

 

My van is going in the shop today. It is supposed to be near 80 outside today. They are going to let it sit in the sun this afternoon and drive it around until it starts acting up. I hope the guys don't get out some place and the van quit on them. But if it did they would see how bad the problem is.

 

Might also be the fuel filter is restricted. Winter gas kind of washes out the tank and all the gunk gets stuck in the filter. The filter flows enough gas to run when cold but if it gets too hot, the system may vapor lock since there is barely enough gas getting thru.

This is a real common problem with winter blends, especially if the filter hasn't been changed in a long time.

Jim Henderson