I have a 95 aerostar with the 4.0. After driving a while it wants to lose power. It only happens after the van has been running for a while, at least 2 hours or more. So of course I have mostly noticed it at higher speeds because I was on the interstate going a long distance when it happened most recently. But it has also happened at lower speeds, after the van had been running/driving for about 4 hours. The van doesn't die right off. It is idling as the van slows down. So I can come to a stop, and the van is still running. I can get out and look at it sometimes, it eventually will cut off. Pushing the gas does nothing, other than perhaps encourage it to stall sooner. It is a complete loss of power but the engine remains running at an idle. If I wait 15 minutes it will go a couple more miles down the road. If I wait about an hour, I can get even further. Let it sit overnight and it seems like it will drive endlessly but not so.

Any ideas or opinions?

If I try to restart it immediately, sometimes it will run/stutter for a moment. I can wait a few minutes and it will run for a minute then die. After repeated tries to get it to start and stay running it just won't, and then I just wait patiently for an extended amount of time (30 minutes or more). Also on a couple of occasions the exhaust has smelled very rich, and sometimes was black. All of this has been in the last couple of days and 600 miles.

It isn't throwing any codes.

 

Probably not the main problem, but has the fuel filter been replaced lately? It's pretty simple and relatively inexpensive. Next question is what condition are the spark plugs? I recently had a plug or spark plug wire fail on me and it had less than 20K miles on them. Another area to check is fuel pump pressure, either with the pump or the pressure regulator being the culprit. Ignition could also be having heat soak problems.
A couple of years ago, I had the mass air flow sensor fail on my '94 4.0 and gave me all kinds of driveability problems. It threw codes (LOTS of them), but none of them pointed to the real problem.
With out anybody else being there, we will just be encouraging you to be a parts replacer.

 

I once had symtoms like this that was caused by a bad tank of fuel. Also the temperture was very hot at the time. I can remember sitting along the interstate waiting for the engine to start and run long enought to get out of the sun.

 

Fuel pump or filter..Most likely pump..IMO. I would check pressures.

 

Yup, time to run some tests. Sounds like a fuel pump to me, thats what most of my pumps that went south in the past did. Most were associated with a whining or buzzing noise from the pump, but the last pump that went south on me was still quiet. I would recommend the Motorcraft unit despite its cost. Since you report the problem after hours of driving, it sounds to me like you can make it a while from home or your rely on your vehicles a lot. You don't want some cheap aftermarket pump going south on you in either of those conditions. If someone could actually find a good alternative pump, that would be great, the problem is so much of the stuff on the market is garbage made in China. I have not tried the Bosch pump, it might be better than the other stuff, though I'm not assuming that because of the brand. The Bosch might be made in Germany, US, Canada, or Mexico. And AC Delco pump might be good if you can find one.

In any case, if you can find a way to test the pressure when it is acting up, that will go a long way towards sorting what is happening.

 

Is there a fuel gauge hookup on the Aerostar? like a shrader valve?

The fuel filter was changed about a month ago, according to the gentleman I bought the van from. He warned me about it stalling. Said it had happened once five years ago and twice this month. But I didn't inquire as to his driving habits so he might have very seldomly driven it that far.

I put two tanks of gas through it, so I don't think it was just bad gas.

What stinks about testing it is that I have to drive it four hours before it acts up, LOL.

The truck is also in New Mexico, as I bought it for my friend, and I am back on the east coast. I will be returning there at the end of November, so I want to get together a list of stuff to take with me so I can hopefully fix it and be done with it. I am going to try and collect some spare (used) parts in case it turns into a "change out parts until I find the right one" fiasco. In the meantime I figure he can use it around town (which is his primary need) and perhaps whatever is wrong will break completely. Its always easier to fix something when it is totally broken instead of randomly intermittent.

Checking the fuel pressure was the only real thought I had. And perhaps the voltage going to the fuel pump also.

I appreciate the thoughts. If anyone can give me a heads up on the location of fuel pressure port that would be helpful.

thanks,
ray

 

There is a schrader valve on the fuel rail near the front passenger side. It is not easily visible, and you may have to feel around behind the snorkel or heater hoses to get to it. But I recall it was accessible with the snorkel on, as i was able to run the engine with the pressure gauge in place.

 

On the 4.0L the schrader valve is on the passenger side. It is right behind the fuel pressure regulator, which is right behind the upper radiator hose. You may have to remove the plastic cover from the throttle body to get better access.

It is often nice if you can access the gauge from inside. You can run it through the doghouse.

 

check/clean the mas.

 

So did you find the prob?



Dick

 

I'll throw one out there that hasn't been mentioned. It's simple to check. Next time it happens, take the fuel cap off and see if it gets any better. Maybe there's a vacuum building up in the tank as the fuel level decreases. A plugged / restricted tank vent would be the cause. Something in the evap system could be messed up. Just a thought.

 

I would replace the sending unit as well if I was dropping the tank to do a new fuel pump... you know darn well that if you don't, you will have to have it done sooner then later, and might as well do it when the tank is down....