I have a 95 Aerostar that I'm having a problem with. In hot weather when the van in under a load (such as going up a hill with the AC on), the engine will quit as if it has run out of gas. It will restart for about a second and then die again. If I let it cool down for about an hour it will restart and run fine for a while. I have changed the fuel pump, fuel filter, mass air flow sensor, crank sensor, and ignition module. None of these have solved the problem. It seems that it is a fuel problem. It occurs more with a low level in the tank than a full level.
Does anyone have any ideas what this problem may be?

Thanks!

 

You've replaced all the logical culprits and then some. This is just a shot in the dark, but I'm wondering if you could have a vapor recovery system problem that would be generating sufficient vacuum in the tank that would be offseting the efforts of the fuel pump. Next time this happens, before trying to restart, open the fuel cap and see if there is a large vaccum present. (There is generally a mild vacuum anyway, especially on a near empty tank). Presence of a heavy vacuum would indicate a carbon canister or other vacuum routing problem in the recovery system. Releasing the vacuum should allow the engine to start and run as usual - until it reoccurs. As the vehicle sits for an hour, the vacuum bleeds off. Just a thought!

 

I have taken the gas tank cap off when it won't start but no help. When I open it, there appears to be a pressure on the tank, not a vacumn.

 

Is this a 3.0 or 4.0l engine in question? Does this happen around town (i.e. short trips) or just on the highway? Do any
indicator lights come on before or during these episodes? Lastly, has the van ever been hit in the rear or sustained damage that may have affected the fuel cut-off switch?

 

It is the 4.0L engine. In all instances, it has been on the highway after more than 30 minutes of driving. No indicators come on before an episode. After the engine dies, the normal lights come indicating the engine is not running.

I bought the van when it had about 50K miles on it. It now has 170K miles. As far as I know, it has never been a wreck at all or rear damage.

The problem only occurs when the temp is around or over 90. I live between Denver and Colorado Springs. In all but 1 case, it has happened when I was going up a long climb with the AC on max.

At this point, I'm not sure if it is an electrical problem or a fuel problem.

I want to drive it the next time the temp is around 90 and have a can of starting fluid with me. When it dies, I want to see if it will restart on the starting fluid. If so, I think it would point towards a fuel or fule system problem.

Danny in Larkspur, CO

 

[font size="1" color="#FF0000"]LAST EDITED ON 22-Aug-01 AT 07:46 PM (EST)[/font][p]Well, here's another shot in the dark. How about the next time it happens, spray some of that electronic parts cooler on some of the ignition components like ignition control module and see if it starts up. Other things to do would be to tap some of the relays, like the fuel pump relay or the computer relay and see if that makes any difference. One other thing that you can do, if you have a code scanner, is to scan for the code that tells you if power to the computer was lost. This code does not light up the check engine light so you wouldn't know unless you scanned for codes. Then, if the code was there, you'd have the tough job of figuring out why.

This sounds like a tough one. Good luck and post back with results.

 

You mentioned replacing the fuel pump. The fuel pump suction pickup filter was replaced at the same time, wasn't it?

Your problem sounds almost like vapor lock. But with the fuel injection systems fuel recirculation, that's very unlikely.

It's also possible that the fuel pressure regulator is going bad.
Has a fuel system pressure test been performed?

Just some more thoughts.

-Mark

 

Yes, the fuel pump suction pickup filter was replaced at the same time as the fuel pump.

Even before I replaced the fuel pump, I had a fuel system pressure test performed. It showed everything in good shape. The problem with this is that when the test was done, the van was running fine. I need some way to diagnose the problem when it dies and won't restart.

Any suggestions?

Danny

 

What is a code scanner and where can I get one? I need some way to diagnose the problem when it dies. Unfortunately, this usually along the side of the Interstate with no mechanic around!

 

[font size="1" color="#FF0000"]LAST EDITED ON 23-Aug-01 AT 03:33 PM (EST)[/font][p]A code scanner is a gizmo that you hook up to the computer to find stored fault codes. I have seen two types. One type is just a scanner with some LEDs that will flash and you count the flashes to come up with a code number. Then you have to look up the code number to figure out what it means. This type costs about $40 or so. Actron makes one. The other type will not only give you the codes, it will translate them so you don't have to count flashes. Also, it can display various sensor readouts and I believe some other engine parameters like injector pulse width. This type is more expensive. The Auto X-Ray is an example and costs about $170. Check out http://www.autoxray.com/index.htm for more info on their product. Disclaimer: I am not endorsing (nor have I used) these products as I have been fortunate enough to not need one (so far).

Note that you may not get any stored fault codes if the computer loses power. On OBD I systems, the faults can be cleared by removing power.

You should be able to get either type scanner at Checker/Schuck's/Kragen, Pep Boys, etc., and I think Summit Racing even carries some.

 

I have used the simpler flashing light scanner and find it rather confusing. You don't get just a single code but a multiple coded sequence of flashing lights that is so long you can't tell when the initial code stops and when it begins to repeat. I would be curious to know if the readout versions are worth the extra dollars.