I have a 93 Aerostar with a 3.0 engine. I've had it since it had 4 miles on the odometer. It's acting a bit odd at idle. Almost like it surges and drops off. It continually does this. I unplugged the O2 sensor and there was no change. Mileage is horrific. I'm also getting a very loud buzz from where I suspect the fuel pump would be. That has gotten louder over the years. There are too many possibilities to throw parts at it. The check engine light is not on except for when you first turn the key like it should. I'm fielding any ideas.

surge

where do you think the fuel pump is?the fuel pump is in the tank on the aerostar.you probably have a bad idle air control motor.this is mounted near the throttle body go to autozones website and look it up to see what it looks like.these can make a buzzing sound also.could be alot of things.i am a proffesional mechanic in nj,let me know if you need more help,kevin

sorry i know i spelled professional wrong:

The buzzing is near the right rear cargo area. It sounds like it's coming from under the floor. Seems too far back and wrong side for the fuel pump though. The rear windshield washer fluid pump is back there. I'll check that to eliminate it. I was also thinking something on the throttle body. Strange there wouldn't be a check engine light since it runs so poorly.

I'm dealing with this on my 88 250 as well, it will idle nicely at first, then it wants to try to die and then will race. I did the IAC, now it seems next course of action is to check the TPS to see what it shows me. I'm more used to GM's systems, which don't behave like that for a bad tps, or even map sensor. These EECIV systems can be a pain sometimes...

surging

i just got to work and looked up where the tank is.you probably have a bad fuel pump or clogged filter.i would start by replacing the filter it is easy and cheap and see if anything changes.if you have access to a fuel pressure gauge there is a test port under the hood on the fuel rail pressure should be 35-45 psi key on engine off and 35-40 running.BE CAREFUL WHEN CHANGING THE FILTER THIS IS HIGH PRESSURE FUEL ESPECIALLY IF THE FILTER IS CLOGGED.the check engine light very rarely helps you with these early models.if you need more help let me know

I got the surging idle problem fixed. The IAC was bad. I bought a new one. The engine is pretty smooth now. I still have that buzz/hum from the cargo area though. We are about to get a blizzard, so the fuel filter will have to wait.

surge

its good when things work out.good luck in the snow ,kevin

78F250 said:

I got the surging idle problem fixed. The IAC was bad. I bought a new one. The engine is pretty smooth now. I still have that buzz/hum from the cargo area though. We are about to get a blizzard, so the fuel filter will have to wait.

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sounds like fun.

Oddest thing. The buzz/hum wasn't there today after I put some more gas in it.

Other Needed Repairs

Yesterday I replaced the sliding door. The original was jammed partially shut. A crowbar and patience resulted in it popping open. I had to replace it anyway. The whole thing was screwed up inside.
I pulled out the carpet in the back area and cleaned it, sort of. The front carpet I left in place and cleaned it. I put down some floor mats. I think that will help a lot.
The driver seat used to lean way back. Once I pulled it apart I found it was because the frame was craked. I pop riveted it back together. Seat covers made a big difference.
I pulled the instrument cluster out and replaced all the bulbs that were out. It was nearly impossible to see the speedometer.
The alternator was dead, so that was replaced.
I got the idle fixed by replacing the Idle Air Controller. It still needs a tune up and oil change.
The front bumper is beat up from sliding into a ditch. I might be able to save it though.
I took it off and gave it the once over. There is no saving this bumper.
The front upper and lower control arm bushings and shocks on both sides needs replaced. There is a thunk now and then going down the road. I've never done any suspension work before.
I almost forgot. I had to replace the turn signal switch. I cleaned the old one but the hazard light part quit working.

I still haven't done a tune up yet. The van is bucking going up hill. I figure new cap and such will take care of it.

Changed the cap and rotor today. The bucking going up hill has ceased. Wires and plugs are going to be a pain.

78F250 said:

Changed the cap and rotor today. The bucking going up hill has ceased. Wires and plugs are going to be a pain.

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why? they arent bad at all. actually one of the easiest things to do.

Not in an Aerostar. I did it once before.

I fianlly got up the gumption to change the oil, plugs and wires on the Aerostar. Those plugs are as much a pain as I remember. I measured the gap on the plugs I pulled out. The average was .060 and considereing it is supposed to be .044 it should run even better.