Aerostar Engine stalls, fuel pump wont quit running?

[12Footer]

My son-in-law has a 1992 Ford Aerostar with a wierd stalling condition we can't finger-out....<br /><br />The van runs intermittantly. It runs, but then, it stalls seemingly at will,making no difference to throttle position- (it's stalled at a traffic light while idling, when going a steady 20MPH, accilerating, and when tromping it). The wierd part is when it stalls, the fuel pump can be heard running constantly. The filter canister and fuel pump have been changed, thinking the fuel pump was running, but not pumping fuel. No improvement.<br /><br />Disconnecting the line comming into the filter, the pump runs briefly, pumping fuel, then shuts off.<br />Any ideas?<br />I'm leaning towards O/2 sensor, but the thing is 70buks, and would like to know for sure before sending this poor kid to the auto parts store for a new one. Can the CPU be "tricked" into thinking the O/2 levels are within range, as a 'cheap and dirty' test?

 

[mellowyellow]

Re: Aerostar Engine stalls, fuel pump wont quit running?

defective filter cannister? still got old one?<br />leaning towards O2 sensor too 12'.

 

[SpinnerBait_Nut]

Re: Aerostar Engine stalls, fuel pump wont quit running?

If the fuel line is loose and not hooked to anything, should the pump not keep pumping till it felt resistance and then shut off?<br /><br />I thought that is how they worked.<br />When they pumped the system full, they would shut off till they were needed again.<br /><br />I know that is how mine are.<br />I can hear them run when I first turn the key on, but after a few seconds they stop.

 

[Skinnywater]

Re: Aerostar Engine stalls, fuel pump wont quit running?

The O2 sensor will not cause an engine to stall.<br />A bad O2 will cause the engine management system to go into open loop.<br />Open loop is a rich running condition. Open loop at operating temperatures will cause the engine to not run at optimum, but not as you describe.<br /><br />I'd be looking at the primary or secondary ignition. Your symptoms are classic for the Ford duraspark module breaking down.

 

[Paul Moir]

Re: Aerostar Engine stalls, fuel pump wont quit running?

Fuel pressure regulator perhaps? If the problem ever turns up with the engine cold, it can't be the O2 sensors since no attention is payed to them until after warmup.<br />Put a pressure guage on the fuel rail and see what it's doing.

 

[kd6nem]

Re: Aerostar Engine stalls, fuel pump wont quit running?

My wife drives a 92 Aerostar with the 4.0 motor. I could almost swear the thing is haunted. Actually the first owner got tired of throwing money at it a pretty much just gave it to us as a gift. Had a lot of miles, though it did have a rebuilt engine. We've had this same problem with the stalling intermittently, and it runs rough at times; it does not like hard accelleration at all when it is in a bad mood. I've done most of the diagnostics I can myself (not many at all), and like the previous owner had it in the shop for diagnostics. Everyone agrees there is some unknown issue they cannot put their finger on. Honestly, the shops rarely can even get the computer to talk to their diagnostic systems even after new computer modules were installed. Since other electrical issues have been observed (like digital cluster display blacking out, and random beep alarms while driving, and false ABS alarms), I have come to the conclusion that the beast may have some grounding problems. It does seem to be worse on rough roads. Ironically or not, it still passes emissions tests with not problems. Ford did issue some service bulletin regarding some possibly related electrical issues, though not quite as specific as what we have experienced. Poor grounding is often the root cause of squirrely problems which get blamed on other issues. If all else fails consider this as a possibility. Hope it gets resolved much more quickly than ours.

 

[12Footer]

Re: Aerostar Engine stalls, fuel pump wont quit running?

Thanks for all the input,folks. One added point I needed to make but forgot is, that when it is in "run normal" state, the fuel pump does run when the ignition switch is turned on,and stops running when it reaches pressure (usually a couple seconds). When it decides it's time to play "road-block", THAT's when the fuel pump can be heard running constantly, but zero pressure at the rail.<br />Skinnywater, given this added info, would you still suspect the pri/sec ignitions?

 

[DJ]

Re: Aerostar Engine stalls, fuel pump wont quit running?

You are losing one or both of two things: spark and/or fuel.<br /><br />Borrow a fuel pressure guage and tie into the Schrader valve on the fuel rail. When it stalls, does fuel pressure go away?<br /><br />Also, use a timing light to detertmine if spark goes away.<br /><br />My inclination is that you are losing run circuit power. I would be looking at the ignition switch. Or, the power relays (fuel/ignition) under the hood. The same applies to Bearcat Powered's A'star with the 4.0.<br /><br />O2 sensors will NOT cause a stall condition.

 

[kd6nem]

Re: Aerostar Engine stalls, fuel pump wont quit running?

You know how to easily monitor this while driving 50 miles down a rough road to get it to happen again without using a computerized diagnostic monitor which won't talk to the system? I HATE intermittent problems!<br /><br />Actually the diagnostic computer issue should be able to be traced down with just a bit of perseverence, and if my hunch is right we might even fix the other problems at the same time. I really get the feeling that Ford did a lousy job with assembling the electrical on this beast. Now it is power windows, too. Not that there aren't cheesy trim, sliding door, and other issues. Guess I forgot that autos are just supposed to be automatically thrown away at 100K. <br /><br />12 Footer, I really am curious about that fuel pressure. I am not at all familiar with that system but wonder if there is a pressure transducer flaking out or perhaps even more likely the fuel pump is for whatever reason not able to deliver the fuel needed. <br />I no longer trust timing lights to tell me whether there is spark or not. They can amplify an exceedingly weak/virtually non-existent spark and still flash just fine. My preference would be to either use an inline spark tester or rig up some other way to see the spark for yourself. At least if there remains any question about the quality of the spark. I learned this one the hard way....

 

[DJ]

Re: Aerostar Engine stalls, fuel pump wont quit running?

Bearcat,<br /><br />You missed my point. NO computer diagnostic system is going to pick up a battery power loss to circuits. The diagnostic machines (NGS, WDS) just think you turned the key off.<br /><br />You have a major connection problem somewhere. I still think it is in the power relay area or an ignition switch.<br /><br />The power relay isue can be addressed by simply pulling them and cleaning them or switching them around.<br /><br />Ignition switches are cheap and easy to replace. You do realize I am not talking about the key switch? I am referring to the switch that the key operates, down on the column.

 

[Skinnywater]

Re: Aerostar Engine stalls, fuel pump wont quit running?

THAT's when the fuel pump can be heard running constantly, but zero pressure at the rail .<br /> Skinnywater, given this added info, would you still suspect the pri/sec ignitions?

Nope, sure wouldn't.<br />Given this added info, I'd have to be looking at the sock/screen/filter/inlet inside the tank. <br />Or the pre-pump if it has one.

 

[kd6nem]

Re: Aerostar Engine stalls, fuel pump wont quit running?

Didn't mean to half hijack here. DJ, I agree there is a major connection problem. But would the dumb thing run at all if the computer got the signal thinking it was time to power down? The things I see are intermittent, and my mechanic says the codes don't come up. But how can there be no power to the computer if it is running? What am I missing here? (I hope I am oversimplifying- I mostly understand the gist of control circuits, just not familiar with automotive ones, and certainly not this one) How many power leads do these modules have, and which are controlled by the relays?<br />If it is the power relay or ignition switch (electrical not mechanical portion) then it would be a really valuable tip indeed- best news I've heard in a while, really.

 

[jimr]

Re: Aerostar Engine stalls, fuel pump wont quit running?

does it act up more with less than say 1/2 tank of fuel? I have seen on some vehicles the small rubber hose that connects the fuel pump to the sending unit will crack and when the fuel level is above it will run ok below it and they will act up.like you said pump will run and no pressure. did this start before or after the pump was changed and what brand pump did you use?

 

[12Footer]

Re: Aerostar Engine stalls, fuel pump wont quit running?

I'll have to crawl under there and chjeck that hose to the sender. Can I get at that without dropping the tank again?<br />I don't know when the problem first surfaced, or what brand it is, as I didn't do the original work. His mechanic did that. But my best guess is it was changed-out because of the same problem.<br />How much pressure should the gauge read normally? I ask, because I'm using a water pressure gauge that ranges to 120 pounds.<br /><br />And I've found something that may be significant, and I need to go take a pic of it, and post the pic. It's a wire dangling from the ignition coil plug. This coil is mounted on the rear of the driver's side valve cover. There are three wires comming out of it, and the small, 28gauge green wire goes nowhere (?)<br />In the pic below, my finger points to this wire.<br />Please tell me Where do it go, y'all. <br />

<br /><br /> CLICK HERE IF PIC DONT SHOW UP