91 ford aerostart will start but not run

[Soundguy]

Wife has an old ford aerostar minivan ( 3L v6) that is cargo'ed out. We use it to haul musical gear to gig's. Gets run about 1 per month. Long story short. aftermarket (sony) cassette deck in it went bad and killed the battery dead flat. Amazingly, the 39$ walmart battery came back to life and cherged back up. Van will crank over good, start, and then run about 1.5-2 seconds before stalling. Will immediatly recrank and then stall again.. Will do this as long as you want to start it over.

When you turn the key on, everything sounds about normal.. fuel pump runs for a couple seconds .. etc.

Check engine lamp does not stay on, and no codes are set on the ECM.

Has plenty of fuel.

Ideas?

I'm thinking either fuel pump for FI not coming back on, or crank sensor not working so turns FI pump off.. or something along those lines.
\Hate to spend money to drag in an old beater to a mechanic for a diagnosis.. any ideas guys?

thanks

soundguy

[podagrower]

Did it run well before the weather turned cool (I would say cold, but it is FL)
My truck (97 Dodge) will not idle when the weather turns cold, until it has been driven several hundred miles and the computer gets used to the change in air density.
A 91 will have OBD1 (I think), which may not turn up codes until vehicle reaches normal operating temp (I think)
Can you keep vehicle running by keeping your foot in the gas?
Cam sensor? Crank sensor? Mass air flow sensor?

[karman 4564]

sounds like a clogged fuel filter

[RonMar]

That sounds like a "hard fault" scenario and even OBD1 should throw a code for that. But Podagrower is correct that some will not be stored till normal op temp is reached.

How exactly are you checking for codes? I used to have a 96? that was right at the changeout between OBD1 and OBD2 and you could still jumper a test connector under the hood and read codes in the form of check engine light flashes. I think a 1-1-1 was all clear, no faults but I got rid of my reference info when we traded in the vehicle.

IF no codes are stored, first off I would pull the battery "-" terminal and let it set for a few minutes to completely clear the ECU memory just in case something is confused. While the battery terminal is off, check all under hood connections you can reach for proper connection, then try another start and see what happens.

How did you charge the battery, high rate or low? IMO, high rate should not be used with the battery cables connected as the excess voltage that a high rate charge uses to cram lots of current into the battery, can harm onboard electronics.

If you were messing with battery terminals, could you have loosened some other electrical connection? Mass airflow sensor comes to mind as possibly delivering this type symptom. It starts under program mode then fails to run as soon as it trys to use airflow data to meter fuel. This might not throw a code as it is perhaps getting data within it's failure limits, but not within limits capable of delivering a running state. Try unplugging the MAS and starting the engine. This will cause a hard fault and the engine should go into "limp- home" mode with the ECU disregarding the MAS and delivering fuel based on it's RPM/Throttle/temp lookup table. Also check the air filter. If it dosn't get run much, you may have uninvited guests. Once had a mouse build a nest in the airbox under the filter. The trash it brought in nearly completely clogged the filter. This would cause similar symptoms of startup, then air starvation with increased running flow shuts down the engine.

I have also seen a bad ballast resistor do something similar, engine cranks and starts while resistor is bypassed for startup, then as soon as you try to draw current thru the ballast(key from start back to run position) the engine shuts off. I think even that year aerostar had electronic ignition though.

Good luck.

[tallyho8]

Could be a bad connector on the ignition switch if it runs while on start and then kills when switched to run. I saw one with a small leak in the windshield and the water dripped on the steering column and burned out the plug on the ignition switch.

[Soundguy]

Did a 2a charge for about 20hrs.

Will go back and recheck the bat cables, and also pull them and let the ecm clear, and try at it again.

I work a double on xmas day, so will try to work on it wednesday.

thanks for the ideas. I'm not ruling anything out.

I also need to put my hands on a fuel line press gauge to see if fuel pressure is staying up for the efi,.


thanks

Soundguy

Originally Posted by RonMar

That sounds like a "hard fault" scenario and even OBD1 should throw a code for that. But Podagrower is correct that some will not be stored till normal op temp is reached.

How exactly are you checking for codes? I used to have a 96? that was right at the changeout between OBD1 and OBD2 and you could still jumper a test connector under the hood and read codes in the form of check engine light flashes. I think a 1-1-1 was all clear, no faults but I got rid of my reference info when we traded in the vehicle.

IF no codes are stored, first off I would pull the battery "-" terminal and let it set for a few minutes to completely clear the ECU memory just in case something is confused. While the battery terminal is off, check all under hood connections you can reach for proper connection, then try another start and see what happens.
How did you charge the battery, high rate or low? IMO, high rate should not be used with the battery cables connected as the excess voltage that a high rate charge uses to cram lots of current into the battery, can harm onboard electronics.

If you were messing with battery terminals, could you have loosened some other electrical connection? Mass airflow sensor comes to mind as possibly delivering this type symptom. It starts under program mode then fails to run as soon as it trys to use airflow data to meter fuel. This might not throw a code as it is perhaps getting data within it's failure limits, but not within limits capable of delivering a running state. Try unplugging the MAS and starting the engine. This will cause a hard fault and the engine should go into "limp- home" mode with the ECU disregarding the MAS and delivering fuel based on it's RPM/Throttle/temp lookup table. Also check the air filter. If it dosn't get run much, you may have uninvited guests. Once had a mouse build a nest in the airbox under the filter. The trash it brought in nearly completely clogged the filter. This would cause similar symptoms of startup, then air starvation with increased running flow shuts down the engine.

I have also seen a bad ballast resistor do something similar, engine cranks and starts while resistor is bypassed for startup, then as soon as you try to draw current thru the ballast(key from start back to run position) the engine shuts off. I think even that year aerostar had electronic ignition though.

Good luck.

[Soundguy]

It IS a replaced ignition switch, so I will deffinately check the wireing there.

thansk

Soundguy

Originally Posted by tallyho8

Could be a bad connector on the ignition switch if it runs while on start and then kills when switched to run. I saw one with a small leak in the windshield and the water dripped on the steering column and burned out the plug on the ignition switch.

[MrJimi]

Are any trouble codes showing up ?
Jim

[WTA]

Just get in it, set the parking brake hard, step on the foot brake, restart the engine and then immediately put it in gear and

feather the gas pedal up to about 1000 RPM and hold it there for a minute or so. (ONLY FEATHER THE GAS IF YOU HAVE TO)

It should automaticaly go to IN GEAR mode for rpm which opens the IAC more anyway but if it doesn't want to then idle it up manually before it dies and slowly come off it as it picks up itself.

You have to put it in gear and up the rpm within 3-5 seconds if I remember right or this doesn't work.

Keep it in gear for at least 10 minutes idling with the AC off and not doing anything else. It should relearn fairly quick but 10 minutes is minimum. Then drive it around the neighborhood so it can relearn everything else. It will probably run weird for 20-30 miles or so.

If the battery went completely dead this is probably all it is. It happens sometimes.

All 91's that I've ever seen are EEC-4 computers. This is the standard way to fast learn the idle again after a dead battery or a computer swap.

It should pick it up itself but it probably has a filthy IAC solonoid. If you have the IAC that has two screws attaching the solonoid to the actual valve you can take it off the throttle body first, then seperate the solonoid from the valve and spray some foamy window cleaner in the valve then let it sit a couple minutes. Then rinse good with hot water. Repeat this untill it's clean.

DO NOT use carb or brake cleaner. Unless you want to be cleaning it a lot more often. It will take off the anti stick coating on the inside of it.

eec-4 obd-1 and obd-2 will all set codes when the engine is first started and cold. Not always though. Usually when it doesn't on an eec4 then it's just a failure to control idle problem because it's memory has dumped and needs to relearn. It doesn't know how much to tell the iac to open till it's too late. This rarely sets a code because it tried but the engine died before it got there. Now if there were an electronic fault then it will set a code.

[kenmac]

1991 mod. ever had the fuel pump replaced ?? May not have enough fuel pressure

If you can't do it yourself. Have someone check fuel pump pressure. There should be a port on the fuel rail to check fuel pump pressure