1991 Ford Aerostar Cranks Wont Start

Tiny
DJMONEYSTL
  • MEMBER
  • 1991 FORD AEROSTAR
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
I have a 91 Aerostar w/3.0 TFI IV Fuel Injected 6cyl. It sat for a week and when tried to start it would turned over but wouldnt start. Noticed smell of gas when trying to start. Replaced coil & cap & rotor. Ign Mod tested at autoparts store. I have spark between coil and dist. I also have spark between dist and plug. Tested with a spark tester. I have fuel at pressure port but it doesnt seem like alot.
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Thursday, January 1st, 2009 AT 8:09 PM

16 Replies

Tiny
DAVE H
  • EXPERT
Crank it over a few times and pull a spark plug out to see if your getting fuel to cylinders. If your getting fuel and spark it should fire up?

FUEL PRESSURE REGULATOR
The fuel pressure regulator is attached to fuel supply manifold assembly, downstream of fuel injectors. It regulates fuel pressure supplied to injectors. Regulator is a diaphragm-operated valve with one side responding to fuel pressure and the other side to intake manifold vacuum.
When intake manifold vacuum is low, an internal spring increases pressure on diaphragm, blocking off fuel return passage and increasing fuel pressure. When manifold pressure is high, spring pressure is overcome by vacuum, opening fuel return passage and lowering fuel pressure. Excess fuel is by-passed through regulator and returned to fuel tank.
The regulator also controls fuel line vapor formation, allowing for rapid restarts, assistance in engine idle stabilization and maintenance of fuel pressure when engine is turned off. Pressure is adjusted at factory to compensate for fuel flow differences between injectors.
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Thursday, January 1st, 2009 AT 8:38 PM
Tiny
DJMONEYSTL
  • MEMBER
I did pull a plug and it was soaked. I then cleaned it and checked for spark and there was. I was thinking about the fuel pressure regulator also. I also was concidering the fuel filter, fuel pump or timing chain. I just bought a fuel filter and plan on installing it tomorrow. If that doesnt work I plan to replace the fuel pressure regulator. Beyond that, how would I check the timing if it wont run? I have a light and do know how to set timing. But not in this case. Thanks for your answer!
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Thursday, January 1st, 2009 AT 9:21 PM
Tiny
DAVE H
  • EXPERT
The pump is working if your getting fuel. If the plugs are soaked it may just be flooded. Try starting it again in the morning without touching the gas pedal. Remove a plug again and see if it's soaked again. Install filter try again and let me know. And we will go from there.
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Thursday, January 1st, 2009 AT 9:33 PM
Tiny
DJMONEYSTL
  • MEMBER
Not to sound ungreatful, because I DO appreciate your help, but. It's Fuel Injected. Therefore I never touch the pedal when starting. Good suggestion if it had a carb, though. Someone did tell me that if the fuel pressure regulator was bad that it would cause to much fuel in the cylinder and therefore soak plugs. Any other suggestions?

Thanks!
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Thursday, January 1st, 2009 AT 9:44 PM
Tiny
DAVE H
  • EXPERT
Some people still try giving it pedal. When a vehicle will not start. It could be the pressure regulator overloading the cylinders. That is why I put it in my first post. And that is why I advised you to let it dry up over night and test it again. If it is soaked again with NO pedal we need to test regulator?
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Thursday, January 1st, 2009 AT 9:54 PM
Tiny
DJMONEYSTL
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I will do just that. I am curious. How do you test the pressure regulator?

Thanks Very Much!
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Thursday, January 1st, 2009 AT 9:57 PM
Tiny
DAVE H
  • EXPERT
FUEL PRESSURE REGULATOR
Ensure key is off. Connect fuel pressure gauge to Schrader valve on fuel rail. Ensure manifold vacuum supply tube is connected to fuel pressure regulator. Start and run engine for 10 seconds. Stop engine and wait 10 seconds. Start and operate engine for 10 seconds. Stop engine and remove pressure regulator vacuum hose. See Fig. 10 . Check vacuum port for fuel.
Fig. 10: Fuel Pressure Regulator Component ID
Courtesy of FORD MOTOR CO.


http://www.2carpros.com/forum/automotive_pictures/266999_fpr_1.jpg



If fuel is present, replace fuel pressure regulator and repeat test. If fuel is not present, start and run engine for 30 seconds. Stop engine and check fuel pressure gauge. If fuel pressure does not drop, go to step 4). If fuel pressure drops more than 5 psi (34.5 kPa) in 60 seconds, disconnect and plug fuel return line at engine. Cycle ignition key on and off until normal fuel pressure is obtained.
Turn key off and check fuel pressure gauge. If gauge drops more than 5 psi (34.5 kPa) in 30 seconds, replace high pressure fuel pump (dual pump system) or fuel sender/pump assembly (single pump type). If gauge does not drop more than 5 psi (34.5 kPa) in 30 seconds, replace fuel pressure regulator.
Ensure key is off. Relieve fuel pressure. Remove fuel pressure regulator. Check "O" ring, gasket and mounting surfaces for cracks, cuts or other damage. Connect vacuum pump to fuel return tube and apply 20 in. Hg. If maximum vacuum loss exceeds 10 in. Hg in 10 seconds, replace regulator. If maximum vacuum loss does not exceed 10 in. Hg in 10 seconds, recheck entire fuel delivery system for cause of fuel pressure loss.
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Thursday, January 1st, 2009 AT 10:09 PM
Tiny
DJMONEYSTL
  • MEMBER
But the procedure for testing the fuel pressure regulator, states that I must start the vehical and run it for X amount of time. IT DOESNT START! LOL! Hahahaha! So what do I do about that? My plan was to replace it and if it started. Wha la THAT was my problem. I would rather diagnose the problem rather than be a parts changer. I dont have internet at my shop so, I was hoping to nail down as many possiblities before I left for the shop.

Thanks So Much!
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Friday, January 2nd, 2009 AT 10:33 AM
Tiny
DAVE H
  • EXPERT
You have to cycle the key on/off a few times if the vehicle won't start. To check the pressure regulator. I am aware it won't start. You was curious and asked about checking.?
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Friday, January 2nd, 2009 AT 10:52 AM
Tiny
DJMONEYSTL
  • MEMBER
I didnt even think about that. Cycling the key would cause the fuel pump to pressurize the fuel manifold. I guess thats why you make the big buck$. Lol. You rock. Thanks again. Heading over to the shop now. When I get home I'll post my results to you.

Thanks A Bunch ! ! !
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Friday, January 2nd, 2009 AT 11:46 AM
Tiny
DJMONEYSTL
  • MEMBER
I put the new fuel filter on and tested the pressure at the shrader valve (just pressing it down). I got alot more fuel! I went ahead and picked up a pressure regulator (being that it's only $25) and installed it. I replaced all the plugs except one, which I'm still working on. (Passenger side rear is a booger!). So, I'm gonna go back to the shop today and finish the last plug and see if she won't start. I'll let you know. If she don't start, I'm thinking either the computer or timing chain. Any thoughts on that? How do you test the computer, and again I ask how does a mechanic check the timing when the engine wont start?
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Sunday, January 4th, 2009 AT 2:14 PM
Tiny
DJMONEYSTL
  • MEMBER
Is there a sensor on these Aerostars that would cause a catastrophic failure such as this. MAP, O2 TPS or something to this end?
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Sunday, January 4th, 2009 AT 2:20 PM
Tiny
DJMONEYSTL
  • MEMBER
Well I finished the plugs and I tried to start it to no end. I did how ever find a few cracked vaccum hoses. So when, I repeat WHEN, I get it running, it should get better gas mileage. LOL! Now I am left with the same question. Is it the timing chain or is it the ecm/pcm (Computer Brain).I would love some help on this. It's starting to get expensive and time consuming now ! ! !

Thanks Again For Your Advise!
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Sunday, January 4th, 2009 AT 11:12 PM
Tiny
DAVE H
  • EXPERT
The PCM (brain) controls sensors. Most sensors cause running problems. Other sensor would prevent spark or prevent fuel or both of these. You are saying your getting both of these. So the engine should be firing up. It may run rough if there is another fault but your getting spark and your getting fuel. It should fire unless there is no compression?. You need to check for compression?. Also check if the catalytic convertor is plugged/blocked?
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Monday, January 5th, 2009 AT 10:09 AM
Tiny
DJMONEYSTL
  • MEMBER
Funny you should say compression. I wouldnt understand how I could lose compression to that extreme when I drove it and parked it and it was running fine when I parked it. Unless, the head or block cracked. Massively! I will check it, but #3 and #6 are such boogers I dont know that I can get them. How do you check the cat converter?

Thanks
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Monday, January 5th, 2009 AT 2:29 PM
Tiny
DAVE H
  • EXPERT
ENGINE COMPRESSION
Check engine compression at specified cranking speed with engine at normal operating temperature, all spark plugs removed (on dual plugs, remove exhaust side only) and throttle wide open. Ensure crankcase is full and oil is correct viscosity. With compression gauge installed, use remote starter to crank engine.
Crank engine at least 5 revolutions, and record highest reading. Repeat procedure for all cylinders using approximately same number of revolutions. Lowest compression reading should not be less than 75 percent of highest compression reading. No cylinder compression reading should be less than 100 psi (7 kg/cm2 ).
COMPRESSION RATIO SPECIFICATIONS
Application. Compression Ratio
2.9L & 4.0L.9.0:1
3.0L.9.3:1

EXHAUST SYSTEM BACKPRESSURE
Using a vacuum or pressure gauge, check exhaust system. Remove O[I2] sensor or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge, and run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi, exhaust system or catalytic converter is plugged.
If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port, and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restrictions.
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Monday, January 5th, 2009 AT 9:53 PM

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