dirtybagg
New Member
- Joined
- October 2, 2012
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- Year, Model & Trim Level
- 1996 Ford Aerostar AWD
Hello Ford Geeks,
I'm new to this forum, so I'm introducing myself, as requested by the forum. I'm not a sporty, off-road motorist, nor Henry Ford throwback by any means-I prefer bicycling to driving on most commutes, and I wanted to find a Toyota Previa-AWD, before settling for the Aerostar-both are terrible for engine work-one is a Toyota
My 1996 Aerostar AWD is a low capital tool, For access to mountain recreation, weekend car camping, and moving stuff-a box on wheels. With built in child safety seats, the ladies cannot deny it's blatant sex appeal With a good heater, 4 drive-able/affordable (14") snow tires, room to sleep inside- it's the ski bum's ultimate answer to the oft lifestyle cramping expense of the Subaru. Explorer with much more, and flatter CUFT-awesome. Mods include "air lift" pneumatic helper springs inside the rear coils, winterforce snow tires, and a rubber floor mat (for camping). I'm posting here because I appreciated reading such forum posts while troubleshooting my van's Engine issues. After two years chasing down the root cause in the title, I want to share my struggle to limit the suffering of the next ignorant home mechanic.
When I purchased the vehicle in 2008 (only 107K mi), it idled a little roughly, sometimes stalling at stop lights-tune up (1hr/spark plug!!)-minor improvement.
2010-new state, failed emissions inspection. At this time the check engine light was on-much to my surprise (the dash check engine bulb had actually burned out). After a bit of research, I tried cleaning my EGR tube with carb cleaner, sniffed for vacuum leaks with carb cleaner, cleaned MAF(mass air flow) sensor wire, replaced the MAP(EGR position sensor) & attached hoses . Some noticeable gains were made. After several trips to the emissions test shop, they were tired of seeing me, and let me register.
A year later, the van started idling VERY roughly, but at odd times. Eventually I recognized the pattern; perfect cold starts, rough warm starts (drive 10 min, shut off 2 min, rough start) I figured this was a thermal expansion/vacuum leak or stuck choke valve issue. I armed myself with carb cleaner ready to catch vacuum leaks in the moment-none found. IAC (inlet air control-AKA choke) was replaced-no change.
2012 Emissions inspection-fail again. This whole two years, the codes (not available for older than 1996) kept telling me I needed O2 sensors-sometimes resetting would keep codes at bay for several weeks (it's parked more days than driven). While revisiting the EGR diagnosis, a mechanic at the do-it yourself garage, pulled up diagnostic data reporting live reads on both O2 sensors (fore and aft cat converter). Also fuel trims were observed in an acceptable range-pro mechanic was stumped- I avoided messing with my f-RUST-rating exhaust system-it had to be something else.
After another 4-6 hours of internet forum searching, I found a post about an F-150 V8 with the exact same symptoms. The problem was isolated by this vehicle having two fuel tanks, and problems with only one. This truck's problems were solved by replacing the fuel pressure regulator (in fuel pump cluster). A few more forums were cross referenced before I jumped on this theory. I was off to the parts store to fetch a fuel system pressure guage and regulator, incase I needed it.
FUEL PRESSURE REGULATOR REPLACEMENT: Fixed my problem immediately, it made my vehicle drive as if it were 10 years younger! Another symptom I struggled with (caught by state safety inspection too) was grabby braking (attributed to rear braking-RABS-rear ABS lights always turn off at start-up). Though I did remove my drums for visual inspection at the time of FPR replacement (finding no restrictions or issues), the braking & overall handling improved immensely upon fuel pressure regulator replacement. (either vacuum connection to brake system and/or simply a rear drive/brake axle that wasn't fighting an indecisive, confused engine experiencing back pressure spikes from a fuel leak in the valve train)
4L AEROSTAR FPR-FUEL PRESSURE REGULATOR-REPLACEMENT:
I had some awful cell phone photos ready to share, but I didn't find the button on this thread to do so.
1 - air intake duct-just the plastic tube -two hose clamps
2 - giant blocky plug against firewall-it won't unclip or separate-take out the bold on the top to unplug it. The body slides up and out of the metal mounting bracket.
3 - DRAIN COOLANT-(drain plug-valve at bottom passenger side of radiator) and remove the coolant manifold, which contains thermostat, on the front of the engine block-3 bolts
4 fold all wires and hoses out of your way, now you can actually find the part in question-it has a metal sleeved fuel hose bolted to the top
FUEL SYSTEM PRESSURE TESTING: I watched some youtube videos about this diagnostic process-and it seemed very useful-but none were shown for the Aerostar. In practice, I borrowed the equipment-thanks O'Reilly, but avoided using it. How somebody can do a pressure test while this 4L Aerostar engine is running in it's box, is beyond my comprehension-Though the Schroeder (purge or relief valve in All-Data?) is find-able behind the FPR w/out removing coolant components, It seems very difficult to attach the gauge with coolant system intact.
OIL SNIFF: While wrenching away, my auto mechanic expert friend called, he told me another diagnostic tip for the FPR - sniff my oil dipstick for fuel, which I had never thought to do. He was right, it smelled like something volatile in my oil. I suppose I'm due for an oil change too-maybe it will evaporate or burn off now that the fuel leak is repaired?
NOW: I have to tear my dash apart and replace my check engine bulb before I can register-or find another test center. I plan on disconnecting my neg batt terminal for 30 min to clear the O2 sensor code, and hope it doesn't come back (at least until after I register again). I honestly believe my O2 sensor alarmed because I was essentially flooding my engine (via valve train-from vacuum hose on defective FPR) every other time it was being started-dumping an excess of fuel ie, unburned hydrocarbons through the cat converter-hence consuming unaccounted for O2. In my state, for my 1996 OBD exuipped vehicle, no tailpipes are sniffed, inspections are all by OBD code-no check engine=pass?! I hope that several (low mileage) years of this hasn't clogged, or melted my cat converter, or other critical components. For now it runs like a top, and I'm thrilled after a long time troubleshooting. Some youtube mechanics were pointing fingers at higher ethanol fuel contents damaging (eating) fuel system components-FPR fuel pressure regulator diaphram? I have used sea foam and other fuel preservatives/injector cleaners as well, but mainly to help this issue, and for long term (month long) storage.
I'm new to this forum, so I'm introducing myself, as requested by the forum. I'm not a sporty, off-road motorist, nor Henry Ford throwback by any means-I prefer bicycling to driving on most commutes, and I wanted to find a Toyota Previa-AWD, before settling for the Aerostar-both are terrible for engine work-one is a Toyota
My 1996 Aerostar AWD is a low capital tool, For access to mountain recreation, weekend car camping, and moving stuff-a box on wheels. With built in child safety seats, the ladies cannot deny it's blatant sex appeal With a good heater, 4 drive-able/affordable (14") snow tires, room to sleep inside- it's the ski bum's ultimate answer to the oft lifestyle cramping expense of the Subaru. Explorer with much more, and flatter CUFT-awesome. Mods include "air lift" pneumatic helper springs inside the rear coils, winterforce snow tires, and a rubber floor mat (for camping). I'm posting here because I appreciated reading such forum posts while troubleshooting my van's Engine issues. After two years chasing down the root cause in the title, I want to share my struggle to limit the suffering of the next ignorant home mechanic.When I purchased the vehicle in 2008 (only 107K mi), it idled a little roughly, sometimes stalling at stop lights-tune up (1hr/spark plug!!)-minor improvement.
2010-new state, failed emissions inspection. At this time the check engine light was on-much to my surprise (the dash check engine bulb had actually burned out). After a bit of research, I tried cleaning my EGR tube with carb cleaner, sniffed for vacuum leaks with carb cleaner, cleaned MAF(mass air flow) sensor wire, replaced the MAP(EGR position sensor) & attached hoses . Some noticeable gains were made. After several trips to the emissions test shop, they were tired of seeing me, and let me register.
A year later, the van started idling VERY roughly, but at odd times. Eventually I recognized the pattern; perfect cold starts, rough warm starts (drive 10 min, shut off 2 min, rough start) I figured this was a thermal expansion/vacuum leak or stuck choke valve issue. I armed myself with carb cleaner ready to catch vacuum leaks in the moment-none found. IAC (inlet air control-AKA choke) was replaced-no change.
2012 Emissions inspection-fail again. This whole two years, the codes (not available for older than 1996) kept telling me I needed O2 sensors-sometimes resetting would keep codes at bay for several weeks (it's parked more days than driven). While revisiting the EGR diagnosis, a mechanic at the do-it yourself garage, pulled up diagnostic data reporting live reads on both O2 sensors (fore and aft cat converter). Also fuel trims were observed in an acceptable range-pro mechanic was stumped- I avoided messing with my f-RUST-rating exhaust system-it had to be something else.
After another 4-6 hours of internet forum searching, I found a post about an F-150 V8 with the exact same symptoms. The problem was isolated by this vehicle having two fuel tanks, and problems with only one. This truck's problems were solved by replacing the fuel pressure regulator (in fuel pump cluster). A few more forums were cross referenced before I jumped on this theory. I was off to the parts store to fetch a fuel system pressure guage and regulator, incase I needed it.
FUEL PRESSURE REGULATOR REPLACEMENT: Fixed my problem immediately, it made my vehicle drive as if it were 10 years younger! Another symptom I struggled with (caught by state safety inspection too) was grabby braking (attributed to rear braking-RABS-rear ABS lights always turn off at start-up). Though I did remove my drums for visual inspection at the time of FPR replacement (finding no restrictions or issues), the braking & overall handling improved immensely upon fuel pressure regulator replacement. (either vacuum connection to brake system and/or simply a rear drive/brake axle that wasn't fighting an indecisive, confused engine experiencing back pressure spikes from a fuel leak in the valve train)
4L AEROSTAR FPR-FUEL PRESSURE REGULATOR-REPLACEMENT:
I had some awful cell phone photos ready to share, but I didn't find the button on this thread to do so.
1 - air intake duct-just the plastic tube -two hose clamps
2 - giant blocky plug against firewall-it won't unclip or separate-take out the bold on the top to unplug it. The body slides up and out of the metal mounting bracket.
3 - DRAIN COOLANT-(drain plug-valve at bottom passenger side of radiator) and remove the coolant manifold, which contains thermostat, on the front of the engine block-3 bolts
4 fold all wires and hoses out of your way, now you can actually find the part in question-it has a metal sleeved fuel hose bolted to the top
FUEL SYSTEM PRESSURE TESTING: I watched some youtube videos about this diagnostic process-and it seemed very useful-but none were shown for the Aerostar. In practice, I borrowed the equipment-thanks O'Reilly, but avoided using it. How somebody can do a pressure test while this 4L Aerostar engine is running in it's box, is beyond my comprehension-Though the Schroeder (purge or relief valve in All-Data?) is find-able behind the FPR w/out removing coolant components, It seems very difficult to attach the gauge with coolant system intact.
OIL SNIFF: While wrenching away, my auto mechanic expert friend called, he told me another diagnostic tip for the FPR - sniff my oil dipstick for fuel, which I had never thought to do. He was right, it smelled like something volatile in my oil. I suppose I'm due for an oil change too-maybe it will evaporate or burn off now that the fuel leak is repaired?
NOW: I have to tear my dash apart and replace my check engine bulb before I can register-or find another test center. I plan on disconnecting my neg batt terminal for 30 min to clear the O2 sensor code, and hope it doesn't come back (at least until after I register again). I honestly believe my O2 sensor alarmed because I was essentially flooding my engine (via valve train-from vacuum hose on defective FPR) every other time it was being started-dumping an excess of fuel ie, unburned hydrocarbons through the cat converter-hence consuming unaccounted for O2. In my state, for my 1996 OBD exuipped vehicle, no tailpipes are sniffed, inspections are all by OBD code-no check engine=pass?! I hope that several (low mileage) years of this hasn't clogged, or melted my cat converter, or other critical components. For now it runs like a top, and I'm thrilled after a long time troubleshooting. Some youtube mechanics were pointing fingers at higher ethanol fuel contents damaging (eating) fuel system components-FPR fuel pressure regulator diaphram? I have used sea foam and other fuel preservatives/injector cleaners as well, but mainly to help this issue, and for long term (month long) storage.
