90 Aero running rough
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New User
Joined: Jun 2007
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90 Aero running rough
I have a 90 Aero 3.0 with 218000 on it. Three weeks ago it died on me on the way home from work. Stopped at a red light and it just stopped running, got it started again drove about a half mile more stopped at a sign died again. I got it towed home ran the codes everything pointed to fuel pump. Finally got around to changing it started right up seem to be idling good went on the road on when I come to a stop it runs rough and when I take off from a stop runs rough until it gets up to about 35. Changed filter and Pressure Regulator tried cleaning throttle body and ran codes again but got an okay sign. Checked pressure on fuel rail read 23lbs car not running key on and 30+ with car running. Took A chance drove it to work today thinking maybe needed to get on the on the road. Any thoughts.
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
Your fuel pressure is way too low. Should be about 35 - 40 key on-engine off, and should be about 35 when idling. Should jump to between 38 - 45 when you snap the throttle.
Sounds like you might still have a bad fuel pump, or the wiring to the pump might have high resistance.
Sounds like you might still have a bad fuel pump, or the wiring to the pump might have high resistance.
Elder User
Joined: Apr 2005
Posts: 882
Likes: 0
From: Wichita
Try another fuel gage before you R&R the same parts.
With that many miles you may have a stretched timing chain or some other hi-mileage wear problem. Just the cool-off period might have "fixed" it long enough to start up again.
With that many miles you may have a stretched timing chain or some other hi-mileage wear problem. Just the cool-off period might have "fixed" it long enough to start up again.
Elder User
Joined: Dec 2006
Posts: 830
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From: Kitchener,Ontario,Canada
Can we assume your plugs, wires, etc are in good shape ?
If your gauge is correct, fuel pressure is much too low, pull off the vac line to the FPR at idle speed & make sure the fuel pressure increases about 5 PSI. That proves that the FPR is working correctly but the low pressure problem is something else. The engine runs fine at wider throttle openings?
Does the engine start & idle O.K.when cold?
Idle speed controller? or IAC
Pull off the IAC plug & see what happens to the idle speed?
Can you post the codes?
ATB Aeroman.
If your gauge is correct, fuel pressure is much too low, pull off the vac line to the FPR at idle speed & make sure the fuel pressure increases about 5 PSI. That proves that the FPR is working correctly but the low pressure problem is something else. The engine runs fine at wider throttle openings?
Does the engine start & idle O.K.when cold?
Idle speed controller? or IAC
Pull off the IAC plug & see what happens to the idle speed?
Can you post the codes?
ATB Aeroman.
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
vacuum leak
check the vac lines to the tranny vac modulator, fuel fumes purge tank under air cleaner, vac. tree on top of valve cover rear.
also check intake manifold gaskets for leaks
use spray can of carb cleaner. spray small spot and listen for rpm increase=leak
check the vac lines to the tranny vac modulator, fuel fumes purge tank under air cleaner, vac. tree on top of valve cover rear.
also check intake manifold gaskets for leaks
use spray can of carb cleaner. spray small spot and listen for rpm increase=leak
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Thanks
Thanks for all the suggestions as soon as the rain stops I will be out digging a little deeper. When I got it home the other day I pulled the codes key on engine off I got a 14 running I got a 77 and 41. Plugs wires and cap about a year old I am going to check those.
Elder User
Joined: Dec 2006
Posts: 830
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From: Kitchener,Ontario,Canada
Check sensors
77 is probably operator error (WOT sensing during test)
41= system lean or stuck lean, no switching. Replace front o2 sensor or may- be intake air leaks, get carb cleaner spray to check.
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Post Fiend
Joined: Oct 2005
Posts: 5,242
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From: Kiev, Ukraine
seems to me this is bad fuel pump. drop a tank, replace and n'joy....
Vac leak cause rought idle but when engine load is more then 40% you cant feel vac. leak.
Your engine wont starting with gas pedal pressed so you have bad fuel pressure only.
Vac leak cause rought idle but when engine load is more then 40% you cant feel vac. leak.
Your engine wont starting with gas pedal pressed so you have bad fuel pressure only.
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Post Fiend
Joined: Oct 2005
Posts: 5,242
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From: Kiev, Ukraine
one more tip....
bad filter makes pressure lover slowly, day by day, bad FPR usually leaks causing reach mixture.... Fuel pump dies day by day, but one day you got very low pressure, not enought for idle.
be sure cat is not clogged. To check pull out oxy sensor and start engine (labda controll data is stored in ECM RAM (on later models in EEPROM) and first some minutes till engine is cold it will run well w/o lambda controll. But if you can see no difference, cat is sill good
bad filter makes pressure lover slowly, day by day, bad FPR usually leaks causing reach mixture.... Fuel pump dies day by day, but one day you got very low pressure, not enought for idle.
be sure cat is not clogged. To check pull out oxy sensor and start engine (labda controll data is stored in ECM RAM (on later models in EEPROM) and first some minutes till engine is cold it will run well w/o lambda controll. But if you can see no difference, cat is sill good