rich has many causes. yes, 91 (usa) is 8valve TBI single injector engine. (injector is inside throttle body)
is the eCU flashing code 12 on demand? (if not code 12, that can mean , nasty failsafe mode is in force (rich , and retarded timing = black smoke, low mpg and stink)
(diag jumper is always 1st check.) (type CEL in my search box)
fuel pressure too high 60psi is too high. .. 34.1 to 39.8 PSI spec. (type pump in my search box)
The injector or it's 2 o-rings leaking? Can be eyes on, while person to keys on like 3 times. (main pipe off, key on, off , and off, person too watches the injector for leaking) as seen below.
http://www.fixkick.com/IDLE-AIR/Slide_Sh...age_6.html
fpreg, vacuum nipple leaking fuel with the hose off? FPR is mounted to front of TBI body.
ECT wires fell off (code 12s will not happen in this state) and causes failsafe, in this class failure.
MAP hose fell off, or is clogged, or hose split.? map is on right side of fire wall above the battery.
compression over 150psi??? low compression has many causes, and vast numbers or 24year old cars , are like that. (most are parked gathering dust)
CAT converter not melted, blocking exhaust ,fully or near full blockage.
Set the spark timing with a timing light yet, ???? using the timing freeze jumper?
besides that:
basics list)
engine ok? (tests) can pump air ok, can make compression at spec, or more. even a dirty air filter?
spark oK, tuneup , timed, etc.
fueling. if the above are good, then it must be a fueling issue.! (no injector leaks. , fuel filter clean, gas not bad. ecu sensors working, fuel pressure at spec)
is the eCU flashing code 12 on demand? (if not code 12, that can mean , nasty failsafe mode is in force (rich , and retarded timing = black smoke, low mpg and stink)
(diag jumper is always 1st check.) (type CEL in my search box)
fuel pressure too high 60psi is too high. .. 34.1 to 39.8 PSI spec. (type pump in my search box)
The injector or it's 2 o-rings leaking? Can be eyes on, while person to keys on like 3 times. (main pipe off, key on, off , and off, person too watches the injector for leaking) as seen below.
http://www.fixkick.com/IDLE-AIR/Slide_Sh...age_6.html
fpreg, vacuum nipple leaking fuel with the hose off? FPR is mounted to front of TBI body.
ECT wires fell off (code 12s will not happen in this state) and causes failsafe, in this class failure.
MAP hose fell off, or is clogged, or hose split.? map is on right side of fire wall above the battery.
compression over 150psi??? low compression has many causes, and vast numbers or 24year old cars , are like that. (most are parked gathering dust)
CAT converter not melted, blocking exhaust ,fully or near full blockage.
Set the spark timing with a timing light yet, ???? using the timing freeze jumper?
besides that:
basics list)engine ok? (tests) can pump air ok, can make compression at spec, or more. even a dirty air filter?
spark oK, tuneup , timed, etc.
fueling. if the above are good, then it must be a fueling issue.! (no injector leaks. , fuel filter clean, gas not bad. ecu sensors working, fuel pressure at spec)
http://www.fixkick.com