Symptoms (in order):
- Freeway operation was fine, then the car would stumble & start to stall when coming off the freeway & stopping at the first light -- had to keep foot on the gas & brake to keep the revs up. Then similar stalling at low speed (0-15 mph) and when accelerating to change lanes or enter the freeway.
- The car then began to have problems starting -- turn the key and the engine would crank but not start, turn the key off and on and the car would usually start on the 2nd or 3rd try. (battery ok, distrib cap, wires, plugs replaced approx 1,500 miles ago). But just after starting & while still in park the engine would on occasion race or stumble, or both -- different symptoms on different starts.
- Car finally stalled out at freeway speed & had to be towed home. Refuses to start since.
- The car will crank fine but not start
- No error code (other than 55 end-of-codes)
- Fuel filter is clean and working (removed & inspected)
- Car will start immediately if TB/Carb cleaner is sprayed into the throttle body - but will only run while the TB/Carb cleaner is present in the TB. When started w/cleaner the engine sounds strong & smooth - so it doesn't appear to be distrib, wires, rotor etc.
- When turning the key, the fuel pump whirs for 1-2 sec (as normal) & fuel pressure builds up (don't have a fuel pressure gauge but fuel is definitely getting up into the fuel line in the engine compartment and to the fuel regulator (see below)
- Fuel is making it up to the engine compartment - I took off the rubber hoses from the fuel lines in the engine compartment to test, cranked the engine and fuel is pumping just fine, return line is dry.
- Removed throttle body & cleaned thoroughly and as far into the plenum as I could without removing the plenum - no change in starting after.
Neighbor said it's the fuel pump (his guess) but given that the pump does whir & push fuel up into the engine compartment line I'm hoping that the pump is working ok. I also tend to think that because of this (getting fuel up into the line) that the car would at least fire on it's own, and then possibly die out if the fuel pump pressure wasn't sufficient. Again, the car starts immediately when TB/Carb cleaner is sprayed into the TB, and as long as there is sufficient fuel from the cleaner in the TB the engine revs strong & sounds smooth.
I've read all sorts of posts for this engine regarding MAP sensors, HALL effect plates, fuel rail/injectors, O2 sensors, TPI sensors, PVC, etc., but before I start shotgunning these sort of things, or just jumping in and replacing a fuel pump, I'd appreciate any advise on what logically I should check next and in what order.