For the past year, I have had intermittent hard starting. Noticed it after clutch change but it well could have started before. Car seems to struggle to start although the engine turns and starter seems to give a good effort. Occassionally will hear back fire from excess fuel with longer starts. At most, 3 cranks needed. Car will run fine otherwise, once started. I cleaned the crank POS, changed starter/battery, checked plugs, checked base idle, cleaned throttle body, replaced IACV.

I am about to order a new fuel pressure regulator. Here's why: Even though my fuel filter has only 15k miles, I decide to replace that thinking it may be clogged. I remove the fuse for the fuel pump, and to my surprise, the engine starts and continues to run, although it starts to idle roughly. It never stalls out! Every other time I removed the fuse for the fuel pump, the car normally dies within seconds of startup and then will not start. This time, I can start up the car again and again and it will continue to run! Am I right to suspect the FPR? Could it be the fuel pump? When I detached the fuel filter, there was a little bit of "spray" from line pressure.

I am thinking the FPR is faulty and dumping excess fuel into the manifold on startup. With the fuel pump fuse out, the faulty FPR is allowing residual fuel line pressure to start and run the car. Sounds reasonable?

 

That's normal, with my 5spd I could crank for hours with the fuel pump removed and it would start and run for a bit on every crank. Did you take off the gas cap to relieve all pressure when starting? You said that the trouble started whan you replaced the clutch right? Could the teeth on the flywheel be the culprit? Maybe they were worn down too much?

 

That's funny. WHen i took the fuel pump fuse out before, the engine would die within seconds. Man, if it's normal, I guess I am back to questioning why. I did not remove the gas cap so I guess that could explain residual fuel line pressure.

I *think* the trouble started with the clutch swap. Not entirely sure though as that was a year ago and the hard starting is more frequent. About half the time, it will start normally, and then the other half the car will embarrass me with 2 or sometimes 3 cranking attempts. The teeth looked fine when I had the flywheel off. Nothing unusual. The crank POS sensor was cleaned of filings. It just is a mystery to me that the car was starting fine before the clutch swap (again, if memory serves me) and then not afterward. The crank sensor should not just go after you remove it.

The starting is not a solid continuous turning of the starter. There usually is a couple of brief hiccups or pauses as if the engine wants to start but then doesn't and then the starter resumes. If I disconnect any of the crank/cam sensors, the starter will give good continuous turnings (of course, with no starting). I cannot question the electrical system since the grounds look good and I have since swapped out starter/alternator/battery. I do not want to just buy a fuel pump/fpr/crank sensor/camshaft sensor/injectors and not get results... but I think i've ruled out everything but these.

I appreciate the comments, Dave.