My 2001 Volvo S40 is upredictable and hard starting. Sometimes fires first try and runs good other times it takes several cranks and will idle ruff. One time it would not start at all, I removed the plugs and one was soaked, I cleaned and put them back and it started great. Car idle is a bit erratic. Car pulses at slow speeds. Car has dirty black rear bumper as if burning way rich. Would a leakly fuel ingector be a likely cause? What other possibilities? How hard is it to replace ingectors? I replaced the fuel pressure regulator a while back and that solved the long cranking problem, this if different.

 

I would check the fuel pressure. You need to know if it is still correct. No guesses.

Check your spark plug color. A rich burn will leave black powdery soot.


The injectors are built to last a long time. I would suspect stuff like a faulty MAF or MAP or Coolant Temp Sensor, something feeding the engine bad info before worrying about an injector.

They are easy to remove though. Once you have the fuel line and vacuum disconnected you remove two bolts, the four injector wiring clips, and then you can pry the injectors out with the rail attached. If you pry under the rail it will lift out (leaving the injectors) but it bends the thin metal plate which holds the injectors to the rail. It does hammer back into shape though. Not that I've done it (twice ).

 

Thanks for the suggestion Huddini, however before I got this reply I had already purchased injectors. I thought that solved it for a week or so but had it do the same thing the other day now. So back to the ideas you suggested. I got thinking about the coolent temp sensor and realized the fan does come on at unusual times, such as a cold starts. Would it make sense for this to be the cause of occasional hard or no start?

 

Unfortunately it could be several things. That is why I suggested getting some kind of tester for the fuel pressure since this is the usual suspect in long cranking times after the car has been sitting for a while. Harbor Freight sells a very cheap (price and quality) fuel pressure tester for $20. They call it a fuel injection pump tester for some odd reason. Fuel Pressure Tester & Fuel Injection Pump Tester

Other things like a bad coolant temp sensor should set off the check engine light. Plus your temperature gauge should be off such as high or low or frozen.

Do you own a smart phone? There are devices that let you access the OBD-II port and actually see what the coolant temp sensor is reporting to the computer. I use VIDA with a DiCE tool so I have not tried any of these generic devices yet.

 

I purchased a code reader, Memoscan U480, just to see if there were any issues. I plugged it in according to instructions and the car started going haywire. Check engine light came on, started throwing codes left and right, car was starting and running erratically, transmission went into limp mode, etc. Finally, I disconnected the battery for 15 minutes, performing the reset, and it all went away. Now the car runs as smooth as silk with zero problems. I contacted the company to let them know and set up a return of the product.