manche Posted October 11, 2008 Share Posted October 11, 2008 ok the problem is one i was driving one night my truck all the sudden turned off and wouldnt start but would crank antidisestablishmentarianism could of happened the fuel pump works but for kick i think it may be my ignition coil Link to comment Share on other sites More sharing options...
mjdoa Posted October 11, 2008 Share Posted October 11, 2008 Pull a plug wire,see if you have spark,that'll confirm or eliminate the electrical system, diagnose from there. Let us know. Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 11, 2008 Share Posted October 11, 2008 I know you have a 2.5L, but your description so far is highly indictive of a CPS failure. It is quite common on the 4.0L engines for them to do just as you have stated here with your 2.5L. Check for spark as mjdoa said. If there is no spark, but you have good fuel pressure, that would also point to CPS. Disclaimer: I am not "real" familiar with the 2.5L so I could be way off here too as they may have other common issues causing this that I am not aware of. ;) Link to comment Share on other sites More sharing options...
manche Posted October 11, 2008 Author Share Posted October 11, 2008 well i knw its getting gas cuase i smell the raw gas just building in the TB and you say is it does spark it would be cps ? Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 11, 2008 Share Posted October 11, 2008 Having no spark would indicate a CPS issue. Link to comment Share on other sites More sharing options...
Pete M Posted October 11, 2008 Share Posted October 11, 2008 Maybe. I thought the 2.5L computer controlled the spark and the injectors. Why would the computer open the injectors if it can't read the CPS? Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 11, 2008 Share Posted October 11, 2008 My scenario is completely ASSuming that the 2.5L works similarly to the 4.0L, so I could be completely off base ;) . I have never owned anything but a 4.0L Jeep and when I was a technician back in the 80's...I didn't work on Jeeps so I am pretty much a one track mind here. Guess I should shut up and wait for someone with more knowledge on this one come in and help me learn too... :smart: :D Link to comment Share on other sites More sharing options...
Pete M Posted October 11, 2008 Share Posted October 11, 2008 As I understand it (and this applies to the 4.0 and FI 2.5), if the CPS is faulty, the computer won't fire the plugs or the injectors. If he's smelling gas, it could be something further down the line (like corrosion in the coil wire as I found in my 86, but not until after I blew up the muffler). I'm not saying that it can't still be the CPS, but if he's smelling gas, then it might not be the CPS. manche, have you been able to observe the injector while someone else was cranking? Is it squirting? Make sure you wear eye protection, just in case it backfires. Link to comment Share on other sites More sharing options...
mvusse Posted October 11, 2008 Share Posted October 11, 2008 Is the 2.5 not throttle body injected? If it is it doesn't need a crank position sensor to decide when to open the injector. Link to comment Share on other sites More sharing options...
Pete M Posted October 11, 2008 Share Posted October 11, 2008 I always figured that the computer opened the injector. So it doesn't? Link to comment Share on other sites More sharing options...
mvusse Posted October 11, 2008 Share Posted October 11, 2008 It does, but for throttle body injection is it timed to an interval. Let's say the computer works off .5 second intervals. It will allow the injector open for x ms for every .5 seconds, regardless of what position the crank is in. The actual length of time it is open in each interval depends on the throttle position, rpm and sensor input like O2 sensor, MAP or MAF sensor. Full throttle at max rpm it will be usually be open continuously. It doesn't matter what position the crank and cam are in, as each cylinder will suck in the air/fuel mixture on it's intake stroke, and all cylinders work off the same air fuel mixture. Multi port injection, where each cylinder has it's own injector pointed directly at the intake valve you have to make sure the injector is open only when the intake valve is open, so crank (actually, cam) position becomes an issue because you don't want to waste fuel by spraying it at the back of a closed valve. Link to comment Share on other sites More sharing options...
manche Posted October 13, 2008 Author Share Posted October 13, 2008 ok so were is the sensor located? and to clear things up does the ecu control the injector? :hmm: Link to comment Share on other sites More sharing options...
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