Very Hard Starting Hot

[TecMan]

I have a 1996 TranSport 3.4L w/187k miles. The car starts great when engine is cold but cranks and cranks when warm or hot and won't start unless I press and hold pedal just slightly...then it starts, revs up fairly high and dies. I will do this again and then it stays running. The car has no other drivability problems and runs fine. It has a new IAC valve and a new fuel pump and filter about 5k miles ago. I also ran a good fuel system cleaner through it recently. I checked the fuel press. regulator vaccuum hose for signs of fuel and saw none. I realize it could be a number of different things but I'm trying to avoid the $80-$100 shop fee to put it on a scanner. Oh yah, the vehicle is NOT throwing any codes. Please advise regarding possible causes and how I can check. From what reading I've done I've come up with TPS, CKP Sensor, Temp Sensor, Fuel Press. Reg., leaky injectors, EVAP System problems, or ? My newer fuel pump does come on and then shut off with key to "on". The car does have another occasional symptom..high idle, but it hasn't done that for awhile. Any help would be greatly appreciated.

[LMP]

High idle CAN be caused by stray air intake...and 3.4 intake gasket leak is common. Notice stray air is not measured and does not bring the proportional amount of fuel; depressing pedal will let more air through MAF sensor and bring some more fuel...Check for other vacuum leaks, power brake...
...Sounds logic...I hope it could be the real thing...air intake manifold gasket is not really a piece of cake, but available documentation is very good.

[TecMan]

Thanks LMP for the reply. I need to say that the high idle hasn't happened for quite some time...but the hard starting hot is every time. I hear what you're saying but I'm really hoping it's not the intake gasket, I don't relish doing that repair even though I may have to. Of course I would much rather have the hard starting hot problem to be caused by a sensor or something more easily replaceable...but wishing won't make it happen! So far I haven't found any vaccuum leaks anywhere, but I'll keep looking. I'm hoping I can eliminate (by checking and this forums feedback) some of the sensors etc. before I would perform the big job of replacing the intake gasket without being absolutely sure. In the past when I would occasionally get the high idle, if I shut the car off and restarted it the car would idle fine!

[LMP]

..I found this:
http://www.automotiveforums.com/vbul...d.php?t=925732
..the solution starts at nov-5 2008...near the very end of the thread ....what it means, in simple terms, is "vapor lock"....
To test that option, I'd install a fuel rail pressure gauge. THe pressure should hold for several minutes normally, but if it starts falling down within seconds, it could prove that theory...or as suggested, I'd simply depressurize the fuel rail after stopping the not engine..and test starting a few minutes later...

I have built a fuel rail pressure gauge from an a/c refiller kit...
www.avigex.ca/xport/fuelpressuregauge.jpg

[TecMan]

Thanks LMP for all the info and help. I believe I found the problem regarding the very hard starting when warm/hot. I decided to check the temp. sensor, first I checked it's resistance cold and then I was going to check it hot, so I connected it back up and started the car. As I was waiting for the car to warm up I continued checking for any vaccuum leaks and I decided to check the fuel pressure regulator one more time. This time, after I disconnected the vaccuum line I just happened to notice a tiny droplet of gas spit out of the regulator and then another one! If I hadn't been looking very closely I never would have noticed it. I'll be picking up a new regulator tommorow PM and install it that evening or the next day. The other day when I checked the regulator I even held my finger on the regulator tube and felt and saw nothing. Anyway, I can't seem to find the fuel rail pressure relief valve and my book does not show where it's at either...would you be able to tell me where it's located? As you know, there is NOT much room under the hood and I can't get my head in there to take a good look!

[LMP]

OK...
verify this
http://www.ehow.com/video_4804005_re...gm-engine.html
NO idea for the 3.4 pressure port..my 3.8 is easy reach...

[TecMan]

Thanks again LMP for the info and help.