Cold start problem

[Rollin]

Hello,
Ok, the colder out it gets the longer cranking it takes for it to start. The other morning it was about 30 deg. out and it must of turned over 20 times before it would start up. Soon as it fires up it runs great, runs about 1200rpm for about a min. then drops to about 800rpm and purrs like a cat. It starts right up when the motor is warm or its not cold out.
There are no codes , I have replaced the ect sensor, gaped plugs , new upper intake gaskets, new fuel filter, no vacuum leaks, cleaned the Maf sensor, ran sea foam in it.
Now I did replace the throttle body with one from a 95 motor and they looked the same except 95 has two small air holes on butterfly valve--the 90 only had one hole. But I think it was still hard starting then too.
I noticed on the side of upper intake manifold there is a sensor there what does it tell the computer what to do. Like I said the motor throws no codes and runs great after its started up and warm, or its not cold out.
I am not sure what to try next. I do have a fuel pressure regulator from the 95 motor , can I throw that on and see if it help or is it different pressure from the 90.
Thanks

 

[Bob Ayers]

Next time it is cold, try turning your ignition key to the "RUN" position for a few seconds, and then go back to off. Repeat this a couple times, then go to "START" and see how it starts. If it starts ok, then the check valve on the fuel pump is bad, allowing the fuel in the lines to drain back to the tank.

 

[Rollin]

I have already tried that, turned the key on about 4 times and herd plenty of gas draining back into the tank, and it still turns over a whole bunch before it fires up.

 

[modelageek]

http://www.therangerstation.com/forums/images/smilies/icon_confused.gif

 

[Rollin]

Does that not make since what ive said so far, I would think with it being fuel injected, after a few cranks of the motor it should fire up, the 5.0L we have fires right up with out alot of cranking. This 4.0L should do the same. Something isnt right.

 

[modelageek]

i am confused because one of you thinks the fuel should be running back into the tank and the other doesn't think the fuel should be running back into the tank

 

[Rollin]

oh,
Well the fuel I here is running back from the return line I believe. After you turn the key on and off a few times.

 

[Rollin]

Well, I think I may have fixed the cold start up issue. This morning I threw on the other fuel pressure regulator from the 95 motor, turned key on an off about three times to make sure the pressure was up and hit the key and it fired right up. Before it had to crank and crank an crank. I will find out tomorrow morning again after it sat all night and is good an cold.

 

[creepinjeepster]

If it is the FPR. They run about 27 at autozone.