Hard to start rough idle...now what...?

[azscott]

Arghhh...had no isue the first month...now....?

 

The last couple of days it has been a little hard to start. Sometimes it will start ...idel rough and then stall. Or just idle rough for 2-3 minutes.

It accelerates fine...but will stall or almost stall for the first 1-2 minutes on startup?. Seems to only di this if warm or hot. When it sits all night no problems starting...so far. If I stop for 10 minutes or so and get back in it is more likely to do it....although sitting for an hour or two will also.

Runs fine other than that.

I checked for vacuum leaks but that should cause a high idle I would think...but anyway...none were found. TPS was adjusted a month ago but it was fine as was the other idle thing next to it( name escapes me. MAP seems to work fine and tested fine.

I still plan on replacing the O2 after some recoomendations for the low idle as I have no ideas left on that. But now this hard starting/rough idle for the first 2 minutes it starts has become an issue all of a sudden.

What would be the logical approach to this.

I love the truck...runs great overall...even with the Puegot tranny ( hey what can ya do.

again this is an 89, 4.0 5 speed. ( I will put that in my signature shortly)

scott

[64 Cheyenne]

I would check for fuel pressure at the fuel rail first, probably after it sat for 10-15 minutes.

If that was good, I would either unplug/plug the CPS, see if that helps, or replace the CPS.

[azscott]

I can check that. But wouldn't the problem be worse when it sat overnight if theere was a fuel pump pressure problem? Or am I looking at it wrong.

I will pick up a fuel pressure test kit later today as I wanted one anyway.

scott