VERY HARD cold start 3.4

Hey,
Just got my truck back from Bill (it had been sitting for 4-5 years) and he rebuilt the top end. Anyway, the truck is very hard to start and I can keep it running with the gas pedal but when it goes into closed loop, the truck starts to run normal (although with a 1500 RPM idle). I cleaned the MAF sensor but my next thought is the IAC/Throttle body.
Any other thoughts?

 

I guess I should say, it was sitting for 4-5 years before I dropped it off at bills! No takers?

 

Its brand new.

 

Its probably a clogged fuel filter or gummed up fuel pump.

 

It has a new fuel pump but the filter is old. Why would it run fine in closed loop if the filter is clogged?

 

It would run better once the pressure builds up, but during startup it would cause some problems. You probably should change the filter if it hasn't been done anyhow.

 

It is literally like a switch goes on when it goes into open loop and it runs smooth.

 

If the IAC was sticky it would affect the idle. You should take it off and clean it out.

When gas sits for that long it separates into gum and varnish and other things. This might have made the injectors and other fuel system parts dirty. Redline SL-1 is supposed to be a good fuel system cleaner to use. You should anyhow since it sat for many years. You're lucky the fuel pump didn't quit, it happens a lot on vehicles that sit unused.

It does seem like a fuel system problem, but hard to say without some testing and diagnostics.

 

Changed the fuel filter and it runs/idles great now. The idle is still high so I am going to mess with the IAC valve now.