Idle Climbing

[eldgenb]

Hi Guys, I have an 818 with the 250 and I am having an idle problem, after searching I have replaced all the fuel lines, removed a fuel tank and selector valve and replaced all the fuel filters. Here is my problem, when the truck is cold it idles perfectly at 700 rpm, once the truck warms up the idle holds at about 1200 to 1500 rpm constantly. Any ideas?
thanks in advance.

 

[Scout]

Sorry I don't have anything useful to add - but my truck does the same thing. It does it only in cold temps (freezing), not just with a "cold" motor.

 

[eldgenb]

Yeah it is just a little strange, I have over 100 miles on the truck since the changes that I made so I would thing that all of the air would be out of the system by now, I am sure it is something specific that someone on here will shed light on.

 

[eldgenb]

bump
any ideas?

 

[jimmcld]

From what I understand, the speed is controled by the pressure of the fuel. If your return line was clogged, it might tend to build up pressure.

 

[armytruck63]

I was thinking some sort of a small air leak in the fuel system that gets worse as the engine heats up. I would check the return line like jimmcld says and also check the fuel filter cannisters to make sure there are no leaks or cracked gaskets.

 

[jwaller]

I had a similar problem with mine. the throttle was too tight and it would pull it while driving the truck, ie normal frame flex. once I loosened the throttle some it went back to normal.

 

[eldgenb]

thank you for the replies, I will check all of these.
Eldgen.

 

[cbvet]

My 813 with Cummins has a similar problem.
It idles just fine at about 800 RPM, but if I pull out the hand throttle any amount at all, engine speed steadily climbs to 1700 to 1800 RPM.
Push the throttle back in & it's okay.