1986 6.9 Starts Rough Runs Fine

[MJ86F250]

Hi I have a 1986 6.9 starts rough but then runs fine...I just changed the fuel filter and then this happened is this a coincidence or should I be looking at the plugs or return air line. Once I give it a bit of gas it is fine... Ideas please and thanks. It only has 42000 kilometers 26000 miles
MJ

 

[Thewespaul]

Welcome to the forums, when starting out here its best to read read read, most of these common issues have been answered a thousand times over. Try the magic button that says search. Or even try google, and go from there, the stickies on the top of this page hold many tech articles and faq that would be very useful for you.






I think I'm going to start copy pasting this answer...

 

[dgr]

All the time or only cold? Have you driven it a few miles?

 

[BrianX128]

Once I give it a bit of gas it is fine...

As in if you tap the throttle after it starts it clears up or you have to hold it down until it's warm? Sometimes when I've started mind cold without pushing down on the go pedal some it will start but run like ass because it's in this weird 450-500 rpm limbo and a simple tap of the throttle and it holds at a normal rpm. Just sounds like a super slow Detroit 2 stroke idle.

 

[franklin2]

It has a fast idle solenoid. The solenoid is strong enough to hold the throttle open to increase the idle, but it's not strong enough to push the throttle open on it's own. You have to help it each time you start it cold. My 89 has the starting procedure on the back of the sunvisor.

After changing the filter it may start rough a couple times, it has air in the system. Drive it some, it should work the air out. If it still is not running right, check for leaks are something else you may have knocked loose under the hood.

 

[icanfixall]

The fast idle solenoid is not strong enough top kick up the cold idle speed without some help from your foot. ALL fast idles on these engines are like this. Its even printed on the sun visor in many trucks. I know it is on my 89. Mine talks about how far down you press the throttle depending on outside temps.