!996 Crazy Idle

[monkeyoil]

Ok I’m very new to Diesel trucks so please forgive me if this is something easy.
Bought my first diesel about 6 months ago everything has been great till about a month ago.
Now if you drive the truck awhile say I get out for something and go to start it back up it idles like a top fuel dragster?
give it some fuel say up to about 1500 RPM’s then let off it idles like it should. It does not cause any issues while running.
Runs and drives fine plenty of power just goes crazy every now and then.
Anyone ever ran across this?
Thanks everyone.

 

[94f450sd]

Could be a few things.how many miles on it? Last oil change? What oil was used? Could be injector orings, ipr orings, dirty fuel pressure regulator screen.

 

[monkeyoil]

262,000 last change about 1000 miles ago. Rottela T also if it helps i now see a small fuel leak right under the truck about where the back of the motor is. i only see the leak when its cool in the mornings now when it heats up no leak??

 

[94f450sd]

That could cause it.pull the top cover off the motor.look down behind the fuel filter youll see the fuel pump and short pieces of blue fuel line.one them could be leaking.be a good idea to replace them anyways with your mileage.on the other end of the pump there is a banjo bolt holding the metal lines to it.its common for it to loosen up.its a pita to tighten it.do a search for "banjo bolt" , should find a thread on how to tighten it.fix the leak first

 

[NJKen]

That could very well be the beginning of the injector wiring harnesses (UVC harness) going bad. Check the 4 connectors on the valve cover gasket (2 on each inside edge of the valve cover) for any signs of melting. With the milage on the truck they are way overdue if they are still original.
Ken

 

[monkeyoil]

well i have nailed it down on the leak today. dont seam to be the banjo bolt or the pump. its the black sensor on the right side of the filter bowl. not sure what that is but it has one wire hooked to it?

 

[94f450sd]

wich connector?squarish plug is the fuel heater the other is the water in fuel sensor.

 

[monkeyoil]

if your facing the truck its on the right side top where the furl filter goes has one red wire plug on it. its round.

 

[monkeyoil]

ok well i think its fixed? had an older gentelman show me where it was leaking. It was the sensor to tell you when to change the fuel filter. He told me to replace it with a 1/8" pipe plug so i did. No more fuel on the ground and so far for three days no crazy start up idle. It could just be in my head but seams like it runs a ton better also. He said it was letting air in the fuel systeam. Sounds true i guess?

 

[94f450sd]

sorry i didnt get back to you on that sensor.my truck no longer has any of the stock fuel system so i wasnt sure what sensor you were talking about and never got around to looking for a picture.that leak will let air into the system especially at night when it sits,dont know about when its running.my fuel system didnt last long enough for me to worry about how it worked.