Deuce oscillating at idle--any ideas

[gem1410]

my deuce is hard to start and when it does it oscillates between 450 rpm and 1200 rpm with my foot off the pedal--it has been sitting for 3 years as a no start truck--i replaced the injector hh since the orginal hh had a stuck center valve--with the new hh the truck starts up but only holds steady idle when i bring the idle to 850 rpm with the pedal--oscillating is both cold and hot--pump in tank works and filters are clean-exaust is black and does not clear up when engine gets hot-------any ideas---thanks

 

[bratpackdad]

So you replaced the fuel filters? You checked for bad injectors? You replaced the hydraulic head? You drained the tank and replaced the old nasty fuel?

 

[gem1410]

Fuel is clean --replaced filters--replaced hh--injectors working--when i installed the hh the alignment was not in the valley between the red tooth and the next tooth--it was aligned on the next tooth towards the front of the truck--could timing cause the idle problem

 

[bratpackdad]

The red tooth, should be one tooth to the right of the pointer or rear of the pointer.

 

[gem1410]

Thanks--i do have that correct--

 

[Ferroequinologist]

I'd check for an air leak as well. In tank pump working?

 

[gem1410]

In tank pump is working and have good fuel flow from it--sprayed degreaser over all fuel fittings--did not see any leaks --

 

[mudguppy]

my truck started doing that recently as well and it has not been in a 'storage' condition.

try raising the idle a little by adjusting the throttle stop. i try to keep my idle at 800-850 rpm.

 

[airmech3839]

I would say that it is likely air. Try bleeding it right after shutting down and see if it has air in the secondaries. If so I would say your primary is sucking in some air, reseat bowl and try again... even if you have no leaks does not keep air from getting in... trust me... ask me how I know this!! Good luck!

 

[jeffhuey1n]

Check the return line that goes back to the pump(?), not exactly sure. There's a plastic line that runs near the manifold that is supposed to take excess fuel and return it to to where it can work it's way back through the system. I'm going on memory so you might check the TM. If that line is cracked it can cause the condition you describe.

 

[eddiec]

You may also want to turn up the fuel pressure a bit, but only after you have checked for air leaks. Only move the nut a flat at a time and check to see if the issue is clearing up. After a few flats, if it does not start to idle smooth out, return it to it's original setting. Also recheck your air filter, and air inlet.

 

[gem1410]

Eddiec--where is the nut to turn up the fuel--thanks George

 

[eddiec]

Pm sent

 

[TexAndy]

Well, according to the "operator" cartoon, you're supposed to idle it above 700 lest vibrations shake loose any fasteners.