RPMs drop too low

[JeremyB]

Hello all,
I was wondering if anyone might know why my RPMs drop down to about 500 when I let off the throttle and then the truck will shudder for a few seconds and then rebound to about 800 rpms. It really prevelent when I first start it up but is a constant at all times.

 

[jeffhuey1n]

I don't have an answer but my 72 with a whistler turbo does the same thing till it warms up. Then it idles fine. My other 72 starts right up and Idles perfectly, difference, no whistler. Coincidence? Don't know...

 

[JeremyB]

Mine has the D turbo,but my older one had a C turbo and started/ran like a champ,so who knows...

 

[Earth]

air sucking fuel line

 

[WillWagner]

Turbos have nada to do with it. Matbe dirty fuel filters, a crushed fuel line or as mentioned above, air in the fuel.

 

[jeffhuey1n]

Little more info on mine: first has an LDS 465-1A (low idle when cold); second has LDT 465-1D (no idle problems). First one runs like a frisky critter in heat, the second is slow on the draw. Possible sucking air, but wouldn't that cause surging as well? Possible worn igniters? Naw, that wouldn't cause low idle just crappy start up...I've got a full filter change out. I'll give it a try this weekend and let you know how it went.

Would a crushed fuel line cause crappy performance accross all power setting? Sorry, throttle settings?

 

[jeffhuey1n]

Darnit....Blizzard's blowing AGAIN!!! You'dthink by April we be done with this mess. No filter work today, if fact no work today period. Try again next week.

 

[Floridianson]

Check boost / raise fuel .

 

[jeffhuey1n]

Weren't the fuel filter. Once it gets good and warmed up, there's no problem with idle. Can igniter plugs do it? I don't know the ignition system yet. Is the ignition a constant on system? Meaning it stays hot at all times? Seems strange that engine temp improves engine idle. I'm not edumakated enough on these yet to get really creative. I'll save more troubleshooting till I learn more.

Sorry it took so long to reply back on the filter change...had to wait for weather that was ok for outdoor playing.