Different Idle speeds after warm up

[djawahir]

I find that my idle speed changes from anywhere between 600 and 850. I could be driving 30 miles and stop at a stop light and the idle will hold steady at 600. After the next few miles and another stop light, the old girl will idle steady at 850. Next time, it could be 700. This seems to happen often and I can't figure out why the idle speed could be different from minute to minute.

I've rebuilt the carb, replaced plugs, wires, disty cap, half of the vacuum hoses, replaced the HAC valve, cleaned the EGR Modulator, run Seafoam through the oil & engine & gas tank, replaced fuel filter.

I don't think there are any leaks anywhere, except for possibly that little L-shaped pipe thing that sticks up under the carb on the driver's side. I JB welded that a few months ago, but I don't know if I sealed it all the way.

Also, there's that little rubber boot that controls something on the second barrel of the carburetor that's torn. Could that be causing a problem too?

Any ideas?

 

[FJTOYMAN]

The L shaped pipe supplies the EGR with vac. You can test for leaks by spraying with carb cleaner and listen for the rpm to kick up. This might be your problem.
I had a similar problem with mine. I noticed that if I pulled up on the throttle a little it would go back down to the 650 mark. I think for some reason some of the linkage was hanging up. I put a return spring on the linkage and that seams to have fixed the problem.

 

[Team Zissou]

Not to highjack, but I've had a similar problem after rebuilding my carburetor. My RPMs would drop down to 500 though, occasionally forcing the engine to stall.
Thanks for the info, here's hoping it's a good fix

 

[cabron]

Try "kicking up" the gas pedal at idle. Does it return to normal RPM levels. Mine did this and is was just sticking, I greased it and the problem went away.

 

[beaufort-fj60]

where did you get this in red? did you paint it?? that might be the wrong part

 

[beaufort-fj60]

for reference

that part is green.white.black 50cc/min

 

[djawahir]

It's supposed to be the green VTV from SOR. (The part number on their site is:048-08D). Is that not the right part??

 

[djawahir]

So from the diagram beaufort-fj60, I don't even see a red body one. That kind of irks me. I don't even know what that red part is?!?! I guess I'll have to have Specter send me another one. Hopefully they won't charge me for it.

 

[FJTOYMAN]

It looks like just the body is red. Normally they are green and black with a white body. I don't think that would be causing your problem.

 

[Bookseeb]

Had the same prob., so I took apart all the linkage, cleaned and lubed it and put on a new return spring. Don't know if it will help with your prob., but it helped with mine.

 

[djawahir]

Just updating the posting.

It was my linkage that was sticky. When I lifted up the gas pedal, the idle went back to 650, where it belongs. I will lube up the gas pedal linkage. Thanks guys!