Odd Idle problem.

[SpareParts]

So i have had this truck 3 or 4 weeks now i notice a slight problem with the idle. It's always smooth
When cold and first start it does not go over 1k rpm (maybe normal i dunno)
Once warm it idles at 550rpm but after running maybe 20 minutes or so the idle is up to 700rpm and it seems to take longer to shift from 1st to 2nd.
I think its temp related causing this?
My Temp gauge never gets to 210 but using Torque Pro it will read 218 is the highest i have seen so i assume the factory gauge is not reading right and the higher idle is a result of temp.
Plan is tomorrow to do a radiator flush and fill a couple times till i get clear water since the PO mixed green and orange antifreeze.
I also notice using Torque Pro that the IAC counts are 0. I don't believe it would idle smooth with a bad IAC valve but ill hook up a proper scanner tomorrow and check.

 

[tom3]

I'd suspect a vacuum leak somewhere. Could be hard to find. I have an old medical stethescope to probe around everything and listen for a leak. Do you get any codes when scanned?

 

[SpareParts]

I would think a vacuum leak would cause a higher idle all the time?

 

[S33k3r]

I would think a vacuum leak would cause a higher idle all the time?

Not if it were leaking at first start and then swelled shut with heat. I suggest you simply check all pieces of your air intake system, and I also suggest you check your fuel system. This could also be a sign of a fuel pump starting to die, or your charcoal canister leaking pellets into the breathing tubes. Nothing major, but highly annoying.

It occurred to me that you might also want to look at the accessories running on your accessory belt and the tensioners. I had an alternator going out on me at one point, and it killed gas mileage until it died. I went from 15 to 17 MPG, by just replacing the alternator.

 

[SpareParts]

Checked the FP and idling im at 48psi.
Wanted to order a new pump, regulator, filter from Rock Auto but dam* i cant figure out what pump to order.
I have California emissions, EVAP. Can't figure out if i need the long or short pump.
Any know what the requirement is for a long or short pump?

 

[Fless]

I'd suggest looking at the IAC and cleaning it and the throttle body, if it hasn't been done. If your IAC is stuck at "0" then focus on that. Also it wouldn't hurt to properly clean the MAF.

So this Suburban is the 2500, and we're talking about the front tank pump.(?) If you have RPO code K53 (robust) you would use the fuel pump specified for the robust fuel system. Look at the code on the inside glovebox to see if you have RPO code K53.



You could also enter your VIN into GMPartsgiant.com and look there for the OE part number.

 

[SpareParts]

Part of what i dont understand is, I dont have a front or rear tank. Fuel tank is on the DR side inside the frame
No K53 on this truck.
Im pretty sure the IAC reading "0" is a erroneous reading on Torque Pro.

 

[S33k3r]

I thought all the 2500s had a tank between the spare tire and the bottom of the cabin? You might want to look.

Did You Know That Some Suburban’s Have Two Fuel Pumps? We Found Out The Hard Way

 

[nonickatall]

As far as i know the tanks are all on the same place, but the difference is fuel flex or not and the production date, because later years have no seperate fuel filter.

 

[SpareParts]

Well dang did not know that. Guess ill need to look underneath and may need to order 2 fuel pumps.