2000 volvo isx idle go up and down when first start

[Alflores]

hi folks,i am looking and probably buy this truck 2000 vnl volvo 660 with an isx 400 hp,when i first start the engine idle is kind a wierd,idle go up and down for the first 2 or 3 minutes,the dealer told me that this idle up and down is normal on this engine,so i tried another volvo but 2003 with a 450hp isx too and that engine does not do that,the idle does not change.i sent an oil analisys to jonhson cat dealer at riverside and they said it was a nice engine,did not find any coolant,fuel,water in the system but that idle does not like me.is this true that this idle normal on this engine when we start them in the mornings.thanks for any info.p.s.they want $26,000 for the truck,600,000 miles.pretty clean truck.please help with any info

Check for a either a cracked Fuel fileter bowel on the Feul water Separator or a sliced or ring there. Somehow Air is getting into the fuel system not enough to cause a no start but enough to cause surging. What you are describing is surging from air getting into the fuel system.

[Alflores]

i'll check it out this sunday,thanks

[KAIMIKAZEE]

Check for a either a cracked Fuel fileter bowel on the Feul water Separator or a sliced or ring there. Somehow Air is getting into the fuel system not enough to cause a no start but enough to cause surging. What you are describing is surging from air getting into the fuel system.

are you talking about the fuel filter bowl??

what do you mean by a "sliced or ring there"???

just recently my truck takes a while cranking before it starts

"vrrr.vrrr.vrrr.vrrr.vrrr.vrrr.vrrr.vrrr.vrrr.vrrr .vroooom"

as opposed to "vrr.vrr.vrr.vroom"

you get the idea...what could be causing that (isx 500)

it seems to be only doing that when the truck is runned for a couple of hours. and yes my idle goes up and down but i usually pay attention to that until now...