Flucuating rpms and flucuating fuel pressure from airdog
 

Question #1- When I first start my truck Ive noticed that the rpms have been flucuating between 750 and 850 is this normal for these trucks to do, but after the truck has been driven they seem to hold steady at around 850 or so I think. And they seem to do when the truck is in cool down mode is this something to be concern with or just normal. Question #2- Here lately Ive noticed that my fuel pressure has been bounceing around from 17 to 13 psi. Is this normal for the airdog to have flucuating fuel pressure or is it being caused from the impluses from the vp44 :humm:

Thanks for any help and advice guys

Andrew

Watch your volt meter when its doing the fluctuation and see if it is dropping down from the grid heater,this also causes low voltage to the fuel pump.This is common event and a good place to start.

It does fluctuate while the grid heaters are cycling but it also does when they arent cycling. Like last night when I was going to work I stop at the store on the way and the truck was up to operating temp but the rpm needle was "bobing" up and down. I had the attitude monitor set to show the rpms and they were fluctuating from about 820 to somewhere around 850. It just puzzles me about this cause u would think the rpms and the needle would hold steady and they do at times but theres other times they dont.

how old is the AirDog ? anybody got any ideas?

Itll be a year old in febuary. I wouldnt think the fuel would be gellen to cause the pressure to drop b/c it hasnt been really cold around here just in the 20s. Would this be a sign that the pump itself needs cleaning:humm:?

mine used to "bob" also. it would do it when cold. after a good highway drive it wasn't noticeable. NOT THE HEATERS. i hit 160k and decide to do valve lash. i think i had 3 valves out of spec and another 6 that barely met the spec. afterward it stopped. only time the rpms move is if the ac compressor kicks or the grid heaters cycle

:humm: I am having the same rpm deal and was thinkin bout adj. the valves on mine as well here shortly and its really got me wonderin now might just have to do the adj sooner than later. thx guess who :tu:

my pump is only a month old and my pressure bounces like that. I dont have any kinks that i could see. But i my rpm is for the most part steady

if the fuel pressure bounces...i think that usually means that the pump is sucking air somewhere... don't use plumber's tape... use a quality thread sealer... the stuff i used was marine grade and looked similar to tar
do it right and do it once! :thumbsup