ok i had it scanned got code p0251 ip metering and p0370 timing refrence high currently shes runnin ok till the lite gets tripped theres still the short cycling gp but the ip code has me worried so what do i do now...thanks-mack

Do you add any lubercant to your fuel? Those codes usually mean the IP is on it's way out and lubricity additives can extend it's life.

damn thats what i was afraid of what kinda lube do you reccomend...i know theres no real answer but do you have any thoughts as to how long i have damn shame i guess ill have to get rid of it now im goin tomorrow and see what the trade in will be i travel a bit and cant afford to get stuck also cant justify the bucks for replacement...does gm 10/120 apply to new motor/pump it was replaced entire motor and turbo at 60k or original sale date hehe...and i did like this one too thanks-mack

Those two codes together indicate problems with the optic sensor, and if they're not 'hard' codes, the most probable answer is air in your fuel supply.

Or bad fuel , i had the 0251 code and it was bad fuel.

i dont think it is bad fuel this has been going on for a while maybe 4 months..kinda getting worse but just a little how bad is it to change the pump i know i could do it its just a matter of the time...where would one get a pump and do you need any special tools...i dont want to get rid of the truck,actually i want to work it a bit but at the same time i dont want to pee in the wind if you know what i mean then theres the short gp cycle here and there another issue

I think you can change out the optic sensor :confused: TDG and QM would probably know for sure

You can not just change out your optical sensor. It is the whole IP or nothing from what I understand.

Oh you can change the optic sensor, but that won't fix your problem.

Intermittent optic sensor codes are almost always caused by air or dirt in the fuel, failing that, wiring harness problem would be a long shot.

this is intresting how would one verify if there is air in the line fuel in filter chamber is clean

to test for air in fuel, put a piece of clear hose from ip return to return line. Run truck and watch for bubbles in clear line,

And I might add watch it for a while too, Like sereval days or a week or two. Check it under different conditions, like in the morning or after truck sits for a while and after running and while running.

intresting info todayfrom gm if the engine was replaced with a new not rebuilt unit i have 100k warrentee from time of replacement the guy did not know the time limit and will be calling back with that.now i need to find out what dealer did the work as it apparently did not show up in the comp which he said happens all the time.i know its a ling shot but its only a phone call or 2