need HELP bought this half ton chevy truck has 6.5 turbo diesel in it with 5000 miles this is a new motor w/ new pump.... problem i am having is i replaced lift pump for a day with a 15 psi then got the pump i guess is to be on it and truck just seems like not enough fuel to run it.?? when the 15 psi on it truck ran fine real good but when i went to the one it calls for runs like crap..... i was told the 15 lb pump would damage the injection pump is this true ????? this motor is to be a up graded 6.5 reciept says DS506-AF-C combo 6.5l turbo drop-in engine diesel--4 bolt w/p can anybody help ??????

no. it wont, if anything it would help the IP.

what year is your truck?

94 1/2 ton

if you get a pump for a 93 you will get the most PSI, if your read some threads they will have more info on it

why does chevy diesel tech say it will ?? never had diesel before really like but for this prob having right now have already been down the P M D road. think i have a spare now cause all the hic-ups i was having thought it was the pmd ended up being lift pump

did you change the OIl Pressure Switch too?

ok thanks i will read down the page to see i was going to put the 15 lb back on but did not want to cost myself 600 to 1000 bucks cause i was stupid

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no the guy i bought it from said he just did that before i got it but should do it so i will know myself put new fuel filter in it the new lift pump was to run between 5 to 9 lbs thats when i was told bout the 15lb one hurting my injection pump

when you replace it make sure you do with AC Delco. dont get anyone else, i put one in my white truck and it lasted 2 weeks, the ac delco still works.

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"at idle should be around 9 to 12 psi

normal driving 7 to 9 psi

foot to the floor 3.5 to 6 psi"
-Thank Crazy

the oil pressure switch you talking bout ??? DO you think it is ok to put 15 lb back in then ?? cause it really ran much better will it hurt injec. pump???

it shouldnt i dont see why it would if anything it is helping the IP because it doesnt have to work as hard

thanks for ur help today think will change it to the 15........ someone said that the fuel lines could be plugged dont know bout that only thing i do know that with the pump it calls for just seems like it dont get the fuel it should.... thanks again

The pump housing seals are only rated for around 12 psi. I would give you an exact number but it's been a while since I've read the stanadyne rebuild manual.

That being said, you should be fine.

I run my raptor 100 at 15 psi on my DS4.

No issues.

There's a stainer on the pickup tube in your tank. After these trucks get old (which one isn't by now?) the "sock" gets a bit clogged up. If you've got good LP pressure and a new filter in it, that might be a place to look.

Can you define "not enough fuel to run it" a little better first though?

Hesitating, stalling, bucking, etc.....

yes when i start down the road and dont get into the foot feed it will run fine but when i do get into it it will run down the road bout 100 yards or so it will start hesitating a bit little bit of bucking then when i back off alittle and to me let the fuel filter fill back up some it will start evening out somewhat. it does the same thing going up a long hill to where it almost stalls out then when i ease over the top of hill, and to me catches back up to itself, it will smooth out again makin me nuts when i had the 15 lb lift pump did not have that problem that baby just kept building power and mph. thanks

Sounds like you have an issue with the lp you installed or the ops is not providing power to keep it running...

What brand is the 15 psi pump?

Never heard of one that bolts in the factory location that puts out 15 psi. Lots of guys would be interested in that.

A bad fuel cap will also allow too much vacuum to build up in the tank. A little vacuum is normal, a lot is not. Failed fuel caps have been known to collapse the sides of the fuel tank.

In order to get fuel out, you have to let air in.....


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the pump is a carter...... i also loosened the fuel cap to see and that didnt help at all either.... back to the pump it is a carter and you have to take the three bolts out of the top of bracket and invert the bracket and move the rubber bushings to the holes in the bracket that are already there this lets the pump sit the way it has to for the 'out' to be headed the right way to the filter at the engine..... thanks again for your help