Need stock specs for base/idle fuel psi on a 99 suburban / vortec 350 please,

Dads burb is having slight off idle drive ability problems and I'm suspecting fuel pump getting weak / possible bad spider injector, Thanks in advance

 

55-60 psi KOEO and 55-65 KOER
Good way to check volume is if your pressure gauge has a bypass button on it press it with engine idling. If motor dies pump is not putting out enough volume.

We've had a fair amount of those trucks in the shop lately with bad injector spiders. They weren't designed for corn gas we have now day's and they aren't liking it.

 

Thankyou , appreciate the info .

That confirms my suspicion the spider is going bad , but I'll check the pump also while I'm there .

 

KOEO spec is 60-66 psi.

be sure to upgrade to the MPFI spider over the old CSFI spider.

peace
Hog

 

Thankyou hog , didn't know that , wonder how one would know which is which ?
Hard to trust most people behind the parts counter .

 

This article discusses it
CSFI to MPFI - Vortec Engine Fueling Fix - Fuel Injection - Off-Road Magazine

As does this GM document
http://www.acdelcotechconnect.com/pd...sb_05D-105.pdf

CSFI top, MPFI bottom


If you peer down the throttlebody, sometimes you can tell by which hoses are present. The MPFI have thicker spider arms, while teh CSFI are thinner.

Both spiders flow 23.1 lb/hr The MPFI spider use actual Multec 2 mini-injectors at the end of teh spiders arm, rather than simple poppet valves like teh CSFI setup does. IIRC in 2004 the 4.3 in teh FS trucks went to the MPFI in stock OEM applications.

peace
Hog

 

Kudos Hog ! That's great info , Thankyou very much for sharing , awesome to have members like you .

 

You are very welcome, thanx.

peace
Hog

 

TIM Z did you end up fixing the problem?
I have a 99 2 door Tahoe 4x4 and lately its been running like crap mainly onlt at WOT. From a dead stop or a 30 roll i feel that the RPM climb like they should but feels like if im draging an anchor behind me. I have already deleted my cats, replaced plugs, wires, cap and rotor (ac delco), new fuel filter, cleaned throttle body and also did a sea foam thru the vacum hose. I still cant get it to run like it should I previously owend a 99 2 door 4x4 Tahoe about 3 years ago and it ran way better than my current one. I have been suspecting that it might be the fuel pump and now that i read this its making me wonder if its the spider. Does anyone know of anyway to check to see if the spider is going bad?

 

I have not dove into this yet , my dad bought a 97 sierra for a winter truck , and his burb is parked for now and he didn't want me to tare it apart yet .

I would do like said above and check your fuel pressures , I think it's a safe bet if you have some miles on it and never have changed the fuel and spider it's a good idea to if you plan on keeping it . Also make sure you have the newer intake gaskets installed .