RustyBolts
Full Access Member
I need a fuel pressure spec for a '96-'00 Vortec 350, and my POS chilton manual doesn't give one for '96 and up, just ther '95 and older TBI. Specs for a TBI do me no good at all since I have a CSFI Vortec engine.
Vortec Fuel Pressure Specs
- Thread starter RustyBolts
- Start date
50psi. what are your symptoms? there's a a reason why they don't have a spec for the FP. There's alot more going on in order to get the truck running.
RustyBolts
Full Access Member
It stumbles/misses/skips/pops under light and moderate load, but runs just fine at idle, acceleration, and wide open acceleration up to about 4500 RPM.
I've already put new plugs, wires, cap, rotor, and fuel filter on it, with dismal results.
I've already put new plugs, wires, cap, rotor, and fuel filter on it, with dismal results.
you checked your throttle position sensor first?
doesn't sound like a fuel problem....yet.
I've dealt with cold crank but no start until you give it a whiff of ether but runs all day no prob.
I've dealt with plain no power at all. even with high HC readings.
both are related directly to the fuel dist. the injectors on the vortec are like IDI injectors, they're just pop valves.
more info needed
doesn't sound like a fuel problem....yet.
I've dealt with cold crank but no start until you give it a whiff of ether but runs all day no prob.
I've dealt with plain no power at all. even with high HC readings.
both are related directly to the fuel dist. the injectors on the vortec are like IDI injectors, they're just pop valves.
more info needed
RustyBolts
Full Access Member
Hmmm. I never thought to check the TPS, but it's now next on my hit-list. I'll check it as soon as I get home tomorrow, then I'll post my results here for further consideration.
RustyBolts
Full Access Member
OK, Checked my TPS, and it checks out fine. It has a solid 5V going in, and the output rises and falls smoothly, with no jumps, spikes, or drops in output voltage along the way.
What next?
What next?
hi, it kinda sounds like my '96 did at one time, turned out that the gear on the dist. was worn, replaced that and it ran fine. another time it was the dist cap, i had a brass terminal one and it ran like a bag of dung, i put the cheap cap on it and it ran good again. dunno if this helps but its food for thought-good luck!
RustyBolts
Full Access Member
The last 2 sets of wires, caps, and rotors I've put on, I've gotten mail order from LMC. I don't remember what material the terminals were made of though. I never have checked distributor backlash though.
RustyBolts
Full Access Member
Progress Made
Got my truck in the shop here at school today.
First off I checked my Fuel Pressure.
Pump Running, Engine off-53 PSI
Pump Running, Engine Idling- 50 PSI
Pump Running, Throttle cracked open- 60+ PSI
From that I judge the pump is good, and flowing what it should.
Next, I hooked up the school's Snap-On scan tool, and checked my Cam Retard, and the spec on it.
Spec was +/-2*
Scanner showed -11*
eek
Rotated the dizzy (which is where the cam sensor is) until the reading was in spec.
Truck runs and drives much nicer from what i could tell cruising around town here. I never did get it up on any big roads, but i did find that the stumble has changed a bit. Now, rather than it stumbling while cruising, it does it now accelerating from a dead stop. Once its rolling, it clears up and runs great. It's like a carbureted engine hesitating off idle.
I had one instructor tell me it could be a crack in the pickup magnet in the dizzy, and another tell me it could be the coil, but I'll check both, and probably replace the coil anyway. Engine has roughly 75,000 on it, but the rest of the truck has 346,*** miles, and God only knows how long that coil's been on there.
Bottom line (as of now) is that the Big Blue Bomb runs better than it did when I drove it last.
Got my truck in the shop here at school today.
First off I checked my Fuel Pressure.
Pump Running, Engine off-53 PSI
Pump Running, Engine Idling- 50 PSI
Pump Running, Throttle cracked open- 60+ PSI
From that I judge the pump is good, and flowing what it should.
Next, I hooked up the school's Snap-On scan tool, and checked my Cam Retard, and the spec on it.
Spec was +/-2*
Scanner showed -11*
eekRotated the dizzy (which is where the cam sensor is) until the reading was in spec.
Truck runs and drives much nicer from what i could tell cruising around town here. I never did get it up on any big roads, but i did find that the stumble has changed a bit. Now, rather than it stumbling while cruising, it does it now accelerating from a dead stop. Once its rolling, it clears up and runs great. It's like a carbureted engine hesitating off idle.
I had one instructor tell me it could be a crack in the pickup magnet in the dizzy, and another tell me it could be the coil
, but I'll check both, and probably replace the coil anyway. Engine has roughly 75,000 on it, but the rest of the truck has 346,*** miles, and God only knows how long that coil's been on there.Bottom line (as of now) is that the Big Blue Bomb runs better than it did when I drove it last.
RustyBolts
Full Access Member
I feel like such a ******* now.
Took off my air intake ducting so that I could clean my MAF sensor. While I was at it I decided to take the throttle body off and clean it. While in the removal process, something caught my eye.
On those Small Block Vortecs there's a large rectangular connector for the injectors in that CSFI system. The tab on one end wasn't latched and that end was up a little bit. I pushed it back down til it latched, cleaned everything up and put it back together. The next time I started the truck, it ran and drove great, even after it got good and warmed up.
I really think that connector was my sole problem all along.
Took off my air intake ducting so that I could clean my MAF sensor. While I was at it I decided to take the throttle body off and clean it. While in the removal process, something caught my eye.
On those Small Block Vortecs there's a large rectangular connector for the injectors in that CSFI system. The tab on one end wasn't latched and that end was up a little bit. I pushed it back down til it latched, cleaned everything up and put it back together. The next time I started the truck, it ran and drove great, even after it got good and warmed up.
I really think that connector was my sole problem all along.
