94 Vortec fuel pressure... what when?
#22
02-08-2011, 05:05 PM
eBay has factory service manuals all the time; I got the one for my Bravada for less than $20 shipped.
#23
02-08-2011, 09:51 PM
I'm not sure of anything, but needed to start somewhere. I don't think it's the IAC because its idles just fine. TPS? Dunno.
I've been smelling gas for a while that I couldn't find the source for. I pulled the plenum and there is washing by the FPR, BUT.. it looks old like it's from when it went 4-5 years ago. (I didn't own it then) It doesn't look like it's leaking. The nut kit which was also changed then looks to be leaking, ever so slightly as well as the valve for the pressure gauge. I'm assuming that's where the smell was coming from, but I have a feeling it's NOT the source of the problem.
I'm waiting on the nut kit (as well as free time and good enough weather), then I'll go on from there.
I've been smelling gas for a while that I couldn't find the source for. I pulled the plenum and there is washing by the FPR, BUT.. it looks old like it's from when it went 4-5 years ago. (I didn't own it then) It doesn't look like it's leaking. The nut kit which was also changed then looks to be leaking, ever so slightly as well as the valve for the pressure gauge. I'm assuming that's where the smell was coming from, but I have a feeling it's NOT the source of the problem.
I'm waiting on the nut kit (as well as free time and good enough weather), then I'll go on from there.
Last edited by cas; 02-09-2011 at 09:47 AM.
#24
02-11-2011, 05:12 PM
You can leak check the system before you put the plenum back on. There is a wire with a connector on the right side of the firewall that's in a bundle that's called the "Fuel Pump Prime Connector". The book says to jump it with a 10 or 15 amp FUSED jumper directly from the + on your battery and it will make the pump run. Key doesn't even have to be on. Should be a gray wire in a bundle. Saved me from pulling my plenum off twice.
#25
02-13-2011, 02:57 AM
Yeah you almost have to have a book to work on these things, then you have to be really careful. The books leaves out some things and misleads on others.
What, onetruetom said is what the books says, but they're not talking about the upper manifold (plenum) they're talking about the lower manifold..
In my Haynes manual, chapter 4 "Fuel and exhaust system" it says
"CPI air intake plenum fasteners" 124 in-lbs..I think that's about 12 ft. lbs
What, onetruetom said is what the books says, but they're not talking about the upper manifold (plenum) they're talking about the lower manifold..
In my Haynes manual, chapter 4 "Fuel and exhaust system" it says
"CPI air intake plenum fasteners" 124 in-lbs..I think that's about 12 ft. lbs
#27
02-13-2011, 02:24 PM
Ok, here's what my Chilton manual says Intake manifold 35 ft. lbs. Has a footnote.."Upper intake manifold 124 in. lbs.
Torque sequence #1 first bolt on the left, then clockwise right on around end at #10 front center..not staggered like most things.
Torque sequence #1 first bolt on the left, then clockwise right on around end at #10 front center..not staggered like most things.
#28
02-21-2011, 07:16 PM
Just to update... I changed the TPS just for the heck of it, which did nothing.
I changed the nut kit due to a minor leak, didn't expect it to effect anything and it didn't.
I didn't see any other signs of leaking anywhere else with the plenum off and the system pressurized. The fuel pressure is good and holds well.
Tonight however I found out my oil level is too high and you can definitely smell gas in the oil. This wasn't the case when I first had problems as I checked it early on.
So... I dunno. I'm going to pull the plenum again and change the FPR anyway.
I changed the nut kit due to a minor leak, didn't expect it to effect anything and it didn't.
I didn't see any other signs of leaking anywhere else with the plenum off and the system pressurized. The fuel pressure is good and holds well.
Tonight however I found out my oil level is too high and you can definitely smell gas in the oil. This wasn't the case when I first had problems as I checked it early on.
So... I dunno. I'm going to pull the plenum again and change the FPR anyway.
#29
02-22-2011, 01:54 AM
Man this is keeping me up at night. Just got out of bed to do some more searching.
1. Seems like it's dumping lots of fuel. So either the FPR is leaking when it's running (but not when I watched it), or a poppet is stuck?
2. THIS THREAD problem sounds like my original problem. The stumbling problem feels like someone is throwing a switch on and off. if the connection to the spider is intermittent I would imagine it would have the same feel? I'll check that as well.
Pardon me for sort of talking to myself but it keeps me from forgetting things (especially when I find them at 3AM.)
1. Seems like it's dumping lots of fuel. So either the FPR is leaking when it's running (but not when I watched it), or a poppet is stuck?
2. THIS THREAD problem sounds like my original problem. The stumbling problem feels like someone is throwing a switch on and off. if the connection to the spider is intermittent I would imagine it would have the same feel? I'll check that as well.
Pardon me for sort of talking to myself but it keeps me from forgetting things (especially when I find them at 3AM.)
#30
03-13-2011, 02:41 PM
Hello... just wanted to update this problem for future reference should anyone come across it using the search feature.
I basically had two issues going on. I'd been smelling fuel for a while without finding the source, so when I had trouble I leaned towards fuel, even though it felt electrical.
With the plenum off I found the (fairly new) nut kit leaking slightly. The crank case was loaded with fuel, so I wasn't sure it was a FPR issue, a bad poppet or just from cranking the engine. The fuel lines on the spider had been rubbing together and were worn flat and thin in some spots. I figured I'd remove all doubts and change the whole thing with a remanufactured one, as well as changing the plug assemble. None of these things were THE problem, but were things that needed to be addressed or would have been problems in the near future.
The original issue with the engine was it would run and skip and sputter. Then it changed to where it would start, run for a while, them die. (but only start once a day). I was replacing the ignition module and the plug for the pickup coil just fell apart in my hands. So I ended up changing the module and the pickup coil at the same time. So ONE of these parts was the problem (more than likely the module). That was the cause of the original issue you see in the youtube video, unfortunately the other problems kept throwing me off track.
Thanks for all the help and input.
I basically had two issues going on. I'd been smelling fuel for a while without finding the source, so when I had trouble I leaned towards fuel, even though it felt electrical.
With the plenum off I found the (fairly new) nut kit leaking slightly. The crank case was loaded with fuel, so I wasn't sure it was a FPR issue, a bad poppet or just from cranking the engine. The fuel lines on the spider had been rubbing together and were worn flat and thin in some spots. I figured I'd remove all doubts and change the whole thing with a remanufactured one, as well as changing the plug assemble. None of these things were THE problem, but were things that needed to be addressed or would have been problems in the near future.
The original issue with the engine was it would run and skip and sputter. Then it changed to where it would start, run for a while, them die. (but only start once a day). I was replacing the ignition module and the plug for the pickup coil just fell apart in my hands. So I ended up changing the module and the pickup coil at the same time. So ONE of these parts was the problem (more than likely the module). That was the cause of the original issue you see in the youtube video, unfortunately the other problems kept throwing me off track.
Thanks for all the help and input.