Author Topic: 1991 Crew Cab Going 6.0 LS  (Read 16648 times)

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #45 on: April 25, 2017, 12:10:52 PM »
Brought my DBW Pedal into work and powered it up with an adjustable DC power pack.  I confirmed that my pedal is wired correctly and sensor 1 and sensor 2 are within the proper output voltage range that the 2004 TAC module requires.

Now I am certain that my 1999 6.5 TD pedal will properly interface the 2004 LS and that I re-pinned the pedal connector properly.  A few pin swaps into the correct connector cavities according to the previous posted diagrams was all that it took.
« Last Edit: April 25, 2017, 12:13:20 PM by ehjorten »
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #46 on: April 30, 2017, 07:49:05 PM »
I have a question about my ISS and VSS wiring.

So I have a 1991 4L80e that has the standard plug for the internals and then it has an Input Speed Sensor (ISS), an Output Speed Sensor (OSS) in the tail of the transmission, and finally a Vehicle Speed Sensor (VSS, obviously) in the Transfer Case. I do not have a switch in the transfer case for Low Range.

My engine is a 2004 LQ4 out of a 2004 Yukon XL 2500. Apparently it must have been a 2wd because it doesn't have the VSS going past the transmission. What I have is two connectors that plug into the ISS and OSS like it was stock on my transmission as well as the big electrical connector.

My confusion comes that it looks like the rear plug might be a Pressure Control Solenoid Valve? The color of the wires is correct, but I am really thinking this must be the VSS on the 2004?!

What do I do with the OSS on my transmission? Is it not used? My 1991 V3500 had wires going to the ISS, OSS and VSS?!

Does anyone have pinouts for the 2004 PCM?
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #47 on: May 01, 2017, 07:37:31 AM »
I think I figured my transmission wiring out last night.  Please correct me if I am wrong!

I used a dmm to confirm that my rear plug is indeed pinned to the VSS pins on the PCM.  Strange...I am reasonably sure this was an engine out of a 4WD.  Did GMC just use a jumper harness to get to the transfer case?  I was confused looking at wiring diagrams about the PC Sol Valve.  The diagrams made it look like it was a separate connection.  I see that it is actually part of the big electrical connector on the transmission.

The PNP connector looks like all I need is the Park/Neutral wire and the Backup wire?!
I have this connector:


I still want to go through the pins on the big connector to make sure they match my 1991 transmission and no pins are swapped.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #48 on: June 23, 2017, 01:54:30 PM »
Been finishing up the install of my new tanks and fuel lines, etc.  I also re-did the fuel fills.  The previous owner replaced the bed with a slightly older version that did not have the 3 holes in the bedside for mounting the 87-91 fuel filler plastic cups.  I had to layout the holes and drill them.  Very nervous, but measure, measure, measure, drill and I got them all to line up perfectly!

Now I am working on modifying my fuel lines so that they have the GM Quick Disconnects in the hardlines and run everything through the Corvette Filter/Regulator and then up to the fuel rail.

Trial run with the Mastercool Hydraulic Flaring Tool:

« Last Edit: July 11, 2017, 09:13:10 AM by ehjorten »
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #49 on: July 11, 2017, 09:26:46 AM »
Haven't updated in a while...

The engine, transmission, & transfer case were all put in a couple of weeks ago.

I got a new transmission dipstick and indicator for the 2004 LS that this came out of from my local Chevrolet dealership.  My 4L80e dipstick tube out of my 1991 V3500 had the bracket that goes to the bolt on the bellhousing that was eliminated on the LS bellhousing.  The LS version for the 4L80e goes to the next lower hole.  I confirmed that the dipstick tube on the bottom half is bent exactly like my 1991 version.  I did have a heck (trying to not cause here!) of a time getting it installed.  I had already installed the transmission and now it is painfully clear to me that you should wire up the tube to the firewall and install it at the last few inches of installing the transmission!!!  But...I can confirm that it is possible to install the tube after, but it isn't fun!!!  I almost thought I was going to have to rent a transmission jack again and pull it all back apart!  The tube is a little scratched up, but nothing that a little masking and paint can't fix.







And then I did get a few things crossed off of my list last night...
New oil filter for the LS, filled with oil and installed
Rear 2-piece driveshaft is all installed and lubed
Converter bolts are all installed and torqued
Gear shift mechanism all re-installed and adjusted
Transfer case shifter all installed and lubed

Only about 50 more things to do before this pig gets fired-up!
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #50 on: July 15, 2017, 08:28:36 PM »
Went through the intake valley and installed a new gasket and knock sensor grommets. Did the LS knock sensor TSB. Checked the knock sensors then put a loop of RTV around the valley cover at both knock sensors. Left the back section open for any water to escape. I left the rear foam block on the intake manifold, but once I installed the intake and examined the installation I thought better of it. I was able to remove the rear foam block with the intake manifold installed!

-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #51 on: July 19, 2017, 02:15:11 PM »
Standing back and looking at the thing...and then using my phone inclinometer app, I realized that my engine is sitting with about 4 rearward slant (that's great!) and is heeled-over to the passenger's side 2?! With the intake manifold on, I can see it more clearly. The top of the intake manifold is off of the centerline of the firewall by about an inch. I wonder if my frame is slightly off, or if just all of the bolt holes and fasteners have enough slop for it to tilt that much?! It won't solve all of my header issues, but maybe it will allow the RH header to fit?
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #52 on: September 18, 2017, 08:53:44 AM »
I have a question for anybody that has replaced fuel tanks on the later year square bodies...

So this weekend I powered up my truck temporarily to jumper the fuel pumps and check the fuel system for leaks.  I have completely replaced the fuel tanks, senders, and fuel pumps.  With that I redid all of the flexible lines with new Gates Barricade FI rated hose for the pressure side and Gates Barricade standard hose for the return and vent side.

When I redid the driver's side tank I took the original rubber hose from the frame to the tank...measured and cut new hoses the same length.  The stock hoses were kind of shaped like a bell and I noticed comparing to my '77 that the connection point on the frame and the connection point on the sender are awfully close to each other, which forces the extra length of the hose to bend weird.  When I first installed the tank, I noticed that the lines got kinked up and so I had to drop the tank again.  I readjusted the lines and put the tank back in place.

Well when I went to pressure test, the RH tank built pressure to 60 psi no problem, but the LH tank was not building pressure and the pump sounded weird.

Fast forward and I dropped the tank and rechecked...pump is building pressure just fine to 60 psi...lines were kinked!

So...my question...how have you routed the lines and how long have you made them?  They need some length so you can drop the tank and get access to remove and install the hoses.  Removing the bed is too much work for one guy just to fiddle around with the tank, plus the connections are partially under the cab and I do not know if access would be good enough with just removing the bed.  I am thinking I need to lengthen the lines and then make the loop around to prevent them from kinking.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline 1967KaiserM715

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #53 on: September 18, 2017, 10:54:18 AM »
I've always made a loop, that way you never have to worry about being too short, or kinking.

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Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
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Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #54 on: September 18, 2017, 01:25:54 PM »
Good to know!  I think the stiffer FI rated hose just doesn't want to bend the way the original lines did.  Looping makes sense, though the lines have to cross over each other and there isn't a lot of room when the tank is in place.  I kinda worry about the hoses rubbing on the cab, but it is probably no worse than the factory setup.  You just can't see up in there worth a darn with the tanks in place.

On a side note...for those who have wondered...and I know it has been done before, but I can confirm that at least in my testing of the pumps and checking for any leaks...the plastic Pollak switching valve for these trucks like mine, that are rated for 65 psi do in fact work with the higher pressures.  My switching valve still had the sticker on it that stated 65 psi, so this is not a new switching valve!
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #55 on: September 19, 2017, 09:03:05 AM »
Laid out a template of the connections from the sender to the hardlines on the frame and tested the length of my lines and the routing of the loops.  Cut the new hoses and installed them last night.

Before I mounted the tank back to the frame, I jumpered the fuel circuit again and tested the pumps.  RH of course is still fine...no problem, but now the LH pump is making a God awful racket, but making 60 psi.  However, the pressure gauge needle is vibrating and the pump sounds awful!  Guess I toasted the pump?!  Both tanks have 10 gallons of fuel in them, so I didn't starve it, but the less than a minute running the brand new ACDelco EP381 pump with a kinked line, ruined it?!  Are these pumps that sensitive?!  Guess I need to buy a new pump!
« Last Edit: December 04, 2017, 11:28:24 AM by Captkaos »
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #56 on: September 20, 2017, 10:35:35 AM »
Ordered a new ACDelco EP381 pump to replace the one that is giving me problems.  Warrantying the bad one.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline hwh

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #57 on: September 20, 2017, 10:46:34 AM »
Hate to her problems your having. Changing in tank fuel pps no fun. Guess pump got to hot when line was kinked. I used the ep381 also, hope it last a long time lol.

Offline ehjorten

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #58 on: September 21, 2017, 08:52:08 AM »
Man, I didn't run that pump very long!!!  I would think they should be a little more robust than that.  Might have been suspect right out of the box, but I trust ACDelco more than some off-brand cheap-o pump.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline hwh

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Re: 1991 Crew Cab Going 6.0 LS
« Reply #59 on: September 24, 2017, 12:01:33 AM »
Yea I had a 97 Chevy 2500 years ago had it til 2002. Had to change fuel pump twice during the 289,000 miles I put on it in 5 years. And it was same fuel pump on those trucks.