Author Topic: 1987 Silverado V10 from the frozen north  (Read 3065 times)

Offline nbarr7

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Re: 1987 Silverado V10 from the frozen north
« Reply #60 on: May 30, 2022, 06:54:44 PM »
Ok. I will post a video later, but my check engine light is on (if I hold it with a finger) before startup, and then goes off during startup. I disconnected the negative side of the battery for over 5 minutes and cleared codes. I then ran the truck for 1-2 minutes. Jumpered the obd port, and my check engine light gives me 1-2 over and over, which I read 12 is the start and end of any code sequence, so unless I have an error code of 12, it's giving me no ecm codes currently. The truck is seeming to run a little better, but still has a weird start.

I'm renting a fuel pressure test kit from O'Reiley's in the morning so I'll let you know what I get for a reading there.
1987 Silverado V10 Fleetside

Offline nbarr7

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Re: 1987 Silverado V10 from the frozen north
« Reply #61 on: May 30, 2022, 09:02:09 PM »
Just to avoid any misinterpretation (on my part in how I describe things) here's some video clips of how I checked ecm codes and how the truck is currently starting/running. Fuel pressure test coming tomorrow still.

https://youtu.be/s553Rz0etA8
« Last Edit: June 01, 2022, 10:45:08 AM by nbarr7 »
1987 Silverado V10 Fleetside

Offline nbarr7

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Re: 1987 Silverado V10 from the frozen north
« Reply #62 on: May 31, 2022, 01:04:31 PM »
Rented a fuel test kit this morning. The pressure goes up to maybe 10-11 psi when you first turn the key on, but dwindles after the pump shuts off. Pressure goes back up to about 12psi when the truck is running. Seems constant at this pressure. Once truck shuts off and pump is turned off shortly after, pressure drops back to zero. Here's a video showing the process and hearing/seeing it in real time so to speak. I know the gauge is higher than needed, but it's the only kit O'Reiley's had, and living an hour outside of Minneapolis, I only have so many options.

Fuel pressure video from this morning:
https://youtu.be/w8K2AVJL24s
1987 Silverado V10 Fleetside

Offline bd

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Re: 1987 Silverado V10 from the frozen north
« Reply #63 on: June 01, 2022, 02:32:32 PM »
Code 12 is an ignition "tach" signal code that is normal whenever the ignition is switched ON with the engine not running.  It is a volatile code that will not store in memory and does not indicate a problem. 

Running TBI fuel pressure should be about 12 PSI.  So, the running pressure appears normal, although it should maintain about 7 PSI for several minutes after the ignition is shut OFF, suggesting minor internal leakage through the pressure regulator or fuel pump. 

Verify the spark plug wire firing order 1-8-4-3-6-5-7-2.  Remove the passenger side spark plugs and keep them sorted in order and labeled from front (cylinder #2) to back (cylinder #8).  Make sure none of the ceramic insulators are cracked and then post a clear closeup pic of the electrodes as they were removed from the cylinders.

Wipe the fuel injector tips (nozzles) with a clean rag.  Slip a piece of clean, dry paper towel below each injector, directly above the throttle plates, and cycle the ignition key ON and OFF without cranking the engine.  This will momentarily energize the fuel pump and build fuel pressure.  Inspect the paper towels for wetness to see whether the injectors are dribbling any fuel.

Have you run a cylinder compression or leak-down test?

Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline nbarr7

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Re: 1987 Silverado V10 from the frozen north
« Reply #64 on: June 01, 2022, 03:54:32 PM »
Before I saw this reply about testing plugs etc, I had a little bit of downtime at work so I attempted to time the truck.

Please note I have never timed a car, or even held a timing gun until today, so... I'm learning. Bear with me.

The short story is that the timing was way advanced, I believe (?) and I was able to get a stable timing read with the ecm bypass unplugged. I eventually got the timing to what I believe was zero. Low idle, but running smoothly all things considered. I then disconnected the negative terminal on the battery for 15 minutes, reconnected the ecm bypass, reconnected the negative battery terminal, and tried to start the truck. Ran horrible - backfiring and not even staying running. Checked for ecm codes, and still only have 12 over and over. Here's the video:

https://youtu.be/HP39iIEvRzk
1987 Silverado V10 Fleetside

Offline bd

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Re: 1987 Silverado V10 from the frozen north
« Reply #65 on: June 01, 2022, 05:18:01 PM »
Seeing as how the ignition timing seems all wonky, you should verify that the outer ring of the harmonic balancer hasn't slipped, altering the position of the timing mark with respect to the crankshaft.  If the balancer has slipped, you will never get an accurate timing adjustment.

Remove all of the spark plugs, keeping them in order by cylinder number.  Bump the engine over using the starter until the #1 cylinder barely begins to build compression.  With help from an assistant, bar the engine clockwise by hand (from the perspective of looking at the engine from in front of the radiator) until the #1 piston just reaches its peak upward travel before reversing direction.  You can closely approximate piston position either by peering through the spark plug hole as the piston is moving or by feeling the top of the piston using a thin probe inserted through the spark plug hole.  Once the piston has exactly peaked in its cylinder, look at the timing marks to determine whether they align at zero - they should.  If the marks do not align at zero, the outer ring has slipped to the extent of the visible separation and the balancer should be replaced.  There are other methods, but this should work for you in the field; pun intended.

BTW - This does not negate the other checks and procedures recommended thus far.

Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline JohnnyPopper

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Re: 1987 Silverado V10 from the frozen north
« Reply #66 on: June 01, 2022, 08:21:15 PM »
Not so frozen now we see... ;D

bd is right, check that you have a stable balancer before anything else.

If you're off mechanically you will be chasing the wind.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline nbarr7

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Re: 1987 Silverado V10 from the frozen north
« Reply #67 on: June 03, 2022, 09:13:45 PM »
I will recruit my wife to help this weekend with checking the harmonic balancer positioning relative to tdc.

In the interim, I am addressing some electrical gremlins, since electrical is closer to my comfort zone. My fuel gauge now works (it had never worked since I got the truck) and I realized the issues with the brights indicator being on and my temp and oil pressure gauges suddenly not working was the copper stripping around the back side of the clock side of the dash especially, had gotten somewhat bent from removal/install/removal of the dash cluster (both from previous owner and me) and the ground strip and one other piece were actually severed in one place. So, delicately soldered and checked continuity on those and I have a fully working dash (except the clock is really hard to set since the post/twisty thing is bent and corroded). I even have a dome light suddenly when turning the lights knob all the way counter clockwise!

I've been reading pinout diagrams and wiring charts (what I have access to via google anyway) and am wondering if someone could provide a comprehensive list of where I should have grounds on this vehicle? It's a big ask, so I'll start with what I know, and maybe someone can fill in the blanks...

Battery negative is grounded to the frame, drinker's side engine bay, which is connected then to the alternator bracket. I also have a ground next to the thermostat. I do have continuity between the body and neg/bat, so the body ground appears to be working . I have verified gas tank/fuel pump is grounded in both send/return lines and the separate frame ground. I've found and verified the ground for the dash cluster at the plug as well as the system grounds at A12 and D1 at the ecm plug. I've verified o2 ground at D6 and crank sensor at C9 on the ecm plug. I do NOT have a ground for D2 or "Map Ground" but looking at the wiring diagram, it maybe seems like I shouldn't? I'm basically trying to find if I have a short to ground in any circuit I shouldn't kind of thing. Or vice versa, if something isn't grounding out and not completing the needed circuit. I'm also getting a very small spark when I re-connect the negative to the battery, so something is drawing or grounding.
« Last Edit: June 03, 2022, 10:00:41 PM by nbarr7 »
1987 Silverado V10 Fleetside

Offline bd

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Re: 1987 Silverado V10 from the frozen north
« Reply #68 on: June 04, 2022, 12:55:33 AM »
All of the GM factory manuals are available in our Technical Forum \ General Information and Maintenance \ 1973-87(91) Factory GM Pickup Manuals

Basics: Vehicle Ground catalogs the major ground points that are shared by all of the 73-87(91) squarebody trucks.  For application-specific grounds, you will need to reference the appropriate year factory wiring manual.

Sparking at the battery is common.  To determine whether it is significant, measure the current draw using a proper ammeter.

FYI - Ground connections should be validated by voltage drop, not by resistance (continuity) measurements.  Even minuscule resistance can prevent the proper functions of moderate to high current circuits (e.g., arbitrarily, greater than ~2 amps).  Most ohmmeters are not sufficiently sensitive to accurately measure such small resistance.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline nbarr7

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Re: 1987 Silverado V10 from the frozen north
« Reply #69 on: June 04, 2022, 10:05:55 AM »
Super helpful. I apologize I didn't find those resources earlier. Google doesn't suggest them as readily as other forums and resources apparently. Thank you.
« Last Edit: June 04, 2022, 10:10:33 AM by nbarr7 »
1987 Silverado V10 Fleetside

Offline nbarr7

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Re: 1987 Silverado V10 from the frozen north
« Reply #70 on: June 04, 2022, 10:46:44 AM »
In inspecting the harmonic balancer, I found my coolant leak. Unfortunately it looks like it's coming from the bottom of the water pump. I'm assuming that's shot then. Makes sense why I'd lose coolant worse after driving (why I was afraid of a head gasket way forever ago).

1987 Silverado V10 Fleetside