Vehicle shutoff while driving

[RacingTurtles]

Hello there,
I had a bit of a weird shut off while driving, happened to me twice on my way to get the suburban inspected.
This has never happened before and I wanted to see what theories you guys may have.

1990 GMC Suburban
5.7L TBI gasoline
700R4 4x4

THEORIES
1. BAD WIRE CONNECTION TO BATTERY / PINCHED WIRE AT PASSENGER SIDE ENGINE MOUNT
HAPPENED IN 2019, REMOVED WIRE AND PUT SILICONE VACUUM LINE THERE.

2. POSITIVE VOLTAGE IS SHORTING SOMEWHERE ( FROM BATTERY, ALTERNATOR, OR SOMETHING, FUEL PUMP CIRCUIT)
BASICALLY CHECK ALL WIRING INSULATION OR JUST RUN NEW WIRES / BIG 3 UPGRADE

3. LOW ON GAS SO GOING DOWNHILL IT SUCKED UP SOME AIR. DOESN'T EXPLAIN THE IMMEDIATE SHUT OFF
LIKE A KEY OFF AND WHY IT SHUTOFF THE SECOND TIME.

4. BAD IGNITION SWITCH.

I'll post up the history in other replies because I do keep some background on this thing.

Thank you for opening this thread up and attempting to help.

 

[Snoots]

In the distributor: 1) ignition module, 2) pick-up coil

 

[Rickf]

Do the headlights or other electrics (radio, heater etc.) still work? Or is it just the engine?

 

[dvdswan]

How much fuel was in the tank? If it was low, FI models are known to have an in-tank pump fail and start back up again. Pump can get hot and quit. After it cools run fine for a while again.

Also, check tank grounds for corrosion.

 

[RacingTurtles]

INCIDENT LOG
11/20/2023

I was driving the vehicle in stop and go traffic to get it inspected.
It ran normally, temps/oil pressure were normal operating parameters.
Gas gauge said 1/4 tank full.

Drove downhill, not a steep grade by any means, and the vehicle shut off.
It did not sputter, shake, or make any sort of issue other than complete electrical loss.
As if the key was just moved to the off position.
No pothole was hit at this time, no swerving or any sudden jerks.
Shifted from D to N and would not restart.
No electronics came on, no warning lights.
Coasted truck into center emergency lane.

Once stopped, there seemed to be electrical power but it showed lower than normal voltage.
Maybe just above the 8V mark when it is usually at the middle 13V mark.
Would not start. It would crank but not start. As if there is no fuel.
Key still in ignition, went to grab jump starter.
Hooked it up, cranked it for longer than usual but started up again.
Truck behaved normally and drove normally.

Drove 2 miles to the nearest gas station to fill up, thinking it was just low on fuel or something.
Fill up, idled for a few minutes.
Left the gas station.
Gas station has some steep ramp to get in/out and after I exited, it shut off.
I came out slowly but the truck swayed aggressively and my keys were jangling excessively.

Again would crank but not start as if not getting fuel.
About 1-2 mins pass.
Hooked up jump pack and started again.

I started to drive home but then turned back and went to inspection station (which also had a steep on ramp)
While waiting, I cycled ignition and it worked fine everytime. I always need to hold throttle open to start it.

I explained to mechanic, he said with the maintenance I did, try changing the entire distributor.

At this point, I separated key from keychain, started it and drove it home.
It drove home perfectly fine, maybe the best it's ever driven.

 

[RacingTurtles]

HISTORY OF REPAIRS

Purchased not running in March of 2018.

06/2018

SPARK PLUG WIRES SET
DISTRIBUTOR CAP & ROTOR
SPARK PLUGS
FUEL PUMP HOUSING / ASSEMBLY
FUEL TANK ( 40 GALLON)
VARIOUS FUEL LINES/HOSES RELATED TO GAS TANK INSTALL
VAPOR CANISTER PURGE VALVE / SOLENOID


08/2018
THROTTLE BODY INJECTION REBUILD KIT
THERMOSTAT
THERMOSTAT HOUSING
VARIOUS RADIATOR/HEATER HOSES
AIR FILTER
MUFFLER
BRAKE PADS & ROTORS


11/2022

SPARK PLUG WIRES SET
SPARK PLUGS
DISTRIBUTOR CAP & ROTOR
IGNITION COIL
IGNITION CONTROL MODULE
SERPENTINE BELT TENSIONER KIT
IDLER PULLEY (GM GENUINE)
AIR FILTER





SEPTEMBER 2019
Had issue were I had no electrical power to anything.
The power wire from (+) terminal to starter was pinched in between
engine mount and cross member
Moved wire away and put in some silicone vac line in the gap at the mount.
Solved that problem.

NO NEW PROBLEMS SINCE THEN. USED INFREQUENTLY AROUND THE HOUSE.

JUNE-AUGUST 2022
Took apart front hubs, regreased bearings ( bearings looked ok)
new brake rotors and pads
(still the same brake fluid)

SEPTEMBER 2022
Started daily driving it as subaru was up for wheel bearings/maintainance.

NOVEMBER 2022
Started skipping from idle (~1000 cold to 800-900 warmed) down to like 600-700
spark plug wire making contact with exhaust mani
NEW PLUGS/WIRES/ DISTRIBUTOR ROTOR & CAP / IGNITION COIL
(I broke retainer on one of the harness clips, prob gray one)
(NOT EVERYTHING FROM ROCKAUTO, SOME FROM AUTOZONE /ADVANCE AUTO)
NEW AIR FILTER ( ALSO HELPED IMMENSELY)
AROUND HERE I NOTICE THAT I HAVE TO BE ON THE GAS AT STARTUP.
WILL NOT START ON FIRE TRY WITHOUT THROTTLE OPEN

APRIL/MAY 2023 got new tires

SUMMER 2023 HEAR SOME KIND OF WHINING FROM AROUND PULLEY AREA
VERY FAINT SUPERCHARGER WHINE

NOVEMBER 2023
Winter tuneup
Serpentine belt & tensioner, idler pulley
Ignition coil, ignition control module, dizzy rotor & cap
-I pulled on copper shield on it thinking it was glued down
-but I pushed it back down (SEE IMAGE BELOW)
New air filter
Repaired some breaks/exposed wire around the drivers side tail light harness.

Ran good, still needs throttle on startup.

Copper/Brass shield around magnetic coil pickup is what I pulled up on.
Yes I am an idiot and should not have done that. I thought it just slid off or was glued down. Mine looks really rusty that's why.

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My actual distributor pictured below.

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[gmbellew]

does it ever blow a fuse, like one of the ECM fuses?

I'd also check the harness along the firewall for an orange wire that has rubbed through on a bracket. it is the 440 circuit and gives constant power to the ECM and the fuel pump (ECMB fuse). it can rub through in various places - MAP and cruise control brackets are likely places. I had mine rub through in both spots. it sometimes, but not always, blew the fuse.

if it is the ECMI fuse, it powers the injectors, VSS, and a few other items. I had my line to the VSS rub through on the transmission, but it blew the fuse.

could also be intermittent failure of the ICM, which can be replaced without pulling the distributor.

you may also check the ECM plugs to make sure they are secure and corrosion free.

check for injector spray next time it happens. that will help diagnose.

 

[RacingTurtles]

How much fuel was in the tank? If it was low, FI models are known to have an in-tank pump fail and start back up again. Pump can get hot and quit. After it cools run fine for a while again.

Also, check tank grounds for corrosion.

First time it shutoff going downhill it was 1/4.
I usually fill up at the 1/4 tank mark anyway, as I mainly drive this on the highway.
I thought that being too low on gas maybe it sucked up some air in the lines.
This is because I got a 40 gallon tank and I'm not sure if factory was the 31 gallon or 40;
I remember buying the 40 because I measured the dimensions and it fit so I bought it.
My gas tank will fill up and the needle won't budge until I drive about 100 miles, maybe originally it was the 31.

I hope it's not the fuel pump.
In 2018 I put in a new 40 gallon tank and a Delphi HP10021 fuel pump housing assembly.
That wasn't fun.
I will check the fuel pump circuit for anything wrong and check the grounds again.

Do the headlights or other electrics (radio, heater etc.) still work? Or is it just the engine?

At the time when it shut off while moving, nothing worked.
Stopped the truck, got battery voltage (which read low) and wouldn't start.
Hooked up a jump pack and it cranked forever but wouldnt start like there was no fuel.
Eventually started back up.

Radio has never worked in my ownership. Heater worked when truck restarted.

 

[RacingTurtles]

does it ever blow a fuse, like one of the ECM fuses?

I'd also check the harness along the firewall for an orange wire that has rubbed through on a bracket. it is the 440 circuit and gives constant power to the ECM and the fuel pump (ECMB fuse). it can rub through in various places - MAP and cruise control brackets are likely places. I had mine rub through in both spots. it sometimes, but not always, blew the fuse.

if it is the ECMI fuse, it powers the injectors, VSS, and a few other items. I had my line to the VSS rub through on the transmission, but it blew the fuse.

could also be intermittent failure of the ICM, which can be replaced without pulling the distributor.

you may also check the ECM plugs to make sure they are secure and corrosion free.

check for injector spray next time it happens. that will help diagnose.

Normally, no I don't recall blowing an ECM fuse.
Originally when I got it in 2018 I had loose, live wires that blew some radio fuse but not ECM.
Since addressing those, I've not had any issues with blowing fuses.
I also drove it home perfectly fine after the shutoff incident, however I will inspect that entire circuit to rule that out.
Even a short would cause issues.


I replaced the ICM 2 days prior to this incident.
It could be a crappy unit out of the box.
I actually bought 2.
STANDARD MOTOR PRODUCTS LX340 & THE LX340T.
I installed the LX340 as it had some better features over the LX340T ( T being the economy variant, saving it as a spare).
In case you care to read about them here are some links
LX340 ( better one)

More Information for STANDARD MOTOR PRODUCTS LX340

LX340T ( OE style )

More Information for STANDARD MOTOR PRODUCTS LX340T

I also believe it has been installed correctly and I used the supplied dielectric grease.
Connectors looked ok, sprayed with contact cleaner and given ample time to air dry.

Will definitely check ECM connector & harness connection.

Injector spray pattern seemed to be ok when I performed the maintenance.
When engine was running ( air cover removed) I couldn't even see the spray but I could see the cylinder area where the injectors were firing into.
I could tell it was "wetting" the cylinder but I could not see a spray cone.
When I first got the truck, one injector had a slight, steady leak similar to a faucet drip. The TBI rebuild kit fixed that.


I appreciate your suggestions man. Hopefully you survived the wall of text haha.

 

[pinballlarry1]

Years ago, our '99 Venture van had intermittent issues with random dying. Like all 12-volt power was gone. It would usually restart after a few minutes. I eventually tracked it down to the positive battery cable on the starter where all the other power goes to the fuses. The connection looked and felt secure, but after putting the van on ramps and crawling under, I was able to disassemble the power connection on the starter and see that corrosion was present between the ring terminals. After cleaning and reassembling, the Venture van has never failed us.

 

[Snoots]

That last pic leads me to believe the pick-up coil (NOT the ignition coil) is your problem. When ICM go bad, that's it. They're digital. They either work or don't. EVER! Pick-up coils have an attitude and can be very 'iffy'.

 

[RacingTurtles]

In the distributor: 1) ignition module, 2) pick-up coil

That last pic leads me to believe the pick-up coil (NOT the ignition coil) is your problem. When ICM go bad, that's it. They're digital. They either work or don't. EVER! Pick-up coils have an attitude and can be very 'iffy'.

ICM was replaced 2 days prior to incident, but I'm sure it could be a bad one out of the box.
Damn I'm really hoping it's not the pick up coil. I'm just not confident doing the distributor, I've never done one.
I know it's just nuts/bolts and aligning/inserting it correctly, but there's something in my mind that makes me dread doing it.
It has to be done because of how rusted it is.

Years ago, our '99 Venture van had intermittent issues with random dying. Like all 12-volt power was gone. It would usually restart after a few minutes. I eventually tracked it down to the positive battery cable on the starter where all the other power goes to the fuses. The connection looked and felt secure, but after putting the van on ramps and crawling under, I was able to disassemble the power connection on the starter and see that corrosion was present between the ring terminals. After cleaning and reassembling, the Venture van has never failed us.

Yup!
Something similar happened to me in 2019.
This was my thread

1990 V1500 Suburban No Power No start

INTRO Hello and thank you for clicking on this thread. My name is Apu (yup, get your jokes goin) and I've got this old gal. Shes a 1990 GMC Suburban Geneva edition. I made an introduction thread when I first got her. She's been running fine for some time, had no issues and even loaded her...

www.gmsquarebody.com

Basically the main power feed to the starter got pinched.
Starter connections didn't look too good either, I took it apart and cleaned it. May be time to do it again.

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Pinch at the mount

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[RacingTurtles]

Just so this thread isn't entirely a wall of text

This is the vehicle in question.
Taken in 2019 when I had a similar no electrical power issue.
I bought another set of identical wheels and powdercoated them black. Thats about the only visual difference.

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[RacingTurtles]

Just wanted to provide an update.

I haven't had much time to work on this. I finished getting another car roadworthy so I have some transportation.
My mechanic thinks it is the distributor. He suggested to wait until better weather to do it.

I noticed my battery was dated from March 2018, so I took that to get tested.
It was inconsistent, would say "Bad battery" then "good battery". So I just went ahead and got a new battery.

Plan is to check the things listed in this thread, install the Big 3 (or Big 4) upgrade with the new battery and see what happens.

 

[RacingTurtles]

Another update: Unfortunately the problem seems to persist.

I made the repairs outlined in this post and the next post.
I also verified that there aren't any other wires that I can see with exposed wire showing through the insulation.
Someone mentioned the orange/black wire for the 440 circuit, which I checked.
I also cleaned up the starter wire (+) feed connection (Green), but I didn't clean the other terminals that may be on it.

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I also had my new battery charged up to full again.












These are my repairs I did over the past few months.

I made some new power & ground wires for the following:
(+) Battery to alternator (+)
(+) Battery to Starter (+) connection
(-) Battery to engine (-) ground on manifold or head (wherever it previously was)
(-) Battery to frame (-) ground, new location
(-) Battery to radiator (-) ground

These were all made over winter and installed recently (end of march, early april) on days that it didn't rain or snow.
All are installed on clean, bare metal and verified for continuity and low resistance readings before insulating with dielectric grease.

2/8/24 - moved fuel tank ground somewhere else.
Red is the old ground. There are two nuts on that bolt and the terminal was between it.
I cleaned up the terminal, picked a new unused spot, wire wheeled the paint off, mounted it, and verified with a multimeter that there
was continuity and low resistance from terminal to frame.

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