Truck shuts off randomly

[hi54lofi]

Hello all...

My car is shutting off randomly as if I turned the ignition off while driving or idling. Long trips are fine, but it shuts off randomly sometimes in the first 5 minutes of driving as if i took the key out.

at first I thought it might be a fuel pump issue but am now starting to suspect something electrical.

When it happened again today (three times in quick succession, the third killing my power steering and brakes while on the road,) I got out of the car and noticed my left headlight was out. upon starting up again (after some effort to turn over,) both headlights started working. The headlights were aftermarket, so I unplugged them in case that might be an issue.

I ordered an ignition control module in case mine is faulty, some people have similar symptoms and that fixed it. Also, once or twice there has been this relay-type rapid fire clicking that sounds like its coming from the steering wheel or headlight control switch, only occurring for a minute or two. my grounds seem to be in decent condition. I am really hoping to be able to keep my 1997 burb as my daily driver, but I am starting to worry.

I will post any updates. Any insight or info would be greatly appreciated. thanks in advance.

 

[1998_K1500_Sub]

The GM B-bodies of 1994-1997 had a problem on account of the fuel pump sharing a ground with the rear taillights. In their case, the common ground wire was terminated with a self-tapping screw into a sheetmetal member inside the trunk.

I wonder if you've got something similar happening. Read on...

Over time the ground connection in the trunk would degrade. The net result was that, when the system voltage was already low (think: engine at idle, perhaps while coasting), if one applied the brakes (turning on the taillights, which share the ground with the fuel pump), the voltage drop at the degraded ground connection would be sufficient to cause the fuel pump's applied voltage, and thus pressure, to drop and the engine to stall.

This happened on my father's 1994 Caddy Fleetwood and I'm the lucky guy who had to fix it; the local GM dealer wasn't helpful. Fortunately I came across an explanation of the problem on an ImpalaSS website.

Back to your truck, the fact the headlights act goofy may be due to a poor ground (or not), ditto for the rapid relay clicking, which may be indicative of one or more ground problems on the vehicle, particularly under the hood (at the passenger's side fender and driver's side radiator support, IIRC) and those around the backside of the engine (passenger's side) where braided ground cables connect to the engine, frame and body. Don't overlook the fuel pump and rear taillight grounds on the Suburban near the back of the vehicle, either. Measuring the voltage drop across each of these ground connections with a DVM is where I would start, and do so under a variety of load conditions (lights on, lights off, blower fan on high/ on low, brake lights on / off, etc). The voltage drop across any decent ground on a vehicle should be less than 0.3-0.2V and, if in good condition, 0.1V or less IMHO.

But I could be all wrong. Maybe someone's got a better idea

 

[GoToGuy]

These vehicles , our trucks in human terms would be considered senior citizens. And in such consideration it's important to not take for granted " eh, looks ok " . Rather it's important to actually verify as ground is in good condition , remove it and verify it does not have a layer of corrosion hidden under it , insulating from any continuity from the body. Few grounds have any protection from the elements, dirt, mud, road salts, salt sea air, high humidity regions,. As said in above post , multiple connections at a single ground point. Unable to complete the circuit as designed will find another path to ground. And like water finding the path of least resistance, can cause some bizarre reactions , indications.

 

[Schurkey]

My car is shutting off randomly as if I turned the ignition off while driving or idling. Long trips are fine, but it shuts off randomly sometimes in the first 5 minutes of driving as if i took the key out.

Seems unusual that you'd only have problems within the first 5 minutes of startup.

One wonders if this is an "open loop" issue rather than some bizarre power-supply problem.

at first I thought it might be a fuel pump issue but am now starting to suspect something electrical.

Well, a fuel pump on these trucks "is" electrical.

When it happened again today (three times in quick succession, the third killing my power steering and brakes while on the road,) I got out of the car and noticed my left headlight was out. upon starting up again (after some effort to turn over,) both headlights started working.

Might be important, might be pure coincidence. Hard to tell until after the truck is "fixed" and runs reliably.

The headlights were aftermarket, so I unplugged them in case that might be an issue.

Define "aftermarket". Has this truck been converted to some cheap LED or HID headlights?

I ordered an ignition control module in case mine is faulty, some people have similar symptoms and that fixed it. Also, once or twice there has been this relay-type rapid fire clicking that sounds like its coming from the steering wheel or headlight control switch, only occurring for a minute or two.

MAYBE the "relay-type rapid-fire clicking" is one of the circuit breakers in the headlight switch...which might be related to the headlight that didn't work for awhile.

My experience with those circuit breakers is that they don't click "rapid fire", though.

1997 burb

What engine?

You've got some unusual symptoms that may--or may not be related to the engine stalling problem.

Until those can be sorted-out, I'll give you my usual three recommendations:

1. What is the fuel pressure during prime and under load? Is it stable?

2. How old are the usual tune-up items and procedures? Distributor cap and rotor, plug wires, spark plugs? Does the electronic spark advance work? EGR system works right?

3. Connect a scan tool, look for codes, but also verify EVERY sensor and computer output especially during that first five-minute warmup. Check fuel trims and cylinder misfire counts.

 

[hi54lofi]

fuel pressure is 60 primed, and then 53 with engine running, goes up when i press the pedal. cap rotor and spark plugs are brand new, i havent changed the wires since i bought the car though. no misfires. Fuel trim is around 0 on one bank and 3-5 on the other (long term). something else I noticed is that right when this started happening, the chime stopped working, when you first turn the key? theres no chime now. Im fairly certain it has something to do with the turning off.

 

[hi54lofi]

also, it goes from open to closed loop. however, one of my CAT sensors has a bad heater. I got a code for it. No way the sensors are coming out though, I tried my best.

 

[Schurkey]

however, one of my CAT sensors has a bad heater. I got a code for it. No way the sensors are coming out though, I tried my best.

O2 sensors? You have one defective O2 sensor, you've probably got three more that are just as old and ready to fail.

This needs to become a higher-priority.

Yes, they can be a real bytch to remove. For the record, "O2 sensor wrenches/sockets" are great for installing O2 sensors. They're not reliable for removing them, though. The split in the side to allow the sensor wire to pass through makes the socket/wrench weak. Apply enough torque, and the socket spreads open and rounds-off the flats of the O2 sensor wrenching surface.

When I did my '97 K2500 O2 sensors (all four), I had to drop one exhaust pipe out of the vehicle to get the sensor out--I couldn't apply enough torque when the pipe was in place.

I bought a Wright 7/8" deep impact socket specifically for O2 sensor removal. The Wright socket is broached all the way down--a similar Snap-On socket, and most other brands, are only broached about 3/4" down, and so there's no room for the sensor body to fit inside the socket once the sensor wire is clipped-off.

Wright is a family-owned, USA tool company. Very recommended.
www.amazon.com/dp/B002VKBRCC/?coliid=I3QM27R5Q6EZ28&colid=2VLYZKC3HBBDO&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

 

[thinger2]

Hello all...

My car is shutting off randomly as if I turned the ignition off while driving or idling. Long trips are fine, but it shuts off randomly sometimes in the first 5 minutes of driving as if i took the key out.

at first I thought it might be a fuel pump issue but am now starting to suspect something electrical.

When it happened again today (three times in quick succession, the third killing my power steering and brakes while on the road,) I got out of the car and noticed my left headlight was out. upon starting up again (after some effort to turn over,) both headlights started working. The headlights were aftermarket, so I unplugged them in case that might be an issue.

I ordered an ignition control module in case mine is faulty, some people have similar symptoms and that fixed it. Also, once or twice there has been this relay-type rapid fire clicking that sounds like its coming from the steering wheel or headlight control switch, only occurring for a minute or two. my grounds seem to be in decent condition. I am really hoping to be able to keep my 1997 burb as my daily driver, but I am starting to worry.

I will post any updates. Any insight or info would be greatly appreciated. thanks in advance.

Assuming you have the factory side post battery cables.
There are a few problems with gm sideposts.
A 30 year old side post cable will look like its brand new from the outside.
Because of that plastic cover on the end of the cable.
They rot underneath that plastic end and that rot can extend several inches underneath the wire insulation.
Inside of that plastic end is a thin ring terminal that is soldered to the wire.
That ring terminal has 4 "lugs" stamped into the side that contacts the lead in the battery connection.
Those lugs are supposed to dig into the lead on the battery and hold the cable in place and prevent the cable from rotating.
But, every time that cable gets disconnected, when you reconnect it those lugs dig into a slightly different spot.
Vibration through the cable starts to wear the lead and rounds off the lugs on that ring terminal.
The normal response is to snug up the battery bolt.
But, when you tighten the battery bolt on a bad plastic gm sidepost that tension you feel is the plastic of the cable being torqued onto the plastic standoff collar on the battery.
And that aftermarket battery plastic collar around the contact is not the same as the factory GM
And that battery bolt is also lead and it is only threaded about 50 percent into the battery.
Bizzare no start or intermittant heat related starts, shutting off while driving, or running over a pothole and wierd electrical problems are a historic hallmark of GM sidepost batteries.
Cut the red plastic end off of your side post cable and look at the green rot inside of it.
Do the same to the negative cable.
Step one on diagnosing an old chevy electrical problem is always the side post.
If that ring terminal is salvageable,
Clean it.
Two 3/8x16 1 inch bolts
Two small diameter 3/8 flat washers
Four 3/8x16 nuts
Do the postive first.
Run the first nut almost all of the way up to the bolt head buy hand.
Put the battery ring terminal on.
Run the second nut up losely.
Put the washer on.
Finger tight the bolt into the battery as hard as you can.
No tools. If you over tighten that bolt it can punch through the side of the battery.
Hold the bolt with a wrench so it cant turn.
Tighten down the nut nearest the battery.
Now you have the battery ring connector on the bolt and between the two nuts.
Run the second nut finger tight all of the way down onto the ring.
Hold the inner nut with a wrench and tighten the outer nut.
It is very much the same process you would use if you were using two nuts to pull a stud but you are locking the ring connector between them.
Coat it with whatever anti corrosive goo you like and then drive it for the next 5 or 6 years.
Ive have seen so many people chase odd electical problems on chevys and they look at the battery cables and think they are good.
If you have not personnaly yourself replaced those battery cables and done it properly?
They are bad.
And a static voltage drop test can lead you right down the path of looking elswhere.
Because of that intermittant failing bump related heat related rotating crappy plastic encased ring connector.
Cut them open and find the green fuzzy crud.

 

[hi54lofi]

thank you guys for your detailed responses. I will check out the battery cables. I also found a damaged ground to the firewall. Since disconnecting the aftermarket lights I have not had the issue, but it will probably happen again... i will post back with updates, thank you guys.

 

[hi54lofi]

I disconnected the battery terminal, the two rings surrounded by red plastic. I saw no acid, just metal to metal contact. do i have to cut the plastic off to get to the potential corrosion? it did seem a bit loose, i could hear it connecting and disconnecting, after barely any bolt loosening.