Thought my Suburban was going to catch on fire

[87Skier]

My 89 suburban has been having some electrical issues, but I could never figure out exactly what was causing the problems. It was beginning to get worse and a few days ago it finally decided to let go completely.

*** Story time below, skip to bottom to read summary ***

So on some country roads I was doing about 55 when I noticed my speedometer drop to 20 then go right back to 55 (I converted the speedometer to the 90/91 electric speedometer because the cable driven one wouldn't stop bouncing). A few seconds later it did it again. I figured that I should probably head home at this point, but I'm still a ways from home. About 10 seconds later the speedometer drops to 0, temp goes completely hot, voltage gauge reads zero, fuel gauge reads empty, and radio quits.

Still I'm not super concerned as the engine is still running fine, then I start to smell a burning smell, and I realize the situation is far worse than I thought. I'm looking for a place to pull out as the smell was growing stronger. Still no visible smoke though. At this point the engine begins to cut out for the first time as I find a driveway that I can pull out.

I get stopped, throw open the door, look under the dash thinking the problem lies in the cab, but nothing. Then I realize that smoke is coming from under the hood. Pop the hood and there is smoke coming from under the radiator fan shroud, from somewhere between the brake booster and rear of left exhaust manifold, the other side of the engine, and near the battery.

I immediately start looking for anything to disconnect the battery. Wire cutters, pliers, wrenches, anything, but I can't find anything expect a 1/4" slotted screw driver and a pry bar. Neither could be used to disconnect the side post terminals.

In that time I thought for sure it was going to catch on fire. The smoke kept coming and I noticed all four headlights were on, yet the switch in the cab was off. After a very tense few minutes the lights began to dim, the smoke began to dissipate, but this isn't where the story ends. I smell fuel.

I look underneath and there is a 12" wide spot of gas in the gravel, dripping from just behind the starter near the exhaust. It's not going anywhere under it's own power. With nothing to do but wait I start looking around and find that the frame to battery/core support ground has melted the insulation off the wire and has broken off in the middle.

After about 10 minutes, I realize there is another growing spot of power steering fluid. After getting it home and did some looking around and found that the starter cable was rubbing on a hard metal edge and had rubbed completely through the insulation. This had some how melted through the the power steering cooler and the fuel line. It wasn't until this point that realized just how serious this issue actually was. If the electric short was enough to melt a hole in a hard-line it is surely hot enough to ignite gasoline.

About 30 minutes after the incident, I touched the battery and side was still over 80 degrees. Not sure what else was damaged yet. I'm planning on working on it this weekend and will post up pictures of the damage if people want to see the damage.

*** Summary ***

Suburban has electrical problems. They get really bad. Electrical short melts a few wires (that I know of so far), the power steering cooler and the fuel line. Realize that if the electric short melted the hard lines, there's a good chance that the leaking gas could have caught fire.

I've been saying for months that I need to purchase fire extinguishers for all my vehicles.

[Palf70Step]

Wow! I hope you can find the cause, that would be scary fer sure.

[SunSoaked]

Glad to hear it wasn't worse. I don't like electric fires. That's why I did 3 things to prevent/contain them:

1. Rewired starter with a remote solenoid to help with heatsoak and make the battery cable hot ONLY when cranking.

2. Installed a cutoff switch at the battery. A quick flip of the handle kills ALL the electrical.

3. Mounted a fire extinguisher rated for class abc & e behind the driver's seat.

That was the second thing I did after buying my truck. The first was installing a Viper alarm system.

[mongocanfly]

That's a real attention getter...glad there wasn't a worse outcome

[hatzie]

Always good to keep an 8mm box end wrench in the glovebox on older rigs with side terminals.

IIRC The parts and service manuals have the original GM battery cable routing illustrations. The 90 & 91 RV series wiring diagrams have a lot of wire and harness routing detail illustrations that are not in the earlier manuals.

[old Rusty C10]

i bought some insulated wire/cable hold downs so I could make sure the starter cable , which was a little long had somewhere to sit so it wouldn't shift and either rub insulation off or burn

[kipps]

Installing wire loom on the positive battery cables can avoid chaffing as well.

[Pontiac1976]

Just a guess bad ground cab to frame. It might trying to ground speed cable.
I would try to check all your + connection mostly all your - connection make sure there clean & good wires too.
Then check for a draw.