Injection pump causing a runaway

[Aftermath]

Anyone with any knowledge of this ??

[DmaxMaverick]

Mechanical or electronic? It can happen with either, but in different ways. Mechanical would be a mechanical failure (obviously), internally or externally. If electronic, it's usually the PMD that's failed. Air in either can seem like a runaway, but usually just temporary higher RPM's, although no power to actually run anywhere, away.

[Aftermath]

1998 so electronic pump. How do you shut it down in the event of a runaway, or what can you do as a precaution?

[DmaxMaverick]

Turn the key to OFF.

Or move the shifter to N, if it was in gear and trying to go somewhere with you standing on the brakes. Once it hits about 4K, the PCM will shut off the fuel via the FSS (the cylinder on top of the IP, so make sure that's working). If the only issue is the runaway, then no harm done. Problem is, many times folks keep it in gear and try to rein it in. It doesn't hit the ceiling RPM, so it just keeps on trying, smoking tires and making a bunch of racket. Almost always, turning the key to off stops it.

[Robyn]

This type of PMD failure is the most exciting :eek::eek:

PMD's usually fail in one of two ways.

(1) As they warm up they simply stop working and the engine dies.
A restart may be possible after a cool down.

(2) The PMD circuitry locks into FULL FUEL MODE (Rarest failure)

As Maverick said SHUT IT OFF

Trying to hold onto the rampaging beast is futile.

Some years ago I was walking across the grocery store parking lot and a young gal fired off a diesel Burb and started to pull out....

The thing took off HOWLING and rolling coal..... the gal instinctively pounce on the brakes for dear life.

I was within 20 feet of the rig and hustled over to the passenger side, opened the door and jumped in...flipped the key off.

The gal was terrified and just sat there with a death grip on the steering wheel.

I stuffed the thing in park and tried to console her....(She was not amused)

The black smoke skunked up the parking lot really well too :D

A tow truck was called.....


I had one go off while testing a can full of used PMD's on my Burb.

Plugged in the first one...reached in the window and twisted the key....couple seconds go by ..... HOWL AND SHUTDOWN before I could grab the switch.


Tossed that one in the round file :rolleyes:


GM/Stanadyne knew that a failure in the PMD could cause a runaway and the fact that the pump has a positive fuel shut off (Little round job on the top of the IP ) proves this.

A runaway is the most serious condition, especially for a driver that has no idea what's happening.

The instinct is to mash the brakes and hang on....