Engine dies whilst driving

[SarahJ]

Hi Guys,
I've had my 1986 M998 HMMWV for two weeks now and whilst driving today the engine died. I still had lights, but the engine would not turn over. I checked the connectors were pushed home in the ignition switch, which they were. I tried to start my HMMWV again and it started and ran fine. By disturbing the cable or connectors the problem had gone.

Since then I've tried to replicate the problem, but to no avail.
Ive had the ignition switch out, cleaned the connectors, which had a slight amount of dirt on them, and refitted the switch. Though the HMMWV seems to starts and fine I am concerned about it dying on me again, especially at speed, as the brakes and steering got really weak. Any suggestions on what to check or try?

Appreciate any help,

Sarah

 

[Suprman]

Check battery connections. Take them off clean them and tighten. You can check the fuel solenoid connection to the injection pump.

 

[Action]

You should have 1 good brake application after the engine dies.

 

[gimpyrobb]

Buy another one and use that one for parts.

 

[NDT]

Carefully inspect the wires that enter the connector on top of the start box.

 

[DCIV]

Hi Guys,
I've had my 1986 M998 HMMWV for two weeks now and whilst driving today the engine died. I still had lights, but the engine would not turn over. I checked the connectors were pushed home in the ignition switch, which they were. I tried to start my HMMWV again and it started and ran fine. By disturbing the cable or connectors the problem had gone.

Since then I've tried to replicate the problem, but to no avail.
Ive had the ignition switch out, cleaned the connectors, which had a slight amount of dirt on them, and refitted the switch. Though the HMMWV seems to starts and fine I am concerned about it dying on me again, especially at speed, as the brakes and steering got really weak. Any suggestions on what to check or try?

Appreciate any help,

Sarah

Which Bristol are you in? TN, NC? Somewhere else? Just curious how close you are to me as I am in east TN.

 

[155mm]

While you have the battery cables off for cleaning/inspecting, grab the ground shunt on the battery box wall and make sure it is mounted securely and the posts or mount are not loose or broken.

 

[Bulldogger]

Congratulations on joining the club. The first thing you need to do is complete service and a very thorough cleaning of fittings and connections. It doesn't matter how nice it looks the military probably hasn't done maintenance on it for 5 to 10 years. Even a rig you purchased from another civilian may not have seen all the maintenance and refurbishment it deserves, it can just be spiffed up and flipped.

Check all important power related connections that have to do with the ignition. Consider installing a grounding kit, most of us have done it and are glad we did. Definitely check not only the connections to the battery but where their cables connect on both sides of the fire wall. Check your starter connections, since those wires are close to and related to the wires from the battery box.
And by check, I mean remove, clean and reattach. If you take apart any Packard connector rubber connections, give them a tiny bit of dielectric grease before putting them back together it will save you grief the next time they need to come apart.

Bulldogger

 

[NormB]

Welcome to the madness.

I'm guessing Bristol, England as native speakers of Standard American English only use "whilst" if they're pretentious graduates of some backwater elite finishing school in New England - hardly the kind of folk who congregate here.

Connections, connections, connections.

Any time I'm working on or around packard connectors, I use a liberal yet thin slathering of 3M dielectric grease on the RUBBER (you can use something like a thin nail or nail file to force some grease between the male and female connections that have nearly fused together) and I use DEOXIT on the metal connections. The dielectric grease protects the rubber and lets you disassemble the connections. I'm not sold on using dielectric grease on electrical connectors. There are many anecdotal essays on using the stuff here on the board and elsewhere, while others are more on the side of using other agents to ensure a good metal-metal connection. Read and learn, YMMV.

If the rubber has broken/rotted, I've figured out how to replace the connectors without removing the actual metal connections - tedious, but it works - you might want to buy a couple bags of 14 and 16 gauge packard connector SETS from Eriks military surplus or other supplier.

If this is your first rodeo, do a complete service per TM -10 (see section here on manuals), and then some.

The troubleshooting manual should have something about this too.

As others have suggested, disassemble and clean battery and other large connectors (I use a toothbrush-sized stainless steel gun-scrubbing brush or even a Dremel moto tool brush) , apply deoxidizing solution and reassemble. Augmented ground wire harness is a must.

DISCONNECT THE BATTERY GROUND before doing ANYthing to the protective control box, ignition/light switch or batteries, or lighting... you and your pocketbook will thank me.

Have fun, ask questions.

Norm


PS: Definitely check the connector to the injector pump - I have a sneaking suspicion this is a fuel starvation problem. Have you changed the fuel filter? Any leaks in the fuel system?

 

[SarahJ]

Hi Guys,

Thanks for all your help

My Bristol is the one in England, interesting you can tell from from my text

I've checked the battery connections, the ignition switch connections and the connectors that go up into the protective control box. There was a little dirt on some of the connections, but nothing frightening. The fault hasn't reappeared, though I've only done another 80 miles since it happened.

I'll do all the other electrical checks in the next couple of weeks along with the big service, just waiting for the service components to arrive. I'll also follow you advice about a grounding kit as well.

Thanks again for your advice.

Best wishes,

Sarah

 

[Dock Rocker]

Also consider installing a grounding harness. Good insurance for the future and will rule out grounding issues as part of your current problem.


Sent from my iPhone using Tapatalk

 

[TOBASH]

Am I the only bloke who is wondering why battery is such a hot suggestion when our vehicles are Diesel?

Is it possible there is a fuel delivery issue?

Are you running low on fuel? That could imply a fuel delivery pump issue.

Keep her topped off, and consider new fuel pumps.

My humble tuppence.

Cheerio,

T

 

[gcbennet]

As a humble servant in one of Her Majesty's loyal colonies I will gladly share a similar experience. The same happened to me once, and it turned out to be the S3 box was the culprit. However, the issue happened only once to kill the truck for good. Something fried inside. In my search I also discovered the wires on the neutral safety switch were damaged and corroding as well. From experience I say check and clean every connector you can find and use dielectric grease and corrosion preventative for added protection. I've found corrosion hidden within the rubber connectors, corroded splice repairs behind the dashboard, corroded wires in cannon plugs, nicks in wires that have caused corrosion within the shielding, etc. Grounds seem to be the worst for reoccurring issues though. The best you can do once you've cleaned and inspected everything is dig out the multi-meter and follow the troubleshooting guides to the letter to see where the buck stops. If that doesn't work you can try swapping out components one at a time with a known good unit and see if that solves the issue. The latter is definitely the easiest and quickest method of problem solving, albeit much more expensive.