3521 needs some assistance asap! Hmmwv troubleshooting

[Konu123]

Hmmwv at my shop used to die quick when pressing on the brakes hard or turning the steering wheel all the way but just drops rpms now I cleaned fuel injectors on the p/s because the d/s you have to take the alternator off and fuel filter/water separator housing and replaced fuel filter. (Ain’t got a lot of gas in it I know) but the fuel doesn’t seem to have water in it from the valve by the relief valve on the d/s splash guard. It’s been difficult because of a new rule we’re not allowed to have any Jerry cans with fuel sitting around anymore. Before the fuel system was cleaned halfway it was dying so I replaced hydrobooster and power steering pump, changed oil, nothing. Exhaust is leaking from around the turbo and the waste gate was stuck but I took it off and just controlled the lever manually. Haven’t tested all the glow plugs yet but it starts right up. The cold start advanced timing sensor was just replaced. It leaked coolant on a road test after a pm so they towed it back and it wouldn’t start because the smart start box went bad somehow after that. Was wondering if anyone who has had this problem before knows the cause because I can’t find anything on the net anywhere or tm or anyone at work. Pretty sure it’s misfiring or lift knocking. Haven’t ran compression test yet maybe when the coolant leak happened they drove it too far the operators are a bunch of idiots. Or could it be a crankcase sensor or TSU? Should I just clean the other side of injectors? It the turbo causing too much back pressure? So many routes, tired of guessing but they just teach us electrical troubleshooting. So just doing other work until we get new glow plugs but I’m pretty sure it’s not that, thanks in advance if you read all this. I love hmmwvs but this one’s throwing me for a loop.

 

[TOBASH]

Regarding the start box…

How to bypass PCB? I am aware some HMMWV owners have done it.

I'm not trying to speak sacrilege here, and I don't want to precipitate a war of words. :shock: How might I build a manual control box? My 24Volt Landcruiser just uses a glow wire to show glow plugs are ready, and then she just starts right up with the twist of a key. Civilian 6.2 Diesel...

www.steelsoldiers.com

 

[Retiredwarhorses]

First off, the engine sounds terrible…you’re idle is to low and the engine is stumbling. The PS pump is just that, a pump, driven by the
engine, when you load it by turning the wheel and stepping on the brakes “hydro-booster” you will get a decrease in rpm’s.
You need bleed the air from the fuel system, I also hear what sounds like an injector…it’s hard to diagnose via video.

 

[Mogman]

Assuming that truck has a 400A alt the engine is idling too slow, (in that case the tach should read around 850 RPM) and holding the steering against the locks or pressing real hard on the brake pedal is a good way to blow seals

 

[Konu123]

Assuming that truck has a 400A alt the engine is idling too slow, (in that case the tach should read around 850 RPM) and holding the steering against the locks or pressing real hard on the brake pedal is a good way to blow seals

yea it’s idle is too low and should be 800-850 rpms. Didn’t know that about the power steering since that’s how you’re supposed to bleed it jacked up but makes sense. Just wondering if someone had the same issue before.

 

[Konu123]

First off, the engine sounds terrible…you’re idle is to low and the engine is stumbling. The PS pump is just that, a pump, driven by the
engine, when you load it by turning the wheel and stepping on the brakes “hydro-booster” you will get a decrease in rpm’s.
You need bleed the air from the fuel system, I also hear what sounds like an injector…it’s hard to diagnose via video.

Definitely does sound like crap lmao, and idling too way too low. Should it decrease this much though (100ish rpms)? I bled the fuel system, I use the disconnect the injector solenoid method (I think 495A), then crank it for a second while the fuel water separator hose on the d/s splash guard is open. This is the method I seen from an 80’s army video (I’m sure most here seen). Seems better I think than the bleeder screw method. Not sure if this is a bad way but seems to work fine for when we do an PM and change the filters. Yeah might be an injector, not sure how to test other than cracking supply line while the engine is on and listening for a difference, but can only get to the p/s which I did already to no avail, then cleaned them with wire brush and jp8 and soft brush. I can try d/s but it might not be possible to get them all. A huge challenge since the alt is in the way on the top.