Anyone know Mopar 5.7 Hemis?
 

Cranks but won’t stay running. Runs for a few seconds. I can hear the fuel pump in tank. Just thought there might be someone who owns one or works on them?

2008 Jeep GC, fwiw. Thanks!

Bring it over and burn it with the cow carcasses....

That sounds like a Security system fault. Do they have a spare key? Did you scan it yet ?
They also develop all sorts of weird electrical problems with the TIPM ( fuse box )
Let me know if I can help

Thanks, Fred. One possible factor is a plugged sunroof drain and we just had a huge storm. It’s wet above the passenger A-pillar.

Agree with the alarm/ security maybe being at fault. Use the key to lock/unlock the drivers door .. ( with the door closed) and see if that makes any difference.

Doesn’t seem to be related to alarm system. We got it to start but it’s missing badly, sounds like running on 4-5 cylinders. Throwing a P0300 code, (random misfire or something). Doesn’t tell me anything I don’t already know. :confused:

Does that Grand Cherokee have MDS (cylinder deactivation)? Maybe it's activated...

coil packs, plugs or plug wires?

water in fuel tank?

Very odd. Has anything changed or repaired recently?

No, just the big rain storm and the obvious blocked sunroof drain. This car does not have the ECU or other control modules in the front seat floor or passenger kick panel, though. just a few wires.

I can say that it's not a very well maintained car and it was quite low on oil and coolant but this issue came up suddenly. It ran fine to the spot where it failed and now it's barely running.

Lifter failure?

Nah, don't think so.

No other codes? One of the common causes (according to the all knowing google) is low fuel pressure. How long has it been since the fuel filter was changed? Might be something simple to eliminate. My gut says it's ignition but if it's individual coil packs (not sure on a 5.7) it would throw a code for which bank or cylinder experienced the misfire.

That's an issue I just learned of. Apparently he disconnected the battery briefly when they broke down and inadvertently erased all prior codes. I don't know why he did that but probably just attempting to fix it w limited knowledge while stranded far from home.

There are a number of parts, such as a fuel filter, that might be the cause but now it's a guessing game. We'll probably be chasing our tails on this one. :mad:

I'd start with something cheap like the fuel filter if he's not sure when it was last changed. If the vehicle doesn't get driven much, it could have some nice sludge in the filter from ethanol fuel. From there, depending on the miles the vehicle has on it I'd move to spark plugs, another cheap "fix".

you guys do know that motor has 16 plugs and coil packs right.
If it was low on oil or long between changes you may have a displacement on demand issue.

So you're talking what? Maybe $50 in plugs? I say it's worth a shot. The coils however can become problematic.

If it came in here, the first thing I would try to do , would be to isolate which cylinders are firing , and which ones are not . You can either old school it and unplug one coil/injector at a time, or drive it till it sets hard misfire codes for those cylinders ,and use your scanner to tell . Maybe your scanner even has live misfire data ?
Then, I would spend a few minutes moving coils/plugs around to see if the miss moves with them.
I think that is about as far as you can go backyarding it

Here is a cheap VW fix.

Let/get the coil packs dry, JB weld to stop the arcing.

Enjoy the ride home and replace.