stranded - engine starts but bucks and stalls out

[luckycamper]

As title states, I’m currently stranded and the comanch won’t stay running fml.  Was running fine today but when i got back in my truck I was met with dread. It starts briefly and wants to immediately stall until i push the pedal in and then it begins to violently shake before stalling. I had an extra fuel filter in my bed for times like these so i just through that one on. Tried it a few more times and it bucks and sputters out just the same. I’m hoping perhaps someone can chime in with a similar experience and possible solution though I know it could be a myriad of things.

 

I’ve been searching and turning through these forums for the past few hrs but w/o every tool being available to me its hard to diagnose. 

 

To sum up: was driving fine today, went to start it up again and engine bucks then stalls. 

[luckycamper]

update: got it running rough in neutral. When I put it in gear, the idle gets erratic and it wants to stall. I moved forward a little bit but by this time i’m suspecting something more internal. 

[Pete M]

what tools do you have?  any carb cleaner?   any means to pour a wee bit of gas into the TB?

[luckycamper]

6 minutes ago, Pete M said:

what tools do you have?  any carb cleaner?   any means to pour a wee bit of gas into the TB?

hey Pete, luckily I have most of my tools in my bed (wrenches, sockets, basic stuff). I just don’t have anything to test vacuum, fuel pressure, etc.

 

Finally managed to talk the gf into picking me up. Nxt dinner date on me. I’m going to try and read up as much as possible and rally for tomorrow morning. 

[luckycamper]

update2: have since abandoned the chariot. Before I shut her off I could hear a noticeable hollow ping. 

 

background info: bought the truck last month. I wouldn’t say I trust the previous owners abilities or choice in parts but they did say they replaced distributor cap, plugs, wires within the last year.

[Pete M]

hollow ping?

[eaglescout526]

Hmm 2.5L as well. I’m curious about some of the other things about it. 

[luckycamper]

49 minutes ago, Pete M said:

hollow ping?

yea, doesn’t sound like the common engine tick or spark knock. I’ll try to take a video tomorrow before I start digging more into it. 

[eaglescout526]

Is it the exhaust cooling off perhaps that you hear? I usually hear a hollo ping after stopping the engine. What color is the coolant?

[luckycamper]

30 minutes ago, eaglescout526 said:

Hmm 2.5L as well. I’m curious about some of the other things about it. 

So many things. I keep finding loose connectors, vacuum hoses, etc and have just been trying to knock out one thing at a time. Currently been refreshing grounds as I also suspect a grounding issue somewhere. Previous owners replaced many parts w budget brands so I’m basically doing cleanup along with everything else. This renix 2.5 is a new beast to me so its a bit of a challenge trying to figure out how things are supposed to be but i’m getting there. 

[luckycamper]

5 minutes ago, eaglescout526 said:

Is it the exhaust cooling off perhaps that you hear? I usually hear a hollo ping after stopping the engine. What color is the coolant?

the sound is while the engine is running in neutral. i haven’t checked the coolant yet but i will in the morning. I hope it is still green.

[eaglescout526]

Sounds like a blast. I’m here to help as I think I took up being the resident 2.5L expert haha. I always ask everyone about the coolant as I’ve had similar issues and if a head gasket hasn’t been done since the MJ left the factory, it will buck and stall to the point where you probably can’t drive any more. 

[fiatslug87]

In case you haven't come across this post with technical and parts manuals yet.

 

[luckycamper]

46 minutes ago, fiatslug87 said:

In case you haven't come across this post with technical and parts manuals yet.

 

thanks man. I did find that page awhile ago and have the fsm saved on my phone!

[luckycamper]

10 hours ago, eaglescout526 said:

Sounds like a blast. I’m here to help as I think I took up being the resident 2.5L expert haha. I always ask everyone about the coolant as I’ve had similar issues and if a head gasket hasn’t been done since the MJ left the factory, it will buck and stall to the point where you probably can’t drive any more. 

Really appreciate it fine sir. I got a ride out here this morning and going to see what i can manage. I’ll chk the coolant and take a video for audio. 

[eaglescout526]

No problem. Look forward to any updates. 

[luckycamper]

-coolant is good.

 

-the airbox/filter looks to be getting oiled a bit so i checked the pcv valve and it is not the correct one for the 2.5 (not sure if it matters). There is movement in it, not necessarily as much as i’d expect

 

-first video was too long going to try again

[eaglescout526]

So that front valve is correct. PN is J8132309 -> 33001239. Only 86 uses that set up so we’re in for 86 oddities. 

[luckycamper]

2 minutes ago, eaglescout526 said:

So that front valve is correct. PN is J8132309 -> 33001239. Only 86 uses that set up so we’re in for 86 oddities. 

ok good to know. I was just going by auto parts store websites. I know, nvr trust em. 

[eaglescout526]

Yeah they’re hard to trust but as long as you have a part number to reference, you should be good to go. 

[luckycamper]

Managed to get home i think by pure luck—green lights and all. Truck stalled a few times and it shook the whole ride. I have some videos (excuse the quality) to demonstrate the sound the engine makes in neutral and while in gear. 

 

[luckycamper]

[luckycamper]

few more while in gear

[eaglescout526]

Your ISA is missing it’s adjustment screw. Miracle it’s even idling. 
 

I hear a vacuum leak, big one actually. And you’re battery light is on lol. 

[luckycamper]

After I got home, I popped the hood and there was a little smoke coming from the exhaust manifold. Idk yet if this is a cause of my troubles or just an effect of something else and driving it the 15min back home. 

 

My experience driving it home was that it would want to die as soon as i lifted off the gas/felt like it was about to lose all power. To keep it from stalling I’d crush the pedal all the way down and it would slowly catch up, low idle speed.