My 4.0 won't start, please help (with audio)

vanguard

vanguard

Well-Known Member
Joined
Oct 19, 2005
Location
Apex, NC
I've been doing a ton of work (suspension) to my rig lately but nothing that would stop it from starting, as far as I know. * To test it I cranked it and it barely idled then died. I couldn't give it gas because my TV cable was blocked. I resolved that and it wouldn't start again.

Hints/Red herrings
* I disconnected the fuel cell and the fuel drained out of the fuel line.
* I use a Ford E2000 (?) fuel pump (has worked for years, it worked a few days ago)
* When I press the relief valve on the fuel rail then crank it gas comes out just fine.
* I don't think I messed up any wires as I moved things around but I guess anything is possible.
* It has good spark. (guaranteed, I saw it and felt it)
* It sounds like this when I crank it. http://www.just4fun.org/images/buggy/rear axle and suspension project/starting_problems.wav

So it has spark and it seems to have fuel but it won't start. Any ideas?
 
My first guess would be the crank position sensor. From hearing the audio it sounds like the timing is out but the timing is not adjustable on the fuel injected 4.0's. The timing being out could result from the cps being bad. If it was the tps then it would run but soon as you touch the throttle it would die. If the map sensor was bad the it would also still run but have a heavy miss to it. It would either be flooding the engine or running too lean. A vaccuum leak would still let it run but it would have a miss and lack power. The only other thing I can think of is the fuel pump is on it's way out or is bad. Just because you have pressure at the rail doesn't mean the fuel pump is ok. A friend of mine picked up a ZJ a little while ago and when we hooked up the fuel press gauge it read fine then the next time it was low then a little later it was fine again. It turned out to be the fuel pump but you wouldn't have known it just by testing the pressure at the rail once. I would suggest getting a gauge and testing it a couple times and see what you get.
 
Have you tried starting it on starting fluid? I don't know what you've got vacuum hose wise, but I know that stock jeeps have them running all over the place. Cap the vac lines off at the engine and try again. :edit: I would also put a fp gauge on the test port.
First try starting it on starter fluid...that would rule a lot out.
 
Sounds like it's out of gas.. more priming on the fuel system!

If you could LIGHTLY pressurize your fuel cell (like 5psi through the vent line), it'll help..
 
Some of these CPS are wired a little tight (harness not having enough slack) and sometimes they just need to be wiggled. Be sure to check it before replacing it.
 
woody, any of this fix it?
 
So I've tried three CPS's and it hasn't changed the symptom. It still sounds just like it did in the audio file in the first post.

I also pulled the plugs, made sure they were dry, removed any fouling (they weren't really gunked up though) and tried again. Still no change, it sounds just like the audio in the first post.

I tried starting fluid and that didn't have any change on the symptom either. I'm at a loss here. I don't know why it suddenly stopped running.

(BTW, I checked every fuse with a multimeter and they were all fine.)
 
have you recently taken the cam or distributor out lately?> When I was firing my stroker the first time, i had the dizzy off one tooth on the cam, and it sounded the exact same as your audio clip. if oyu have, un bolt the dizzy, pull it up slowly, and turn it so it only moves one tooth on the cam, you may need to try turning it more than one direction........if you havent pulled either of these lately, check all your engine grounds, sounds like a fuel pump issue, if other than dizzy issue
 
I haven't had either out but the idea that I screwed up a ground to the motor seems possible. I want to say something is wrong with fuel delivery but it didn't start when I used that pryo starting fluid and when I press the schrader valve on the fuel rail the gas came pouring out. I've taking a quick break for lunch right now. I'll check the spark on more than one cylinder in a few minutes.
 
BTW, it's sorta kinda firing. It seems like one cylinder is firing because it goes ra ra ra ra ra humph, ra ra ra ra ra humph and there is a little exhaust smoke with each "humph". (As heard in the audio in the first post.)
 
Keep bleeding the fuel rail. I have to do this everytime I lose fuel on the trail. It still has air in the line.
 
Cycle the key 2x, then crank it over. Bleed at the rail using the schraeder valve. Repeat until it cranks.
 
It runs! Thanks for the help everybody. I'm guessing that Travis was right about air in the fuel lines but that by itself didn't fix it. I started pulling more plugs and looking at their spark and the some of them were really weak. I went out and bought 6 new plugs. As I installed each one I checked the spark. But the time I got to #4 it ran. I finished up the job and as expected, it started right up.

http://www.just4fun.org/images/buggy/rear axle and suspension project/ir_runs.MP4
 
since this is fixed and i am a little late allow me to now diagnose, hind sight is 20/20, if it was the CPS it would not have any spark you rulled that out, it had spark you could have put a 100 CPS in it would still have spark, when you used starter fluid and it did not crank you ruled out fuel, now were back to poor spark, eratic spark, lack of compression, you had spark to the plug presumably good spark, plugs were the answer.
 
Here's my best guess at what happened.

1) I pulled the fuel cell and the fuel line drained.
2) I hooked up the fuel cell, tested it, and it worked fine with the little bit of fuel left in the line.
3) Two days later when I went to start it again it started briefly, ran terribly, and died because of air in the fuel rail.
4) I cranked and cranked and cranked until the plugs fouled.
5) Travis taught me how to bleed the air from the fuel rail and that problem was solved.
6) I checked the spark again, found the bad plugs, and solved the last problem.

FWIW, I wheeled at Rausch Creek all weekend long and the buggy worked great.
 
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