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What the heck!


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Tried to start it, ignition on, radio, cb starts up, turn ignition to start engine. hear a click in the engine bay, then nothing.  No radio no power.  Try to start it again, nothing.  Poked under hood, after a few minutes,  turn on ignition, radio and stuff start up, hit the starter, click, nothing no power.  Charged the battery for an hour,  same routine.  

I don't know.....

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Thanks guys, that did the trick.   However now that it turns over, it starts for couple seconds then dies.  Took about 12 tries and little pedal action to keep the engine going. 

My guess it's something to do with the computer stuff.

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Thanks guys for the info, ECU might still be learning, the ground cleaning didn't change the problem. Bought a crown vic x cop car with cop tires at a auction last Sat, so it's getting priority. 

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  • 4 months later...

When you turn the ignition on you can hear a faint humming noise and then a click, does anyone know what part that is.  Whatever that is, it isn't doing it anymore and the jeep won't start save a one or two second sputter from the engine.

So far I have, tried a different ECU, checked for voltage on cps, map, tps (and adjustment), checked grd wire behind tail light, got 30 plus psi on fuel rail, got spark on number one cylinder, bypassed resistor by air cleaner, filed the tips on spark plugs, took off ignition coil cleaned contacts, found a hot wire not attached to solenoid (no change), cleaned and tightened battery terminals,  undid the big electrical connector and clean it with electrical contact cleaner, scratched my head more than once and wondered about the fuel pump. Bought the jeep in 1990, maybe it's time to say bye bye.

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The faint humming noise, I would assume is the fuel pump priming up. If it’s not making a sound anymore try a fuel pressure test again. On another note, when I did my engine swap I took everything out and plugged back in the way it was from the donor and it wouldn’t stay started for a couple days. Also from personal experience, make sure the MAP sensor is plugged in.

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Not sure why this 4-month old thread suddenly got revived, but since I missed it the first time around I'll chime in here.

 

First point: The Renix ECU doesn't "learn" anything. It has no static memory. Every start is a new start.

 

A start that dies after a few seconds usually indicates a faulty fuel pump ballast resistor. The start circuit bypasses the resistor, which allows the engine to start. When the key is moved back to the RUN position, if the ballast resistor is bad the fuel pump can't run, so the engine sputters along until it has used up whatever fuel it received during the START cycle, and that's all she wrote.

 

2360, the ballast resistor on a 1988 is on the inside of the driver's side fender, next to the air box. Try removing the spade connectors and jumping them together. See of that allows the engine to keep running.

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Really appreciate the feed back, tried ballast resistor check, no go.  Just out of curiousity, is that connector of consequence?

 

 

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Edited by 2360
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Update!  Swapped a relay with one beside it, turned the ign. on, heard the faint humming noise and it started.  Yah, however it runs real rough and it won't idle, just sputters and dies.

Now I just have to figure out why it's missing one or more cylinders.   Moved the tbs around to no avail, thinking maybe wire harness went bad after removing plugs. Or maybe the used

injectors I put in a little while ago when it wasn't working that  good. :holdwrench: The quest continues.....

After doodling with it , got it idling real rough, has a bad metal on metal knock at the front of the engine, might be piston slap or something else.  I think she's done. 

Edited by 2360
update, bad news.
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A stuck valve, a hole in the piston, a collapsed lifter are all causes of a bent push rod. You probably should remove the push rods to see if you have more than one that is bent. Hard to eye ball if they have a slight bend but they are no good if they do. Best way to check to to roll the push rod on a piece of glass and see if it wobbles. It also allows you to see the area that is bent. Lifters require the heads to be removed. Probably a good thing because you can check to see if #1 has a bent valve as well. If the valve stuck or bent, the cam pushes up on the lifter and then the pushrod and it doesn't want to go any where so it bends. Not catastrophic, but not like changing a spark plug. If the valves are bad rebuild the head. Don't just drop a valve and a push rod in you probably should replace the lifters as well. Good luck, been there done that!

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Yep, bent another push rod.  The intake valve looks a bit lower on number one cylinder, there is lots of play on the intake rocker when torque down. Turned the engine over without the rockers on intake and exhaust push rods both went up and down.  I'm thinking the intake value is stuck somehow.   Looks like the head has to come off to get at the intake valve.  Yuck.

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At this point, remove the head. Pull the entire rocker arm assembly. Keep things in order, don't mix things up. The valve train is worn specific to it's current location. You need to  look at the lifters, once the heads off. Keep them in order, check #1 intake and exhaust for visible damage. If you have a valve spring compressor tool, pull the keepers off and pull the springs. You may have broken a spring. Once the springs are off if the valves are straight, you should be able to move them up and down in thier bores without much effort. If not well you know, the valve stem is bent. Depending on how severe the damage is a replacement head from the bone yard might be the best choice.

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I checked pick n pull, all they have is a 97 Cherokee, not sure if it has a 4.0 or if it does it will fit on my engine.  Hopefully they get an older 4.0 in sometime soon. Thanks for the info, this job is going to take a while.

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