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Sporadic delayed starting


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It's now happening about 50% of the time.  I can't seem to pinpoint a pattern.  Very inconsistent.

 

Anyhow, here's the deal:  Sometimes it takes the engine WAY too long to start upon cranking.  It fires just at the point where you're thinking of shutting key off and cranking again.  When it does start during these times, it'll sputter a bit with low rpm for just a couple of seconds and it then corrects itself.  i usually see a light plum of fuel-stinky smoke out the tail pipe.  The other 50% of my starts happen within a couple of seconds of cranking.

 

I put new NGK coppers in on Saturday but no improvement.  Expensive copper-contact distro cap is maybe 4-5 Months old. Most other engine parts are new (CPS/AIC/TPS, etc).  Wires are 7-Months old and have maybe 8000-9000 miles on them I think.

 

I suppose my first check will be fuel rail pressure, so I'll go and rent the gauge again from Autozone tomorrow.   Perhaps I'm losing pressure over time, but I don't know if i should be shooting out rich fuel smoke upon this delayed engine starting if my fuel rails have less than ideal pressure drop.  I do have all new injectors and injector o-rings so I'm thinking pressure drop is probably unlikely.  

 

This issue crop up on anyone else?  Anything jump out at you guys right off the bat?  

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Sounds like not enough spark.  The white smoke and smell indicate you are flooding out.  You might start with refreshing the coil contacts per Cruiser's tips.  I suppose there is a way to test the coil but I don't know what it is.  I expect someone else will chime in.

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Whoa!  That's far-out.

 

By the way, I did do Cruiser's connections clean up, to include coil removal and refresh.  Performed this 4-5 Months ago.  

1 hour ago, Pete M said:

bad connections on the feed for the coil

Can you describe what you mean by "the feed", please Pete?  you mean the center wire from the coil to the distro cap?

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  • 3 weeks later...

Ok, it's been three days now since I wrapped my inner two 4-hole fuel injectors.  I used camper foam covered in aluminum duct tape (its what I had on hand).  It seems to be working, I'm happy to say.  I now will go ahead and wrap the other four injectors.  

 

I suppose that I was getting some vapor lock.  I recall reading about this somewhere and thought I'd give this a try.  Glad I did, as it seems to be alleviating the problem.  

 

I had began to notice that it seemed to happen more when the engine was warm.  It usually did much better in the morning after it had been sitting all night.

 

Anyhow, if this was indeed my problem, then I wonder if it has something to do with me deleting my EGR system.  I had plugged my crack-repaired Renix exhaust header at the EGR tube port and I did the same for the intake manifold.  

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1 minute ago, cruiser54 said:

Nah. EGR being deleted won't cause that. 

Well, just racking my brain trying to figure out why the problem arose after I did all the work recently--freeze plugs, manifolds mods, exhaust work, etc.  Didn't have this issue prior to that.

 

It's warmer now.  Maybe climate-related....

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8 minutes ago, cruiser54 said:

Or fuel related. 

 

Where did you get your injectors? Maybe they're leaking while shut off and parked with the engine hot.......

I hadn't had the time to go rent a fuel pressure gauge and check pressure leak down yet.  I have all new O-rings installed when I did my recent work, even though the ones

that came on them seemed ok.  There are no visible injector leaks.

 

I bought the Yitamotor brand-new 746 injectors back about 4-Months ago.  

 

 

 

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  • 3 weeks later...

I'm still struggling with this problem.  I had wrapped the injectors, thinking that I was getting some vapor lock or something.  Last night, I performed another Cruiser54 coil contacts refresh ( as I had done six Months ago).  Checked and cleaned all wire contacts in that whole area of the coil.  Pulled my $25 distro cap and cleaned all contacts.

 

Fired her up (again after excessive cranking) and pulled each injector wire to listen for engine drop, thinking that I maybe had a bad injector.  Each injector connector pulled resulted in that minor engine rpm drop.

 

I suppose the next step is to go rent a pressure gauge and see what's going on at the fuel rail.  The strong fuel smell is often embarrassing when my engine comes to life after this excessive cranking.  I find myself parking away from others.  Would pressure drop cause excessive cranking and heavy odor upon start?   The thing is:  i don't get this every single time.  Probably about 75% of the time now, whether engine is cold or warm, been sitting for a few days or setting for 10 minutes.  Can't pinpoint a pattern. 

 

Do I need to recheck all of my throttle body component settings, AIC/TPS?  Does this sound like a TB butterfly index problem, maybe?

 

Engine runs like a scolded dog when she does fire up.  Idle seems fine and highway speed behaviors are great.  Anything that perhaps I'm missing or should try at this point?

 

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someone remind me if renix engines have a camshaft sensor. :thinking:  I was talking to a mechanic a while back who swore that most long crank times for old Jeeps was due to a failing camshaft sensor.  

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6 hours ago, Pete M said:

someone remind me if renix engines have a camshaft sensor. :thinking:  I was talking to a mechanic a while back who swore that most long crank times for old Jeeps was due to a failing camshaft sensor.  

 

4 hours ago, rokinn said:

 

Yep, looks like a PITA to me.  Anybody know how to test them first to see if this is indeed my problem?

 

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  • 2 weeks later...

Just realized that a new OEM distributor is only about $45.  The renix pulse ring on my current distro is slightly rusted/corroded.  All plug wire contacts under the cap are clean and the cap is new.  I'm thinking of just yanking my old distro and sticking on a new one.  By the time I go out and buy an analog multimeter to test my sync signal generator (or CPS) and mess around with testing it, I could have a new unit installed.  i suppose that doesn't guarantee that'll fix my particular issue, however.

 

I read where a dude simply unplugged his sync signal generator pigtail and his irregular-running engine suddenly ran tons better.  As for my symptoms, my MJ does not start any better or worst plugged or unplugged.  I'm not sure if this tells me anything or not.  

 

My cranking problem has progressively gotten a bit worse over the past week.  Just seems that when it cranks over, it is dead to the world until late into the engine cranking process.  Always a great poof of gas smell when it fires up too.

 

 

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4 hours ago, cruiser54 said:

I'll bet the injectors aren't staying closed when the engine is off.

 

Try this. Key On and let the pump run. Key off. Key On again and let pump prime again. Now key to Start and see what the result is. 

 

Unfortunately, cycling the key as you described didn't do anything.  Same long crank times with smelly fuel start.

 

I think I'm seeing a bit of a pattern afterall.  Seems it starts much faster if the vehicle has been sitting for a long period of time.  If I am starting, driving and shutting down frequently, it seems to be at its worst.  Injectors not "staying closed" makes since in my mind.  Symptoms are almost like a flooded carburetor on an old car.  Gotta crank a while to get air to "flush out" all the excessive gas.  I wonder if my new injectors just suck.... I did unplug each while running to see if idle was affected.  Each passed this quick test.  

 

BTW, I did order a new distributor for $46 bucks so I'll be tossing that on maybe next weekend.  But I'm sure leaning towards the fuel side now that you got me pondering.

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On 6/16/2018 at 2:35 PM, Ωhm said:

Check the hose between the manifold and the fuel pressure regulator for fuel. Possible small leak on regulator diaphragm.

You're referring to the vacuum line?  I pulled it and upon close inspection, found nothing.  It was dry inside (no fuel) and there were no cracks/holes, etc.  Hard fuel line with disconnect feeding the pressure regulator appeared to be fine with no visible leaks either.  I'll rent a pressure dial for the fuel rail again and let you guys know the readings.  

 

I sure appreciate your assistance, fellas.

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