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Hard start, runs great

If it is a leaking fuel injector, it washes the oil off the piston and rings, and leads to rapid cylinder wear, and permanent compression loss, and a forked up engine, thus needing a rebuild, $$$$$$$$$$$, so YES. One of our members reported loosing the engine in one day, from a long drive with a leaking injector. It can also quickly burn out the Cat converter.

Try posting a local help request in the Calif Chapter forum? Some one there should have a pressure tester and some spare use injectors.
 
Check your oil, for any signs of gasoline odor to help see how bad the leak is!!! If you smell string gas in the oil, and it feels diluted, thin, then it can be wiping out the lube of everything quickly!!!! So it is not something to mess with, if it is leaking.
 
Or check in your chapter forum if anybody might have one or access to one to help. I've let guys come by my shop to put vehicles on the lift, or others things! Just a thought.
 
Thanks everyone for all the help. I'm going to go over to the appropriate chapter forum and see if I can get a hand just in diagnosing the problem.

I'll update the thread when anything new pops up. I know when I do a search I always get irritated when I never see the results of a tried suggestion.

I will go take a sniff at my dipstick in a few minutes. That'll at least give me a clue as to how severe the leak, if indeed it is a leaking injector, actually is.

Is there any way to repair a leaky injector or is replacement the only option?

Thank you again!

:party:
 
If your injector is internally leaking, you can get it rebuilt but you would be better off buying new ones (upgrade).
 
I sniffed at the oil dipstick and at the oil pour hole in the valve cover. All I could smell was oil, not a trace of fuel.

bigalpha, just what I needed to know, thanks man. :)
 
I don't recall if holding the gas peddle to the floor helped with my hard start when my MAT (IAT) sensor went out, but it was hard to start cold, sometimes a no start cold, but would start warm and restart warm all day. But it also caused a random high idle. It was the Air Intake Manifold air temp sensor that read warm-hot air all the time, cold or hot. But I suspect it was too lean cold. Of course I see no reason a temp sensor could not fail the other way, and thus try to start the engine too cold.

I forget, did we get ohms readings, hot and cold, on the CTS and IAT (MAT) on this one yet? I am only bringing this up, since you did not smell some gas in the oil (yet). The MAP, CTS and IAT (MAT) and the IAC control the engine start fuel/air ratio!!!

Note: Holding the gas peddle to the floor, also allows more air into the engine on start up, thus bypassing the IAC!!! The IAC position for restarting is reset by the B+ relay and a time cycle on the computer at engine shut down!!!! So you might check that relay!!!
 
No ohm readings of any kind.

Hmm, I have had one or two relays go bad already.

I tried to find information on the B+ relay but I came up with nada. I also searched for IAC relay and a few other terms. Which relay is it? Is there a way to test it or should I just swap it out with another just to see if that's the problem?
 
rvmccarthy said:
No ohm readings of any kind.

Hmm, I have had one or two relays go bad already.

I tried to find information on the B+ relay but I came up with nada. I also searched for IAC relay and a few other terms. Which relay is it? Is there a way to test it or should I just swap it out with another just to see if that's the problem?
Click to expand...

I guess the first question is did the 96 still have that relay, and if so did it move. Mine, Renix, 87-90 is one of the four lined up on the passenger side between the firewall and the battery. My FSM calls it a power latch relay, it is the third relay counting from the battery to the firewall.

http://www.naxja.org/forum/showpost.php?p=243864519&postcount=10

Check out the discussion in this thread about an ASD relay on 96?

http://www.naxja.net/forum/showthread.php?t=1071073
 
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I have a '92.

These are my relays, from the firewall going to the front of the truck:

AUX. FAN - FUEL PUMP - ABS PUMP - AC - AUTO SHTDOWN - STARTER - ABS SYSTEM

The relay lid has a map of all the relays a fuses printed inside it. Really helpful!

No relays in the ABS slots.

I pulled all the relays out, wiped them off and put them back in.
 
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Read that link on the ASD and did some other reading on the autoshutdown. Doesn't seem like the issue I'm having. I will try swapping relays around and just see if that changes anything.
 
I just reread the entire thread (too many similar threads, gets confusing, LOL)

This still sounds like a bad O2 sensor and or leaking injector(s).

But a bad O2 sensor would not be involved in a hard start problem. Only the carbon on the spark plugs, and running rich. So if the running rich is just a bad O2 sensor, and not a leaking injector, that leaves a bad CTS, IAT (MAT), or ASD-Latch relay, which ever one resets the IAC on shutdown? I am really not sure what relay would be the one on your year!!

I guess the IAC could be could be sticking when hot, but not when cold too?

OK, on the relay lid, yours is completely different, so I am lost on that part. I was not sure if it was 91 or 96 when they re-did all the relay stuff. On the 87-90 the B+ latch relay reset the IAC for restart idle air flow!!! Not sure how they changed in 91, but the 91-95 still has an IAC in the throttle body!!
 
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so I went and messed with the Jeep for a minute. Of course, it started right up on the first try. Brought it up to temp a bit and shut it down, waited, wouldn't crank without flooring it. Went and swapped the starter and autoshutdown relays. Tried again, still didn't do any better.

Sniffed the oil dipstick again after the engine had been running. It smells like any motor oil that's been inside an engine... maybe that's covering up any fuel smells that might be in there?

It still does that crazy hesistation thing when I give it any throttle from idle. Could that also be caused by a failing injector? It stops once the engine has been running for a little while.

I guess I'll go ahead and order a new set of injectors when I can. As good a place as any to start. :D
 
"wouldn't crank without flooring it" Or would not start? Or ????

That makes no sense? Why did you replace the starter? You never mentioned a cranking problem before?

You also never mentioned hesitation on acceleration before, that I recall?

That can be a leaking MAP sensor Vacuum line, bad TPS, Bad MAP, or O2 sensor problem. A leaking or loose Vacuum line to the MAP sensor could cause a hard start IIRC. I have seen the vac lines to the MAP sesnor come loose at the throttle body connection!! But I would think that would be a hard start all the time.
 
Doh haha It would not start without flooring it. haha sorry I am still a hobby mechanic so I don't always realize when I'm not being specific enough with my terminology. I keep forgetting there is a difference between cranking and starting hahaha

I swapped the starter relay and the ADS relay just to see if one was going bad. No difference.

In one of the first posts, I mentioned that if you gave it any amount of gas, it would rev a little bit, vroom, then stop like you took your foot off the pedal, then immediately rev up to whereever you want it. LIke vroom (pause, about 1 second), then vrooooooooooom normally... hard to describe lol

I checked all the vacuum lines. I'm guessing if it isn't the injectors it could be the O2, since I know the engine runs rich. I just didn't think the O2 could cause a long cranking time/hard start.

Honestly I'm hoping it's just the injectors so I don't have to hunt down the problem. rofl

:D
 
The O2 sensor is not used during cranking to start.

"In one of the first posts, I mentioned that if you gave it any amount of gas, it would rev a little bit, vroom, then stop like you took your foot off the pedal, then immediately rev up to whereever you want it. LIke vroom (pause, about 1 second), then vrooooooooooom normally... hard to describe lol"

The technical term is "hesitation".
 
hahahaha well it didn't seem quite like the hesitations I've felt before, it's a little different, but I can't really describe it.

I think I may have actually used the word hesitation at some point. :D Either way, yeah, it hesitates one time when giving gas until the engine has been running for a little while (maybe 10-15 minutes).
 
You checked vacuum hoses, relays, wiring.
I say the next troubleshooting step needs to be fuel pressure for sure - along with pulling the injectors and seeing if they leak.
 
I got a PM from a guy in my area who has a set of injectors I can try, so that'll either completely eliminate or verify a leaking injector in one fell swoop. lol I'll definitely post back the results as soon as I have a chance to try them out.

Worst case I bet I could pull all the injectors, leave them connected to the rail, pressurize the system and see if any are dripping.
 
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