• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

tempermental starting..

M

mrtosh

NAXJA Forum User
Location
Woodbury, MN
I just bought a '94 Sport this weekend w/180,000 miles on it. Thing runs like a top. The weird thing is that when it's cold it fires right up. Warm it will sometimes take a good 3seconds of cranking, and sometimes it will fire right up.... Don't get it. Poor fuel pressure? when it does take a while to fire and finally fires, it sounds like it's gonna die, like it's not getting enough gas then idles up normally. What gives??

Thanks in advance guys....

PS. This forum is a lot better than jeepforum.com
 
mrtosh said:
I just bought a '94 Sport this weekend w/180,000 miles on it. Thing runs like a top. The weird thing is that when it's cold it fires right up. Warm it will sometimes take a good 3seconds of cranking, and sometimes it will fire right up.... Don't get it. Poor fuel pressure? when it does take a while to fire and finally fires, it sounds like it's gonna die, like it's not getting enough gas then idles up normally. What gives??

Thanks in advance guys....

PS. This forum is a lot better than jeepforum.com
Click to expand...
No worries mate! Most of us crank these beasts for 3 to 5 seconds all the time! And that is with all new parts on them:shocked:.

I would wait, and keep notes for now until the problem gets more problematic, if it is a problem. Could be any one of a dozen parts getting old and ready to go out. So don't :banghead: for now.

In the mean time read up hear about hard starting problems others have experienced and solved in various threads to give you a head start for the day when it becomes a real problem.
 
Last edited:
^^^^Well this is my second jeep. My old '89 XJ always starts up cold or hot around 4 seconds of cranking. I just find it weird how on the '94 it will start up sometimes hard, and sometimes right away. W/it not wanting to idle right, right away on the hard starts leads me to believe it's not getting enough fuel upon start up on the hard starts.. Am I right in assuming so?
 
Possibly the IAC is sticking, one of the first things I check normally. It might not be a fuel thing, but an air thing. The IAC is constantly making fine adjustments to keep the mix right at or near idle. If it gets sticky, wierd things happen.
The wifes (96) would do just the opposite, start hard cold (and idle crappy) and easy warm (mostly). But the syptoms were similiar to yours. The IAC was getting sticky, a little oil in by the plunger cured the problem.
 
IAC is Idle Air Controller, also know as Idle Air Control stepper motor. It slowly adjusts the idle air flow through the throttle body. It is just to the left of the TPS, Throttle Postion Sensor on the front of the throttle body.

Search "Idle Air Control" in this forum for lots of details and how to's.
 
How do you "oil" the IAC? And if need be how much is one to replace it with? This may be a lil bit out there, but my water pump is on the way out. It just went tonight. Previously the temp has and still will climb up to right around 210 and then drop all the way down to 170. It does this every, prolly 2 mins. I'm guessing that may have something to do w/the hard starts recently as well..... Coolant sensor and all...??? Thanks in advance guys...
 
Last edited:
The IAC is held on to the throttle body by 2 machine screws, next to the TPS (Throttle Pssition Sensor), just a bit to the left of it. It has a 4 pin connector attached. Detach the connector, the 2 screws, and drop a few drops of oil onto the machine threaded shaft area between the "Pintle" (looks like a cone shaped piston) and the motor.

If you rotate the pintle on the shaft do not force it, and try to return it as closely as possible to the original location on the shaft before yopu reinstall it. Be careful, they are delicate, precision devices. If you force anything you can damage it beyond repair. Autozone has them for about $65. Dealers, and some forum vendors here should have them too. I have found that it is dificult to find them in the parts store databases due to name variations in their databases.

Names to try:

Idle Air Contoller (IAC)
Idle Air Stepper Motor
Idle Stepper Motor


The coolant leak could be getting electronic ignition parts, or wiring wet and causin hard starts.
 
*Update* Soo, the waterpump just blew the other night and i'm gonna change it this weekend. One thing i did notice is that when i test drove it, the thermostat was stuck open and it never reached operating temp. We drove it for about a half hour and shut it down and started it numerous times, all w/out fail(fired right up). Now I'm wondering if seeing as how the engine never got warm it started just fine because the cpu was keeping it running rich like a cold start. But when warm the coolant sensor is not telling it it's warm, so it is still trying to start like it's cold.... Just a random thought. Might change the coolant sensor as well as the water pump.. What do you guys think????

Sorry for the long post.
 
You can test all the temperature sensors with an ohm meter. I have the ohm data for the earlier Renix models up to 1990, but I am not sure if the sensors in 1994 are the same.

Since you have a known leak and a stuck thermostat now I would bet that something was getting wet from a smaller prior leak when it was hot and that it was causing bad start up data when it was hot?

Also could it have been getting coolant/water into the air filter....on a warm start up due to the leak location?

I am still not convinced 3 seconds of start up time is a problem for a warmed up 1994 jeep????

Have you tried cleaning the throttle body and oiling the IAC yet.
 
Ecomike said:
You can test all the temperature sensors with an ohm meter. I have the ohm data for the earlier Renix models up to 1990, but I am not sure if the sensors in 1994 are the same.

Since you have a known leak and a stuck thermostat now I would bet that something was getting wet from a smaller prior leak when it was hot and that it was causing bad start up data when it was hot?

Also could it have been getting coolant/water into the air filter....on a warm start up due to the leak location?

I am still not convinced 3 seconds of start up time is a problem for a warmed up 1994 jeep????

Have you tried cleaning the throttle body and oiling the IAC yet.
Click to expand...

I read in the manual that the sensor in the thermostat housing should read 7,000 ohms or better when cold, and should read less than 1,000 ohms when warm. That was a misprint on my part in the initial post.. When it was warm it would take about 10-15 secs.. I'm gonna change the water pump, coolant sensor and the fuel filter today. Will update..

Thanks again guys.. :peace:
 
Ah, ha, and extra 12 seconds of cranking time would make a little :D difference, LOL.
 
*Update* Well changed the waterpump, coolant sensor and belt tonight(Man that powersteering pump is a bitch). No real change. The temp gauge still goes up to 210 then drops down to 170, before climbing back up. Cranking time seems to be about the same as well.... I don't know, where to go from here....Blah.... Gonna change the fuel filter tommorow(might as well). Just a quick question, how do you know if the belt is too tight? Haynes Manual claims you should be able to push it down about a 1/4"-1/2" depending on the distance between pulleys. Mine is pretty tight right now and i think i'm starting to hear a real light howling again. Don't know if it's coming from the new water pump. Might be too tight, huh?
 
mrtosh said:
*Update* Well changed the waterpump, coolant sensor and belt tonight(Man that powersteering pump is a bitch). No real change. The temp gauge still goes up to 210 then drops down to 170, before climbing back up. Cranking time seems to be about the same as well.... I don't know, where to go from here....Blah.... Gonna change the fuel filter tommorow(might as well). Just a quick question, how do you know if the belt is too tight? Haynes Manual claims you should be able to push it down about a 1/4"-1/2" depending on the distance between pulleys. Mine is pretty tight right now and i think i'm starting to hear a real light howling again. Don't know if it's coming from the new water pump. Might be too tight, huh?
Click to expand...

Is the electric fan coming on at 210 and bring the coolant temperature down?

Did you change the thermostat?

On the how to tell if the belt is too tight issue, if it is too tight it eats belts and bearings, too loose it squeels. If you think it is too tight loosen it! If it squeels retighten it tell it stops squeeling. Only other ways to know for sure is experience or to use a belt tension gauge. The Haynes manual is right, 1/4 to 1/2 inch.

Might check the CPS and flywheel for the slow start problem.

Also get an FSM at:

http://www.pirate4x4.com/tech/billavista/PDFs/index.html
For more details...
 
Ecomike said:
Is the electric fan coming on at 210 and bring the coolant temperature down?

Did you change the thermostat?

On the how to tell if the belt is too tight issue, if it is too tight it eats belts and bearings, too loose it squeels. If you think it is too tight loosen it! If it squeels retighten it tell it stops squeeling. Only other ways to know for sure is experience or to use a belt tension gauge. The Haynes manual is right, 1/4 to 1/2 inch.

Might check the CPS and flywheel for the slow start problem.

Also get an FSM at:

http://www.pirate4x4.com/tech/billavista/PDFs/index.html
For more details...
Click to expand...

Thanks, I was just reading some other posts in the search, someone said if you can twist the belt 90* or more it's probably too lose.... Any truth behind that? The electric fan isn't coming on. It just reaches 210 then floats down to 170. It cycles like this about every 2 1/2 mins. I did put some thought into the cps, but wouldn't it be running like sh*t. Once it starts it runs perfect. As far as cleaning the IAC, what would you recommend to use and to oil with? Hate to sound like too much of a noob, but what is FSM?
 
mrtosh said:
Thanks, I was just reading some other posts in the search, someone said if you can twist the belt 90* or more it's probably too lose.... Any truth behind that?
Click to expand...

Probably.

[/quote]The electric fan isn't coming on. It just reaches 210 then floats down to 170. It cycles like this about every 2 1/2 mins. [/quote]

Sounds like it may be a sticking thermostat.

[/quote]I did put some thought into the cps, but wouldn't it be running like sh*t. Once it starts it runs perfect. [/quote]

Then the CPS is probably OK.

[/quote]As far as cleaning the IAC, what would you recommend to use and to oil with? [/quote]

Any nonwater solvent, such as brake cleaner, electrical cleaner in aerosol form will work. Any light oil at or below 30W.

[/quote]Hate to sound like too much of a noob, but what is FSM?[/quote]

FSM is factory service manual. See:

http://www.pirate4x4.com/tech/billavista/PDFs/index.html
 
mrtosh said:
Thanks, I was just reading some other posts in the search, someone said if you can twist the belt 90* or more it's probably too lose.... Any truth behind that? The electric fan isn't coming on. It just reaches 210 then floats down to 170. It cycles like this about every 2 1/2 mins. I did put some thought into the cps, but wouldn't it be running like sh*t. Once it starts it runs perfect. As far as cleaning the IAC, what would you recommend to use and to oil with? Hate to sound like too much of a noob, but what is FSM?
Click to expand...

Also, the 170-210-170 F temperature cycling sounds like a cyclic pressure leak, probably the plastic bottle reservoir cap is not holding pressure. Or there is a tiny pressure leak at one of the hose connections or on the radiator.

They can be hard to spot at the early leak stages.
 
You must log in or register to reply here.

Similar threads

J
Cranks, Fires, Dies - 1991 Briarwood Restoration
Replies
17
Views
3K
Jam Master Jay
J
9
Renix lowish idle
Replies
10
Views
2K
90xj06
9
N
New Engine is hard starting
Replies
0
Views
17
NGThomas
N
N
Severe stumble, misfire and no start issues
2
Replies
27
Views
4K
maxbraketorque
M
B
Broke brake line...how to fix?
Replies
5
Views
2K
jeep ride
J
Back
Top