HELP!! NO SPARK, NO START

[54bobby]

So, my 87 2.5 tbi was idling like crap so i did a little lookin and found the iac valve was caput. got a new one installed it cranked her over and no spark. fuel flowing into tb looks good. tested plug wire with open air in line tester along with coil wire, NADDA.i did drain battery by touching the neg cable to the pos. could this have fried something. things that spark are not my strong suit. please help.

[eaglescout526]

Did you test the crank shaft sensor located on top of the bell house? That sensor tells the computer when to fire.

[jdog]

i did drain battery by touching the neg cable to the pos. could this have fried something. things that spark are not my strong suit. please help.

Does this mean you touched the battery cables together with the battery hooked up? Also are you getting power to the coil, have you checked the rotor and making sure it's spinning? Have you checked the crank sensor?

Stock 1988 swb 4.0 ax15 np 231.

[Jeep Driver]

I don't believe you'll get fuel without CPS signal. 

 

No fire is likely coming from a bad coil.

 

Just my guess from afar. 

 

 

Touching the cables together does nothing, did nothing. 

[jdog]

I don't believe you'll get fuel without CPS signal. 

 

No fire is likely coming from a bad coil.

 

Just my guess from afar. 

 

 

Touching the cables together does nothing, did nothing. 

Yea if they are disconnected from the battery, but connected.... But I'm hoping he means he "reset the memory" in which case I'll agree with you as it does nothing.

 

Stock 1988 swb 4.0 ax15 np 231.

 

 

 

[54bobby]

i'm on on the right track then as all tests mentioned above are on tomorrows docket as it was raining pretty good here this evening. gonna start at the rotor and work back.

another question if i may, the idle control motor i removed had a small bolt screwed into the shaft that moves in and out against the linkage plate. the new one i put in has a bolt that's considerably longer and looks to be closer with out it. this is the style i'm talking about.

 

[Eagle]

35 minutes ago, 54bobby said:

i'm on on the right track then as all tests mentioned above are on tomorrows docket as it was raining pretty good here this evening. gonna start at the rotor and work back.

another question if i may, the idle control motor i removed had a small bolt screwed into the shaft that moves in and out against the linkage plate. the new one i put in has a bolt that's considerably longer and looks to be closer with out it. this is the style i'm talking about.

 

 

What's the question?

[54bobby]

18 minutes ago, Eagle said:

 

What's the question?

 is the longer bolt on the new iac going to work on the truck the same as the shorter one on the old valve did? the bolt on the newer motor can not be adjusted to the shorter length of the old unit.

[eaglescout526]

What is wrong with the old ISA? They can easily come apart to be cleaned and re-greased.

[Jeep Driver]

8 hours ago, 54bobby said:

i'm on on the right track then as all tests mentioned above are on tomorrows docket as it was raining pretty good here this evening. gonna start at the rotor and work back.

another question if i may, the idle control motor i removed had a small bolt screwed into the shaft that moves in and out against the linkage plate. the new one i put in has a bolt that's considerably longer and looks to be closer with out it. this is the style i'm talking about.

 

 

 

That stepper motor is meaningless, unplug it, set the idle where you want it at the plunger and it will run just fine. 

 

If you have no spark.............this ain't the cause. 

[54bobby]

7 hours ago, eaglescout526 said:

What is wrong with the old ISA? They can easily come apart to be cleaned and re-greased.

it probably could have been refreshed but for the piece of mind and lack of time, lol, i just grabbed a new one..

 

5 minutes ago, Jeep Driver said:

 

 

That stepper motor is meaningless, unplug it, set the idle where you want it at the plunger and it will run just fine. 

 

If you have no spark.............this ain't the cause. 

i thought that it and the tps were all in bed together with the ecu in regards to fuel/air mixture. truck has a very erratic loping idle so from what i researched, that stepper along with a tps adjustment was in order. it's all on hold till i get in there and find my sparks. where oh where have they gone? hitchin up my boot straps now to go and find them little buggers. lol

[cruiser54]

First off, I'm gonna have more questions than answers here.

 

Fuel and no spark leads me to coil/dizzy area.

But, I can't help but wonder if you bumped something during the ISC replacement.

 

Pull the dizzy cap. See if the rotor is seated properly. Are the spark plugs wet? 

 

Of my Tips, which ones have you completed?

[54bobby]

3 hours ago, cruiser54 said:

First off, I'm gonna have more questions than answers here.

 

Fuel and no spark leads me to coil/dizzy area.

But, I can't help but wonder if you bumped something during the ISC replacement.

 

Pull the dizzy cap. See if the rotor is seated properly. Are the spark plugs wet? 

 

Of my Tips, which ones have you completed?

cap is clean and uncracked, rotor is clean, seated and turns when cranked. with the intake off of the tb and cranked, fuel spits up out of a little hole on the side of the tb throat. is this the normal entry for gasoline to enter the tb? will pull plugs next. if wet, what does that tell you/me? for completing your tips, under hood grounds are done. that's about it. i know, she'll never be right till i get them done but at 65 and still working 75 hours a week, weel, nuff said.  that is some great stuff there though and the mj community is so lucky to have you and i'm gonna go out on a limb here and say you are the soul reason that many many mj's are still on the road. thank you.

[Eagle]

1 hour ago, 54bobby said:

 with the intake off of the tb and cranked, fuel spits up out of a little hole on the side of the tb throat. is this the normal entry for gasoline to enter the tb?

 

 

It's an '87 2.5L. It has throttle body injection. Fuel should not be spitting out of a hole in the side of the throat, it should be spitting out of the injector.

 

Which still doesn't account for a lack of spark. Have you tried verifying the spark with one of these? https://www.harborfreight.com/in-line-spark-checker-63590.html

 

[54bobby]

SHE LIVES, 

   tested the CPS and nadda, removed it and cleaned it up real good as well as the mounting area. used contact cleaner on the conectors as well as doint the same to the coil and all sorounding terminals. cranked her over and BINGO. thanks fellas. back on the track and only dropped a lap or two. by the way, just rolled over on 239k

 

[eaglescout526]

When in doubt, test the CPS first. Congrats!

[cruiser54]

So, cleaning the CPS and it's connector did it?

 

From Tip 7:

 

"Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off."

[54bobby]

On 8/26/2019 at 8:51 AM, cruiser54 said:

So, cleaning the CPS and it's connector did it?

 

From Tip 7:

 

"Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off."

yes, but stil have an eratic looping idle.. on to the tps now.

[cruiser54]

Have you done the ground refreshing and snugging up of intake fasteners along with replacing those pesky vacuum hoses at the intake? 

[54bobby]

18 hours ago, cruiser54 said:

Have you done the ground refreshing and snugging up of intake fasteners along with replacing those pesky vacuum hoses at the intake? 

still have dip stick ground to do along with drivers tail light which i have discovered that the housing screws are toast. looks like they were seized in and someone tried unsuccessfully to drill them out. now all the heads are shot from failed drilling. as for the intake fasteners, as many of the 2.5's have experienced, the front and rear exhaust mani. bolts are sheared off. i'm guessing from the factory using the wrong torque value. i understand there was a change to reflect a different torque for the center bolt. yet another thing to do. all good though, just put it on the list with the 86 bmw, and the 4 mid 60's evinrudes. lol

[54bobby]

[cruiser54]

15 hours ago, 54bobby said:

still have dip stick ground to do along with drivers tail light which i have discovered that the housing screws are toast. looks like they were seized in and someone tried unsuccessfully to drill them out. now all the heads are shot from failed drilling. as for the intake fasteners, as many of the 2.5's have experienced, the front and rear exhaust mani. bolts are sheared off. i'm guessing from the factory using the wrong torque value. i understand there was a change to reflect a different torque for the center bolt. yet another thing to do. all good though, just put it on the list with the 86 bmw, and the 4 mid 60's evinrudes. lol

Never mind the  ground behind the taillight. Do this instead. And, do the dipstick tube stud and the braided strap at the firewall. No time at all to do. 

CRUISER'S MOSTLY RENIX TIPS

IMPROVING THE FUEL PUMP GROUND

JANUARY 3, 2016 CRUISER54 49 COMMENTS

The fuel pump and fuel tank sending unit ground at a sheet metal screw up behind the spare tire on an XJ, and behind the driver’s taillamp on an MJ.

Not only is a sheet metal screw a lousy way to ground things, this ground path is long and travels through some connectors that are prone to corrosion and moisture.

Locate the black wire on  the HARNESS side of the fuel pump/sender 3 wire connector. Remove a 6″ length of the split loom covering. Strip back about 1/2″ of insulation from the BLACK wire.

Take your new ground wire, preferably at least 14 gauge and 12 to 18 inches long as needed, strip it about 3/4″, and wrap it around the exposed part of the harness plug wire.Solder the connection. Tape it up and reinstall the split loom covering.

At the other end of your new ground wire, add a crimp on eyelet. Attach the eyelet under a bolt that goes directly into the chassis. Be sure to clean the attaching point til shiny and apply OxGard to the contact surfaces.

[54bobby]

4 hours ago, cruiser54 said:

Never mind the  ground behind the taillight. Do this instead. And, do the dipstick tube stud and the braided strap at the firewall. No time at all to do. 

CRUISER'S MOSTLY RENIX TIPS

IMPROVING THE FUEL PUMP GROUND

JANUARY 3, 2016 CRUISER54 49 COMMENTS

The fuel pump and fuel tank sending unit ground at a sheet metal screw up behind the spare tire on an XJ, and behind the driver’s taillamp on an MJ.

Not only is a sheet metal screw a lousy way to ground things, this ground path is long and travels through some connectors that are prone to corrosion and moisture.

Locate the black wire on  the HARNESS side of the fuel pump/sender 3 wire connector. Remove a 6″ length of the split loom covering. Strip back about 1/2″ of insulation from the BLACK wire.

Take your new ground wire, preferably at least 14 gauge and 12 to 18 inches long as needed, strip it about 3/4″, and wrap it around the exposed part of the harness plug wire.Solder the connection. Tape it up and reinstall the split loom covering.

At the other end of your new ground wire, add a crimp on eyelet. Attach the eyelet under a bolt that goes directly into the chassis. Be sure to clean the attaching point til shiny and apply OxGard to the contact surfaces.

I'm on it, thank you.