• Notice for iPhone users: DO NOT use the image size reduction option when uploading photos to the forum. This causes portrait images to post as landscape. We have added a warning to the image insert pop-up as well.

spankrjs's Biloxi, MS '83 Scrambler

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Now for the not so fun part.

A few years back, the jeep would randomly stall out. This only occurred when the outside temperature was over 90 degrees, and I was using the AC. I "thought" it was a fuel vapor lock issue, installed a bunch of insulation on the fuel lines. At the time, the fuel pressure was reading high, at 60psi, so I changed the filter/regulator, never had another issue, thought I "fixed" this issue. Until Friday.

On Friday, the Jeep would kind of "buck"/"stutter"/hard split second "cut off". Just randomly. This got progressively worse as the day wore on. The Scrambler had been doing this in the past, very randomly, out of the blue, maybe 1% of the time. When it was random, I just ignored it. Now, it was regular. No "check engine light" (CEL).

On a whim, I swapped on a new Throttle Position Sensor (TPS). The way the Jeep was acting, it was like you were releasing the throttle, then hitting it again. I changed this sensor, the Jeep drove flawlessly for 3 hours Friday night, with the AC on. It was cooler at night, this might play a part.

On Saturday, outside temp around 105 degrees, idling in traffic, the Scrambler sputtered and stalled out completely. Dead in the water. Would not restart. No CEL. I pushed it off the side of the road, let it cool down, it would not restart. I went ahead and pushed in the schrader valve on the fuel rail, as this had "fixed" this issue before. No air came out, only clean fuel. Key primed the fuel pump three times, no restart. I let it sit 10 minutes, and it restarted, ran like crap. Stumbling, bumbling, could not give it any gas. It cleared up after about 30 seconds, and I was able to drive it home. It did OK on the way home. Again, no CEL.

Time for some research, the Mopar MPI instructions, plus some of my notes:

10.jpg

Some other reference material:

11.jpg

At this point, I am thinking fuel or spark. Checked the fuel pressure key prime and running, right at 54psi. I also was able to check the fuel pressure when it would stall out, right at 54psi every time.

From the Haynes manual:

12.jpg

My fuel set up mimics a 1997 and later 4.0 Cherokee. I use this combination fuel filter/pressure regulator:

14.jpg

From the Hesco/Mopar MPI instructions:

16.jpg

Hesco also mentions this other setup, with a separate regulator, as does the Haynes manual:

15.jpg

13.jpg

Using the Grand Cherokee filter/regulator, and the TanksInc internal fuel pump, I am dead on at 54psi. Not sure why Hesco says 50psi MAX, the filter they supply mimics a Cherokee that can have up to 54psi, like I have:

17.jpg

Long way around, I am 99% sure I do not have a fuel pressure/supply/vapor issue.

Once the Scrambler was home, I could let it cool off for 20 minutes, then restart it. It would start and run perfect for 5 minutes, then just completely die. It would studder real quick, then cut off. If you tried to restart the Jeep, no bueno. It would spit and back fire and if it did restart, it ran like the timing was way out of whack. Again, this whole time, no CEL. I pulled off the TPS with the engine running, as a test, and the CEL came on and gave me a TPS code. So, the CEL works, I am assuming the PCM is not totally dead.

So, all Saturday afternoon, I "data logged" what was going on with this Scrambler. AC off and on. I compared this to my Red Scrambler, which is running perfect. Sorry for the terrible hand writing:

18.jpg

Besides the AIS always being low on my Green Scrambler, nothing really popped out. The low AIS "could" mean I have a vacuum leak at idle, I checked, could not find one. I read on the "internet" that the AIS should read around 32, it reads 16 on my Red Scrambler which runs and idles perfectly. But, pretty sure the idle air control is not the issue.

The numbers on the green one jump around a bit, too, because I was swapping sensors (TPS/MAP/AIS) around to see if it would "fix" the issue. I keep new/spare sensors, so it did not cost anything. Regardless, changing those sensors did not work. Also, when you swap in new sensors, mainly the AIS, it takes the computer a bit to "learn/manipulate" them. So, reinstalled the original sensors, no bueno.

The only thing I noted, with the scan tool plugged in, right before the engine would choke down and die, the timing was jumping up to 24 degrees:

19.jpg

I only have a simple OBD1 scan tool, but I can read 28 operating data fields. This timing jump was the only thing that jumped out at me. Is this a clue, or a symptom??
 
  • Like
Reactions: SKT

sdsupilot

CJ-8 Member
Member
City
OKC
State
OK
If both EFI systems use the same computer, I would swap the computer to troubleshoot. I have a buddy that is (hopefully) in the last phase of troubleshooting a Howell EFI system on his rig. He installed the system and it wouldn't fire at all. Turned out to be the tach filter. He replaced that and it started but had weird issues that typically started after it was warm. He then chased his tail changing TPS as the voltage range was weird. Turns out the computer itself was bad causing all the crazy symptoms. I also have a bad computer that came with the S10/4.3. It will start and run great, but as the vehicle warms and goes into closed loop it starts running crappy and will eventually die.
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
So, I am thinking timing and or the ignition coil.

When an ignition coil goes bad, sometimes they only exhibit problems when they are HOT. On Sunday, I checked the coil, both COLD, and HOT. Checked out perfect.

So, fuel and spark are OK, no CEL. I am "thinking" timing. On the timing, two major players:

1.) The "cam position sensor" (pickup coil) inside the distributor
2.) The crank position sensor

The PCM has to know where the crank is (crank sensor) and where the cam is (cam sensor) to manipulate the timing (along with all the other sensors functioning correctly).

The strange thing is - the Scrambler starts up perfect/runs perfect COLD, it has to get HOT before failing. Electrical sensors can do this, makes it a PIA to trouble shoot. All the other sensors appear to be working fine (using the scan too) (MAP/IAC/TPS/Coolant/O2).

So, on an educated guess, I decided to check the crank position sensor. Three reasons:

1) The cam position sensor rarely goes bad (on a Jeep 4.0)
2) I had a spare Mopar/Hesco sensor in my garage
3) A fellow member from Michigan with a bronze Scrambler was recently telling me he always has these sensors fail

I performed the following test:


The link above is better then my scribble, but the results:

20.jpg

So, the currently installed sensor was not reading infinite between terminal B and C, the new one does.

Luckily, the Mopar/Hesco MPI kit places the crank sensor on the front of the engine. It uses a special harmonic balancer, instead of the flywheel on a stock 4.0. So, it is easy to get to.

Crank sensor, bolted on top of the aluminum plate that is bolted to the oil pan:

21.jpg

Notches in the harmonic balancer that the sensor reads:

22.jpg

Before pulling the sensor, I checked the "gap", it was still at .035 where I set it (can be .020 to .060):

23.jpg

Part number on the bad sensor, also note the mounting hole:

24.jpg

My "replacement sensor", note the locating hole, and part number:

25.jpg

The "old replacement" sensor I installed was superseded by the bad sensor I pulled off. The only concern is the mounting hole, slotted on the old one, single hole on the new one. Since my Hesco kit came with the non'slotted sensor, they slotted the aluminum mounting bracket to allow for adjustment. Anyway, both Mopar sensors, not super cheap Chinese junk.

Old vs new mounting holes:

27.jpg

The old sensor also came with this felt tab on the end, to make it easy to set the gap.

26.jpg

I checked the resistance on the new sensor, checked out fine. Installed it, Scrambler started right up. Test drove it a few hours yesterday, 105-110 degrees, no problems, no hiccups at all.

28.jpg

To further confirm my bad crank sensor theory, I placed the old sensor on top of the intake manifold while I drove around. With the sensor "baked" from the under hood heat, the resistance was way out of whack.

I am 85% confident I finally fixed this issue :fingerscrossed:
 
Last edited:

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
If both EFI systems use the same computer, I would swap the computer to troubleshoot. I have a buddy that is (hopefully) in the last phase of troubleshooting a Howell EFI system on his rig. He installed the system and it wouldn't fire at all. Turned out to be the tach filter. He replaced that and it started but had weird issues that typically started after it was warm. He then chased his tail changing TPS as the voltage range was weird. Turns out the computer itself was bad causing all the crazy symptoms. I also have a bad computer that came with the S10/4.3. It will start and run great, but as the vehicle warms and goes into closed loop it starts running crappy and will eventually die.

Unfortunately, they use different computers. They are both 60pin OBD1 style Mopar computers, one difference:

Red Scrambler uses a return line on the fuel rail, operates at lower fuel pressure, different injectors
Green Scrambler uses the single line fuel rail, higher fuel pressure, different injectors

Not 100% sure, BUT I would think, the PCM might be different between the two systems, maybe not :shrug:

My LJ had a similar problem along time ago: CEL came on, transmission went into limp mode. Only code was TPS. Installed a new TPS, cleared the code. Ran fine, then went to crap. CEL on again. Checked codes, EVERY engine code was showing. Took it to the dealer, they plugged it into their computer. Best they could tell, the transmission side of the PCM was no longer talking to the engine side of the PCM. New PCM fixed the issue, and about $800 out of my wallet :eek:
 

Randyzzz

Blown Budget
BENEFACTOR
Gold Member
Lifetime Member
SOA Member
City
Redmond
State
OR
Glad to see you might have this fixed! I could tell you story after story about mysterious heat related sensor issues. But the one that your issue reminded me of was a Dodge Stratus that died for no reason and then restarted within a minute. Turns out a bad knock sensor was somehow putting the PCM to sleep. Took a week of test drives and a copilot (data logger) to find out.
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Finished up some more work on this one just in time for Hurricane Ida.

The brake pedal has been getting stiff, not easy to push down, the power assist seems to be lacking compared to the new booster on my red Scrambler. Also, the scan tool was showing the IAC at zero steps at idle, engine must be pulling air from somewhere? The manifold, throttle body, and the other usual suspects for vacuum leaks are clear, so I decided to swap in a new booster.

You can change the booster while leaving the master cylinder hooked up, which is what I chose to do:

20210824_072041.jpg

I could not disconnect the boosters arm from the peg on the booster bracket with the bracket still bolted to the firewall. I had to take out the booster and bracket as an assembly. All of my brake linkage stuff is super tight, no wear or play.

New firewall grommet, painted the new booster black, painted the original seal retainer plate, and resprayed the booster bracket assembly:

20210827_160147.jpg

I have been using this part, from Summit, to replace damaged/missing power brake firewall seals:

20210827_160202_HDR.jpg

Loosely assembled on the tailgate. You have to install the new boot over the brake rod, then get the seal in the fire wall correctly while bolting the entire assembly in place. Kind of a PIA, but seals the hole perfect/tight.

20210827_161527.jpg

I am pretty sure the booster I removed was the original from the factory. Found this piece of tie wire at the firewall, I assume there was some type of paper tag on this at some point in time?

20210827_161830.jpg

And all back in place:

20210827_181253.jpg

Should have painted the "new" master cylinder when I installed it a few years back, oh well. The new booster works great, so a worth while little project.

I will have to plug back in the scan tool and see if the IAC is behaving different with the new booster in place.
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
The AC belt has been quiet for a year. Well, it started squealing the other day when I would turn the AC on. I always thought the belts the kit came with were kind of iffy. Well, good thing I bought two new belts the other day.

This is the belt that spins the AC compressor:

20210827_182909.jpg

20210827_182918.jpg

20210827_182928.jpg

20210827_182952.jpg

20210827_183005.jpg

20210827_183015.jpg

The belt looks like it dry rotted? All the pulleys are smooth and spin free. All pulleys aligned. Nothing on the engine rubs the belt. I am hoping this belt was just old? No damage to the smooth side of the belt, where the "tensioner" and my added pulley ride. I do not have this belt over tightened, so hopefully just a belt that was on the shelf for a long time??
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
The other belt that came with the AC kit, it spins the alternator off of the AC compressor pulley:

20210827_183043.jpg

20210827_183040.jpg

20210827_183129_HDR.jpg

This belt appears to be dry rotting/failing from old age, too? My NAPA PS belt has been on this engine longer than these belts and is still fine, so hopefully just two old crappy belts.

All the black stuff is rubber from the belt. This is the "tensioner" arm for the AC belt:

20210827_183503.jpg

I installed two new belts from NAPA, I will monitor them for early failure. So far, with two new belts, no squeaks or squeals!!!
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Since I was messing with belts, I decided to adjust the "tensioner" pulley. The belt rides to the inside of the pulley:

20210827_184540.jpg

20210827_184730.jpg

I removed the pulley from the arm, and installed a thinner spacer to pull the pulley closer to the arm/more in line with the center of the AC clutch pulley and water pump pulley:

20210827_185002.jpg

I still have .026" clearance between the face of the arm and the back of the pulley, so should be OK:

20210827_185318.jpg

Belt is now more or less perfectly centered on this pulley:

20210827_190757.jpg

Picture of the tensioner pulley bearing, future reference:

20210827_185328.jpg

So, the engine runs super again, no more stalling. Brakes have plenty of power assist, and no more squealing belts!!

I will probably swap on the new rear bumper end caps and call it quits for a few days. Time to hunker down for Hurricane Ida.

That's it for now!!!
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
I installed the new cast aluminum bumper end caps yesterday.

I had no idea my OEM plastic end caps were in such bad shape until I removed them!!! They still looked perfect when they were in place. There goes my early retirement fund!!!

Driver side upper mounting stud spun/cracked the plastic when I was removing the nut. Had to pinch the stud through the plastic with vice grips. It came off intact, then fell off while washing it.

20210828_164341_HDR.jpg20210828_164348_HDR.jpg

The upper mounting stud on the passenger side fell off when washing it. I was using the faucet and a tooth brush, not scrubbing hard.

20210828_164448.jpg

The studs could be epoxied back in place and the repairs would be invisible once they were reinstalled. But, the bigger issue, the plastic is extremely brittle/cracking everywhere.

20210828_164404.jpg

All in all, extremely disappointed that my "thought were in perfect shape bumper end caps" were actually just an illusion.

20210828_164458.jpg

I kept them for now. They could be "repaired", maybe lay some mat material down on the inside and lay a thin layer of epoxy over that to reinforce the entire piece.

I am glad I removed and replaced them. They were probably one extended high speed drive from flying to pieces!!!

The @Kim Dawson replacement cast aluminum end caps installed. They look great and should last for years to come.

20210828_164305.jpg

20210828_164320_HDR.jpg
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Lesson learned from the last storm, this time I took the top off the Harbor Freight canopy, and no Jeep parked inside!!


20210828_120708.jpg

Red Scrambler and Green Scrambler in the garage, Gladiator parked in front of garage doors, hopefully safe!!!

20210828_164634.jpg

20210828_164607.jpg

Hopefully we make it through Hurricane Ida OK.

I have two more projects in hand to install on the green Scrambler.

That's it for now!!!
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Me and the Jeeps and everything else important survived the hurricane, no problems :thumbsup:

The yard is a disaster, so no Jeep work for awhile :(

BUT, I'm not complaining about yard work at all, could be a lot worse.
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
I was going to wait until I "finished" this "little project", but it snow balled, as usual.

Finished cleaning up Hurricane Ida debris Friday night, started working on this new "project".


I am NOT taking credit for this idea, I stole it from a gentleman I met at a PA Jeep show earlier this year, I wish I could remember his name!!! Anyway, he had a beautifully restored '85/'86 CJ-7. When he had the hood up, I thought, "oh, stock Carter carb". Upon closer inspection, I noticed he had the Mopar MPI on his 258, using the stock air cleaner assembly!!!

This will kill two birds with one stone:

1) Enable me to use a regular off the shelf filter, no more exposed K&N
2) I could utilize the OEM CJ "cold air intake snorkel", quit sucking in hot under hood air

It also looks sweet, IMO.

On his Jeep, relatively simple:

1) Adapter coupling to tie 4.2 air cleaner to 4.0 throttle body
2) IIRC, he had to make an adapter plate to slide the valve cover portion forward/back (not sure, haven't got that far yet)

The air cleaner to throttle body adapter:

20210501_145203.jpg

Close up shot of his CJ-7:

20210501_135830.jpg

Relatively simple, great idea IMO.

What my current set up looks like, I hate it:

1.jpg

A TJ air box swap might be simpler, but it is crowded on my PS due to the AC stuff. I thought about a YJ set up, but it would be butch. So, I am stealing this man's idea!!!!!!!!!!

For me, however, two major issues:

1) I need to clean up my original air cleaner assembly
2) I have the wrong grill on my Jeep (1976 grill, more on this later)

Number 1, easy enough. What I am starting with, OEM PB air cleaner assembly:

20210904_095119.jpg

Not terrible, but everything else under the hood is new, so I can't just throw this old stuff on.

Still had some of the "good stuff":

20210904_095123.jpg

Love me some MEK, took everything off except for some light rust:

20210904_110955.jpg

Sand paper, Dremel, hours later, getting somewhere:

20210904_130942.jpg

The most important part, and hardest to clean: the inner portion of the "lid". Filtered air flows through this portion, straight into the intake. You do not want rust/loose paint. Also, the hardest part to clean!!!!

20210904_130949.jpg

20210904_131002_HDR.jpg

I Dremel'd/sanded it the best I could, then dumped some converter inside the lid:

20210904_131534.jpg
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
I removed/salvage the original "lid seal", I can reuse it, will probably find a replacement.
:

20210904_131555.jpg

I hated to do it, but I removed both "trap doors":

20210905_111720.jpg

This air cleaner assembly was 100% functional. I saved the old vacuum motors, and flaps, for spares. I did not want to necessarily do this, but I did not want to spend $200+ on some rusty eBay special. I would rather modify what I already have, and keep the removed parts as spares for other Jeep CJ's. You could leave the TAC system functional, I decided to delete it, no need for it with MPI, and will make for a cleaner install. I will have lots of holes to fill, more on this later.

After probably 10 hours of prep, ready for primer/paint:

20210905_111746_HDR.jpg

I cleaned the hard to reach portions of the lid as well as humanly possible, I am satisfied with it:

20210905_111755.jpg

20210905_111803_HDR.jpg

I left this plastic bracket inside the snorkel, it seemed risky to try and remove it:

20210905_111818_HDR.jpg

I shot a few thin mist coats of self etching primer inside the hard to reach spots first:

20210905_113219_HDR.jpg


20210905_113227.jpg


I am leaving it primered, will be hard to paint. This is more than AMC did LOL. The primer should keep it from flash rusting. So, I have a clean path for engine air to flow through.
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Primed the remainder with self etching primer, then shot some VHT Gloss Black on it, came out pretty good IMO, way better than what I started with:

20210905_124303.jpg

20210905_165459_HDR.jpg

20210905_165534.jpg

Going to let this stuff cure for a couple of days, so finished with the "easy" part, for now.
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Now, the hard part, which was unique, to me.

The original grill that came on this 1983 Scrambler was damaged by the original owner when they pulled it out the barn with a tractor, by hooking a chain to the grill. Yeah, that makes sense.

20210906_102408.jpg

20210906_102417.jpg

This grill has two "holes" that I need, that the currently installed replacement grill does not:

20210906_102433.jpg

I need this hole for the intake snorkel hose:

20210906_102437.jpg

I need this hole for the front light wiring harness to pass through:

20210906_102445.jpg

When the second owner replaced the damaged grill, he grabbed one out of a junk yard. Unfortunately for me, it was a 1976 grill:

20210906_102504.jpg

20210906_102508.jpg

Now, everyone will say "all grills 1976-1986 are the same". They are wrong. 1976 model year grills are unique. I found a few pictures online of "all original 1976 CJ's", their grills match mine. Unfortunately, in this case, being "unique" was a huge PIA.

My 1976 grill does NOT have the "square air hole" on the driver side (or passenger side), it looks like this:

20210906_102530.jpg

In the above picture, you cans see the front light wiring harness passing through the hole. There is no hole on the side of the grill large enough for this harness to pass through:

20210906_102559.jpg
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
I did briefly think about NOT modifying my grill, maybe saving it for someone trying to 100% restore a 1976 model. But, again, I did not want to buy a "eBay special" rusty grill that I would than have to repaint. So, again, better to use what I have, just like my air cleaner housing.

I did NOT want to pull my grill off, did not want to deal with the AC stuff. So, I did this in place, which worked out well.

Stripping down the front driver side to get to the areas I need to work:

20210906_102560.jpg

The Scrambler bed makes a great storage container:

20210906_113403.jpg

Left some stuff in place (wiring harness(s), evap can, ws squirter bottle):

20210906_113417.jpg

Started with the "wire harness" hole, on the side of the grill. This is the "virgin" 1976 grill:



20210906_113436.jpg

Clamped the original grill to the front bumper:

20210906_114538.jpg

Differences are clear:

20210906_114552.jpg

Laid down tape, easier to mark:

20210906_121218.jpg

Skipping around, but the PS of the '83 grill has this large cutout, where AC hoses usually go through:

20210906_121416.jpg

Of course, the '76 grill does not have this, which made installing the AC a PIA:

20210906_121423.jpg

I was able to route the AC lines through the small/existing hole, but it was tight!!!!!!!!!!!

20210906_121428.jpg
 

spankrjs

Scrambler Junkie
Lifetime Member
SOA Member
City
Biloxi
State
MS
Comparing the two grills, besides the missing large hole for the wiring harness to pass through, pretty much identical on this side:

20210906_130717.jpg

20210906_130727.jpg

The exisiting "smaller" hole on the '76 grill fell into where the larger hole needed to be cut, so I was not able to use a hole saw. Instead, I drilled out the perimeter of the hole with a 1/16" bit:

20210906_131336.jpg

Then increased bit sizes a few times:

20210906_132804.jpg

20210906_133749.jpg

Dremel cut off wheel time:

20210906_134420.jpg

I now have an ugly hole:

20210906_134802.jpg


20210906_134813.jpg

About 30 minutes later, various Dremel attachments/files/sand paper, a beautifully smooth hole that mimics the original:

20210906_143020.jpg

20210906_143029.jpg

When I "drilled" this out, I drilled on the lines. So, this hole is around 5mm larger, in both directions. No big deal, and it will be that much easier to pass the wiring harness through!!!!! For the next hole, I did NOT drill/cut on the line, went inside, to more accurately match the OEM dimensions.
 
Top