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  #1  
Old 07-02-2013, 10:14 PM
mgmann mgmann is offline
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88 GW dies when it gets hot

We’ve had some hot weather here in Montana lately and two days ago my 88 GW started stalling when hot. I can drive it 8 or 10 miles and it acts normally then all of a sudden it dies and won’t start again until it cools off. I tried putting a little fuel into the carburetor to see if maybe it wasn’t getting any gas and that makes no difference. After a few hours when it’s cooled off it fires right up.

Any thoughts? Ignition module?
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  #2  
Old 07-02-2013, 10:29 PM
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4x4Dad 4x4Dad is offline
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Ignition module? If you have a spare as most of us do, swap it out next time it stalls.
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88 GW, AMC 360 with Doug Thorley headers, Howell TBI, NP242, TF727, 3.31 gears and the tow package, Magnaflow muffler and cat, BJ's 4" springs + 2" blocks and 1" shackles, and 1" body lift, 32" BFG's, aluminum rad, K20 front brake calipers.
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  #3  
Old 07-03-2013, 12:05 AM
joe joe is offline
 
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If it's a stumble free like you turned the key off, likely the ign module. If it's a surging stumble as it shuts down maybe vapor lock?
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  #4  
Old 07-03-2013, 11:43 AM
mgmann mgmann is offline
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No Luck!

Installed my spare ignition module and even swapped coils. No luck.

Yesterday drove it about 10 miles before it died. Went back out to get it this morning and it fired right up and ran like a champ. Raced for home at break neck speed then let it idle until it died. Doesn't seem to have any spark.

If the problem were vapor lock wouldn't it fire if I put a little gas in the carb?

Any suggestions on where to go from here would be greately appreciated.
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  #5  
Old 07-03-2013, 11:49 AM
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aerocorey aerocorey is offline
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Location: Evening Shade, MO
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Cam sensor. It could be right on the edge of being bad. Electrical resistance goes up when temperature goes up, so it works when it's cold and doesn't when it's hot.

It's a big issue with early XJ crank sensors. Maybe you're having a similar issue?
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Current
87 GW "Big Bear"
76 J20 project "Ox"
90 GW parts rig "Velma"
77 J10 parts rig "NoMo" (as in "no more Jeeps, Corey!")
94 YJ "Coop"

Past
88 GW "Hercules" (had to sell in '08, curious who has it now)
83 Wag parts rig "Shaggy" (used to build Herc, then scrapped)
73 J4000 (had to sell due to PCS in '07)
75 Cherokee "Jerry Lee" (sold in '13 because I'm an idiot)
74 Cherokee "Dino" (used to build Jerry Lee, then scrapped)
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  #6  
Old 07-03-2013, 02:03 PM
FSJ Guy FSJ Guy is offline
 
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Quote:
Originally Posted by aerocorey
Cam sensor. It could be right on the edge of being bad. Electrical resistance goes up when temperature goes up, so it works when it's cold and doesn't when it's hot.

It's a big issue with early XJ crank sensors. Maybe you're having a similar issue?

No cam sensor in a stock 88 FSJ. It should have a V8 AMC 360. Very different from an XJ.

X2 on checking the ignition module. If that checks out OK (ie, it still doesn't start with a different module), try replacing the pickup module inside the distributor. You can replace it without removing the distributor.
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  #7  
Old 07-03-2013, 02:22 PM
aerocorey's Avatar
aerocorey aerocorey is offline
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Quote:
Originally Posted by FSJ Guy
...try replacing the pickup module inside the distributor. You can replace it without removing the distributor.

How is this not a cam sensor?

Quote:
Originally Posted by mgmann
Installed my spare ignition module and even swapped coils. No luck.

OP already tried a spare module. Call it a pickup module, a cam sensor, a hall effect sensor...whatever you want to call it, it just tells the computer where the cam is. I referenced the XJ crank sensor issue just as an anology to illustrate the nature of sensors (and also because I've burned 3 crank sensors on MJs over the years). mgmann, if you do some searching you can prolly find specs on the pickup module and check it for proper resistance.
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Corey

Current
87 GW "Big Bear"
76 J20 project "Ox"
90 GW parts rig "Velma"
77 J10 parts rig "NoMo" (as in "no more Jeeps, Corey!")
94 YJ "Coop"

Past
88 GW "Hercules" (had to sell in '08, curious who has it now)
83 Wag parts rig "Shaggy" (used to build Herc, then scrapped)
73 J4000 (had to sell due to PCS in '07)
75 Cherokee "Jerry Lee" (sold in '13 because I'm an idiot)
74 Cherokee "Dino" (used to build Jerry Lee, then scrapped)

Last edited by aerocorey : 07-03-2013 at 02:35 PM.
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  #8  
Old 07-03-2013, 07:00 PM
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serehill serehill is offline
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LMAO

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  #9  
Old 07-03-2013, 07:15 PM
mgmann mgmann is offline
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Join Date: Jun 12, 2007
Location: Helena Montana
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Removing trigger wheel?????

Got a new pickup coil at a pretty cheap price. The manual says to use a small gear puller to remove the trigger wheel. Nowhere in the town where I live can I find a small gear puller. Any other way to remove the wheel and if not who sells a small puller that will work?
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  #10  
Old 07-03-2013, 07:25 PM
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babywag babywag is offline
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I've always just used 2 flat screwdrivers.
Be mindful of the little roll pin have a magnet handy.
They come right off w/ a little pressure.
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  #11  
Old 07-03-2013, 08:20 PM
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4x4Dad 4x4Dad is offline
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Ditto on the flat screwdrivers. The two biggest you have that will fit under it, 180° apart. First time I did it, I lost the pin babywag mentioned. A section of coat hanger wire worked, but not recommended as a permanent solution.
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88 GW, AMC 360 with Doug Thorley headers, Howell TBI, NP242, TF727, 3.31 gears and the tow package, Magnaflow muffler and cat, BJ's 4" springs + 2" blocks and 1" shackles, and 1" body lift, 32" BFG's, aluminum rad, K20 front brake calipers.
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  #12  
Old 07-03-2013, 11:23 PM
FSJ Guy FSJ Guy is offline
 
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Location: Colorado
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Oops. Sorry. I missed that the OP tried replacing the module already.

Not trying to pick a fight on the internet, but I've never heard the distributor pickup called a cam sensor. <shrug>

Cam sensors are for those new fangled multiport FI engines. :-p
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1987 Grand Wagoneer, slightly longer than stock.

www.bigscaryjeep.com

Don't mess with me. I once killed a living hinge.
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  #13  
Old 07-04-2013, 09:54 AM
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aerocorey aerocorey is offline
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Eeh...my bad, I just read that again and I came off a Lil harsh. Didn't seem like that in my head when I typed it.

Cam sensors in more modern ignition systems with distributers sit in the same place as ours and do the same job. It's all semantics.

OP, how's it coming?
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Corey

Current
87 GW "Big Bear"
76 J20 project "Ox"
90 GW parts rig "Velma"
77 J10 parts rig "NoMo" (as in "no more Jeeps, Corey!")
94 YJ "Coop"

Past
88 GW "Hercules" (had to sell in '08, curious who has it now)
83 Wag parts rig "Shaggy" (used to build Herc, then scrapped)
73 J4000 (had to sell due to PCS in '07)
75 Cherokee "Jerry Lee" (sold in '13 because I'm an idiot)
74 Cherokee "Dino" (used to build Jerry Lee, then scrapped)
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  #14  
Old 07-04-2013, 10:16 AM
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FSJunkie FSJunkie is offline
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Cam sensors on the newer Jeep 2.5, 4.0, 5.2, 5.9, and probably a few others were inside the distributor, under the rotor, and read the on-off pules from a one-bladed reluctor ring to tell the ECM when to fire which spark plug and fuel injector.

FSJ's have a sensor in the same place on an 8-bladed reluctor ring to tell the (primitive) ECM when to fire which spark plug. It serves a very similar purpose.

The difference is the distributor on newer engines is locked into place, so the distributor position correlates directly to camshaft position, hence why the sensor in the distributor is called the camshaft position sensor. On our FSJ engines, the distributor can be rotated independently of the camshaft, so the distributor sensor has no correlation to camshaft position. It is merely a distributor position sensor, pickup coil, trigger coil, whatever you want to call it.
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  #15  
Old 07-04-2013, 01:10 PM
mgmann mgmann is offline
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Join Date: Jun 12, 2007
Location: Helena Montana
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Trigger wheel slot - which one or does it matter?

Well, couldn't get the trigger wheel off without removing the distributor. No biggie, have done it many times. Didn't turn the engine while it was out, so everything should have lined up perfect. Just can't seem to get it timed right. When I put the trigger wheel back on I noticed that it has two slots for the pin. They seem to be on exact opposite sides of the wheel, so I didn't think it mattered which one I used. I tried to use the one that was used originally, but not sure.

Please don't tell me it matters which slot is used to line up the wheel!

BTW - thanks for all the help. Notice your list of vehicles - first car I ever had was a 64 rambler. Not too impressive, but a station wagon with lots of room when the rear seat was folded down
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  #16  
Old 07-04-2013, 01:58 PM
Ristow Ristow is offline
 
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don't matter. put it together and run it. if you look at the slot,you can usually see scratch marks from the roll pin.
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  #17  
Old 07-04-2013, 03:01 PM
FSJ Guy FSJ Guy is offline
 
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Quote:
Originally Posted by aerocorey
Eeh...my bad, I just read that again and I came off a Lil harsh. Didn't seem like that in my head when I typed it.

No worries, Cory!

I would just try to retime the engine the old fashioned way by turning the engine to TDC and dropping in the distributor and lining it up.
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1987 Grand Wagoneer, slightly longer than stock.

www.bigscaryjeep.com

Don't mess with me. I once killed a living hinge.
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  #18  
Old 07-04-2013, 04:18 PM
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aerocorey aerocorey is offline
304 AMC
 
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Location: Evening Shade, MO
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Quote:
Originally Posted by FSJunkie
Cam sensors on the newer Jeep 2.5, 4.0, 5.2, 5.9, and probably a few others were inside the distributor, under the rotor, and read the on-off pules from a one-bladed reluctor ring to tell the ECM when to fire which spark plug and fuel injector.

FSJ's have a sensor in the same place on an 8-bladed reluctor ring to tell the (primitive) ECM when to fire which spark plug. It serves a very similar purpose.

The difference is the distributor on newer engines is locked into place, so the distributor position correlates directly to camshaft position, hence why the sensor in the distributor is called the camshaft position sensor. On our FSJ engines, the distributor can be rotated independently of the camshaft, so the distributor sensor has no correlation to camshaft position. It is merely a distributor position sensor, pickup coil, trigger coil, whatever you want to call it.

Sigh...really? You're gonna tell me that it's a completely different sensor from one engine to another based on whether or not the distributer body is capable of being rotated? Ok, dude, you got me. I have no idea what I'm talking about. You should probably talk to me like I'm stupid and pick apart the totally legit advice I gave to OP which was immediately followed by someone else giving the same advice.

I guess this is what IFSJA turned into while I was overseas for a few years. Y'all have a nice day.
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Corey

Current
87 GW "Big Bear"
76 J20 project "Ox"
90 GW parts rig "Velma"
77 J10 parts rig "NoMo" (as in "no more Jeeps, Corey!")
94 YJ "Coop"

Past
88 GW "Hercules" (had to sell in '08, curious who has it now)
83 Wag parts rig "Shaggy" (used to build Herc, then scrapped)
73 J4000 (had to sell due to PCS in '07)
75 Cherokee "Jerry Lee" (sold in '13 because I'm an idiot)
74 Cherokee "Dino" (used to build Jerry Lee, then scrapped)
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  #19  
Old 07-04-2013, 09:25 PM
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Carnuck Carnuck is offline
 
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Incorrect taxonomy aside, it sort of works the same way. With EFI cam sensor housings are generally stationary (with either a rotating signal generator or a hall effect sensor that reads a tone ring) and most are non-adjustable as they tell the computer excatly when the motor is at TDC and how far it is from TDC intake stroke to control fuel injection.

The Jeep ignition pickup is a hall effect sensor that sends pulses to a transistorized ignition box to control spark only and not differentiate between which cylinder. The ignition rotor controls what cylinder gets the spark at the cap. The pickup coil just tells the ignition when to make a pulse and it doesn't know or care which cylinder. In that way it's more like a crank position sensor.
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  #20  
Old 07-05-2013, 10:21 AM
mgmann mgmann is offline
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This is drving me nuts!

This is driving me crazy! I’ve replaced distributors many times, and never had this kind of problem. Set timing mark to TDC, rotor pointing to #1 wire, position of the distributor is identical to what it always was but all I can get is a back fire. I move the distributor a few degrees one way or the other and it still doesn’t work.

I’m on the verge of just going out and buying a new distributor but first I’ll see if anyone can give me some hint as to what might be going on.

Thanks again……..
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