redwolf624 Posted July 16, 2013 Share Posted July 16, 2013 today i was at the scrapyard and i startin havin issues keepin my MJ running i finally left the yard and got bout 2 miles down the road at a red light, light turned green i tried to go but the MJ shut off, wouldn't crank over from there, pushed it off to the side of the road called a tow truck and magicly the truck starts, i'm thinkin it vacum locked or the coil is bad, any ideas what it could be? Redwolf Link to comment Share on other sites More sharing options...
87MJTIM Posted July 16, 2013 Share Posted July 16, 2013 Does it crank but not fire up? Try the CPS. My $0.02 Link to comment Share on other sites More sharing options...
redwolf624 Posted July 16, 2013 Author Share Posted July 16, 2013 it'll crank and start up now but earlier today it wouldn't, and what's the cps? Redwolf Link to comment Share on other sites More sharing options...
87MJTIM Posted July 16, 2013 Share Posted July 16, 2013 Crank Position Sensor. It mount on to the top of the trans bell housing. It scans the flywheel for the position of the engine crank. It tells the engine lots of important info, like when to send a spark to the plugs. I ve had to replace two through the years. Looks like http://www.ebay.com/itm/SMP-STANDARD-PC87T-Crankshaft-Position-Sensor-Distributor-Pick-Up-Assy-/271236282803?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1987%7CMake%3AJeep%7CModel%3ACherokee&hash=item3f26f139b3&vxp=mtr#ht_1136wt_930 Link to comment Share on other sites More sharing options...
Biotex Posted July 16, 2013 Share Posted July 16, 2013 what's the cps? Redwolf http://comancheclub.com/topic/12163-acronyms/ Link to comment Share on other sites More sharing options...
redwolf624 Posted July 16, 2013 Author Share Posted July 16, 2013 Crank Position Sensor. It mount on to the top of the trans bell housing. It scans the flywheel for the position of the engine crank. It tells the engine lots of important info, like when to send a spark to the plugs. I ve had to replace two through the years. Looks like http://www.ebay.com/itm/SMP-STANDARD-PC87T-Crankshaft-Position-Sensor-Distributor-Pick-Up-Assy-/271236282803?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1987%7CMake%3AJeep%7CModel%3ACherokee&hash=item3f26f139b3&vxp=mtr#ht_1136wt_930 ah ok, well i don't think they'll be the issue, i don't my MJ has that cause that sounds computer related and i don't have a computer, Redwolf Link to comment Share on other sites More sharing options...
redwolf624 Posted July 16, 2013 Author Share Posted July 16, 2013 what's the cps? Redwolf http://comancheclub.com/topic/12163-acronyms/ shorthand for everything wow thanks, Redwolf Link to comment Share on other sites More sharing options...
Eagle Posted July 17, 2013 Share Posted July 17, 2013 Crank Position Sensor. It mount on to the top of the trans bell housing. It scans the flywheel for the position of the engine crank. It tells the engine lots of important info, like when to send a spark to the plugs. I ve had to replace two through the years. Looks like http://www.ebay.com/itm/SMP-STANDARD-PC87T-Crankshaft-Position-Sensor-Distributor-Pick-Up-Assy-/271236282803?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1987%7CMake%3AJeep%7CModel%3ACherokee&hash=item3f26f139b3&vxp=mtr#ht_1136wt_930 ah ok, well i don't think they'll be the issue, i don't my MJ has that cause that sounds computer related and i don't have a computer, Redwolf You don't have a computer? What year MJ and what engine? Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted July 17, 2013 Share Posted July 17, 2013 '86 with the 2.8 V6 if it's the one in his signature. Link to comment Share on other sites More sharing options...
Eagle Posted July 17, 2013 Share Posted July 17, 2013 '86 with the 2.8 V6 if it's the one in his signature. Crap! I wish people wouldn't be so "designy" with their signatures. Whatever color his is, on my monitor it doesn't even show up unless you squint and look for it. I didn't know he HAD a signature until I saw your post. (Yeah, I know ... it's the forum default. That doesn't make it good, it just shows that whoever wrote the forum software doesn't know jack about how the human eye perceives color.) Whatever happened to basic black? Link to comment Share on other sites More sharing options...
ParadiseMJ Posted July 17, 2013 Share Posted July 17, 2013 Nevermind Link to comment Share on other sites More sharing options...
Biotex Posted July 17, 2013 Share Posted July 17, 2013 what's the cps? Redwolf http://comancheclub.com/topic/12163-acronyms/ shorthand for everything wow thanks, Redwolf No problem. You are welcome. First thing you need to do when you have a no start engine, is figure out if it is Air, Fuel, or Fire the engine is lacking. We can eliminate timing right off the bat because the engine does run (sometimes). So, start with the obvious stuff first. If you are starved for fuel, check fuel filter and fuel pump. If it is lack of fire, check coil and then ignition components. If you don't have points, then you have an electronic ignition which means there is a module somewhere. Module like coils, get hot and open electrically. Check for spark first: The easiest way to check for spark is with an induction timing light. You have 3 connections to make. pos. and neg. at the battery, then you clip onto any spark plug wire. Have someone crank the engine while pressing the trigger on the light, and see if it flashes. If it does, then fuel is the problem. Do this, and report back if you still need help. Link to comment Share on other sites More sharing options...
redwolf624 Posted July 17, 2013 Author Share Posted July 17, 2013 what's the cps? Redwolf http://comancheclub.com/topic/12163-acronyms/ shorthand for everything wow thanks, Redwolf No problem. You are welcome. First thing you need to do when you have a no start engine, is figure out if it is Air, Fuel, or Fire the engine is lacking. We can eliminate timing right off the bat because the engine does run (sometimes). So, start with the obvious stuff first. If you are starved for fuel, check fuel filter and fuel pump. If it is lack of fire, check coil and then ignition components. If you don't have points, then you have an electronic ignition which means there is a module somewhere. Module like coils, get hot and open electrically. Check for spark first: The easiest way to check for spark is with an induction timing light. You have 3 connections to make. pos. and neg. at the battery, then you clip onto any spark plug wire. Have someone crank the engine while pressing the trigger on the light, and see if it flashes. If it does, then fuel is the problem. Do this, and report back if you still need help. i know it's got a spark cause it wanted to start yesterday but i never could get enough power, it deffently can't be fuel cause i just installed a fuel pump (electric) and i just checked all that stuff the other day, lines, wire to the fuses everything, i'm thinkin it's either the coil on the carb or my truck can't run for a really long time and when it gets really hot it has issues to stay runnin or i need a new battery and alternator, or what i don't wanna believe it is, the engine had a vapor lock. Redwolf Link to comment Share on other sites More sharing options...
redwolf624 Posted July 21, 2013 Author Share Posted July 21, 2013 thought of somethin, my air filter is a light brown now, could all the dust kicked up by other trucks had killed my truck? just a thought, Redwolf Link to comment Share on other sites More sharing options...
Eagle Posted July 21, 2013 Share Posted July 21, 2013 i know it's got a spark cause it wanted to start yesterday but i never could get enough power, it deffently can't be fuel cause i just installed a fuel pump (electric) and i just checked all that stuff the other day, lines, wire to the fuses everything, i'm thinkin it's either the coil on the carb or my truck can't run for a really long time and when it gets really hot it has issues to stay runnin or i need a new battery and alternator, or what i don't wanna believe it is, the engine had a vapor lock. Redwolf It's an internal combustion engine. It only needs three things to start and run: Fuel, Air, and Spark. If it won't start, ONE of those three things is missing. Air is unlikely, since it's free and there's almost no way to NOT have air, unless you have a totally clogged air cleaner or multiple broken valves or lifters. So that leaves fuel and spark. You may have a new fuel pump, but is it pumping? Is the filter clogged? Is the fuel pressure regulator allowing it to build sufficient pressure for the injectors to inject? Do you know that the injectors are functioning? You may have enough spark to make it cough, but that may not be a strong enough spark to actually light off a cylinder full of fuel/air mix. One other possibility -- if the distributor has been worked on or monkeyed with, the timing may be off. Link to comment Share on other sites More sharing options...
redwolf624 Posted July 22, 2013 Author Share Posted July 22, 2013 well bad news folks, i now have a MJ that won't even make and effort to start, the battery is good and charged when i turn the key to on i get all my lights but when i go to start it i get a loud THUNK and all the lights are gone, i did have my starter sittin in the sun all day yesterday and today so could that have fried it? Redwolf Link to comment Share on other sites More sharing options...
cruiser54 Posted July 22, 2013 Share Posted July 22, 2013 Starters don't get sunburned. Link to comment Share on other sites More sharing options...
redwolf624 Posted July 22, 2013 Author Share Posted July 22, 2013 yeah i learned that when i took it to advance to have it tested, turns out the stud that one of the wires goes to on the cly somehow got backed out enough to not make the starter engage, i'm waitin till it cools off to install the starter and see what happens, i still have yet to find out why my MJ died multiple times a week ago, Redwolf Link to comment Share on other sites More sharing options...
redwolf624 Posted July 22, 2013 Author Share Posted July 22, 2013 well good news, i got the starter in, and the truck starts, makes a loud grindin noise on start up though but i think the cly was my dryin problem cause the coil is good, fuel system and as perfect as perfect gets, but what could be causin the grindin noise, could the starter be to tight or to loosely bolted up? Redwolf Link to comment Share on other sites More sharing options...
rocketwheels Posted July 24, 2013 Share Posted July 24, 2013 Yep, it is a GM unit. shims? Do our trucks with the v6 come with shims usually? I don't know, never had a Gm powered MJ. But I've had plenty old style GM's and they all have starter shims. Plus, your spark/ignition problems could be inside the dizzy if it is a typical GM unit. Whats that dealy called under the rotor in the diz? Plenty S-10's on the side of the road intermitantly back in the day due to it failing. I'm going from GM experiences, hope these apply to the v6 powered MJ Link to comment Share on other sites More sharing options...
redwolf624 Posted July 24, 2013 Author Share Posted July 24, 2013 my starter does have a shim and i did find out why my MJ wouldn't start after puttin the transmission back in, the distributor had been backed out a little so i could get to the top transmission bolt, but the MJ starts fine now but i have a grindin problem still and i know it's comin from the starter i just can't figure out what's wrong with it, weather it's too far in, bolted up too tight or too lose, i'm just waitin for a none rainy day (maybe this weekend) that i can play with the starter and bleed my clutch cly again since gravity bleedin doesn't work, Redwolf Link to comment Share on other sites More sharing options...
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