Comanche_Fanatic Posted January 12, 2011 Share Posted January 12, 2011 ive got a stubborn MJ, the batterys hooked up and the lights come on. but when I turn the key it disconnects. if it stays connected and cranks, it won't start up. it starts when I put some gas in the throttle body but only for a short while. I'm confused, ideas anyone? Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 12, 2011 Author Share Posted January 12, 2011 still waiting for ideas, i got class at 6 -.- Link to comment Share on other sites More sharing options...
mnkyboy Posted January 12, 2011 Share Posted January 12, 2011 I would start by cleaning up the battery terminals so it cranks properly. Link to comment Share on other sites More sharing options...
rnobles Posted January 12, 2011 Share Posted January 12, 2011 Can you hear your fuel pump when you turn the key to the "ON" position? Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 12, 2011 Author Share Posted January 12, 2011 thats a problem, I'm hearing impaired. if you can describe very specifically what it sounds like i might be able to notice it. Â terminals seem plenty clean. theres 3-4 extra wires(thin) hooked up to the positive terminal though Link to comment Share on other sites More sharing options...
dasbulliwagen Posted January 12, 2011 Share Posted January 12, 2011 Sounds like a fuel issue, Take a hammer and pound on the bottom of the gas tank several times, then try to start the truck, if it starts, you need a new fuel pump, if it don't, you may still need a fuel pump, but youll need to make sure the pump is getting power first, and a good ground. If I remember right, the ground is behind the left rear taillight. I'm sure someone will correct me if I'm wrong. But try the tank hitting fisrt, hit it hard, but not hard enough to dent the tank. Link to comment Share on other sites More sharing options...
freakjeep93 Posted January 12, 2011 Share Posted January 12, 2011 fuel pump- someting like a whining sound coming from around you rear tires. Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 12, 2011 Author Share Posted January 12, 2011 ok ill try that after class tonight. i think it is the fuel pump as well, since it drove 300 miles from Fl just to get home. it gave in the next morning tho. Link to comment Share on other sites More sharing options...
brdhntr Posted January 12, 2011 Share Posted January 12, 2011 i'd say fuel pump. i think the ground is behind the right rear taillight as well. the fuel pump will hum or wine. the best way to listen for a fuel pump, inho, is to lay under the tank and have somneone turn the key. it should hum a little when the key is turned on and when it first starts to crank, you should be able to hear it. once you're cranking the engine it gets hard to hear it over the starter. Â you can try hitting the bottom of the tank as stated before. sometimes rocking the vehicle around a bit then hitting the bottom of the tank will work to help give it a little incentive to start. Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 13, 2011 Author Share Posted January 13, 2011 alright ill try that, its dark and cold outside, plus the batts in my YJ. so ima wait til first light. i hope it is the fuel pump Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 13, 2011 Author Share Posted January 13, 2011 i went under the car and listened to the pump, and also put my finger on it slightly to feel if it came on. grandma turned the key and I heard/felt nothing from the pump. now ive got questions about it... Â will the pump turn on if the ground is bad? will the pump turn on if the gas tank is bone dry empty? the p.o. got the wrong size pump, but it did work for 300 miles. does this have any effect? whats the best solution to fix this? Link to comment Share on other sites More sharing options...
jimoshel Posted January 13, 2011 Share Posted January 13, 2011 Everything sounds like fuel pump. If grandma's hearing is better than yours have her stand at rear wheel opening and listen. It will sound somewhat like a blender. If you have a multi meter set on amps 0-15 range. remove the wire from the fuel pump ballast resistor. Insert the meter between the resistor and wire. Turn on key. If pump is working it will read 6-10 amps. Remove gas line from TBI. Turn on key. Gas should spray out from line. Catch it in a can. Don't let it spray on the engine. Pump will not work with bad ground. Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 13, 2011 Author Share Posted January 13, 2011 Everything sounds like fuel pump. If grandma's hearing is better than yours have her stand at rear wheel opening and listen. It will sound somewhat like a blender. If you have a multi meter set on amps 0-15 range. remove the wire from the fuel pump ballast resistor. Insert the meter between the resistor and wire. Turn on key. If pump is working it will read 6-10 amps. Remove gas line from TBI. Turn on key. Gas should spray out from line. Catch it in a can. Don't let it spray on the engine. Pump will not work with bad ground. Â i hear better than her ofc, she hate the rock music i play as well lol. and no i do not have a multimeter nor the money for it this month. where is gas line on the tbi again? anyways I'm sure it won't spray gas cause pump isnt even coming on. and how do i fix ground if its bad? Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 13, 2011 Author Share Posted January 13, 2011 i think i may have found the problem, ive got no idea how to operate a voltmeter. but when i tried i spotted this. its the wiring that goes to the fuel pump, laying right over the exhaust. what u guys think? and where is the fuse for the fuel pump  Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 13, 2011 Author Share Posted January 13, 2011 taped up the wiring, same problem still. where is the fuse for the fuel pump? Link to comment Share on other sites More sharing options...
Dirteatr717 Posted January 13, 2011 Share Posted January 13, 2011 Ran out into the cold to check the owners manual in the dash :fs1: ... It doesn't say which but I would check number 6 in the top right corner. It gets a 10 amp fuse or number3 which is dead center that gets a 20 amp... If not I'll check tomorrow when it's light out and a bit warmer -Nick Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 13, 2011 Author Share Posted January 13, 2011 Ran out into the cold to check the owners manual in the dash :fs1: ... It doesn't say which but I would check number 6 in the top right corner. It gets a 10 amp fuse or number3 which is dead center that gets a 20 amp... If not I'll check tomorrow when it's light out and a bit warmer-Nick  right, but WHERE is the fuses? hood? under the steering? etc etc Link to comment Share on other sites More sharing options...
brdhntr Posted January 14, 2011 Share Posted January 14, 2011 it should be under your dash under the steering wheel. depending on the year it probably has no cover and is easy to see. Â no the fuel pump will not work with a bad ground. Â the wrong fuel pump could work for a short time but die due many reasons like it's pumpin too slow or too fast. there would be a difference in performance but if you're new to the truck you may not notice. such a situation could cause a pump to burn out. if it's the wrong size pump, there may be a modification to the wiring harness near the pump to make it work. Â you can check the actual performance of the pump by checking the fuel output at the tbi. this will not tell you if the pump isn't working for sure though. if the filter is plugged, there may be no or little fuel. take the line off at the fuel filter (then you leak fuel into a bucket, not in the engine compartment) then turn the key. no fuel-bad pump. fuel-good pump, plugged filter. Â if oyu need a pump, check out rockauto.com or autohausaz.com. i get parts from both of them alot and have gotten a great deal from each on different fuel pumps. just an fyi if you do need to replace it. Â keep us informed with you problem. Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 14, 2011 Author Share Posted January 14, 2011 it should be under your dash under the steering wheel. depending on the year it probably has no cover and is easy to see. Â no the fuel pump will not work with a bad ground. Â the wrong fuel pump could work for a short time but die due many reasons like it's pumpin too slow or too fast. there would be a difference in performance but if you're new to the truck you may not notice. such a situation could cause a pump to burn out. if it's the wrong size pump, there may be a modification to the wiring harness near the pump to make it work. Â you can check the actual performance of the pump by checking the fuel output at the tbi. this will not tell you if the pump isn't working for sure though. if the filter is plugged, there may be no or little fuel. take the line off at the fuel filter (then you leak fuel into a bucket, not in the engine compartment) then turn the key. no fuel-bad pump. fuel-good pump, plugged filter. Â if oyu need a pump, check out rockauto.com or autohausaz.com. i get parts from both of them alot and have gotten a great deal from each on different fuel pumps. just an fyi if you do need to replace it. Â keep us informed with you problem. Â ah yeah i checked there already. i didnt see one for fuel pump. will check again tomorrow. how do i check and repair bad ground? Â theres no fuel coming out of the tbi, the fuel filters new, lines are good. will add fuel in the morning to see if it works. we did make the pump fit on the sending unit, we use a tie tho. Link to comment Share on other sites More sharing options...
jimoshel Posted January 14, 2011 Share Posted January 14, 2011 There is no fuse for the 2.5 fuel pump. You might try swapping the fuel pump relay with the one next to it. They're the same. See what happens. A volt meter would be a great help troubleshooting this. Don't have or can't afford one, get a test light. Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 14, 2011 Author Share Posted January 14, 2011 i knew there wasnt a fuse. and alright ill do that as well. i borrowed my stepdads volt meter but got no idea how to set it, am i supposed to turn it to DCV 2? Link to comment Share on other sites More sharing options...
jimoshel Posted January 14, 2011 Share Posted January 14, 2011 If you want to tick your stepdad off by burning out his meter. There should be a 15V DC range. Set it there or whatever range it has that is more than 13V. Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 14, 2011 Author Share Posted January 14, 2011 If you want to tick your stepdad off by burning out his meter. There should be a 15V DC range. Set it there or whatever range it has that is more than 13V. Â give me one second, ima post a pic Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted January 14, 2011 Author Share Posted January 14, 2011 here's what I'm using, now which setting Link to comment Share on other sites More sharing options...
jimoshel Posted January 14, 2011 Share Posted January 14, 2011 Turn the the knob counter clockwise to the 20V position. Make suer the black lead is in the com hole and the red lead is in the Volt hole. Link to comment Share on other sites More sharing options...
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