HELP from any techs?

[wheeler4life]

ok ok, yes i'm asking a question in my own line of work but hell, if i knew it all it wouldn't be any fun! here we go....just bought an 85 mustang 5.0HO (carb) on saturday. sunday after driving about 45 min it started to jerk a bit (about 10 sec) and finally the engine died. pulled over and it fired right back up. drove another 50 yards and same thing. when i went to start it the battery didn't have the juice to make it happen. everything else worked but it just didn't have enough to turn it over. i found the negative terminal loose on the battery so i tightened it a bit and a friend showed up after awhile and gave me a jump. fired right up and drove great. drove it plenty on sunday (never over 30 min though) without any incident. same exact thing happened tonight. i threw one of the batterys in my jeep in the stang just so that if it did happen again at least the battery was good but i'm pretty sure that isn't the root of the problem. i'll do a load test at work tomorrow to rule it out though. it seems like the waiting period (15min or so) of letting the car sit is letting something cool down enough to let it run again. at first i thought vapor lock but seems kinda weird on something all factory design. maybe the coil is going bad and after prolonged use it's heating up? intermittent problems are such a bastard.

help........anybody?

[Scoutsteer]

It sounds almost like coil expansion to me to. Unless you alt is dead and the battery got to low to support the electronic ignition and caused it to die, and by letting it sit the battery might have built up suffecient surface charge to allow it to work for a short period again

[wheeler4life]

coil expansion makes sense. i have seen it happen before. i'll know for sure tomorrow at work about whether the alt is working. i belive it is cause i've had an alt die plenty of times on a ford ignition system and usually higher rpms are affected first, lights go dim, etc.

KEEP THE IDEAS COMIN GUYS!!!!

[carnuck]

Originally posted by wheeler4life
ok ok, yes i'm asking a question in my own line of work but hell, if i knew it all it wouldn't be any fun! here we go....just bought an 85 mustang 5.0HO (carb) on saturday. sunday after driving about 45 min it started to jerk a bit (about 10 sec) and finally the engine died. pulled over and it fired right back up. drove another 50 yards and same thing. when i went to start it the battery didn't have the juice to make it happen. everything else worked but it just didn't have enough to turn it over. i found the negative terminal loose on the battery so i tightened it a bit and a friend showed up after awhile and gave me a jump. fired right up and drove great. drove it plenty on sunday (never over 30 min though) without any incident. same exact thing happened tonight. i threw one of the batterys in my jeep in the stang just so that if it did happen again at least the battery was good but i'm pretty sure that isn't the root of the problem. i'll do a load test at work tomorrow to rule it out though. it seems like the waiting period (15min or so) of letting the car sit is letting something cool down enough to let it run again. at first i thought vapor lock but seems kinda weird on something all factory design. maybe the coil is going bad and after prolonged use it's heating up? intermittent problems are such a bastard.

help........anybody?


That has the crappo module on the dist? They warm up and if no-one put the heat sink paste on there, it'll die, cool down, then go again. You probably fried the alt, but first try replacing both cables and make sure you have a battery to body ground. (alt won't charge right without it. The one to the motor has to pass power all the way back through the driveshaft to get lights, etc working without it) The nose bushing in the starter may be bad, which will cause the armature to touch the field winding when hot, but not cold (VERY common on direct drive starters and Ford and Jeep Motorcraft ones more than most!)

[Nobody]

I'm 99% percent sure it's the ignition module.

[Roger]

Originally posted by Nobody
I'm 99% percent sure it's the ignition module.

My 99% makes it 198%.

That year doesn't have the 'crappo' TFI module on the dizzy. They came with the FI years. It's still Duraspark. Change out the module. Pick up a couple of spares in the wrecking yard for a couple of bucks. If they plug in they are the right ones.

[T1H5 TA3]

Originally posted by Roger
My 99% makes it 198%.


well, my 99.9% makes it 297.9% sure its those stupid moduals...

best recomendation, un hook it and see how far you can throw it. have a berr and calm down, then plug a msd 6a in its place..

[wheeler4life]

well...after replacing the coil and ign module (yes w/new units) today it did it again on the way home probably after 15 min of driving. they were factory ones so it didn't hurt to replace them i guess. but now i've got a buck or two into it so it's time to get serious. i let it sit for no more than five minutes and it fired up after five or so rotations. drove the ten more minutes to home. alt checked out ok and the new battery solved the starting problem. it almost makes me lean toward a fuel problem. there's not much left to go wrong on the spark end of things. maybe fuel pump getting too hot? or possibly a partially clogged fuel filter? i checked the one at the carb and it was all good. now when i bought the car i filled it up and no problems arose until the tank was at about half. and now that i'm down below a quarter it's happening sooner than when it did the first time. i'm not positive off the top of my head but i think it has a frame rail filter. i'll check it tomorrow. probably wouldn't hurt to change it anyway.

i really appreciate the input guys. keep it coming! the car was an amazing deal at under a thousand bucks so i guess i can't complain too bad about some quircks.

[carnuck]

There is a screen in the tank and you may have crud bobbing around in there that is blocking it off (I just had to fix that in my '73 J4000)

[Kev]

maybe a pick-up coil in the dizzy i just did one in an escort today same prob. are you losing spark? when it wont start and have to let it cool. when you pull the dist cap what does the pick-up look like is it clean and normal looking?

[wheeler4life]

pickup coil 'looks' ok anyway. i didn't know they would generate heat and shut down if they were bad. could be though. i wish i knew if i was loosing spark. i can't get it to die in the shop where all my tools are. of course it's always in the morning on the way to work or on the way home. even then, by the time i got out and hooked anything up it would fire back up by then. it's not an instant engine stall. it will cut out a little then be ok for 50 ft then cut out and eventually just shut down. no bad sputtering or blowing of smoke. the one thing i just thought of though is i never noticed it smelling like fuel which i would think it would if i was loosing spark. maybe not though. would a plugged vent in my fuel tank create enough vacum in 15 min to stop fuel flow? i'll check it next time it dies. see if i open the gas cap and get some excessive suction.

[Roger]

Ok, the 99% it wasn't. :( First check for a rail mounted filter and check that. If you have a souce of compressed air remove the fitting at the carb and blow back through to the tank. If the pickup screen is clogged it might just clear it out. If it works ok after that you might also want to pull the tank and flush it out.

[Nobody]

Sorry about the bum steer. 99% of the time it is the ignition module. I still suspect something electrical..... possibly the pickup in the distributor

Divide and conquer - Next time it chokes, check for spark...if there is spark, give it a shot of starting fluid in the intake and see if it fires.

[EBSTEVE]

Check all the grounds, then I would do a fuel filter because they are cheap and it probably needs one anyway. I had problems from WA to CA in my Bronco, it was all fuel filters and that clogged the pressure regulator (before I went EFI)
check all the easy stuff like the rotor to make sure it's not cracked or something stupid, it's probably a $2 problem but they almost always cost $200 to fix.
And IF I would not have seen it I would have added another 99% to the above.

[carnuck]

hook a vacuum gauge to a tee in the fuel line before the fuel pump and if it climbs when you gun the motor or is off the zero mark when it stalls, you have a clog in your line to the tank someplace. (the fuel hoses can also turn into piccolos from the MTBE in the gas)

[carnuck]

To see if it's spark or not, I get one of those cheapie timing lights (the ones with no trigger) and hang it through the hood opening so I can drive and see the blinking. When the vehicle cuts out, I crank it and see if the light is still blinking. Pretty easy test.

[wheeler4life]

am i allowed to pull my hair out yet?!?!:sad: well, a couple of the guys at work suggested the pick-up coil and since it was cheap i went ahead. runs better but didn't solve the dying problem. when it died on the way home tonight i immediately jumped out and cracked the gas cap. no vacum so the vents working. i hit the accellerator pump and got a medium squirt the first time and half a squirt the second, then nothing. not knowing what the float bowl level is this really points me in the direction of a fuel pump. can't say i've ever seen one act like this but stranger things have happened. hopefully i'll get a chance and slap a pump in there and blow the line out at work. the damn things so low i can't get it on a jack, only on the hoist! inbetween cars today i had let it run for 45 min at about 1400rpm( go figure it wouldn't die then) and quick slapped it on the scope. i did notice it started to run rougher after about 15 min. everything on the electrical end checked out looked alright and didn't see any out of the ordinary patterns. the alt was running a tad on the weak side but definitely working. by the way, i haven't had it up in the air to check if it's got a frame rail filter but the one at the carb looks great.

don't worry about it not being the suggested parts:rolleyes: over the comp diagnosis is about as tough as it gets. it's just nice to know that people are willing to help. thanks again.

[Hip]

well it might have a fuel accumulator on the frame rail also. these things are famous for getting clogged. no way to clean them either just have to replace them. not certain thay come on carbed must but they are on the efi ones. mine was near the tank mounted to the framelike area and resembled a black plastic filter looking thing. has a sediment bowl like thing. two lines in and two lines out. hope that helps.

[wheeler4life]

well, thought i'd let everyone know i finally have a happy mustang now. turned out i had a mech. fuel pump that got weaker as it got warm and eventually would give out. never seen it before but oh well. kinda sucks cause i threw a bunch of parts at it but hey, at least i know all the stuff new. gotta keep the dialy driver happy ya know. now it's time to really dig into the jeep!

thanks for everything guys.

~nick