so i have a 92 740. 175k miles on it. it was running really rough, kinda spitting, could of been misfiring idk the difference, and when i sat at a light or had it idling it would shake .got a diagnostic and they told me it was spark plugs and wires, and distributor cap and rotor.

SO i changed the spark plugs first and started her up and it ran perfectly fine, no rough idling. did a lap around my apartments and it dies a minute in, and now refuses to start. so we changed the spark plug wires along with the distributor cap. nothing. any suggestions?

also, i just put 2 12's in it and an am the day before it started messing up. idk if that has anything to do with it but figured id say it

 

Check your crank position sensor. It is located on the top of the bell housing where the engine and transmission mate. It has a fat black/gray cable that runs to a connector on the firewall. If the insulation is cracked or flaking off then it needs replacement. Wiggle the cable and try starting. Many times replacing the spark plug wires causes the cable to lose connection and the result is a no-start. If it starts up after wiggling it then it needs to be replaced.

 

just tried that, the wire itself looks just fine, no burns or flaking or anything. still wont start

 

"2 12s' ?

 

You can tell Pierce is old lol...... 12s are Subwoofers speakers!

I would double check every thing you did first before moving forward!!
It started and ran so its possible something came loose possibly.
Goldenblock 2million miles and still going

 

how many watts is the amplifier for those subs? presumably you had to run some heavy gauge power wiring from the battery to that amp? does the amp switch itself off when the stereo is turned off ?

(re subs, heck, my kid's party truck has a pair of dual 18" subs, each with a 2000W Crown amplifier, along with a pair of 15" 3-way mains that also each have a 2000W Crown amp... but ithat truck is just a bit bigger than a Volvo, and he runs the sound system off a onboard 5000W diesel generator)

 

yeah 2 subs. and yeah after the diagnostic i just changed the spark plugs and it started up ran perfect and now it wont turn all the way over. tried the crank shaft wire but it still looks great even the little clip in part looked good.
did a bit of googling issues and reading thru these forums with people with similar problems and tried a few things. fuel pump relay still looks good.

i was trying to find the radio suppression relay cause that was suggested but i literally cannot find it anywhere. im not very car savvy at all.

could this audio place maybe messed something up during installation?

also tried starting it and pulling a spark plug after i tried it and it smelled of fuel.

 

they run 1200 watts on a 2k watt amp. and im ganna go check if it turns off when the stereo is off right now

 

the amp turns off with the stereo

 

the radio suppression relay is a 740/940 only thing, no 240 has one.

luckily, car stereo watts aren't real watts, as there's no way your battery and alternator could keep up with an actual 1200 watt amplifier running anywhere near full tilt..

now, the car IS cranking over just fine, its just not starting? or is it not cranking either ?

re car stereo installers messing stuff up? I've seen some horrid butchery done to car electricals by stereo installers.

 

well this is a 740 thats why i was looking for it to check it out.

and yeah i turn the key the engine cranks it just wont catch and start up.

the shop i went to has been around since 89 and is well reviewed. im hoping it wasnt them

 

on a 740, the radio suppression relay is under the hood, its on the vehicle's left side on a turbo, and I think its on the right side on a non-turbo but i'm not sure.

 

Radio relay is close to coolant overflow bottle.
also make sure the wire going to starter solenoid didnt get disconnected!! Goodluck
Goldenblock

 

did you have the sparkplug wires connected in the proper order on the distribution cap?