Electrical problem-"92 5.0"

If I hold the tach at 3000RPM(or any RPM)and turn on Lights,fan motor,ect.the engine cuts out intermittently.A new MSD distributor and fuel pump have been installed.Any ideas on where to look? Thank-you!  

well.. that can be annoying..

do you own a digital volt meter.. they can be had for 7 bucks.. but a 20 to 25 buck version will work just great and last for decades..

please PRINT this.. so you can follow it..   write the results down and post them ...

this is just the FIRST test of several tests i have for you ...  


set the digital volt meter to 20 volts scale...

start the engine and turn on the headlights..

1.   test between the positive and the negative battery posts...   14.1 to 14.8 volts is expected...

2.  test between the Negative battery post and the engine block...   0.04 volts is expected..

3.  test between the Negative battery post and the body...               0.02 volts is expected..

4.  test between the Engine block and the body.. usually at the firewall... 0.02 volts is expected..

if you get 0.00 on test 2, 3, 4 .. reset meter to 2 volts DC scale. and redo the last 3 tests..


please POST Results by number above...  

why do this test..  electrons flow from negative to positive..   if you have a dirty or loose connection.. when you put a load on the circuit.. you may not have enough electrons to operate everything so the voltage drops and the engine dies..

do this test first..  i do it to every car...  

next which part number MSD distributer and ignition do you have.. there are several versions.. each wired slightly differently..

i have an almost 200 page MSD wiring manual..

be very careful with what i am going to ask you to do next..

i would like you to check where you hooked up the positive wire to the MSD..  with the MSD disconnected...

i would like you to stick a test light into that connector.. so you can see the test light from the drivers seat.. with the clip grounded..  i would like you to slowly work the key from the off position to the ON position to the crank position and back to the run position then to off..

i want you to verify that you get a constant power from when the key reaches the RUN  position .. through the crank position and back to the run position..   i have had a LOT of problems with the ford ignition switches with contacts inside the switch that burned away from normal wear and tear ..   this makes them easy to act up...   i have also had them melt and the contacts move around.. so they don't exert enough pressure to maintain a firm contact.. when you give it more load..  it might fail..  

next...

do you OWN a timing light...    we are NOT going to set the timing.. we are going to use it to see if the ignition is failing first causing the engine to stall..

hoot it over the COIL wire..  hook the leads to the battery ...    aim it at the windshield or so you can see the flashing light while you operate the engine...    start the engine and duplicate the failure mode...    when the engine stalls..   does the timing light STOP flashing as the engine cuts out but before it stops turning..   this indicates an Ignition failure or ignition power failure..    if it continues flashing while the engine stops turning..    then you will have to look at the fuel system..

post what you find.. i will be around..


these 3 tests might take you a WHOLE 15 or 20 minutes..  i can do them in under 10..

last week... i got not a lot of spark from a car... i unplugged the coil and  stuffed my test light into the positive side.. as i worked the key from off.. to run to crank and back to run.. i got a good bright light.. this was with the clip end grounded...


i moved the clip to the positive side..  then probed the negative side of the coil connector, again with the coil unplugged..

i found that the negative side..  just sort of flickered as the engine was cranking..    this showed me that the ignition module had failed.. i installed a new module. and the engine fired up instantly...

WHY do i want to warn you ...

MSD on the orange wire to the positive side of the coil..   may have 400 VOLTS on it..  this is why you disconnect the original power wire to the coil and move it to the red wire to feed the MSD remote box..

if you hook a digital volt meter to the primary side of any ignition system with an MSD ignition hooked up.. you have a serious chance of letting the smoke out of the tester...  people have blown up  really expensive tune up type scopes..  

AVATAR,Here are the first numbers.#1(14.5)#2(-0.04)#3(0.10)#4(0.16).i have a digital meter with a new battery.MSD distributor #8546,factory hook-up.Did put the timing light on ,when the motor faulted the light faulted.Thank-you for working with me on this...Janski  

cool.. thank you for doing the tests..

#3(0.10)     find the ground cables between the battery negative and the body.. probably at the radiator core support...  i would bet the small bolts that have a ring terminal with a wire are coming apart..  there are probably ground connections at both end of the radiator core support...  that need to be taken apart and cleaned.. or the wires lengthened and new crimp terminals installed.. warning. . they are probably 8 gauge wire..   so it will take special terminals.. other than the normal large side of yellow..




these are both 1/4 inch ring terminals..

this is what i normally use... the gold plated 8 gauge with 1/4" rings




#4(0.16)

this might be cured by the same repair to the ground connections on the core support...

you might want to search the engine for additional ground connections..


more to come...  

you can see the grounds to the bottom of the drivers side of the block...


you can also see the grounds to the radiator core support on both sides..

 

check the part numbers on the MSD.. as that number shows up for a big block dodge application...

i would like you to check the ignition switch.. but i will await the msd numbers.. as i don't think you wedged in a dodge  

oh... guys who put in stereo systems may have the proper crimp tools for the 8 gauge wire..   i usually use a coaxial cable crimper..  with some skill..

but thats me...  

AVATAR, sorry about the numbers (I am dyslexic) - the true numbers are 8456.  I'll be back at this tomorrow.  Thank you very much!!!  

ok... thats an MSD direct replacement for a ford TFI distributer...

do you get power on pin 3 while cranking????    and pin 4 when you turn the key on...    you can also check for power on the positive side of the coil connector...   with a test light..     from the time you turn the key to the run position.. still on in the crank position.. and then still power when you release the key from cranking to run..



you could have a bad ignition switch.. bad main relay.. bad fuel pump relay..  



as for being dyslexic..  well.. i have a quick test that you might want to do at home..   i am hoping that you have some kind of device .. that when turned off.. has a small single dot of light.. led..   place some masking tape over it to reduce it's brightness..   in a totally dark room..    several feet from it..  stare at it with one eye...   how many dots do you see??? one or multiples???   if you see multiples.. please visit the eye DR..    multiple dots where there should be only one.. is a cause of dyslexia.. as the eye cannot see what's in front of it..  but skips ahead ...  

you might find this link useful...

covers your 92 mustang..5.0

http://oldfuelinjection.com/?p=6


hope this helps..

it gives you the ability to check for power at the proper places...  

#3(0.10)corrected,ground cable to rad. support was the problem.Your link to oldfuelinjection.com is super.My wife put the circuit tester on me & I light right up!As all your info VERL HELPFUL...Weather to cold here,will be on break.I need to put down the wrenches&pick up the paint brush.When I saddle this Mustang & ride it again I let you know the details.THANK-YOU FOR ALL YOUR HELP!Janski...