Ford computer question

[junkyardjeff]

A friend has a 84 small LTD with a 3.8 V6 with throttle body EFI,I can jump the diagnostic connector and get the fuel pumps to kick on but the injectors will not fire up so I am thinking the computer has fried or lost its source of power. Checked the fuse box and no ECM fuse and no manuals for this car so where to look next,when the key is on no pumps or injectors but has ignition as it runs off starting fluid.

[rooster]

Check for cam and crank signals to puter (input's) without those injectors won'work.

When you turn key to " on" do you get the service engine soon light?

[junkyardjeff]

This one does not have a CEL,I think it was a couple years later when they go them,years ago I had a 84 crown vic and it had no CEL.

[kb426]

If that's the same as the v8, there is a vacuum port on the bottom of the control box on the left inner fender. If you can get it to run and hook up a mityvac or similar, it has a sequence that will do diagnostics. With your description, that probably won't work.
I found this. I haven't watched it but it could be helpful.

[wayne petty]

i have manuals ..

you can have a copy if you look carefully at this site.. there is a link to a ZIP file there..

http://oldfuelinjection.packrad.net/

or just visit the individual sections..

a few quick test light type tests... these work on any EEC4, Or EEC5 and OBD2 ford..  well at least most of them..

push probe of test light into the COIL Positive connector cavity.. you can leave the connector hooked up..   ground the test clip..  slowly turn the ignition key to the RUN position.. the light should come on.. crank the engine.. return to the RUN position.. the light should still be on.. and it should NOT have gone out.. or flickered.  this tests the ignition switch..  so many have failed.. .. this is dirt simple..

next..  on your CFI model..  probe the power wire to the injectors..  turn the key on.. the power will come on for either 2 seconds and come back on while cranking or usually STAY on with the key..

this tests the EFI/EECIV MAIN RELAY OUTPUT..

and depending on the year.. this next test varies..

i find the inertia switch.. i back probe the connector with a test light.. while its plugged in.  grounding the test light clip  turn the key on and you should get 2 seconds of power there.. and fuel pump spinning noise..   cranking the engine should also get you a constant test light.   this tests the positive side of the circuit..  one actually needs to examine the various wiring diagrams for the exact year model..  i will look up yours in a little while.  as sometimes ford installed the inertia switch to break the ground side of the fuel pump circuit..  guess what. that is almost as good.. unplug the inertia switch connector..  use a digital volt meter with at least a 10 AMP DC setting and jump that with the test leads into the disconnected pigtail..  see if you are pulling more than about 6.5 amps.  you should not be..

if you also.. set your volt meter to 20 amps DC scale.. with the inertia switch plugged in..  back probe both terminals.. and have somebody crank or start the engine.. you should have over 0.00  but less than 0.04 volts ..  if you have more than 0.06 volts.. replace the inertia switch..  its a ball or roller bearing across two contact bars and they do fail ..  inertia switches are always closed.. except when something hits them hard enough to make them go TILT like a pin ball game..

later models 88 thru 92 have had serious issues with power supplied to the fuel pump relay contacts..  the wire from the starter relay /fusible link has become partially disconnected somewhere .. only supplying the fuel pump relay contacts with about 8 volts instead of 12 to 14..  not enough to power the pump properly..  this is the contacts. not the coil windings.

next test... SPARK from the coil to the cap.. unplug the wire to the middle of the cap..  you should get a 1/2" bright blue snappy spark..  if you only get a dim orange spark.. you have an issue..

next. check for spark from more than one spark plug wire. almost as hot a spark ..

[junkyardjeff]

I will do those tests the next time I am at the car,I do know the ignition works as it will run on starting fluid. When turning the key to run the fuel pump will not kick in,I could only get the fuel pumps to kick on by grounding at the diagnostic connector but when i tried to start nothing coming from the injectors. I tried finding the inertia switch but could not find it.

[wayne petty]

i have the diagram .. i have been marking it up to help you..

don't worry about the inertia switch..  if you can get the pumps to run.. its working .  

note on this diagram.. that the ignition switch is shown in TWO locations. its the same IGN1 wires feeding the COIL positive and the TFI and also turning on the EECIV main relay at the extreme lower right corner.




and since it will run on starting fluid..  you are going to need to test the TFI module first.. make sure its sending out the proper signal to the computer..

http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

this will take you at least 20 minutes..

the TFI module and its wiring can fail..  do exactly this.. no spark timing to the ECM..

more than likely you have a bad ECM..   since you turn the key on and ground the fuel pump test connector.. you have mostly proven the EFI main relay works..

do you know what a bad solder joint looks like on a computer board.. ?


this is a toyota circuit board.. 83/84.. so same age.. can you see the thermally damaged solder joints. i put a B next to one..  almost everything below the B has been resoldered by me..  that took me about 3 hours to resolder the 500 or 600 connections on that board.

[wayne petty]

take a new EFI main relay with you .. just in case..  

az wells  Part Number: 19841
Alternate Part Number: MR59

the brown relay socket is the EECIV main relay..

the GREEN relay socket is the FUEL pump relay..

there are differences between the relays...

the EECIV MAIN RELAY does not have a diode in the diagram on the side..

the EECIV FUEL PUMP RELAY DOES HAVE A DIODE in the diagram on the side.

a diode on the side diagram looks like this.. -|>-  

why one and not the other.

the IGNITION switch turns on the main relay..

the fuel pump relay coils is powered up by the main relay.. but the computer pulls the coil to ground to make the complete circuit for the coil.. this needs diode protection to protect the computer circuit from reverse EMF as the magnetic field collapses in the winding..  without the diode.. you can have a 100 volt AC spike that will blow the control circuit device in the ECM..


oh. and if you don't have the proper ford sized fuel injection tester.. this 20 buck unit from HF i am almost sure has the right side thread.

http://www.harborfreight.com/fuel-injection-pump-tester-92699.html

this is the actron version..
http://www.autozone.com/autozone/accessories/Actron-Fuel-pressure-tester-kit/_/N-25eb?itemIdentifier=84174_0_0_
Actron/Fuel pressure tester kit
Part Number: CP7818
the test port uses the same size thread as tire valve stems.. but the valve core is way deep in the recess so you cannot just use a tire gauge..  gm except for TBI motors use the 1/4" sae flair with a valve core like R12 systems.

one last thing.. try to run a KOEO test..  make sure the computer is alive..

its in the firewall  on that model.. you will need to unbolt the engine side of the bulk head connector to get at it as i recall.. be sure to take a 1/4 inch universal joint and sockets and 1/4" extensions.. so you don't spend an hour turning it a fraction of a turn at a time.

[junkyardjeff]

Been trying to find another computer to see if it will run and its either gone of the car has a carb,did find the lincoln version but the windshield was broken out and water got down to the computer so I am not going to try it. Since it looks like it has the same wiring as a 5.0 I did find a 84 crown vic with a throttle body EFI 5.o and was wondering if that computer will work,I still need to check the module on the distributor and do have a good used one to try off a good distributor.

[wayne petty]

that is a hard one to find..

E4VF-JA, GA, HA, PA, R

do you feel like opening the computer case and examining the circuit board and photographing it..

i actually have a reman computer catalog that i can cross reference which will work.. its in one of the 18 boxes next to me in a stack full of manuals.

you can always.. if you don't have to smog it.. bolt on a holley 2300 or a motorcraft 2100 or 2150 2 barrel and some kind of stand alone distributor.. you might get by with a module swap.. just to try it..

there is no centrifical or vacuum advance built in to that distributor..

you will need to reduce the fuel pressure by changing the pump or putting in a bypass style of fuel pressure regulator.  all depends on what you have around..

[junkyardjeff]

I will be pulling the computer soon and can open it up,it does not have to be smogged and have been thinking about converting to a carb since I know where two are that have carbs. That car is like the trucks that have two pumps and the intake pump I think only puts out 5 psi so it could be wired up seperately and used without a regulator,I should be able to find switched 12 volts somewhere and wire up a duraspark ignition.

[wayne petty]

computer calibrations that should work.   i have had a JA on my work bench for resoldering before..
E4VF-JA, GA, HA, PA, R



78-4203 Application: Without California emission
Notes: O.E.M. #E4VF-GA

~~~~~~~~~~

78-4211 Application: Without California emission
Notes: O.E.M. #E4VF-MA.

~~~~~~~~~~~

78-4240 Application: Without California emission
Notes: O.E.M. #E4VF-HA

~~~~~~~~~~~~

78-4377 Application: With California emission
Notes: O.E.M. #E4VF-TA

~~~~~~~~~~~~

78-4319 Application: With California emission
Notes: O.E.M. #E4VF-JA.

these fit 84 and 85 various ford full size  5.0 CFI..  ford CV, lincoln town car and mercury grand marquis


edit.. you might want to swap in a 85 86 camaro fuel pump with a carb.. should be about the right size.

the CFI fuel pump has an amazing rating of 123PSI max... wow..

http://www.autozone.com/autozone/parts/Airtex-Fuel-Pump/1985-Chevrolet-Camaro/_/N-ijj0sZ8vcz2?itemIdentifier=362335_917336_4921_

1985 Chevrolet Camaro 5.0L 4BL HP 8cyl
Part Number: E3903

Maximum Free Flow Rate (gph):    35
Maximum Pressure Range (psi):    5
Minimum Free Flow Rate (gph):    20
Minimum Pressure Range (psi):    3
Outlet Attachment:    Hose
Outlet Count:    1
Outlet Size:    3/8


if you look at the wiring diagram above..  it will be really easy to rewire the existing fuel pump relay to come on with key by only needing to ground ONE wire..   you may need to splice in a switched ignition wire..

you could even convert to a 3 terminal gm oil pressure switch so the fuel pump shuts off with the lack of oil pressure..  bypass circuit driven perhaps by the starter solenoid I terminal.. so it comes on while cranking.

[junkyardjeff]

Put a junkyard computer in it yesterday and it fired right up but only ran about 20 minutes and doing the same thing again.

[wayne petty]

well.. could be the computer...

could be the other components..

would you like me to start the diagnostic again..

when changing the computer did you find the pair of ground wires sticking out of the side of the harness close to the computer connector. they will have ring terminals on them.. were you able to wire brush them and get them clean and tightly installed on a proper stud or bolt that had also been cleaned..  so the computer gets its electrons from the negative side...


i am taking you have a timing light... so you can clamp it over the ignition coil to distributor cap wire and rubber band the trigger in the on position.. so you can see what shuts off first.. if the light stops flashing before the engine stops turning.. then its an ignition problem...

pulling the jumper out of the harness next to the distributor removes the computer control.. so it if runs or creates spark from the coil with the plug removed. then its not a TFI issue.. its a computer or other and there is a link above to the ranger station for TFI testing.


do you have a digital volt meter with at least a 10 amp DC setting..  you can find the inertia switch and if you can get the engine started.. with the meter set at 20 VOLTS DC.. backprobe the connector for the inertia switch.. you should have a reading very close to 0.00..  

move one of the probes to the body.. you should have over 12 volts.. post what you get... if you are not getting close to 12 volts..  we need to look at the green colored fuel pump relay or its power source connection for the contacts.. ..

engine off.. unplug the inertia switch.. you will need to create some quick connects to hook into the front face of the inertia switch pigtail.. switch the meter over to 10Amps DC and move the wires on the meter face..  the red one goes in a different connection on almost every meter.. . you can now hook up to the connects you have installed. or perhaps you can back probe the connector.. get somebody to start the engine or just the prime connector to ground to make the fuel pump run... measure the  amp draw of the fuel pump in this way..

[junkyardjeff]

Just got this car back tonight and going to see if I can fix it before converting to a carb,my friend had someone work on it but they gave up so its now in my driveway.  The battery was dead so I put one on my extra batteries in it and drove it home and it ran great all the way back so that got me thinking could there have been something wrong with the battery that was in it causing the computer to go nuts.