it drove to the crash i bypassed the impact switch still no spark

[feellnfroggy]

Power to the coil, but nothing out of the coil.....have you thought about replacing the coil?

 

[Shran]

do what sfwjesse did with his Inertia switch (it shuts off spark incase of an accident).

The inertia switch does not have anything to do with spark, just fuel. It shuts the fuel pumps off in an impact so in case a fuel line is cut, little to no fuel will be pumped out.

my truck started right up after installing a dist moduel. it had to go away at impact the truck was hit really hard in the pass door so it works thanks

BUT the other truck i put a engine in ? I drove it for a month then it wouldnt start one day . well i repaced its moduel also and yes it got spark back the moduel was the spark issue . but theirs no power at the bump switch conection ? i put a hot wire jumper to it and i got fuel pressure but it does not start or try to start .question is -- where does it get power from ? And does that power source also afect injectors ? Is their a fuesable link i missed ? i found a few of the starter solinoid and they all tested good.
again thanks for any ideas

I don't know where to tell you to start... you just need to eliminate things one by one. If you have spark, adequate fuel pressure past the injectors, compression, and your timing is right then theoretically it should run. Your problem could be in any number of places. Diagnosing wrecked cars is especially hard and you really just have to start tracing wires and follow the process of elimination.

 

[AllanD]

The "impact switch" has NOTHING to do wth "spark".

If impacted sufficiently to trip, it turns off the fuel, which is whay it's called
a fuel cutoff switch.

It is spark signal from the ignition module to the computer that tells the computer to turn on the fuel pump relay...

AD

 

[NITRISGTO]

if their is no feed of 12volt power to the impact switch

their is no feed of 12volt power TO the impact switch on this truck now . where does it come from the wire is dead ? because that power - source -may also feed something else that does have a afect on the injector pulse or computer performance . ..where will i find a complete wiring diagram on one page that has part names at junctions ford

 

[Shran]

Check and make sure your fuel pump relays are working.

 

[kimcrwbr1]

Did you put plenty of heat sinc grease on the TFI before you installed it. If not pull it and do that or it will fail again. By the way you were correct the inertia switch impact switch only turns off the fuel pumps in an accident the fuel will not just keep pumping out of the tank it has nothing to do with ignition. I am old school too you need to slow down your thoughts and focus on one at a time. When I get going I forget to punctuate also and even confuse myself when I proof read a post. Still working on that, go through alot of the qustions you have can be answered in the tech library, and probably alot you haven`t asked yet.

 

[NITRISGTO]

good advice thanks

actualy i did put dilectric grease on it i think thats a heat sink grease i used on gm moduels. thanks for the tips , any idea where the fuel pump relays are ? im thinking on the pass inner fender but how to tell what does what is the question. focus ? LOL i think i been in overdrive since i was 2 mayby 3 .
and i am focused on just the one trucks issue right now . that is no power to the bump switch and fuel pump relay sounds like a great idea to look for . now if i can get some one to tell me how many relays and where ? but i will go to the tech library and look . it would be a lot easier than pulling wires out of looms to trace them from the bump to the relays ? relay ? thanks again for all the help out their

 

[kimcrwbr1]

I believe ther are two relays next to each other on the passenger side wheelwell close to the battery one is for the EEC-IV and the other is for the fuel pumps. one is white and the other is black not sure which is which. Once you find the relay on the connector put a jumper wire between the two big terminals and the fuel pumps should run. check for power to the yellow wire and the orange/ltblu goes to the pumps check it for ground thru the pumps. As far as the ignition coil you should have power to both terminals a little less on the neg side thru the coil. Once you get the pumps working and the coil tests good I am guessing it will start. The easy way to test the coil is to put a plug in the coil wire to the dizzy and set it on ground turn the key on and touch a jumper wire from the neg side of the coil to ground every time you touch it the plug should fire a bright blue spark. If that all checks out the next thing is the pick up coil in the dizzy a little harder to test and not subject to damage from a collision. Here is the link for troubleshooting the igition it is godd reading for someone new to TFI ignitions read it all the way thru and plan your attack. http://www.therangerstation.com/tech_library/TFI_Diagnostic.html

 

[NITRISGTO]

GREAT tech imfo thanks

THANKS great tips and the tech stuff looks like what i needed to make this last problem go away . hopefully before the tabs run out on the truck

OK UP to date

Today the wheeler quit same problems as the last truck all of a sudden died .I had no fuel pressure when i added power to the impact switch i got fuel pressure .But it did not even try to start even though i had spark and fuel pressure ---(((same problem different truck ))------------so i believe the fuel pressure relay supplys power to the impact relay and ALSO kills power somehow to the injector pulses. no fuel pump or injectors opening even when i cheated by adding 12 volts to the impact switch direct . But when i replaced the faulty fuel pump relay it started right up all three trucks run like a champ thanks for all the pointers