russ_alabama

First, where exactly is the EEC on a '86 F150 302 EFI truck? I've heard in the cab, and its not under the kick panel (just checked last night)... saw on Bronco forum that year model Bronco had it behind the little storage tray on the driver's side... think that's where it is?


Truck came to us 5yrs ago with 18kmi from an estate sale with lots of fuel issues. Original owner just carried a boat 3mi to the river and back since buying the truck at retirement. Fuel issues scared off the rest of the auction guys. Tank selector reservoir and fuel pump relay were greatest issues then. Truck's used for a pasture farm truck mostly.


6kmi and 5yrs later, I get back from trailering a mower to another location and turn it off. Try to crank it later and it never hits a lick. I think to try the inertia switch. Fires up immediately. Went thru the morning path next morning and hit a large hole, and engine dies. Try the inertia switch, and nothing... turns over but not a lick hit... but, noticed the connector was a hair warm (was checked within 10sec of the truck going dead). Did a bypass small piece of wire on the connector to take out the inertia switch, and nothing.


Knew that several things could be bypassed by putting a fused 12V into the side of the connector that went to the tanks (went thru this 5yrs ago -- and it cranked back then, leading me to the fuel pump relay). I had a fused wire that I used for the atv sprayer in the back of the truck. Did this and heard the fuel system running, tank pump, high pressure pump, and fuel rail (and could hear the pressure regulator ticking, releasing the pressure buildup). Truck just turned over fast when trying then, and not a lick hit, same as before. I got my cousin to drag me out (with a nice Ford '89 model 4wd 300 six 5spd, if that helps ).


So, I ordered a OBD1 reader, thinking I'll use it in the long run, and while waiting, I used a trouble light on the OBD1 connector (followed the klricks site online)... "a jumper wire between the single pin connector and pin 2 of the 6 pin connector" and "Test light connects between pin 4 and positive terminal of the battery"... makes sense, only no pulses at all.


Threw my back out very badly that night, got the reader in and was able to stand enough to hook up and same deal, no codes. Starting hunting the EEC in the cab and back couldn't stand it. Am about to go back in. Have a spare EEC relay on hand to try and klricks' troubleshooting guide.


Noticed (from klricks site and attached schematic off the web) that there's that yellow fuse link wire going to "hot at all times"... I've read that its along the starter on routing... and sometimes fails... as do connections to power with it (up at the solenoid, I think I read -- where suggested to clean those connections)... so, I'm assuming that the ignition switch enables the coil of the EEC relay and if the yellow fusible link wire is 12V all the way up at the EEC relay like it ought to be, that'd be carried to the red wire to power the most importantly the EEC, the EGR solenoid, and second most importantly the hot side of all the injectors on the rail.


If I see all that switch like it ought to, I'll assume EEC issues? Seems odd to fail all of a sudden (and I'll try reseating it too), but old electronic ignition modules used to die all of a sudden like that.


Assuming my bad back will let me lay in the floor board this week after work (and mosquitos ain't kicking up this week), I'm looking to try that next. May pick up one of those little spark-in-the-wire detectors on the way home tonight also (handy to have on hand and I've lost track of my last one a few decades ago).... and I've got an old o'scope I could put on an injector also.

So... behind the little compartment on the EEC location?

Any ideas (I don't mind critisizm on my reasoning or paths either, and suggestions to try)...


Thanks,
Russ...

biggdaddyp

Engine controller is mounted under the dash just a little to the right of the accelerator as I recall. Your engine is cranking over so that's good next I would check for spark and fuel. You already know the injectors need to be powered by the EEC relay so check that and then use you scope on the ground side of the injectors to check to see if the processor is driving them. If all that is good I would check for fuel pressure not just listening for the pump to run. Hope this helps.

russ_alabama

Thanks! I'd found the Engine Controller, and like you say it's squeezed in up and toward the dash front from the accelerator. EEC relay had power from the yellow wire, so the fuse link wire is good. And the relay appeared to be switching on power to the engine controller and on down to the fuel pump relay.

My knee jerk reaction, with no code activity is to believe the controller is bad. I remember in a thread that someone said there could be grounding connector corrosion for the ground wire off the EEC, though. Might check for that too.

But as you say, it's not the much more to do to find my rail pressure gauge (harbor freight model) and put on the rail. And check voltage at the high pressure pump. That high pressure pump had been replaced by the previous owner six years ago, but you never know. If there's pressue there and voltage at the injectors but the ground side ain't switching (as you say, scoping there), then I'd want to point at the controller some more.

I only get an hour every day or two to check another thing, between farm stuff, work, and commuting an hour and a half to work. My backs in perfect shape again though, so I'm eager this weekend to get more clues.

biggdaddyp

If it turns out that you have fuel pressure and voltage to the injectors but the ECU is not triggering the ground side of the injectors don't forget about the ignition module. The ECU has to have an RPM signal to know when to fire the injectors so it all could be traced back to an ignition problem.

Chris_1

iTrader: (1)

Reading through all this, I don't see where you checked for spark.
Find a spare spark plug, plug one of your spark plug wires on to it and use a booster cable to ground it. Then crank and watch for spark.
To test for an issue with the fuel system, spray starting fluid directly into the throttle body - a 3 second burst - then crank it.
If it fires and dies, the problem is in the fuel system (glad to hear you have a pressure gauge). You need 30 to 45 psi.
If it won't fire with starting fluid, the problem is likely ignition related.

russ_alabama

Thanks for that heads up on the ignition module... Thats at the distributor, or in it?

russ_alabama

Will do on the plug... Got a set of plugs in the glove box. Good immediate path on the starter fluid deal... Got a can in the 544 international tool box (it loves the stuff below 50F). I have a gauge from when we were doing the first round of issues when my late Dad got the truck... 30-45lb at the point of attempting to crank should be on the rail, then (as opposed to when it's already running).

Thanks much for the info.

Chris_1

iTrader: (1)

Key on engine off you want to see something in the low to mid 40's psi (42?). That should drop when the engine is started - at idle - then climb back up to max pressure as you open the throttle and drop back down when the throttle closes (fuel pressure regulator).

russ_alabama

Thanks... That helps know what to look for.

russ_alabama

Had a few minutes after feeding and before going to work, so I did the plug with a booster cable to battery ground. Had spark. Ironically, my starter fluid can went to drooling immediately and I only got a seconds worth in the intake port. Did kick and try to crank immediately and then ran out of fumes. So, this is good... Likely fuel instead of spark. Will check rail pressure and the ground switching on the injectors this weekend.

Good deal... A little further along. Thanks.