So i have a 92 f150 with the inline six 4.9, it has a snow plow on it and mainly only use it for plowing or maybe some occasional wood hauling. Hadn't really used it all summer maybe started it here and there to move it around well a few weeks ago i went to move it and it would crank and crank and then start and run really rough and then die, would do this over and over again, if i stayed on the throttle it would stay run but would run terrible. I thought it would maybe the IAC valve so i swapped it off an old truck with the same engine and it seem to run ok after that, i ran it up to the garage and put the charger on it, the next day it did the same thing, couldn't get it to stay running on its own and with the throttle down it ran terrible. I then tried swapping the TPS sensor and Map sensor and no change, eventually after trying several things over and over again it proceeded to get worse and eventually it wouldn't run at all, just crank and crank and then i noticed the fuel pump was constantly running with just the key turned forward and not in the start position. After doing some research i found that the EEC/ECM goes bad causing a spark issue and causes the fuel pump to run constant like that with the engine off. So i pulled the EEC off and took the cover off and sure enough the capacitors were blacken at the connections and broken, so i thought great i'll get a new one and put it in and should solve the issue, well i put a new one in and the fuel pump would then cycle normally, but it still won't start, it'll crank and sometimes halfway fire but still wont' start. I'm getting very frustrated as i've already pulled the codes and nothing except an EGR fault which it has had since i got it. I completely stumped as to why something would happen so sudden and i find a problem and fix it and it still won't run. anyone have experience with the early 90's f150's?
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1992 f150 4.9 cranks but won't start etc.
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Black_Thunder
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I also tried the Ignition module from another truck as well and nothing changed.
You need to diagnose it or have it diagnosed.
fuel lines, fuel filter...rule them out first. since the vehicle sits for long periods make sure nothing has made a home in the air filters or exhaust. Rule out plug wires and make sure your connections are good etc. Make sure choke not sticking. lots of little things could cause what you are experiencing just from sitting for long periods.
darnedest things. I just gave up on fixing a 99 yukon that ran one night and wouldn't fire the next. it had fuel, compression, and even spark. recent plugs, wires, cap/rotor, fuel filter. pump ran, fuel sprayed from the test port. we knew the coil was old so we installed a new coil and new crank sensor. no joy. had it towed. it was the cap and rotor.
I'd looked at both, and they showed wear but nothing off.
Yet the dealer invoice showed new cap and rotor and it ran fine after that.
I've worked on cars for well over 30 years. I've never seen a cap and rotor go from 100% to 0% overnight without obvious physical markings.
I'd looked at both, and they showed wear but nothing off.
Yet the dealer invoice showed new cap and rotor and it ran fine after that.
I've worked on cars for well over 30 years. I've never seen a cap and rotor go from 100% to 0% overnight without obvious physical markings.
Originally Posted By: meep
darnedest things. I just gave up on fixing a 99 yukon that ran one night and wouldn't fire the next. it had fuel, compression, and even spark. recent plugs, wires, cap/rotor, fuel filter. pump ran, fuel sprayed from the test port. we knew the coil was old so we installed a new coil and new crank sensor. no joy. had it towed. it was the cap and rotor.
I'd looked at both, and they showed wear but nothing off.
Yet the dealer invoice showed new cap and rotor and it ran fine after that.
I've worked on cars for well over 30 years. I've never seen a cap and rotor go from 100% to 0% overnight without obvious physical markings.
I had a Mustang 2.3 turbo back in the 80's which had no spark thanks to the rotor. I found nothing physically wrong with it. Must have been an internal carbon track.
darnedest things. I just gave up on fixing a 99 yukon that ran one night and wouldn't fire the next. it had fuel, compression, and even spark. recent plugs, wires, cap/rotor, fuel filter. pump ran, fuel sprayed from the test port. we knew the coil was old so we installed a new coil and new crank sensor. no joy. had it towed. it was the cap and rotor.
I'd looked at both, and they showed wear but nothing off.
Yet the dealer invoice showed new cap and rotor and it ran fine after that.
I've worked on cars for well over 30 years. I've never seen a cap and rotor go from 100% to 0% overnight without obvious physical markings.
I had a Mustang 2.3 turbo back in the 80's which had no spark thanks to the rotor. I found nothing physically wrong with it. Must have been an internal carbon track.
Yeah you need to have it diagnosed -- NOT!!!
My '93 did same, I repl the leaking capacitors in the computer and it ran fine(I repaired electronics almost 40 years)...
If you haven't checked the plugs then do so as they are possibly fouled from over fueling...
Also I've seen injectors stick from setting up for long periods(if gas isn't rancid, probably not this)...
Third the fuel pressure regulator could be leaking causing a flooding condition(see if there is gas in it's vac line)...
And fourth if the MAP sensor vacuum line is split, loose etc it'll be so rich it won't run...
None of these conditions will give a static code but render engine not runnable... Luckily most of this is easy to check and not expensive(unless you are paying for diagnostics)...
If none of this fixes it, run a compression test to be sure it doesn't have valves hanging open, foul gas can gum the stems till they won't fully close...
My '93 did same, I repl the leaking capacitors in the computer and it ran fine(I repaired electronics almost 40 years)...
If you haven't checked the plugs then do so as they are possibly fouled from over fueling...
Also I've seen injectors stick from setting up for long periods(if gas isn't rancid, probably not this)...
Third the fuel pressure regulator could be leaking causing a flooding condition(see if there is gas in it's vac line)...
And fourth if the MAP sensor vacuum line is split, loose etc it'll be so rich it won't run...
None of these conditions will give a static code but render engine not runnable... Luckily most of this is easy to check and not expensive(unless you are paying for diagnostics)...
If none of this fixes it, run a compression test to be sure it doesn't have valves hanging open, foul gas can gum the stems till they won't fully close...
Check fuel pressure at rail. Check air filter to make sure a squirrel didn't build a big nest in the housing or snorkel. Check spark at plugs. Remove plugs and inspect. Does the engine sound normal when cranking?
Vacuum leak? Degraded PCV hose?
If you have an MT-2500 w/eev iV connectors(they are dirt cheap on ebay) I believe you could monitor data streams and see fuel trim. Yes, EEC IV had some of this. I know I could see alot on my 91 tbird.
Ethanol gas can turn to [censored] too.
If you have an MT-2500 w/eev iV connectors(they are dirt cheap on ebay) I believe you could monitor data streams and see fuel trim. Yes, EEC IV had some of this. I know I could see alot on my 91 tbird.
Ethanol gas can turn to [censored] too.
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Black_Thunder
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thanks for the tips/replies
I've already checked the FPR for leaks as well as pulled the air filter out and checked the box for a next etc.
i guess next on the list is to pull the plugs even though they aren't very old, same as the wires and the cap/rotor.
and then check the fuel pressure.
I just don't understand how the EEC was bad (it was definitely bad) and then have another issue at the same time when one day it ran fine and then not the next.
I've already checked the FPR for leaks as well as pulled the air filter out and checked the box for a next etc.
i guess next on the list is to pull the plugs even though they aren't very old, same as the wires and the cap/rotor.
and then check the fuel pressure.
I just don't understand how the EEC was bad (it was definitely bad) and then have another issue at the same time when one day it ran fine and then not the next.
Does the truck you are swapping parts with still run?
Black_Thunder
Thread starter
yes i verified that the TPS is still good along with the map sensor.
now today i did a little more research and found that there is a ground for the EEC on the chassis above the headlight, i check those and the connections did look a little corroded so i replaced the terminals and still no change, but today now i noticed the fuel pump is running all the time again with the key in the on position just like it did before with the bad eec. so i pulled the eec back out and compared it to one from a different truck that i tried before. the old eec from this truck i had to give for a core but it was the same inside and out same circuitry etc, the reman that i got the casing looks different but the plug was the same, i was able to pop the back plug off where you can put in a aftermarket chip and i noticed the circuitry on the inside looks completely different, the layout and the amount of capacitors is different, i took it back the parts store thinking maybe its the wrong one like it was labeled wrong etc, the guy behind the counter didn't really know what to tell me so i will go back there tomorrow and talk to the store manager about it and maybe get a different reman. so i guess right now i'm at a standstill.
now today i did a little more research and found that there is a ground for the EEC on the chassis above the headlight, i check those and the connections did look a little corroded so i replaced the terminals and still no change, but today now i noticed the fuel pump is running all the time again with the key in the on position just like it did before with the bad eec. so i pulled the eec back out and compared it to one from a different truck that i tried before. the old eec from this truck i had to give for a core but it was the same inside and out same circuitry etc, the reman that i got the casing looks different but the plug was the same, i was able to pop the back plug off where you can put in a aftermarket chip and i noticed the circuitry on the inside looks completely different, the layout and the amount of capacitors is different, i took it back the parts store thinking maybe its the wrong one like it was labeled wrong etc, the guy behind the counter didn't really know what to tell me so i will go back there tomorrow and talk to the store manager about it and maybe get a different reman. so i guess right now i'm at a standstill.
Most sensors will not cause a no start situation. Like I said, check the basics and don't worry about sensors right now. I can take the plug off my tps or vacuum lline off my map and the engine will start but run very poorly.At this point, you have no idea what's missing or affected.After the basics are checked, I can tell you what I encountered with my 4.9 with a no start. The pickup coil in the distributor and had a hole blown thru the pintle on the EGR valve.Those are easily checked without changing out.
BTW, there are revisions to an ECM over time so there could be some differences.I am surprised he will take it back after you took it apart.
BTW, there are revisions to an ECM over time so there could be some differences.I am surprised he will take it back after you took it apart.
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Black_Thunder
Thread starter
i didn't take it apart, there's just a little plastic cap on the back that pops off with a screwdriver, its meant be to taken off if you were to put in a chip etc.
either way there is something still wrong because the fuel pump is running all the time again with the key on and engine off, and the only thing to cause that is the eec or something electrical.
either way there is something still wrong because the fuel pump is running all the time again with the key on and engine off, and the only thing to cause that is the eec or something electrical.
rubber hose on the fuel pump assembly (inside tank) may have gone bad. this happened on a ranger i owned. pump was running cause it was pumping fuel inside the tank.
wow!!! i dont understand why you are asking for advice then COMPLETELY ignoring the good diagnostic advice ///stop wasting time / money and actually follow a path to explaining why it wont run ..
If your starting path is fuel ..check that fuel pressure is at the sharader valve on the rail ( assuming it has one ) ...heck a poor man check you can even pray some starting fluid in the intake at if it starts up then dies it is most likely fuel ...injectors..filter... pump
again //stop listing to people saying this part or swap that part ..and determine it the part is bad ... you tube ..check shreodinbgers box
If your starting path is fuel ..check that fuel pressure is at the sharader valve on the rail ( assuming it has one ) ...heck a poor man check you can even pray some starting fluid in the intake at if it starts up then dies it is most likely fuel ...injectors..filter... pump
again //stop listing to people saying this part or swap that part ..and determine it the part is bad ... you tube ..check shreodinbgers box
Black_Thunder
Thread starter
if people would pay attention to what i said about the fuel pump running all the time when the key is on and the engine is off and seeing that i had a bad eec they would realize its not something easy thats why i posted it in here to begin with.
i realize at this point its something more then the eec probably in the wiring etc i guess i didn't think i would get harped on about checking for spark/fuel etc when thats never what the issue was to begin with. i did plenty of research before i posted this thread and i posted it because i was frustrated and couldn't figure out what else the issue could be.
and the only part i threw at it was the eec nothing else, i physically took the eec out, took it part and looked at the circuitry and saw the capacitors were leaking/blackened and circuitry was burned, i didn't replace it on a whim.
i realize at this point its something more then the eec probably in the wiring etc i guess i didn't think i would get harped on about checking for spark/fuel etc when thats never what the issue was to begin with. i did plenty of research before i posted this thread and i posted it because i was frustrated and couldn't figure out what else the issue could be.
and the only part i threw at it was the eec nothing else, i physically took the eec out, took it part and looked at the circuitry and saw the capacitors were leaking/blackened and circuitry was burned, i didn't replace it on a whim.
Still, did you actually check the spark at the cylinder? Did you check the fuel inside the cylinder (wet plugs)? Did you spray starter fluid (or brake cleaner etc) in the intake and tried? Why not check the basics first?
Schrodinger Box used to be good. But the popularity has gone to his head now though and he forgets to follow his own advice and then becomes extremely belligerent.
Check South Main Auto videos instead.
Schrodinger Box used to be good. But the popularity has gone to his head now though and he forgets to follow his own advice and then becomes extremely belligerent.
Check South Main Auto videos instead.
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