Burnt Electric Smell in Cab, Now No Power to Fuel Pump(s)
09-24-2009, 06:44 PM
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Burnt Electric Smell in Cab, Now No Power to Fuel Pump(s)
Hello All,
My truck is a '94 F150- 4.9 6cyl. Started up and headed down the driveway this morning, and the truck stalled. Tried to restart, but it just cranked endlessly and did not fire up. Noticed the unmistakeable smell of burning electrical!!! Poked around, but couldn't track it down. It is definitely inside of the cab, but I can't tell where- I assume it is coming from under the dash since that's where most everything is located.
When I turn the ignition on, there is no sound from the fuel pump(s). I have always been able to hear the pumps hum- dual tanks- but now nothing.
I'm hoping someone has had a similar problem, and can point me in the right direction. Otherwise, I'm open to suggestions!!!
Thanks,
Doug
My truck is a '94 F150- 4.9 6cyl. Started up and headed down the driveway this morning, and the truck stalled. Tried to restart, but it just cranked endlessly and did not fire up. Noticed the unmistakeable smell of burning electrical!!! Poked around, but couldn't track it down. It is definitely inside of the cab, but I can't tell where- I assume it is coming from under the dash since that's where most everything is located.
When I turn the ignition on, there is no sound from the fuel pump(s). I have always been able to hear the pumps hum- dual tanks- but now nothing.
I'm hoping someone has had a similar problem, and can point me in the right direction. Otherwise, I'm open to suggestions!!!
Thanks,
Doug
09-24-2009, 08:02 PM
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I've done some poking around, but haven't tracked down the burnt electric smell yet. I did find a "theft deterent system" that I'd forgotton was on the truck- I don't think it works anymore.
Used to be that, to start the truck, you had to press in the little button on the back of the little red led mounted on the dash near the drivers left knee. It hasn't worked in a few years- I'd forgotten that it was there. Anyhow, I don't know if this was original or aftermarket, but I suspect aftermarket as the module is simply tucked up above the emergency brake bracket against the fenderwell.
Running out of daylight, so I guess I'll stay home tomorrow and try my luck at tracing down the wiring- or maybe I'll just run my own wiring and see if I can work around the problem that way...
Doug
Used to be that, to start the truck, you had to press in the little button on the back of the little red led mounted on the dash near the drivers left knee. It hasn't worked in a few years- I'd forgotten that it was there. Anyhow, I don't know if this was original or aftermarket, but I suspect aftermarket as the module is simply tucked up above the emergency brake bracket against the fenderwell.
Running out of daylight, so I guess I'll stay home tomorrow and try my luck at tracing down the wiring- or maybe I'll just run my own wiring and see if I can work around the problem that way...
Doug
09-24-2009, 09:56 PM
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Yep! Checked that pretty early on. Something has shorted out inside the cab. I'll get under it in the morning and see what I can find. If all else fails, I'll just re-wire it to get me back on the road and worry about it later...
04-25-2010, 10:56 PM
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This just happened me to today. I doubt you will read this since you haven't posted anything since September 
Just in case, though, what ended up being the problem?
Just in case, though, what ended up being the problem?
04-26-2010, 03:18 PM
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It was the ECM!
I found the trouble. It was a roasted ECM, which is the little computer module that controls all things fuel injection/engine related.
It's located inside the cab of the truck, but (on my '94) is removed from the engine compartment. Actually, it was easiest to access with the right front wheel removed. Picture a box similar in size to a car stereo. It is mounted inside the cab, but slides in/out from the engine compartment. By jacking up the right front/removing the wheel and partially loosening the plastic "inner fenderwell" so it can be pulled out of the way, it was very simple to access.
There are a gazillion wires that come together into one big multi-pin plug. It plugs into the "face" of the ECM. The location varies depending on the year of the truck, but mine was located down low on the firewall of the truck on the drivers side. Open the hood of the truck, walk around to the drivers side, and look down below the Master Cylinder for the brakes- you should see a thick bundle of wires that appears to "plug" into the firewall. That's where the ECM is; it's what those wires are plugged in to.
To remove it (after clearing the way for easy access) you remove the multi-pin plug. There is a small bolt in the center of the plug. Unbolting the plug allows it to pull off of the ECM. Next, remove the 2 nuts holding on a plastic cover plate. That's all that holds the ECM in it's pocket- simply pull and it slides straight out...
Viola, you've just removed the ECM. If you sniff it, the horrendous smell should let you know that you have the problem in hand!
It's located inside the cab of the truck, but (on my '94) is removed from the engine compartment. Actually, it was easiest to access with the right front wheel removed. Picture a box similar in size to a car stereo. It is mounted inside the cab, but slides in/out from the engine compartment. By jacking up the right front/removing the wheel and partially loosening the plastic "inner fenderwell" so it can be pulled out of the way, it was very simple to access.
There are a gazillion wires that come together into one big multi-pin plug. It plugs into the "face" of the ECM. The location varies depending on the year of the truck, but mine was located down low on the firewall of the truck on the drivers side. Open the hood of the truck, walk around to the drivers side, and look down below the Master Cylinder for the brakes- you should see a thick bundle of wires that appears to "plug" into the firewall. That's where the ECM is; it's what those wires are plugged in to.
To remove it (after clearing the way for easy access) you remove the multi-pin plug. There is a small bolt in the center of the plug. Unbolting the plug allows it to pull off of the ECM. Next, remove the 2 nuts holding on a plastic cover plate. That's all that holds the ECM in it's pocket- simply pull and it slides straight out...
Viola, you've just removed the ECM. If you sniff it, the horrendous smell should let you know that you have the problem in hand!
Last edited by JustDoug; 04-27-2010 at 10:14 AM. Reason: added some clarification
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04-27-2010, 10:10 AM
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Junkyard Fun
Well, it took 2 tries but I finally found a replacement ECM in the junkyards in my area. Needless to say, these are a popular item.
One interesting note: I wound up abandoning the findings of my online research, which involved looking for specific part #'s on ECMs in a variety of vehicles, and simply hunting down a truck with my same engine/tranny combination.
The first "match" I found was based on the part #/code cross reference method- big pain because to read the numbers you basically have to remove the damn thing. The info is printed on a sticker located on the ECM right where the cover plate makes it's seal around the protruding receptacle that the wiring harness plugs in to.
So I found one with the right stuff on the sticker, and... it didn't work with my transmition (Auto/OD). It started right up, but to drive it you had to manually shift gears- in drive it just stayed in high gear. Perhaps I got a bad unit, or maybe my cross-reference list was wrong...
Anyhow, I finally found a truck like mine that still had it's ECM- like I said, these are popular items- and put her back on the road in minutes. Funny how it sometimes takes a week to find a 10 minute fix...!
One interesting note: I wound up abandoning the findings of my online research, which involved looking for specific part #'s on ECMs in a variety of vehicles, and simply hunting down a truck with my same engine/tranny combination.
The first "match" I found was based on the part #/code cross reference method- big pain because to read the numbers you basically have to remove the damn thing. The info is printed on a sticker located on the ECM right where the cover plate makes it's seal around the protruding receptacle that the wiring harness plugs in to.
So I found one with the right stuff on the sticker, and... it didn't work with my transmition (Auto/OD). It started right up, but to drive it you had to manually shift gears- in drive it just stayed in high gear. Perhaps I got a bad unit, or maybe my cross-reference list was wrong...
Anyhow, I finally found a truck like mine that still had it's ECM- like I said, these are popular items- and put her back on the road in minutes. Funny how it sometimes takes a week to find a 10 minute fix...!
Last edited by JustDoug; 04-27-2010 at 10:24 AM.
04-27-2010, 03:42 PM
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I feel like an idiot. My truck is 94 not a 96. My van is a 96 and I transposed their years in my head lol
So my ECM should prove to be exactly where yours is. I also have an automatic with overdrive, so that is good info to have. I am pretty sure this is what it is going to turn out to be because I switched to the front tank and it still wouldn't start.
I hope that if it is this, I can find in the junk yard on my first try because the closest junkyard is over an hour away
So my ECM should prove to be exactly where yours is. I also have an automatic with overdrive, so that is good info to have. I am pretty sure this is what it is going to turn out to be because I switched to the front tank and it still wouldn't start.
I hope that if it is this, I can find in the junk yard on my first try because the closest junkyard is over an hour away
04-28-2010, 09:27 AM
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If you have that burnt smell, then pulling out your ECM to check would be my next step. That stench lasted for days inside the cab, even with windows and doors open for the hours I spent screwing with it. The problem was I couldn't quite find the source. I swear the smell seemed to "move" as I climbed around upside down with my head under the dash. The smell is unmistakeable- nothing stinks quite the same as fried electronics.
Before driving an hour to the yard, I'd pull the ECM and check it out. If the smell isn't a giveaway, you can open up the unit to inspect- chances are there will be a big scorch mark on the circuit board (think mine was a failed capacitor).
I spent hours pulling the dash apart/tracing wires/testing switches and relays. I even ran power directly to the fuel pumps, then through the wiring and dual tank switch... I just knew there had to be a short somewhere. Which, technically, there was. It was inside that damned ECM!
Before driving an hour to the yard, I'd pull the ECM and check it out. If the smell isn't a giveaway, you can open up the unit to inspect- chances are there will be a big scorch mark on the circuit board (think mine was a failed capacitor).
I spent hours pulling the dash apart/tracing wires/testing switches and relays. I even ran power directly to the fuel pumps, then through the wiring and dual tank switch... I just knew there had to be a short somewhere. Which, technically, there was. It was inside that damned ECM!