Strange noise
Thread Starter
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Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Strange noise
I have a new to me 92 F150 5.0 AOD. The engine was dead as well as the tranny when I got the truck, 244,000 miles on the clock. I got a new rebuilt engine and tranny in it and now have about 1000 miles on it. The truck has some electrical issues, the PO tore the hello out of the dash monkeying around in it. The front tank gauge stays at 3:00, the rear is a fast dropper stays on E a while before running out of gas. The factory radio is very weak.
Yesterday while driving it out in the country and the should have been strong AM radio station was barely coming in, I was picking up engine static over the speakers like a 50s model. I found if I was pressing the gas pedal I got the noise, but if I lifted off the noise stopped instantly, mash the gas noise, lift and it stops.
Any ideas on where to start looking for this issue?
John
Yesterday while driving it out in the country and the should have been strong AM radio station was barely coming in, I was picking up engine static over the speakers like a 50s model. I found if I was pressing the gas pedal I got the noise, but if I lifted off the noise stopped instantly, mash the gas noise, lift and it stops.
Any ideas on where to start looking for this issue?
John
Elder User
Joined: Sep 2004
Posts: 941
Likes: 4
The Ford EEC-IV cuts the fuel delivery right to zero as you decellerate. The fuel injectors stop opening, which means current stops passing through them. The ignition, on the other hand, will continue to provide spark to the cylinders, albeit at a lower frequency as the engine slows down.
My guess is the electrical noise comes from the fuel injector pulses, rising and falling with engine RPM, but going away completely on decell.
Check the quality of all the ground connections, especially the pigtail running from the radiator support to the negative battery post. Check that your alternator does not have a blown diode. Check the high-current connections at the alternator -- the "spade lugs" were not one of Ford's better ideas.
Check the antenna wire for being firmly plugged in, and any cuts or damage on the route from the radio to the antenna.
My guess is the electrical noise comes from the fuel injector pulses, rising and falling with engine RPM, but going away completely on decell.
Check the quality of all the ground connections, especially the pigtail running from the radiator support to the negative battery post. Check that your alternator does not have a blown diode. Check the high-current connections at the alternator -- the "spade lugs" were not one of Ford's better ideas.
Check the antenna wire for being firmly plugged in, and any cuts or damage on the route from the radio to the antenna.
Posting Guru
Joined: Dec 2002
Posts: 1,113
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From: Remsen, NY
The rear tank gauge thing is just a normal Ford truck thing. My father's '87 and '93 both did that from the time they were new (still 1/2 full when it showed empty) and my '95 does it too, still 1/3 full at 1/8 showing. For some reason my '91 showed it accurately in the rear though. Who knows, different sending units bent just a little different.
Thread Starter
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Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Thanks guys, Not having driven it before, I don't know what to expect from this truck. My other truck is a 66 with a Big ol FE in it. arg arg arg When ya mash the gas it takes off, this one is a sick dog.
We put new plug wires on before the install, but will give them a once over again. The interesting part of the noise was the instant I lifted off the gas pedal, the noise stopped. It wasn't a decelleration action. It took a couple seconds to hear the noise, but it stopped instantly. I'll see if we can take a look at the injectors in the next few days.
I had a 79 E250 with dual tanks and both gauges worked pretty evenly. Most of the Fords that I have owned over the years have gas gauges that stay on the full side for a while and then start over.
The am station that I was listening to is one of those 50,000 watt ones that I have been listening to for over 50 years and I know their signal is good for 50 miles further out from where I was. I'll try to check the antenna leads. I really am hesident to look to far into the dash, I am kinda afraid of what I might find. I can not get over how the front of the dash is destroyed.I have been looking for and buying parts off Ebay trying to get it back to parr. Ya think that when ya find a rust free truck it'll be good all the way through. NOT
John
We put new plug wires on before the install, but will give them a once over again. The interesting part of the noise was the instant I lifted off the gas pedal, the noise stopped. It wasn't a decelleration action. It took a couple seconds to hear the noise, but it stopped instantly. I'll see if we can take a look at the injectors in the next few days.
I had a 79 E250 with dual tanks and both gauges worked pretty evenly. Most of the Fords that I have owned over the years have gas gauges that stay on the full side for a while and then start over.
The am station that I was listening to is one of those 50,000 watt ones that I have been listening to for over 50 years and I know their signal is good for 50 miles further out from where I was. I'll try to check the antenna leads. I really am hesident to look to far into the dash, I am kinda afraid of what I might find. I can not get over how the front of the dash is destroyed.I have been looking for and buying parts off Ebay trying to get it back to parr. Ya think that when ya find a rust free truck it'll be good all the way through. NOT
John
