engine keeps shutting off
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Senior User
Joined: Mar 2002
Posts: 490
Likes: 1
From: Phx, AZ
engine keeps shutting off
i also posted this in the electrical and wiring forum. I have a 78 Supercab newly rebuilt 400 motor. The problem I'm having is the engine keeps shutting off as if someone turned off the key. I'll wait 30 seconds, start it back up, then it keeps repeating. I've checked the voltage at the positive side of the coil and at the ignition side of the starter solenoid and it ranges from 7-12 volts at various times, with the engine off. The negative side of the coil ranges from 1-6 volts. The distributor was rebuilt with the motor, so that's new. I don't know how old the dura-spark box is, but it ran good before I rebuilt the motor. The altenator is putting out 15 volts, but I've noticed my volt meter in the cab only reads 14 volts. All connections are new and clean. Has this ever happened to anyone? Any help would be appreciated.
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
engine keeps shutting off
Take the spark box to a good parts store and get it tested, usually a free service. Always mount your spark box with 1/4" spacers under it to allow for cooling air under it. Get a Motorcraft ignition module if you need to replace yours. All the other brands are junk.
Thread Starter
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Senior User
Joined: Mar 2002
Posts: 490
Likes: 1
From: Phx, AZ
engine keeps shutting off
i found a spare spark box in my shop. so i put it on and the truck ran ok. so i took the old box to AutoZone an had it checked out. it was bad, and it was a motorcraft box. i called the dealer for the Motorcraft box and the wanted $153. i thought that was OUTRAGEOUS!!!! so i got a new one from AutoZone for $16.99 with a life time guarantee. an it was made by "Wells" works great.
Elder User
Joined: Feb 2002
Posts: 987
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From: East Bend, Carolina, U.S
engine keeps shutting off
I have one of the Wells ignition modules and it has worked fine for a year and a half now. Just curious why they are considered junk? The original module was a factory installed one and it suddenly started to cause sponteneous shut down and backfire. There was no reason for it to do this except the module itself had a component failure. No bad connections or wiring. I remember when these ignition systems came out and the original units were failing with people I knew enough of the time to remember thinking I wouldn't want one. How is the Wells module any worse than the Ford module?
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
engine keeps shutting off
I had an old van that would eat a box every 6-12 months. I tried every brand, Wells, Standard, BW, Store brands etc all with lifetime but when they failed for the second time i would try another brand. They all failed until I found a Motorcraft unit in the Junkyard and tried it, it is still in there... The last Motorcraft I bought only ran about $50. I figured a couple of tanks of gas at 50% mileage would pay the difference between that and a cheapie.
The ignitions that were failing were the TFI modules mounted on the side of the distributor. The duraspark modules never had a problem that I am aware of.
The ignitions that were failing were the TFI modules mounted on the side of the distributor. The duraspark modules never had a problem that I am aware of.
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Elder User
Joined: Feb 2002
Posts: 987
Likes: 2
From: East Bend, Carolina, U.S
engine keeps shutting off
The type I am referring to that failed are the first inner fender mounted type. When the first electronic ignition system came out they often faltered and failed where I grew up. I am sure heat had a major factor in why they failed. A hotter environment is an often overlooked reason for ignition component failure.
The modules I witnessed failing were in vehicles owned by people who lived in Texas and Oklahoma and some of these vehicles made trips through Arizona and New Mexico. I live in North Carolina now and the milder climate here is easier on these ignition systems. I have friends here that had and still have vehicles with these modules and they are surprised at the idea that they failed so much out west. The native North Carolinians I know all say they know of very little if any problems with any of these modules including the Wells brand. It isn't a scientific study, but it is close enough for me.
The modules I witnessed failing were in vehicles owned by people who lived in Texas and Oklahoma and some of these vehicles made trips through Arizona and New Mexico. I live in North Carolina now and the milder climate here is easier on these ignition systems. I have friends here that had and still have vehicles with these modules and they are surprised at the idea that they failed so much out west. The native North Carolinians I know all say they know of very little if any problems with any of these modules including the Wells brand. It isn't a scientific study, but it is close enough for me.
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Posting Guru
Joined: Jul 2001
Posts: 1,613
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From: Gainesville, FL
engine keeps shutting off
All,
Very interesting input. I have a bone to contribut e to this pile.
Electronic component failure in texas may, or may not be due to the heat. I worked for GM for awhile and we saw our largest electronic warranty return from Texas.
It turns out, that Texas does not use the same Federal communicaton standards as the rest of the country. This means that electronic components are exposed to higher levels of eletro magnetic fields than anywhere else in the US.
Higher temps are just another log on the fire of warranty return.
KingFisher
Very interesting input. I have a bone to contribut e to this pile.
Electronic component failure in texas may, or may not be due to the heat. I worked for GM for awhile and we saw our largest electronic warranty return from Texas.
It turns out, that Texas does not use the same Federal communicaton standards as the rest of the country. This means that electronic components are exposed to higher levels of eletro magnetic fields than anywhere else in the US.
Higher temps are just another log on the fire of warranty return.
KingFisher
New User
Joined: Apr 2003
Posts: 9
Likes: 0
From: New York City
engine keeps shutting off
I'm a firm beliver Heat is the number one killer of those units. Next to switching back to pionts, You can try mounting those things in a cooler spot. Like the wheel well. The modules are water "resistant" usualy, so it doesn't mind getting wet. I worked at a parts store for a while and during hot weather we definetly sold alot more ford ingnition modules. We even would stock up on them for heat spells. Good luck !
New User
Joined: Apr 2003
Posts: 9
Likes: 0
From: New York City
engine keeps shutting off
I'm a firm beliver Heat is the number one killer of those units. Next to switching back to pionts, You can try mounting those things in a cooler spot. Like the wheel well. The modules are water "resistant" usualy, so it doesn't mind getting wet. I worked at a parts store for a while and during hot weather we definetly sold alot more ford ingnition modules. We even would stock up on them for heat spells. Good luck !