1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

[axe2011]

1986 F150 RWD Automatic 5.0 EFI.

I am having an issue with the injectors. If you turn the key to the on position (engine not started) some of the injectors spray fuel continuously. I thought maybe it was a bad ECC so I got a new one and put it on, but the same issue is occurring. If I unplug the injectors the fuel does not spray when I pressurize the injectors by turning they key to on. If I move the plug from injector to injector the spraying issue follows the plug. From these tests I believe it is a wiring issue, but I want to make sure I am not off mark before I start trying to decipher wires. Any suggestions are greatly appreciated!

[Gary Lewis]

Welcome to the Bullnose Forum!

You may have missed the email that you were sent asking you to go to the New Members Start Here folder, read the guidelines, and then start an introductory thread there. Many people miss that message, but the intent is to give you ample opportunity to read the guidelines. That's because we hold everyone to them.

So, before we launch into problem solving can you assure me you read them?

[axe2011]

Welcome to the Bullnose Forum!

You may have missed the email that you were sent asking you to go to the New Members Start Here folder, read the guidelines, and then start an introductory thread there. Many people miss that message, but the intent is to give you ample opportunity to read the guidelines. That's because we hold everyone to them.

So, before we launch into problem solving can you assure me you read them?

Hi there! I did miss the email, I left the computer to feed the toddler and when I came back I was able to post. I apologize. I have set up my signature block and have read the beginner guide. I am ok with a manual and maybe some youtube at more simple repairs, but electrical is something I have not dealt with much so I will probably be a rocky getting into it. Thanks for letting me join the group!

[Gary Lewis]

Hi there! I did miss the email, I left the computer to feed the toddler and when I came back I was able to post. I apologize. I have set up my signature block and have read the beginner guide. I am ok with a manual and maybe some youtube at more simple repairs, but electrical is something I have not dealt with much so I will probably be a rocky getting into it. Thanks for letting me join the group!

Yeah, that happens. Our joining process is broken and we are trying to fix it.

Anyway, welcome! Where is home? I ask because we have a map (Bullnose Forum/Member's Map in the menu) and we could add you if we had a zip or city/state.

On the injectors, I've included the pertinent schematics from the 1986 Electrical & Vacuum Troubleshooting Manual (EVTM) below. But you can find it at Documenation/Electrical/EVTM's/1986 EVTM.

On the 2nd page you can see that injectors 1, 4, 5, & 8 are tied together and 2, 3, 6, & 7 are tied together on their bottom sides, the side that goes to the EEC. Your system is called "bank fire" as four injectors go at the same time. So if you have injectors firing when the key is just turned on it is important to know which ones as it is likely you have all four in one bank firing.

Another thing to note is that the EEC grounds the injectors to fire them. In other words, when you turn the key on all of the injectors are given power via the EEC power relay. So if there is a short to ground in the wire going to the EEC from the injectors the injectors will fire.

So if you work out which injectors are firing then you know which wire to check - Tan/Orange or Tan/Red.

[axe2011]

Yeah, that happens. Our joining process is broken and we are trying to fix it.

Anyway, welcome! Where is home? I ask because we have a map (Bullnose Forum/Member's Map in the menu) and we could add you if we had a zip or city/state.

On the injectors, I've included the pertinent schematics from the 1986 Electrical & Vacuum Troubleshooting Manual (EVTM) below. But you can find it at Documenation/Electrical/EVTM's/1986 EVTM.

On the 2nd page you can see that injectors 1, 4, 5, & 8 are tied together and 2, 3, 6, & 7 are tied together on their bottom sides, the side that goes to the EEC. Your system is called "bank fire" as four injectors go at the same time. So if you have injectors firing when the key is just turned on it is important to know which ones as it is likely you have all four in one bank firing.

Another thing to note is that the EEC grounds the injectors to fire them. In other words, when you turn the key on all of the injectors are given power via the EEC power relay. So if there is a short to ground in the wire going to the EEC from the injectors the injectors will fire.

So if you work out which injectors are firing then you know which wire to check - Tan/Orange or Tan/Red.

I am from Dubuque, Iowa (52003). I bought this truck because I remembered riding around with my dad and grandparents in their old 80s fords so I thought it would be nice to puts around in. I also like tinkering, but I electrical is not my strong suite. It’s a beautiful truck but has some electrical issues. I watched the previous owner back it up and pull it onto my trailer and it was running a little rough then. When I pulled the dip stick there it seemed fine. When I got it home I added three gallons of gas, it started but ran rough. It stopped starting which I thought was weird, I checked the dipstick and it looked very full and thin. When I pulled out the oil plug almost 3 gallons of fuel and oil came out of the block! I then pulled a plug and thought maybe it was a stuck injector. Through a series of tests I have come to my current state.

When looking at the engine compartment the right hand side of the motor shoots fuel out of the rear most injector and the front most injector continuously when the key is on. The left hand side seems to shoot fuel only out of the rear. If I move the plug around on different injectors then that one shoots fuel out. I apologize I don’t know the sequence of the plugs to be more accurate.

If it doesn’t happen to the whole bank simultaneously then could it just be an individual plug grounding issue?

 

[Gary Lewis]

I am from Dubuque, Iowa (52003). I bought this truck because I remembered riding around with my dad and grandparents in their old 80s fords so I thought it would be nice to puts around in. I also like tinkering, but I electrical is not my strong suite. It’s a beautiful truck but has some electrical issues. I watched the previous owner back it up and pull it onto my trailer and it was running a little rough then. When I pulled the dip stick there it seemed fine. When I got it home I added three gallons of gas, it started but ran rough. It stopped starting which I thought was weird, I checked the dipstick and it looked very full and thin. When I pulled out the oil plug almost 3 gallons of fuel and oil came out of the block! I then pulled a plug and thought maybe it was a stuck injector. Through a series of tests I have come to my current state.

When looking at the engine compartment the right hand side of the motor shoots fuel out of the rear most injector and the front most injector continuously when the key is on. The left hand side seems to shoot fuel only out of the rear. If I move the plug around on different injectors then that one shoots fuel out. I apologize I don’t know the sequence of the plugs to be more accurate.

If it doesn’t happen to the whole bank simultaneously then could it just be an individual plug grounding issue?

You are now on the map.

The cylinders number 1 - 4 front/rear on the passenger's side and 5 - 8 front/rear on the driver's side. So the rear-most on the driver's side is #8 and the front-most on that side is #5. And the rear-most on the left hand/passenger's side would be #4.

As previously said, one bank is 1, 4, 5, & 8. And you said that 4, 5, and 8 fire continuously. I'd bet that #1 does as well but you may not have noticed. So the issue has to do with the Tan/Orange wire that goes from all four of those injectors to the EEC. In the schematic below I've circled C160. If you can find it and disconnect it you can test to see where the ground is. Oh wait, do you have a digital volt meter?

[axe2011]

You are now on the map.

The cylinders number 1 - 4 front/rear on the passenger's side and 5 - 8 front/rear on the driver's side. So the rear-most on the driver's side is #8 and the front-most on that side is #5. And the rear-most on the left hand/passenger's side would be #4.

As previously said, one bank is 1, 4, 5, & 8. And you said that 4, 5, and 8 fire continuously. I'd bet that #1 does as well but you may not have noticed. So the issue has to do with the Tan/Orange wire that goes from all four of those injectors to the EEC. In the schematic below I've circled C160. If you can find it and disconnect it you can test to see where the ground is. Oh wait, do you have a digital volt meter?

I have a coworker who has a voltmeter and may be able to help me look for this issue. I will ping him at work tomorrow and see if he can help.

[Gary Lewis]

I have a coworker who has a voltmeter and may be able to help me look for this issue. I will ping him at work tomorrow and see if he can help.

Ok. C160 is said to be brown and have 4 pins. You can see on that schematic that it will have the red wire for circuit 361 that takes power to the injectors. And it has both the tan/orange and tan/red wires that ground 1/2 of the injectors. So I think the 4th pin in it is unused.

I would find that and disconnect one side from the other - very carefully so as not to break the connectors. Then I'd use the DVM in resistance mode to see if the tan/orange wire is grounded. In other words, put one lead of the DVM into the connector and touch the pin of the tan/orange wire, and put the other lead on a good ground - like the negative terminal of the battery. You should not see any resistance, but if you do you have to find out where it is coming from.

Then I'd do the same on the other side of the connector, the side that goes to the EEC. But in this case you might see some very small resistance, depending on the scale you are on, as the EEC will show some. However, what I think you'll see is a very solid ground that will be down around 1 ohm or less. That means the wire is shorted to ground somewhere.

[axe2011]

Ok. C160 is said to be brown and have 4 pins. You can see on that schematic that it will have the red wire for circuit 361 that takes power to the injectors. And it has both the tan/orange and tan/red wires that ground 1/2 of the injectors. So I think the 4th pin in it is unused.

I would find that and disconnect one side from the other - very carefully so as not to break the connectors. Then I'd use the DVM in resistance mode to see if the tan/orange wire is grounded. In other words, put one lead of the DVM into the connector and touch the pin of the tan/orange wire, and put the other lead on a good ground - like the negative terminal of the battery. You should not see any resistance, but if you do you have to find out where it is coming from.

Then I'd do the same on the other side of the connector, the side that goes to the EEC. But in this case you might see some very small resistance, depending on the scale you are on, as the EEC will show some. However, what I think you'll see is a very solid ground that will be down around 1 ohm or less. That means the wire is shorted to ground somewhere.

Thanks for the info I’ll test it tonight after work and be back with updates…hopefully good

[axe2011]

Ok. C160 is said to be brown and have 4 pins. You can see on that schematic that it will have the red wire for circuit 361 that takes power to the injectors. And it has both the tan/orange and tan/red wires that ground 1/2 of the injectors. So I think the 4th pin in it is unused.

I would find that and disconnect one side from the other - very carefully so as not to break the connectors. Then I'd use the DVM in resistance mode to see if the tan/orange wire is grounded. In other words, put one lead of the DVM into the connector and touch the pin of the tan/orange wire, and put the other lead on a good ground - like the negative terminal of the battery. You should not see any resistance, but if you do you have to find out where it is coming from.

Then I'd do the same on the other side of the connector, the side that goes to the EEC. But in this case you might see some very small resistance, depending on the scale you are on, as the EEC will show some. However, what I think you'll see is a very solid ground that will be down around 1 ohm or less. That means the wire is shorted to ground somewhere.

So I think there is a wiring harness issue. The wire coming out of 58 on the eec is green and white not the color on the diagram. When I follow this wire it splices and one leg goes up to a 4 plug connector that goes to injectors, the other leg goes out another branch of harness rona diode. Anywhere I test the green and white cord from end near ecc to end near diode I get a .6 reading on 200 ohm setting. If I test a injector plug wire to the other end where the c160 plug is I get a 30 on one prong in the plug and a .6 on another. Not sure if this is useful information or not.