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1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

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axe2011

1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

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!

1986 F150 RWD Automatic 5.0 EFI

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

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?

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

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!

1986 F150 RWD Automatic 5.0 EFI

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

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.

Gary, AKA "Gary fellow": Profile

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

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?

1986 F150 RWD Automatic 5.0 EFI

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

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?

Gary, AKA "Gary fellow": Profile

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

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.

1986 F150 RWD Automatic 5.0 EFI

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

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.

Gary, AKA "Gary fellow": Profile

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

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

1986 F150 RWD Automatic 5.0 EFI

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

In reply to this post by Gary Lewis

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.

1986 F150 RWD Automatic 5.0 EFI

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

The .6 is basically a dead short to ground. The 30 is probably the resistance of the coil in the injector.

Well, looking at the EVTM there is a Dark Green/White wire on pin 30 of the EEC and it goes to a diode, as shown below in the lower left. That is called the Neutral Drive Switch. Does it look like someone has hacked your wiring and connected 30 to 58?

If so, I would disconnect the hack and just have the wire from the injectors go to 58 and nowhere else.

Gary, AKA "Gary fellow": Profile

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

I’m not sure the wiring harness is original the wire in the 58 pin position is actually green and white instead of the color in tan orange it’s supposed to be….near the oil cap there is a spot where once I unwrapped the wire I found every wire was connected…this just got much more complicated! So does .6 mean the wire is grounded out?

1986 F150 RWD Automatic 5.0 EFI

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

Yes, .6 ohm is almost a dead short. Zero ohms would be a dead short, but I'll bet if you touch the leads of your DVM together it only comes down to .2 or .1 ohms. In that case you are seeing the resistance of the leads - or a meter that hasn't been zeroed.

Your truck may well be like many others - an onion you'll have to peel and cry, peel and cry. But eventually you'll have enough for a mess of onion rings!

Seriously, you will need to sort out that wiring. It is ok for the wire to be the wrong color as long as it goes from the right place to the right place(s) and nowhere else. So get the injector wiring sorted and then, once the engine will run, work on the next layer of the onion.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

In reply to this post by axe2011

Here is a 1986 EFI harness I sold to another member. C160 is circled, I believe it has 4 wires in it.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

Thanks, Bill. The EVTM, which we got from some nice old guy, only specifies three wires in it but says it has four pins. If there is a fourth wire I'd be curious what it is - but I guess you no longer have the harness.

Gary, AKA "Gary fellow": Profile

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Yeah this wiring is painful! The connector pictured is the same that is in my truck and has 4 wires. Not sure what it is for but I will start nugging away at it.

1986 F150 RWD Automatic 5.0 EFI

Gary Lewis

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

Please let me know what the wire colors are. I'm curious what else is in that connector.

Gary, AKA "Gary fellow": Profile

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

This is what the plug looks like. Tan green red and black wires

1986 F150 RWD Automatic 5.0 EFI

85lebaront2

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Administrator

In reply to this post by Gary Lewis

It will have 4, they will be 12V power to injectors, bank 1, bank2, O2 sensor. In the picture, the injector harness is the one shorter portion beyond C160. I would start there, on the injector side and using a multimeter, first check that # 5 & 8 injectors are connected to red and one of the other wires (should be tan with an orange hash). Then repeat for # 6 & 7 those should be red power and tan with a red hash. Colors will fade and change after 35 years. Once you have verified those then there may be a wiring issue or a bad EEC.

The 4th wire in C160 is the O2 sensor and is supposed to be dark green with a purple hash.

One common problem with these first gen EFI trucks, the ground for the entire system is a two 1/4" pin connector that is pigtailed to the battery negative cable clamp. It is very prone to corrosion which will really mess up the functions.

Bill AKA "LOBO" Profile

axe2011

Re: 1986 F150 RWD Automatic 5.0 EFI. - Injector Problems

Ok I’ve been busy today. I took out the injector harness side of the c160 and took it inside. I then unwrapped it and traced all the wires and labeled them using the diagram to get a handle on colors.

When I touch the tan and orange (pin58 wire on ecc) wire prong inside of c160 to the blue wire that goes to injector 5 I get a reading of .8

T/o to injector 8 tan and blue is also .8

T/o to injector 4 is .8

T/0 to injector 1 is .8

When I test all the wires spliced to the pin 69 wires injectors 6,7 and 2,3 I also get .8.

I have the meter set at 200 ohm am I doing it wrong?

I peeled back all the wires to inspect them and didn’t see any obvious damage other than the O2 sensor which looks not good.

1986 F150 RWD Automatic 5.0 EFI

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