The only purpose of the in-tank boost fuel pumps is to fill (prime) the selector valve and get fuel to the high pressure pump and snap (aline) the selector valve to its tank. Once this is done you no longer need the boost pumps to even run unless you go up a step hill, run out of fuel in that tank, do a very high acceleration or to switch tanks. Other wise the engine will run just fine on the tank the valve is aligned too as long as it was once primed.

With the in-tank boost pumps running and no fuel coming out of the supply fuel line from that tank means you have a bad pump or bad fuel line or very low voltage to the connector on top of the tank.
You might try putting power right on the plug on the top of the tank. The plug pin-out should be like the photo below.

Note if this is an RV fuel pump and you hooked the fuel line to the generator to the engine supply line and the engine supply line to the generator fuel line the pump will pump with no output.



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Good morning,

Instead of referencing Mr. Subford, can I go with Bill? Not that its gonna fix this van any quicker, but at least I'll be accomplishing something.

I stayed up last night well past 2 in the morning reading all past fuel and fuel part related issues that might be a contributing factor. Other than the items you just replied with. It makes sense that you say if neither tank is giving fuel to the selector valve, the problem has to be from between the backside of the selector valve and the tanks. What are the chances of fuel lines being crimped on both supplies to the selector valve. Its a possibility, but I do not think so because I had the front tank down and replaced that pump and the rear tank down to clean it out. Plus the van did run for some time correctly since both tanks have been put back. I'm thinking probably not on a fuel line issue. Its got to be something that is in common with BOTH tanks. I do not think it is either pump either. One pump being bad would not cause the other to not work I'm thinking. That leaves electrical.
Like I said, I did a BUNCH of reading last night here and I saw quite a few times where you were talking about the fuel pump relay and another relay that pulls the fuel pump relay closed, the EEC relay. I located the fuel pump relay last night just to find it. I also saw where you mentioned more than once that little black and green GND wire leaving the neg. post on the battery and leads 6 inches away to a big bundle of ground connections for various things. I am by no means a ground connection expert or clear on what S100 means in the FORD book. But I am assuming that S100 is that big bundle(connection) 6 inches away from the battery where ground is supplied to various things. One of which it looks like is the EEC/its relay. Also quite interesting is the fact that the S100 connection node supplies the ABS valve assembly and the vehicle speed sensor. My ABS light has ALWAYS been on and off on the instrument panel but I was always going to just get to it someday. The brakes were definitely touchy ALL the time. Also, just recently, recently being in the midst of all these fuel troubles my cruise control stopped working for some reason. Looked for a fuse for that and never found one. I figured I'd come back to that as well. I wonder if this S100 ground being supplied to the vehicle speed sensor could mess with my cruise control.
Ok sir, after all of this out loud thinking last night and reading I took my flashlight outside and looked at that ground (BLK/LG) wire coming from the battery. Well to say that where it leaves the lead connector is in sad shape would be an underestimation. What few, half, wires are still securely connected to that battery connection, they are not very clean and you can see where that area of the battery connection is just plain dirty, corroded, and "scaley".
From the beginning, I have never had a very good battery terminal connection on either post. And I know from me putting the post connections on and off of the battery more than several times, I could have been partly to blame for the shape of that ground connection(BLK/LG) being stressed and ripped.
So after my story and just about as much info as I can give you, me helping you help me, Do you think the shape of this ground wire on the battery or the underside of the fuel pump relay and other sensor connections being "ugly" could contribute or cause these fuel issues? Either way, I am going to go out right now and fix that ground wire. Either strip it back and reattach somehow or get a GOOD ground to S100 somehow. Then clean the bottom of the relays. Where is the EEC relay please? Also, with this vacuum/electrical FORD book in hand, in the up front "ground" section, how do you locate these "S nodes" or ground connections in your vehicle?

Thank you very much Bill for your patience and help.

I'll let you know what I find out here in a while. I will not let this thing kick my butt.

Sid

 

Well to start with S100 means a splice inside the wiring harness and not a ground connection.
A ground point would be something like G100.

Yes you can call me Bill.

The EEC power relay is located just to the left of the fuel pump relay in post #23 of this thread above. The fuel pump relay has a green bottom and the EEC power relay has a brown bottom.

The EEC power relay does supply power to the coil of the fuel pump relay over a red wire. It also supplies power to all the fuel injectors, EEC Computer pins 37 & 57 and other solenoids over a red wire.
The EEC computer grounds the other side of the Fuel Pump relays coil to complete the circuit from the fuse link on the starter relay through the contacts of the fuel pump relay and on to the inertia switch. From the inertia switch the power goes to the high pressure fuel pump and the power input to the selector switch. The selector switch will either power the front or back fuel tank boost pumps.

What year did you say this van was, I think it was a 1990 but not for sure.

 

Well Bill it seems the relays and connectors for the relays although not clean and definitely needed some attention, were not the problem. Neither was the BLK/LG ground wire coming from the battery. Last night it looked worse than it really was, but it too is working as it should. It is just so hard to think that either I have 2 bad fuel pumps, when I bought one new a few months ago or there is something wrong with both supply lines coming from both tanks.

I really do not know what else to do other than to like you said, somehow get to the in tank pump connectors and check for proper voltage there or drop both tanks again and check the lines.

You see any other alternative? Yes Bill, it is a 1990 with a 302 and the C6 tranny. It is of the cargo extended variety.

Sid

 

The only thing I can see electrical other than the tanks and their grounds would be the selector switch on the dash that has caused other posters problems. I think we have went over that switch above in this thread but do not remember what we said about it.

 

Bill,

The selector switch is the first thing I replaced. I went and got the Autozone replacement you recommended. I know its wired correctly. I think I triple checked it when I was doing it and labelled everything. Not sure if this matters or not but the selector switch is just hanging right now from the wire harness where I spliced in. It is not secured back to the bracket where the other switch was. Also, I did not cut the OEM connector for the switch. I just went and got those crimp splices where you can tap into a wire. You think by the sswitch hanging and not secured back to the metal bracket could be causing a ground issue with the switch. I have known that some switches use the case of the switch as a ground. Not sure in this instance.
As far as the tank grounds go, are there "tank" grounds? I do not remember messing with any ground straps on either tank. I thought the pumps themselves would need to be grounded. Let me know what you think or know should be about the Autozone switch, my splices, and the way it is NOT mounted right now. Also not sure if there are tank straps that need to be correct for grounding purposes.

Got about 4 more hours of sunlight.

Thanks Bill
Sid

 

No the switch does not need to be grounded.
I do not have a 1990 wiring diagram manual so I do not know where the fuel pumps are grounded. But the gauge also uses the same ground so if the gauges work OK then I would think the pumps have a good ground also.
The ground location on a 1988 E-series is under the dash on the drivers side on the ground bus.

 

Good morning,

Back again at it early. I feel today is the day. Too windy to hunt anyway.

I have a question. By grounding pin 6 and then turning the key, shouldn't the hi pressure pump and whichever tank is selected run continuously until you remove the ground from the backside of the fuel pump relay? The more I thought about the test pin 6 test the other day, the more I do not remember it running continuously. Just coming on and off. I need to do this again. If anyone knows, please tell me. I am at my end here and will begin dropping the tanks as there is no other steps left to troubleshoot this.

Thank you all.

Sid

 

Yes as long as pin #6 in the test plug is grounded (or shorted to pin #2) and the key is ON with the engine NOT running the high pressure pump and the selected in-tank boost pump will run continuously.

 

Well after another all day event under in and around the van, I think I am starting to get somewhere with this non-fuel issue.

List of new parts so far;

1. Front tank fuel pump
2. Tank selector switch
3. Selector valve
4. Fuel filter

Bill I have been saying all along that both tank pumps have been working as well as the hi pressure pump. After you replied saying the pumps will run continuously as long as pin 6 is shorted to pin 2 on the test plug. I disconnected the hi pressure pump to protect it while check the others first. Selected the front tank first because I knew I already replaced that pump. Turned the key and it did its thing as long as I kept the key on. Selected the back tank, turned the key and there was silence. No noise out of the rear pump at all. Now I didn't disconnect the fuel lines going into the selector valve like the other day to see if fuel was flowing. I just wanted to know that the pumps were getting their signal and working. I reconnected the hi pressure pump. Turned the key and it too fired up and ran as long as I had the key on.
Ok so now I know either my rear tank pump is bad or the wiring from the selector switch to the pump is bad, shorted, cut or something. I checked for the voltage going into the switch as well as coming out of the switch. It was just like it was suppose to be. Bill I have the FORD OEM 1990 Econoline vacuum/electrical manual. Of the 6 wires attaching to the tank selector switch all of my wire colors and locations match except for pin 1 which is the pump motor feed for the rear tank. The manual is calling for B/R which I am thinking is Brown/Red? My wire is Brown only.
Next I need to know which of the four wires at the connector by the rear bumper that goes into the rear tank pump is connected to pin 1 of the selector switch. The wires that are back there are a larger gauge than all the others(Orange). Then 2 smaller, same size (Black). Then the fourth which is smaller yet and it too is black. The manual shows all Black. I checked continuity on all four wires to pin 1 of the switch and I got nothing that looked right. Is this the only wiring diagrams that Ford has? how do I know if there are any splices along the way from the switch to the tank? In the manual it looks like there are a couple of connectors between the switch and the tanks. LF-C1 and LF-C2. Then there is something called just FW. It looks like FW is firewall connector and LF is left fender. Does that mean that from the switch it goes through the firewall connector to the fender connector and from there its just a bunch of long wire back to the respective tanks?

This should get me going for tomorrow I think.

Thanks all.

Sid

 

Ford put out a large fold-out wiring diagram for the 1990 vans and then someone has taken this fold-out wiring diagram and made the FORD OEM 1990 Econoline vacuum/electrical manual as they think it sould be from reading the fold-out wiring diagram.
The FORD OEM 1990 Econoline vacuum/electrical manual will have errors in it as all of the FORD OEM vacuum/electrical manuals I have seen do. If you study very close the fold-out wiring diagram you can see how the errors were made. Then the FORD OEM vacuum/electrical manuals were sold by Helm Inc. to the public.
Then other after market manual sellers made drawings from the FORD OEM vacuum/electrical manuals and put in their manuals. They copied the errors along with putting some errors of their own in the drawings. They even tried to make their drawings cover a few years each.
At least this is the way I understand the drawings.

I do not have the a copy of the FORD OEM 1990 Econoline vacuum/electrical manual but do have a copy of the FORD OEM 1990 F-series vacuum/electrical manual.
You should have a wire color chart in the front of your manual saying what the wire colors and symbols mean.

Most of the time the power wire to the rear tank is just Brown with a white stripe but I have seen just brown used also.

The black and orange wires are ground wires. They will have no power on them at any time but must have continuity back to the NEG post of the battery.

 

Alrighty then sir. Thanks for the info on the manuals. Like I said it looked like 3 black wires going to the rear pump. Two of one gauge and one of another, but in the ldark laying on my back one of them could very well have been brwn or brwn with a thin white line. So I am going to look at the orange as the one that will have a continuous 12 volts as long as the pump is running. That is going to be my first victim.

I'll keep you posted. Of course the van gods blessed me with a nice cool rain today. Today has GOT to be the day.

Thank you sir

Sid

 

But the orange wire is a ground wire!
NO 12V on the Orange wire!

 

Well at least I'm inside before the sun set today anyway.

I started with continuity checks across the selector switch to make absolutely sure I wired it up correctly and that it agrees with the book. I did that yesterday but I checked again. On the gauge side of the switch, pin 5 connecting to either pin 4 or 6 depending on which tank, I always had continuity to both 4 & 6 from 5, no matter what tank I selected. Pin 2 on the power side connected both to 1 & 3 correctly depending on what tank of course was selected. Something was up with the gauge side of the switch. I disconnected the switch from the harness by disconnecting C110 below the brake booster. Checking continuity again at the switch everything was correct now. Something downstream from the switch when connected to it was causing pins 4 and 6 always to be connected to pin 5. I reconnected C110 and checked again. Same problem with the gauge side of the switch. I went to the back of the van where the pump connector is just inside of the rear bumper attached to a cross member. I disconnected that and checked continuity again at the switch. The gauge side was working correctly again. Reconnected the pump connector and continuity was goofed up again. At that point I pulled the tank and it is now sitting under my deck where I siphoned all the gas out. I removed the lock ring to the pump and lifted the pump as far out as I could to just get a visual of the thing. It almost looks brand new. No frayed wires, no rust, clean sock, no goopy buildup or anything. How can I test this pump as it is right now please?

Thanks again

Sid

 

In post #31 above there is a photo that should tell you where to put your ground and hot wires to test it.

When the plugs are hooked up you will have continuity from pin #5 to Pins #4 & 6.
Not a short but you would have continuity through the sender to ground and back through the other sender to the switch.

I also noticed that the 1988 E-series diagrams are showing an Orange wire powering the front in-tank boost pump.