Fuel Selector Valve on '86 E150

Hi!
I'm new to the forum and am looking for help with the fuel system wiring on my '86 E150 5.0L EFI.  Hoping that its similar enough to the F150s that I can finally get this figured out.  I've had this van since 1998 when it had 163K miles.  Four years and 10K miles ago I replaced the rear tank sending unit.  Three years and 8K miles ago I replaced the OEM fuel selector valve.  My van has the "hot fuel handling" set up - each tank has an electric lift pump, and there is a high pressure pump on the frame rail forward of the fuel selector valve (OEM E67B-9F271-AA).  

Recently while driving, shortly after switching tanks the engine died.  I was able to restart but both tanks showed no fuel, though both had about 3/8 of a tank.  I was able to drive only 20-50 yds at a time before it would die again.  I got it home (about 2 miles) by restarting, driving a short distance, dying, restarting, repeat. The whole time neither tank would register any fuel.  Checked it the next day, and a couple times since, and the front tank pump and sending unit are working now, but the rear are not.  When the rear pump runs, it's easy to hear it underneath the van and the front tank is easy to hear by listening at the fuel inlet.

A similar problem happened three years ago. Only then, the rear tank pump wouldn't turn on but the rear fuel gauge would continue to read the fuel level that it had been reading on the front tank.  At that time, I tested the switch (it was ok), and after purchasing a wiring diagram, I determined the problem was most likely the fuel selector valve.  The universal replacement available at any parts store would not work without drilling new mounting holes and changing the fuel line connections (I have quick connects).  The only OEM replacements (E5TZ-9189B) I could find then were several hundred dollars so I opted for the chinese replacement that's available on Ebay (6C3Z9189A) for $50.  That fixed the problem...for a while.

Looking at the this page (http://www.garysgaragemahal.com/fuel-system-wiring.html), although my van is an '86, I appear to have the setup that is on the 1985 EVTM page - 4 wires leaving the switch, each pump wire (R to rear and BR/W to front) splits with one going to the pump and one to the FSV.  Though my wire colors are slightly different (R/Y to rear, BR/O to front), they seem to follow this schematic.  

However, my '86 wiring schematic only shows the front tank pump wire (BR/O) splitting.  For the rear tank, it shows a R/BR wire coming from the fuel pump cutoff relay to the pump and only an orange wire between the FSV and the sending unit. That doesn't seem to be what I have.

My questions:
1 - does anyone have an EVTM trouble shooting guide for the 1985 5.0L EFI?  I found the '86 but given the different wiring not sure it would help.

2 - I have found the intertia switch before but where is the fuel pump cutoff relay?  and if either were the problem, wouldn't both tank pumps (and the high pressure pump) not turn on?  That's the point of the intertia switch, right?

3 - If the selector switch tests okay, then that leaves wiring or FSV.  But since both rear sending unit and pump are not working, both wires would have to be cut/shorting out, yes?

I had to get a new fuse for my multitester so will start testing circuits this weekend.  I'll post a photo of my schematic tomorrow when I can take a pic in daylight.

thanks

Your E-series is very similar to the F series of those years, but I can't swear that all the wire colors etc. are the same. You should have the fuel reservoir on the frame near the high pressure pump. This also functions as the tank selector valve, it has two diaphragms in it that are pressurized by the in-tank low pressure pumps.

On the rear tank, not having had one out on an E-series, I can't say how hard it is to get to the connector on the pump/sender assembly but those are a common problem on F-series trucks of that era. There will be 4 wires into that connector, red/yellow is pump power, orange is gauge sender and the 2 black wires are grounds.

Looking at my AllData diagrams, it does not show the reservoir, but shows a motor driven tank selector valve like the 460 engines with hot fuel handling used. The diagrams also show that the grounds for each tank are near the tank, G402 is the rear tank and location is given as "attached to center of last crossmember". This is based on you having the EFI engine and implies that only 2 high pressure pumps were used which I question the accuracy of as I worked on a 1989 E-150 and it still had the three pumps and frame mounted reservoir.

Have you not found our 1985 EVTM?  It is at Documentation/Electrical/EVTM/1985 EVTM in the menu.  However, it is specifically for the F-Series and full-sized Broncos, not the E-Series vans.  But Ford was pretty consistent in the wire colors and systems, so it should help.  And it does have the 5.0L EFI info in it.

ah, yes, now I see it.  Pages 108 and 109 here - http://www.garysgaragemahal.com/electric-fuel-pump-control1.html

Now to find where the G701 is on this van...

LOL!  John/Machspeed and I were just texting about G701.  On a pickup or Bronco it is on the firewall behind the instrument panel, just to the right of the radio.

On Page 67 of the '85 EVTM there is an illustration showing where G701 is on the trucks.

Try this: Note there is no G701 listed for the E150, also the tank unit (pump and sender) are grounded near the tanks rather than being brought up inside the cab.

Ok, first, the E series wiring is different than the F series, for one thing the grounds for the tank units are at the nearest cross member, not brought up inside the body like the pickups. The diagrams I am finding show the three pump system, but since I do not have what I believe to be completely correct information regarding the reservoir for the high pressure pump (maybe the 1985/86 E series didn't use it, I know the 1989 E series did as I have dealt with one of those. Here are the two versions I have found, both show a tank selector valve which is probably the big motor operated 6 port the carburated 460 with hot fuel handling package used in the F series. Maybe one of our parts guys can shed some light on the plumbing.

Here is what I have found:

First the 1986 E150 diagram:


Second one identified as 1985-1987 multiple applications. This shows both a tank selector switch and a tank selector valve, I am interpreting that as a one or the other, not both as theay are show as wired in parallel.

Bill,  if it's anything like what is going on with the trucks, the valve does switch power to the in-tank pumps and which sender is connected to the gauge.

The Pollak valve has seemed a good replacement for most applications I've have to deal with.

Jim, I am aware of how the F series and the 89 E series I had worked on were set up on the EFI systems. The 460s with the hot fuel handling package used the 6 port motor operated valve. The EFI systems through 1989 used the diaphragm operated switching valve in the fuel reservoir (filters were used in 1985/86 on F series).

The main difference I see is that the inertia switch is after the relay on the smaller engines.

It's interesting that Ford would choose to complicate things by adopting two different setups.

Jim, you have to remember, EFI was being rolled out in steps, 1985 - 5.0L EFI, 1987, 4.9L, and base 5.8L EFI, 1988, all gas engines got EFI. The other item was the 460 hot fuel handling package was used when certain criteria were met, AC, hot climate or ambulance chassis where vapor lock would be an issue. The EFI had one or two in-tank pumps, probably 10-15 psi and a high pressure pump 35 psi on V8s and early 6s, 55 psi on later 6s, the hot fuel handling package was 2 low pressure pumps 6 psi is the spec and those needed a 6 port motor operated selector valve that also changed the sender connection as 6 psi wasn't enough to work the selector valve for the EFI system.

351 carbureted engines used a mechanical pump and 3 port valve.

My 460 uses a mechanical pump and a 3 port valve.....

I'm not certain why an EFI system that has a lift pump in each tank and a reservoir/boost pump on the frame rail needs the inertia switch after the fuel pump relay, but a Hot Fuel truck should have the inertia switch feeding the fuel pump relay.  

I'm just to dumb to understand what Ford engineers reasons were.

Bill,
Thanks so much!  That top diagram matches exactly what I have traced down on the van, including where the grounds are.  Since I have yet to find the C134, C135, S108 or  S113, I've only been assuming those connections based on wire colors at the switch, valve and tanks.  

Now that my multitester is working again I'll look harder for all of those connections and doublecheck the grounds but this reaffirms my suspicion that there are really only a couple of possibilities when both the rear pump and sending unit are out - switch not flipping the polarity of the circuit running into the FSV, or FSV solenoid no longer functioning (I guess both wires to the rear tank could be broken but given how the problem started that seems unlikely).

Thanks again.

Ok, I have the list for connectors and splices printed out.
C134 - LH side of dash panel near ignition module (underhood)
C135 - On rear crossmember
S108 - in the harness probably near C134
S113 - probably the same area

On the splices, factory they are essentially spot welded. I would unplug C134, C135 and the fuel tank selector valve. Check continuity from C134 Circuits 739 and 808 to the selector valve connector and 739 to C135. 808 will involve unplugging the front tank connector, since it is working I would leave it alone. Circuit 286 is rear tank sender and Gary has a chart (I believe) on the site with resistance values.

You might get lucky and find C135 unplugged or just plain dirty. Good luck!

I finally had time to get back to this and I think I finally grok these circuits (thanks again, Bill).  

After all the disconnecting/reconnecting of wiring and cleaning of connections, the original problem that almost left me stranded - neither tank sending unit or pump working - is now gone.  Both sending units are working (I added gas to the front tank to make sure it was reading a different level than the rear) and the front pump turns on.  The only thing that does not appear to turn on is the rear tank pump.  

On the 739 circuit (pump) I get 10 V at the tank.  The 286 fuel gauge circuit reads 0-4 V pulsating.  I disconnected both circuits at the C135 (it was hidden between the tow bar and the bumper) and tested the circuits from there to ground.  The pump read 3 ohms and the sending unit read 30 ohms.  

What should the resistance across the pump be here (C135 to ground)?  I can't access the front sending unit connections so I don't know what a working pump should read.  

I also tested voltage at the FSV connector. When switched to the rear tank, I get 10V on 739 and 0 V on 808 circuits.  When in the front position, I get the inverse - 10V on 808 and 0 V on 739.  This tells me the dash switch is working properly (I also pulled the switch and tested the connectors in both positions and it behaves correctly).

In either switch position, the 673 sending unit circuit from the gauge reads 1-5V pulsating at the FSV connector.  That seems correct.  The 285 and 675 circuits read 0 V, as expected, because those circuits to the tanks are disconnected when the FSV connector is disconnected.

All this tells me the switch and the FSV are working correctly (recall, I can hear when the front pump is running), and the problem is the rear tank pump.  When I knew it was working you could definitely hear it.  One last test that I still need to do is disconnect the From Tank fuel line at the FSV and confirm that no gas is being pumped when rear tank is switched on.

This pump was replaced 4 years and 10K miles ago (its probably only been used for about 6K miles of that though).  Am I missing anything else, or did I just get a lousy pump?

and, of course, what caused the initial problem is still a mystery, but until that happens again, not sure what I can do about it.  I suspect the FSV solenoid got hung up when I switched tanks on that drive since it happened right after that.  I may invest in a spare...

thanks

Glad to hear you're getting it figured out!

Bummer the rear pump seems to have given up the ghost.  

Yes, so glad you are making progress!