1986 F350 - 460 7.5L - in-tank or in-line fuel pump

[ramses]

Bought truck with an in-line fuel pump and manual switch (done by previous owner), but fuel gauge was disconnected. Old sending unit is still in tank (side mount tank) as well as 4-pin connector, just not connected. Thinking of getting new sending unit to both have fuel gauge working and a pump that I dont have to turn on and off. However, saw some models have an additional in-line pump. My engine does nto have fuel injection, so do I need to keep the in-line pump? Or take it out and just use sending unit?

If I need to keep it is there any wiring I have to be aware of?

[Gary Lewis]

This sounds so similar to another that's currently being worked. You might want to read through this thread: http://forum.garysgaragemahal.com/Misfire-wont-smog-test-Need-some-advice-td56255.html as it might have some info for you.

Having said that, if you have a manual switch to turn the pump on then you have a ticking time bomb. If you get into an accident the pump will keep on pumping.

So, if it was my truck I'd put it back essentially stock. In fact, I did just that. Big Blue was badly butchered in this area and I had to reconstruct it, so I'm familiar with this area and issue.

The wiring diagrams are here: Documentation/Electrical/EVTM/1986 EVTM and then Electric Fuel Pump Control. The diagram for a single tank is shown below. The key is the oil pressure switch and the inertia switch. Those need to be controlling the pump.

But that doesn't mean you have to ditch your pump. You could keep it, but just control it with those two safety items.

Having said that, do you know if you have an electric pump in the tank? If so, is it good?

[ramses]

This sounds so similar to another that's currently being worked. You might want to read through this thread: http://forum.garysgaragemahal.com/Misfire-wont-smog-test-Need-some-advice-td56255.html as it might have some info for you.Having said that, if you have a manual switch to turn the pump on then you have a ticking time bomb. If you get into an accident the pump will keep on pumping.So, if it was my truck I'd put it back essentially stock. In fact, I did just that. Big Blue was badly butchered in this area and I had to reconstruct it, so I'm familiar with this area and issue.The wiring diagrams are here: Documentation/Electrical/EVTM/1986 EVTM and then Electric Fuel Pump Control. The diagram for a single tank is shown below. The key is the oil pressure switch and the inertia switch. Those need to be controlling the pump.But that doesn't mean you have to ditch your pump. You could keep it, but just control it with those two safety items.Having said that, do you know if you have an electric pump in the tank? If so, is it good?

Dont know if there is a pump inside the tank (although it has a sending unit installed) or if its working. Will try to test. Should I take it out first and inspect tank? Its empty right now.

 

 

If I keep the in-line, what are the benefits?

 

 

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From: Gary Lewis [via Bullnose Enthusiasts] <redacted_email_address>

Sent: Thursday, April 16, 2020 7:06:41 PM

To: ramses <redacted_email_address>

Subject: Re: 1986 F350 - 460 7.5L - in-tank or in-line fuel pump

 

 

This sounds so similar to another that's currently being worked.  You might want to read through this thread:http://forum.garysgaragemahal.com/Misfire-wont-smog-test-Need-some-advice-td56255.html as it might have some info for you.

 

Having said that, if you have a manual switch to turn the pump on then you have a ticking time bomb.  If you get into an accident the pump will keep on pumping.

 

So, if it was my truck I'd put it back essentially stock.  In fact, I did just that.  Big Blue was badly butchered in this area and I had to reconstruct it, so I'm familiar with this area and issue.

 

The wiring diagrams are here: Documentation/Electrical/EVTM/1986 EVTM and then Electric Fuel Pump Control.  The diagram for a single tank is shown below.  The key is the oil pressure switch and the inertia switch.  Those need to be controlling the pump.

 

But that doesn't mean you have to ditch your pump.  You could keep it, but just control it with those two safety items.

 

Having said that, do you know if you have an electric pump in the tank?  If so, is it good?

 

 

http://forum.garysgaragemahal.com/file/n57049/909962.jpgGary, AKA "Gary fellow":ProfileDad'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 in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI

 

 

 

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[Gary Lewis]

Taking the sender out is a pain, but if the tank is truly EMPTY it isn't too hard. But if it has some in it the sloshing can make it unwieldy. However, there's not a lot to see if you take it out, so how will you know if it works?

The previous owner probably put the extra pump on for a reason - like the one in the tank is probably bad. So if you want to keep it, then maybe all you need to do is to put the safeties back in place and run the pump with them. And you may be able to pull the wiring for the pump out of the 4-pin connector so the sender still works.

Does the truck run ok on the new pump?

[ArdWrknTrk]

A cab & chassis will only have the side tank.

If you can peek at the top, (with a cell phone or whatever) look at the plug in the bung.

4 wires means it came with an in-tank pump, two wires, and it had a mechanical pump on the side of the timing case.

Setting it back to stock (so it is safe) should not be a problem.

 

[ramses]

A cab & chassis will only have the side tank.If you can peek at the top, (with a cell phone or whatever) look at the plug in the bung.4 wires means it came with an in-tank pump, two wires, and it had a mechanical pump on the side of the timing case.Setting it back to stock (so it is safe) should not be a problem.

Yes, truck runs ok with new pump, but its awkward to manually turn on and off. Hadnt thought of safety issue, so now its even more important.

 

 

The harness has 4 wires, so it should have in-tank pump. Makes sense the inline was installed to "replace" faulty in-tank pump but since schematic shows both, could it be it ised both?

 

 

Should I keep both working in series? Looks as if both are tied in to the right source wire they could work safely. But, again, should I use both or choose one?

 

 

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From: ArdWrknTrk [via Bullnose Enthusiasts] <redacted_email_address>

Sent: Thursday, April 16, 2020 7:54:29 PM

To: ramses <redacted_email_address>

Subject: Re: 1986 F350 - 460 7.5L - in-tank or in-line fuel pump

 

 

A cab & chassis will only have the side tank.

 

If you can peek at the top, (with a cell phone or whatever) look at the plug in the bung.

4 wires means it came with an in-tank pump, two wires, and it had a mechanical pump on the side of the timing case.

 

Setting it back to stock (so it is safe) should not be a problem.

 Jim,

Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with an Edelbrock 1826 and Performer intake.

Too much other stuff to mention.

 

 

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[kramttocs]

A cab & chassis will only have the side tank.

If you can peek at the top, (with a cell phone or whatever) look at the plug in the bung.

4 wires means it came with an in-tank pump, two wires, and it had a mechanical pump on the side of the timing case.

Setting it back to stock (so it is safe) should not be a problem.

Just to note - I had an 86 with the plastic rear tank (along with our 94 and 95). Not sure if it started in 86 (like the 4wd) or not. This truck also had the really heavy LS rear end so it was a little unique. My 80, 85, and other 86 are just the side tanks.

 

[Gary Lewis]

I don't think you want to run both. If the truck runs on the add-on pump I'd use it and get the wiring to it set up so the inertia switch and oil pressure switch are being used correctly.

[ramses]

I don't think you want to run both. If the truck runs on the add-on pump I'd use it and get the wiring to it set up so the inertia switch and oil pressure switch are being used correctly.

UPDATE 1:

Went under the hood today. Tracked down fuel pump power (pink/black) and it goes to a connector which splits into two (2) pink/black wires, one thicker than the other (Picture 1). This one goes left to what I'm guessing is a relay (I have very little experience on this) near the hood hinge (Picture 2). In fact dont know what any of the three parts in Picture 2 are.

The thinner pink/black, and a yellow wire, loop along the front to the passenger side and into the cabin, where I found this hanging (Picture 3). Inertia switch? Something rattles inside. It was close to where the arrow points.

Here is where it gets messy. Behind the battery the pink/black and yellow reach a connector where the pink/black ties into a blue wire with a fusible link, but the blue wire is cut (Picture 4). So I know the switch in the cabin is disconnected.

But the one that concerns me even more is back on the driver's side. The pink/black wire, that should loop to the passenger side, has a jumper (red wire I'm holding in Picture 5) going into a red wire in another branch. Don't know where that other red goes or what it does, so again any input is appreciated.

So I dont know if the oil pressure and inertia switches are in the loop or not. Quite sure In need to take the red jumper out and reconnect the blue wire, but is there any troubleshooting/testing in between?

In the mean time, took bench seat out, pulled old vinyl, gave frame wire wheel and rust converter. Got sliders loose and oiled but missing a spring and wire that connects both sliders' mechanisms. But guess I'll leave that for another thread.

[ramses]

UPDATE 1:

Went under the hood today. Tracked down fuel pump power (pink/black) and it goes to a connector which splits into two (2) pink/black wires, one thicker than the other (Picture 1). This one goes left to what I'm guessing is a relay (I have very little experience on this) near the hood hinge (Picture 2). In fact dont know what any of the three parts in Picture 2 are.

The thinner pink/black, and a yellow wire, loop along the front to the passenger side and into the cabin, where I found this hanging (Picture 3). Inertia switch? Something rattles inside. It was close to where the arrow points.

Here is where it gets messy. Behind the battery the pink/black and yellow reach a connector where the pink/black ties into a blue wire with a fusible link, but the blue wire is cut (Picture 4). So I know the switch in the cabin is disconnected.

But the one that concerns me even more is back on the driver's side. The pink/black wire, that should loop to the passenger side, has a jumper (red wire I'm holding in Picture 5) going into a red wire in another branch. Don't know where that other red goes or what it does, so again any input is appreciated.

So I dont know if the oil pressure and inertia switches are in the loop or not. Quite sure In need to take the red jumper out and reconnect the blue wire, but is there any troubleshooting/testing in between?

In the mean time, took bench seat out, pulled old vinyl, gave frame wire wheel and rust converter. Got sliders loose and oiled but missing a spring and wire that connects both sliders' mechanisms. But guess I'll leave that for another thread.

Oh, and along with the wiring in this area (drivers side), I found these loose contacts. Only thing close that seemed to match was this connector but, again, no idea (Picture 6). Just a random find.