EFI For Big Blue

[85lebaront2]

The TSB is now shown in TSB/Fuel Cross-Flow, and the parts are available from Amazon. But there's one part number for 1990 & 91, and another for 1992 & 93.

Will need to do some research as to how available the pumps are, but apparently things changed as of 1994, so I wonder if I should go with the later style pumps and bypass the TSB?

Gary. I know the fuel lines changed in 1994 along with the pump modules, the 1994 ones use a pigtail on the module that plugs into the harness. 1996 should be the same and the EVTM will reflect that. On the lines, if you need it I can pull up the 1996 and I also have 1993-1994 F-series manuals, the problem is they only will run in a 32 bit version of Windows so I have to restart the computer in a 32 bit Windows 10 environment.

[NotEnoughTrucks]

Bill - I have both tanks from Huck, and one good pump/sending unit. And I have the fuel lines. But, there are no external check valves on them, so tell me more about those check valves. But, the sending units won't work at all with the Bullnose gauges. As Ray pointed out, the resistance range is backwards. No go.

Ray - I do believe I can put the Bullnose sender on the later pump. But that will be fiddly and not something I expect any of my offspring to be able to do. And, we all know that sending units and pumps are notoriously faulty these days.

I really don't want anything fiddly to maintain. So, I'm thinking about four options:

• Valves: If I had 4 electrically-operated on/off valves, or two 2-way valves they could be driven by the tank selector switch and I could run the 85.5/86 in-tank and high-pressure pumps.

• Later fuel gauge in a Bullnose cluster. Bullnose is 10 ohms full and 73 ohms empty, while the '96 temp gauge, and therefore probably the '87+ fuel gauges, are 74 ohms full and 9.7 ohms empty. Essentially backwards. Could maybe Rocketman modify the gauge?

• Arduino: This is the one that I think has possibilities. I've asked my nephew if he could program an Arduino to run pulse-width modulation to effectively reverse things. I could pretty easily map the voltage that the Bullnose gauge "sees" at various points from Full to Empty and then a table could be created that, when averaged, gives those voltages. That way I can use the later pumps and sending units.

Thoughts?

Crazy how one change induces so many others.

Much as I like that big old reliable frame mounted HP pump, the dual function reservoir becomes a problem. I have never had one fail, but it would seem they used the last bit of unobtanium to build them.

So, on to the later tanks with the fuel delivery modules. Two problems here, the cross fueling issue and gauge compatibility.

It's my understanding that the check valves in the TSB were to correct a deficiency in the early FDM's. Ford has discontinued this part and new FDM's are equipped with a revised shuttle valve that solves the problem. If you are using new FDM's, you should not need the external valves. Not all trucks exhibited the problem, so not all trucks got the recall.

Using an Arduino to reverse the fuel gauge may be effective, but I think it could be done with a relatively simple linear circuit using a transistor for a current sink and a few other discrete components to bias properly. Used to do interface stuff like that all the time back in the 20th century.

I think we all want to preserve as much of the bullnose flavour as possible in our trucks, but there also is the possibility of aftermarket gauges. Personally, I detest ammeters and would change my gauge to a voltmeter. If I am changing one gauge, possibly I may consider a second? Now I am wondering if bricknose gauge movement could be installed in a bullnose cluster?

My fertile mind is now pondering these possibilities. Got cold weather out here to keep me indoors and I think I have a bullnose cluster on hand to experiment with. Perhaps I just need to clean out the fertilizer in my head!

[Gary Lewis]

Gary. I know the fuel lines changed in 1994 along with the pump modules, the 1994 ones use a pigtail on the module that plugs into the harness. 1996 should be the same and the EVTM will reflect that. On the lines, if you need it I can pull up the 1996 and I also have 1993-1994 F-series manuals, the problem is they only will run in a 32 bit version of Windows so I have to restart the computer in a 32 bit Windows 10 environment.

Bill - You should be able to start 32-bit apps in a different mode. Right click on the icon and click Troubleshoot Compatibility.

Anyway, the page below from your EVTM (mine is said to be "in the mail") shows a harness from C205, which is at the firewall, to C441 which is at the tank. Also, there's a note on that page that the sending unit resistance is 22.5 ohms empty to 145 ohms full - which is different than the temp sending unit. But that's not a problem with the Arduino idea, it just changes the equation.

So, do the '94 and later models require a different tank? And what is the difference in fuel lines?

[Gary Lewis]

Crazy how one change induces so many others.

Much as I like that big old reliable frame mounted HP pump, the dual function reservoir becomes a problem. I have never had one fail, but it would seem they used the last bit of unobtanium to build them.

So, on to the later tanks with the fuel delivery modules. Two problems here, the cross fueling issue and gauge compatibility.

It's my understanding that the check valves in the TSB were to correct a deficiency in the early FDM's. Ford has discontinued this part and new FDM's are equipped with a revised shuttle valve that solves the problem. If you are using new FDM's, you should not need the external valves. Not all trucks exhibited the problem, so not all trucks got the recall.

Using an Arduino to reverse the fuel gauge may be effective, but I think it could be done with a relatively simple linear circuit using a transistor for a current sink and a few other discrete components to bias properly. Used to do interface stuff like that all the time back in the 20th century.

I think we all want to preserve as much of the bullnose flavour as possible in our trucks, but there also is the possibility of aftermarket gauges. Personally, I detest ammeters and would change my gauge to a voltmeter. If I am changing one gauge, possibly I may consider a second? Now I am wondering if bricknose gauge movement could be installed in a bullnose cluster?

My fertile mind is now pondering these possibilities. Got cold weather out here to keep me indoors and I think I have a bullnose cluster on hand to experiment with. Perhaps I just need to clean out the fertilizer in my head!

Yes, one change has a huge knock-on effect. And there were many such changes.

On the interface, it doesn't have to be all that accurate. I suggested the Arduino 'cause I can see how to make it work. Just do some math and come up with the guestimated current and voltage for Full and Empty on a Bullnose combo. Do other math and come up with the voltage the Arduino will see at Full and Empty using the later sender. Then write an equation that maps one to the other, using some scaling factors that can be adjusted.

But if you can do it easier, great!

As for the newer FDM's, will the fit in the tanks?

[85lebaront2]

Bill - You should be able to start 32-bit apps in a different mode. Right click on the icon and click Troubleshoot Compatibility.

Anyway, the page below from your EVTM (mine is said to be "in the mail") shows a harness from C205, which is at the firewall, to C441 which is at the tank. Also, there's a note on that page that the sending unit resistance is 22.5 ohms empty to 145 ohms full - which is different than the temp sending unit. But that's not a problem with the Arduino idea, it just changes the equation.

So, do the '94 and later models require a different tank? And what is the difference in fuel lines?

Ok, first, I have tried it, these will only run in a 32 bit OS. Fuel lines, yes they are different, push lock connectors that require a release tool. On the pump modules front tank is C440, rear tank is C441. I will see what I have, I do have the front fuel lines off the F450 here.

[Gary Lewis]

Ok, first, I have tried it, these will only run in a 32 bit OS. Fuel lines, yes they are different, push lock connectors that require a release tool. On the pump modules front tank is C440, rear tank is C441. I will see what I have, I do have the front fuel lines off the F450 here.

Bill - Hold off looking for a bit. I think we have a winner. The FDM off of Huck's side tank fits the 38 gallon rear tank that I have perfectly, although the connections are backwards. However, that means that the rear FDM from Huck will fit the big tank, and its connections are reversed. And, I can use the front/side tank that's on Big Blue with a new FDM, use Huck's side tank with a new FDM, or buy a whole tank/FDM assembly. And all of those parts are available! Plus, I have the necessary fuel lines.

Here's Huck's rear tank and FDM:

Here's Huck's front FDM in the 38 gallon rear tank - connections are reversed from Huck's rear tank:

And, Huck's front/side tank and correct FDM:

[85lebaront2]

Bill - Hold off looking for a bit. I think we have a winner. The FDM off of Huck's side tank fits the 38 gallon rear tank that I have perfectly, although the connections are backwards. However, that means that the rear FDM from Huck will fit the big tank, and its connections are reversed. And, I can use the front/side tank that's on Big Blue with a new FDM, use Huck's side tank with a new FDM, or buy a whole tank/FDM assembly. And all of those parts are available! Plus, I have the necessary fuel lines.

Here's Huck's rear tank and FDM:

Here's Huck's front FDM in the 38 gallon rear tank - connections are reversed from Huck's rear tank:

And, Huck's front/side tank and correct FDM:

Gary, I printed out a bunch of fuel system information from the 1993, 1994 and 1996 Ford service manuals. As near as I can determine the push lock connections replaced the slip on nylon lines with the plastic "hairpin" starting in 1992, in 1994 the fuel pump module was changed from 4 pins on top with a large curved plastic plug with 3 retainers (used as far back as 1983 with the hot fuel handling package) to a module mounted pigtail with a 4 pin plug on the end, this was used through the end of production on the OBS trucks. Apparently with the change, either the extra check valve was incorporated in the module or the internals were modified to where it wasn't needed.

You asked earlier something regarding the over 8500 lb notes, this is the point at which some emission and safety requirements change. The evaporative system on an >8500 lb vehicle has openings to the atmosphere, where the 8500 vehicles even in 1996 did not have air bags, and the F450 Jim stripped did not have ABS, the wiring in the dash is there, but the connector goes to a dummy socket to keep it in place.

[Gary Lewis]

Gary, I printed out a bunch of fuel system information from the 1993, 1994 and 1996 Ford service manuals. As near as I can determine the push lock connections replaced the slip on nylon lines with the plastic "hairpin" starting in 1992, in 1994 the fuel pump module was changed from 4 pins on top with a large curved plastic plug with 3 retainers (used as far back as 1983 with the hot fuel handling package) to a module mounted pigtail with a 4 pin plug on the end, this was used through the end of production on the OBS trucks. Apparently with the change, either the extra check valve was incorporated in the module or the internals were modified to where it wasn't needed.

You asked earlier something regarding the over 8500 lb notes, this is the point at which some emission and safety requirements change. The evaporative system on an >8500 lb vehicle has openings to the atmosphere, where the 8500 vehicles even in 1996 did not have air bags, and the F450 Jim stripped did not have ABS, the wiring in the dash is there, but the connector goes to a dummy socket to keep it in place.

Bill - I assume the connectors shown below are slip on nylon lines with the plastic "hairpin". Right?

Anyway, with the exception of two of those connectors that appear to have gotten too close to the cutting torch that cut Huck in half, I have a complete set of fuel lines. I'll just have to replace those two connectors as well as figure out what to do about the vent lines. As it turns out, while Huck has a GVWR of 8600# he did have the evap canisters.

Having said that, I have some question about what appears to be a filter in the line, so if you could post or send me the diagrams of the 1990 fuel system that might be a big help.

As for the 4-pin connector, that's one of the beauties of this approach - the harness on Big Blue will plug into the FDM's. So it looks like the post-'86 and pre-'94 systems are the way to go, and 1990 appears to be the sweet spot.

Here's one of the connectors - a good one:

And here's one that flew too close to the sun:

[85lebaront2]

Bill - I assume the connectors shown below are slip on nylon lines with the plastic "hairpin". Right?

Anyway, with the exception of two of those connectors that appear to have gotten too close to the cutting torch that cut Huck in half, I have a complete set of fuel lines. I'll just have to replace those two connectors as well as figure out what to do about the vent lines. As it turns out, while Huck has a GVWR of 8600# he did have the evap canisters.

Having said that, I have some question about what appears to be a filter in the line, so if you could post or send me the diagrams of the 1990 fuel system that might be a big help.

As for the 4-pin connector, that's one of the beauties of this approach - the harness on Big Blue will plug into the FDM's. So it looks like the post-'86 and pre-'94 systems are the way to go, and 1990 appears to be the sweet spot.

Here's one of the connectors - a good one:

And here's one that flew too close to the sun:

Yes those are the ones. Was the burned one a straight or right angle one? I should have spares from my kit (If you are going to be doing them for Dad's you might want to invest in one). As for a diagram of the 1990, I can look, but not promise anything. I don't think I took pictures of it laid out, and did the extension work on the truck so there was no question on length.

[85lebaront2]

Yes those are the ones. Was the burned one a straight or right angle one? I should have spares from my kit (If you are going to be doing them for Dad's you might want to invest in one). As for a diagram of the 1990, I can look, but not promise anything. I don't think I took pictures of it laid out, and did the extension work on the truck so there was no question on length.

Here are the pictures I took earlier of the 1995 front fuel lines from Jim:

I think blue is supply and gray is return.