Papelione Posted August 26, 2020 Author Share Posted August 26, 2020 X2! I'm glad you were able to track down the discontinuity in your tail lights. Hi guys When I bought the truck November last year, one of the problems was that the seller had was that the "in tank" pump of the front tank was not working, and he had installed a aftermarket fuel pump on the left fender inside the engine bay. (Picure 1. below). But the sender in the front tank isn´t really up to speed, and will only indicated the first 30 liters of fuel, I believe the front tank holds 19 gallons or 72 liters (picture 2). Further more he wasn´t sure if the rear tank (picture 3) was working, and recommended that I inspected it first. He included a fuel pump, since he himself would like to address this problem , but never got around to do it. (picture 4, Airtex Electric In-Tank Fuel Pumps E2089S). Obviously I would like to use both tanks and get a good reading from both senders, otherwise on longer trips I will have to keep a keen eye on distance travelled or face running dry. But I am uncertain to what is the better choice pump "in engine bay" or "in tank". Guessing in tank pumps was the original setup, but if external pump is better I don't mind keeping that. How would you go about this? drop rear tank and inspect? pour fuel in and try it out? sounds empty and have not been in use for at least 2 years. Pic 1: Current fuel pump Pic 2 : side or front mounted tank, works fine, sender only first 30 liters. Pic 3: Rear tank, doesn't seam rusty (on the outside). Pic 4: Airtex Electric In-Tank Fuel Pumps E2089S, that I got with the truck. Best /Christian Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 26, 2020 Share Posted August 26, 2020 Hi guys When I bought the truck November last year, one of the problems was that the seller had was that the "in tank" pump of the front tank was not working, and he had installed a aftermarket fuel pump on the left fender inside the engine bay. (Picure 1. below). But the sender in the front tank isn´t really up to speed, and will only indicated the first 30 liters of fuel, I believe the front tank holds 19 gallons or 72 liters (picture 2). Further more he wasn´t sure if the rear tank (picture 3) was working, and recommended that I inspected it first. He included a fuel pump, since he himself would like to address this problem , but never got around to do it. (picture 4, Airtex Electric In-Tank Fuel Pumps E2089S). Obviously I would like to use both tanks and get a good reading from both senders, otherwise on longer trips I will have to keep a keen eye on distance travelled or face running dry. But I am uncertain to what is the better choice pump "in engine bay" or "in tank". Guessing in tank pumps was the original setup, but if external pump is better I don't mind keeping that. How would you go about this? drop rear tank and inspect? pour fuel in and try it out? sounds empty and have not been in use for at least 2 years. Pic 1: Current fuel pump Pic 2 : side or front mounted tank, works fine, sender only first 30 liters. Pic 3: Rear tank, doesn't seam rusty (on the outside). Pic 4: Airtex Electric In-Tank Fuel Pumps E2089S, that I got with the truck. Best /Christian I would say (at best!) the fender mounted fuel pump is a patch job. Yes, your mid-ship tank should have a capacity of 19 U.S. gallons. One has to ask, if the rear pump doesn't work, and the side tank pump doesn't work, where does the trouble lie? That underhood wiring looks pretty questionable... I would try to fix the in-tank pump problem and eliminate the pump under the hood. Your 1984 truck has what's known as 'Hot Fuel Handling' There some variations of this system over the years but the basics are that there are two safety features -before the power relays- that will shut off the pumps if the engine stalls or the truck has an impact. You will find a inertia switch in the passenger footwell, with a yellow wire and a reset button on top. This circuit is fed by a fuse, and is the (eventual) power to the pump. Then there will be a relay, that is closed by the oil pressure switch at the back of the engine (behind the EGR valve) Now they're are two variations, either: The power goes directly to the switching valve beneath the driver. Or: The power goes to a tank selector relay, and then to the valve beneath the driver. In all cases the valve moves to connect supply and return lines, and choose which pump is powered. Some valves switch the senders too, and in some trucks that function is provided at the switch on the left of the climate bezel. Typically default is the rear tank. So our first matter of business is finding if power is actually making it to that switch valve. And second is understanding why or how it is the side tank connected, if by default it should be the rear. Link to comment Share on other sites More sharing options...
Papelione Posted August 26, 2020 Author Share Posted August 26, 2020 I would say (at best!) the fender mounted fuel pump is a patch job. Yes, your mid-ship tank should have a capacity of 19 U.S. gallons. One has to ask, if the rear pump doesn't work, and the side tank pump doesn't work, where does the trouble lie? That underhood wiring looks pretty questionable... I would try to fix the in-tank pump problem and eliminate the pump under the hood. Your 1984 truck has what's known as 'Hot Fuel Handling' There some variations of this system over the years but the basics are that there are two safety features -before the power relays- that will shut off the pumps if the engine stalls or the truck has an impact. You will find a inertia switch in the passenger footwell, with a yellow wire and a reset button on top. This circuit is fed by a fuse, and is the (eventual) power to the pump. Then there will be a relay, that is closed by the oil pressure switch at the back of the engine (behind the EGR valve) Now they're are two variations, either: The power goes directly to the switching valve beneath the driver. Or: The power goes to a tank selector relay, and then to the valve beneath the driver. In all cases the valve moves to connect supply and return lines, and choose which pump is powered. Some valves switch the senders too, and in some trucks that function is provided at the switch on the left of the climate bezel. Typically default is the rear tank. So our first matter of business is finding if power is actually making it to that switch valve. And second is understanding why or how it is the side tank connected, if by default it should be the rear. Ok went out under the truck, and found the switch. as I understand this valve from each tank a return and feed line goes into the switch, and from the switch to engine also goes a return and feed, 3 lines in, 3 lines out 6 lines in total. But on mine there seams to be a bypass, where a previous owner has blocked some of the lines, Im guessing feed from front tank to switch, and paired it with feed from switch to engine? seams likely? Next step, pull connectors and test if power, (test light) with key in run? Switch valve seen from the rear, lines going from tanks to switch Switch valve seen from side front of connecter, lines going from switch to engine Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 26, 2020 Share Posted August 26, 2020 Ok went out under the truck, and found the switch. as I understand this valve from each tank a return and feed line goes into the switch, and from the switch to engine also goes a return and feed, 3 lines in, 3 lines out 6 lines in total. But on mine there seams to be a bypass, where a previous owner has blocked some of the lines, Im guessing feed from front tank to switch, and paired it with feed from switch to engine? seams likely? Next step, pull connectors and test if power, (test light) with key in run? Switch valve seen from the rear, lines going from tanks to switch Switch valve seen from side front of connecter, lines going from switch to engine You won't get power in run. Only if the oil pressure safety is bypassed. This is why I say to check the safeties first. If you take the plug loose note the wire colours and positions. This will help us identify which version you have. Gary just very recently went through this with his Big Blue truck. So, it may all be fresher in his mind. At least the diagrams are posted in his thread from a couple of days ago. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 26, 2020 Share Posted August 26, 2020 You won't get power in run. Only if the oil pressure safety is bypassed. This is why I say to check the safeties first. If you take the plug loose note the wire colours and positions. This will help us identify which version you have. Gary just very recently went through this with his Big Blue truck. So, it may all be fresher in his mind. At least the diagrams are posted in his thread from a couple of days ago. Yes, it is fresh - as is the smell of gasoline on my watch band. Jim has explained it well, but just to make sure you understand, Christian, the system has two lines from each tank to the valve, a supply and a return, and two on to the engine. And the hot fuel handling system has a tiny orifice that returns a bit of fuel at all times to keep it circulating and, therefore, cool. But, if I were in your shoes I'd seriously consider if I need two tanks. It is having two tanks that causes all of the problems. Ford went through several iterations of fuel systems on these trucks, and many of them failed. So, the first question is do you need to store your spare tire under the rear of the truck? If not, I'd suggest you buy either a 33 gallon Bronco standard tank or the 38 gallon upgrade tank for the Bronco. It'll fit in the rear where your existing tank is, but you can't get a spare tire under it. However, then you don't need a front tank and you can eliminate the valve, which is a known failure point and expensive to replace. Link to comment Share on other sites More sharing options...
Papelione Posted August 26, 2020 Author Share Posted August 26, 2020 You won't get power in run. Only if the oil pressure safety is bypassed. This is why I say to check the safeties first. If you take the plug loose note the wire colours and positions. This will help us identify which version you have. Gary just very recently went through this with his Big Blue truck. So, it may all be fresher in his mind. At least the diagrams are posted in his thread from a couple of days ago. Ok You want me to check power to inertia switch and relay behind EGR valve. But at the connector to the valve switch there was power in "run" and front tank selected. With rear tank selected, no power in any of the 5 wires. from the top 1. wire is Yellow/blue band-no light 2.wire is white -blinking light 3. wire is blue/green-no light 4.wire is bli/white-continious light 5.wire is red-no light Gary, your right off course. But I would rather like to try keeping the two tanks since it was born with it. Best Christian Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 26, 2020 Share Posted August 26, 2020 Ok You want me to check power to inertia switch and relay behind EGR valve. But at the connector to the valve switch there was power in "run" and front tank selected. With rear tank selected, no power in any of the 5 wires. from the top 1. wire is Yellow/blue band-no light 2.wire is white -blinking light 3. wire is blue/green-no light 4.wire is bli/white-continious light 5.wire is red-no light Gary, your right off course. But I would rather like to try keeping the two tanks since it was born with it. Best Christian The oil pressure switch is behind the EGR. This controls the fuel pump safety relay by providing ground to the pull in coil. If there is no oil pressure the pumps get no power passed to them. Do you have power in-and-out of the inertia switch with the key in 'RUN'? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 26, 2020 Share Posted August 26, 2020 Yes, it is fresh - as is the smell of gasoline on my watch band. Jim has explained it well, but just to make sure you understand, Christian, the system has two lines from each tank to the valve, a supply and a return, and two on to the engine. And the hot fuel handling system has a tiny orifice that returns a bit of fuel at all times to keep it circulating and, therefore, cool. But, if I were in your shoes I'd seriously consider if I need two tanks. It is having two tanks that causes all of the problems. Ford went through several iterations of fuel systems on these trucks, and many of them failed. So, the first question is do you need to store your spare tire under the rear of the truck? If not, I'd suggest you buy either a 33 gallon Bronco standard tank or the 38 gallon upgrade tank for the Bronco. It'll fit in the rear where your existing tank is, but you can't get a spare tire under it. However, then you don't need a front tank and you can eliminate the valve, which is a known failure point and expensive to replace. The 6-port Pollak valve (kit with pigtail) is $75 delivered. I don't think I can buy the dashboard switch for that.... "Expensive" relative to what? How much in parts between your tanks and carb -including the regulator-, and you don't even have a switch valve at all, just a waterproof relay and a project case.. Link to comment Share on other sites More sharing options...
Papelione Posted August 26, 2020 Author Share Posted August 26, 2020 The oil pressure switch is behind the EGR. This controls the fuel pump safety relay by providing ground to the pull in coil. If there is no oil pressure the pumps get no power passed to them. Do you have power in-and-out of the inertia switch with the key in 'RUN'? Yes the connector to the Inertia switch has power in "run". Having trouble finding the Fuel tank selector relay, in the EVTM it says it should be under the dash, but cant see it. Right at the other side of the firewall, LH side at the engine compartment there is a green and grey relay. the engine mounted fuel pump has been spliced into the red wire going to from the green relay, could the green one be the Fuel tank selector relay? /Christian Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 26, 2020 Share Posted August 26, 2020 At the connector to the valve switch there was power in "run" and front tank selected. With rear tank selected, no power in any of the 5 wires. from the top 1. wire is Yellow/blue band-no light 2.wire is white -blinking light 3. wire is blue/green-no light 4.wire is bli/white-continious light 5.wire is red-no light This tells me someone has rewired your truck and bypassed the safety features. If you want to get back to both tanks working, they should be working properly. Link to comment Share on other sites More sharing options...
Recommended Posts