91 e350 5.8 fuel pumps not turning on
#1
03-20-2020, 03:42 PM
91 e350 5.8 fuel pumps not turning on
i have a 91 e350 with dual tanks and a 5.8. I know there are tons of diag procedires online. I have power coming in and out of the eec relay and the fuel pump relay. the computer is supplying the proper ground. Now as I am typing I have thought of something. when I jump the terminals at the relay the fuel pump will come on, but when I try to ground the #6 pin t the self test connector the fuel pump does not turn on. Does this mean anything? Also, i believe its the yellow #4 wire at the fuel relay tht should supply 12v with the key on? well mine is always hot. obviously that is a problem, but all my testing said everything except when i want to test for 12v coming out of the relay. I hook the volt meter up and cuse tht wire is already hot I have 12v but when I turned key it dropped to .5v My battery was a bit weeek so imma chek that now and check the inertia switch for powers as well. Anyone have ny thoughts?
#2
03-20-2020, 09:14 PM
Are you aware the ECA will activate the fuel pump relay for only 2 seconds when you first turn the key on ,,UNLESS, it gets an RPM signal from the ign syst
If you ground that terminal of the diagnostic plug with the key on the fuel pump should run. From the fuel pump relay power has to go through the fuel tank selector sw on the dash , thru the inertia sw down to the fuel pump. If all that checks out , make sure you have a good ground for the fuel pumps to work.
What happens if you switch fuel tanks?.
If you ground that terminal of the diagnostic plug with the key on the fuel pump should run. From the fuel pump relay power has to go through the fuel tank selector sw on the dash , thru the inertia sw down to the fuel pump. If all that checks out , make sure you have a good ground for the fuel pumps to work.
What happens if you switch fuel tanks?.
#3
03-21-2020, 06:09 AM
No difference if I switch tanks. Heres the deal...as I said in the original post, if I jump the fuel relay I get the pump to run...but if I ground out fuel pump connection at the test port I get nothing. Also...I'm only getting 7 volts coming into the inertia switch when the plug is disconnected...if I plug it in I get zero going in and out...or if I put a jumper between the 2 pins at the selector wire I still get nothing. I think I figured out it's a problem with the pink/black wire coming out fuel relay to selector switch. From there it looks like a wire goes to the fuel pump and one to the select switch. I'm thinking if I tap into the connectors and just run 2 wires directly to the selector switch and to fuel pump it should solve that problem correct? Sorry but when it comes to electrical i really lost.but I'm learning more and more.
#4
03-21-2020, 08:03 AM
Some questions,
Are you sure you are grounding the correct terminal at the diagnostic plug, AND are you doing that check WITH THE KEY ON? Those 2 steps should cause the pumps to run , both the one in the selected tank and the hi pressure pump on the chassis rail. Yes/ No
Are you sure you are grounding the correct terminal at the diagnostic plug, AND are you doing that check WITH THE KEY ON? Those 2 steps should cause the pumps to run , both the one in the selected tank and the hi pressure pump on the chassis rail. Yes/ No
#5
03-21-2020, 10:38 AM
[QUOTE=hanky;118106]Some questions,
Are you sure you are grounding the correct terminal at the diagnostic plug, AND are you doing that check WITH THE KEY ON? Those 2 steps should cause the pumps to run , both the one in the selected tank and the hi pressure pump on the chassis rail.
Yes...I am che king with the key on. I believe I am grounding the correct terminal..the#6 terminal. If your looking at it with the smaller end towards the top it's the terminal in the bottom right corner? I know it makes no sense. I also assume this is a problem...the #4 yellow wire on the fuel relay connector is always hot...with out they key on its hot..I have been fighting a huge draw in this thing and I guess I stumbled into finding it with this fuel system diag. If I apply 12 volts at the pump it also turns on so I'm pretty confident the pump not the problem. What about this...I check the connector at the inertia switch and the wire going in I have voltage but only 7volts. When I plug it into the inertia switch I have no volts in or out...thanks for your help btw.
Are you sure you are grounding the correct terminal at the diagnostic plug, AND are you doing that check WITH THE KEY ON? Those 2 steps should cause the pumps to run , both the one in the selected tank and the hi pressure pump on the chassis rail.
Yes...I am che king with the key on. I believe I am grounding the correct terminal..the#6 terminal. If your looking at it with the smaller end towards the top it's the terminal in the bottom right corner? I know it makes no sense. I also assume this is a problem...the #4 yellow wire on the fuel relay connector is always hot...with out they key on its hot..I have been fighting a huge draw in this thing and I guess I stumbled into finding it with this fuel system diag. If I apply 12 volts at the pump it also turns on so I'm pretty confident the pump not the problem. What about this...I check the connector at the inertia switch and the wire going in I have voltage but only 7volts. When I plug it into the inertia switch I have no volts in or out...thanks for your help btw.
#6
03-21-2020, 02:27 PM
If you are looking at the test connector, place the plug so you have the letter H in the middle, and the 2 end terminal openings so the openings look like an upside down top hat. The terminal on the right is the one you would ground with the key on and the fuel pumps should run. Do they? That causes the fuel pump relay to activate and close.
The only time you should be able to measure any voltage at the inertia switch is when you first turn the key on for that 2 seconds unless you have jumped the terminal at the test plug, then you should get power from the F/P relay and the pumps run.
I believe your EEC and fuel pump relays are mounted on the passenger side at the firewall just below the windshield , kinda above the battery.
Looking at the FP relay , on the bottom you should see terminal numbers.
30 is for the power to the relay, 87 is power out of the relay and going to the inertia sw. 85 & 86 are the terminals that activate the relay.(85 =negative term)
Terminal 30 should be hot at all times. Are you jumping 30 and 87 to get the pumps to run? Need to make sure we are both on the same page.
The only time you should be able to measure any voltage at the inertia switch is when you first turn the key on for that 2 seconds unless you have jumped the terminal at the test plug, then you should get power from the F/P relay and the pumps run.
I believe your EEC and fuel pump relays are mounted on the passenger side at the firewall just below the windshield , kinda above the battery.
Looking at the FP relay , on the bottom you should see terminal numbers.
30 is for the power to the relay, 87 is power out of the relay and going to the inertia sw. 85 & 86 are the terminals that activate the relay.(85 =negative term)
Terminal 30 should be hot at all times. Are you jumping 30 and 87 to get the pumps to run? Need to make sure we are both on the same page.
Last edited by hanky; 03-21-2020 at 02:36 PM.
#7
03-21-2020, 04:20 PM
https://easyautodiagnostics.com/ford...-relay-tests-1
That is the link I have been following for the tests I have done. Of course the ford relays I have are not labeled with the typical 30 85 86 87 but 1 2 3 4..but when I figure out the orientation of it all I am jumping the correct relay terminals. There a bit if a discrepancy with the self connector. I have always looked at the connector as the shape of a house. If so, to test the fuel pump I have been grounded the bottom right...everything I search tells me that's the fuel pump test. The way your describing it...based on your top hot analogy, my house would need to be turned upside? And if that's the case I am testing the wrong terminal. Everything else you mentioned checks accurate with what I tested and the results I'm getting....I think.
That is the link I have been following for the tests I have done. Of course the ford relays I have are not labeled with the typical 30 85 86 87 but 1 2 3 4..but when I figure out the orientation of it all I am jumping the correct relay terminals. There a bit if a discrepancy with the self connector. I have always looked at the connector as the shape of a house. If so, to test the fuel pump I have been grounded the bottom right...everything I search tells me that's the fuel pump test. The way your describing it...based on your top hot analogy, my house would need to be turned upside? And if that's the case I am testing the wrong terminal. Everything else you mentioned checks accurate with what I tested and the results I'm getting....I think.
#8
03-21-2020, 06:18 PM
I did look at the site you posted and if that is what you have , by all means use it.
I will attempt to describe the self test connector from a pix I have in front of me.
You are using the correct terminal using the right hand terminal, however, if you originate the plug so all the terminal holes go across the plug on the bottom.
There should be 4 openings in line on the bottom and only 2 openings in line on the top of the letter H located in the center.
I did find a pix of your description of a house and that is OK too.I would say we are pretty much on the same page now.
You should be able to energize the fuel pump(s) grounding that terminal with the key on. What result are you getting?
Using the electrical pix on the site you showed,
#1 is the ground terminal to the relay coil
#4 is the power into the relay ,Hot at all times
#3 is the wire that goes to the pumps
#2 is the wire that provides power to the relay coil to energize the relay
If you ground the terminal on the test plug with the key on, the relay should close and send power to the inertia sw , through the selector sw to the fuel pump, does it?
If so OK. If not what voltage are you getting at terminal 3 of the relay,that wire should go to the inertia sw.
For my own info , which terminals of the relay plug are you jumping that get the pumps to run? It would seem if you by pass the relay manually and the pump runs, it should do the same thing if you energize the relay. If not , there is a good possibility the relay is not sending full voltage down to the pump and could be defective internally. (dirty contacts)
I will attempt to describe the self test connector from a pix I have in front of me.
You are using the correct terminal using the right hand terminal, however, if you originate the plug so all the terminal holes go across the plug on the bottom.
There should be 4 openings in line on the bottom and only 2 openings in line on the top of the letter H located in the center.
I did find a pix of your description of a house and that is OK too.I would say we are pretty much on the same page now.
You should be able to energize the fuel pump(s) grounding that terminal with the key on. What result are you getting?
Using the electrical pix on the site you showed,
#1 is the ground terminal to the relay coil
#4 is the power into the relay ,Hot at all times
#3 is the wire that goes to the pumps
#2 is the wire that provides power to the relay coil to energize the relay
If you ground the terminal on the test plug with the key on, the relay should close and send power to the inertia sw , through the selector sw to the fuel pump, does it?
If so OK. If not what voltage are you getting at terminal 3 of the relay,that wire should go to the inertia sw.
For my own info , which terminals of the relay plug are you jumping that get the pumps to run? It would seem if you by pass the relay manually and the pump runs, it should do the same thing if you energize the relay. If not , there is a good possibility the relay is not sending full voltage down to the pump and could be defective internally. (dirty contacts)
Last edited by hanky; 03-28-2020 at 07:25 PM.
#9
03-22-2020, 01:49 PM
Ok..things have changed..my know it all father in law who is never wrong has made this a difficult process. So, apparently he has not been getting a good connection in the terminal on the test plug. We have done the fuel pump/test plug test many times over the past few days and the pumps have never run. I agree, it makes no sense that I can jump terminals 3 and 4(87 and 30) on the relay and pump turns on but they not turn on with the self test connector. Well, mr. Knowitall made a mistake and last night he finally plugged things in right and grounding out the terminal 6..the bottom right terminal if looking at the test plug with the row of 4 terminals on the bottom, finally the pumps run. This is where I am a bit confused and maybe you can clarify. So far every test from the link I sent you have worked or passed or end result was what you would want up until test 5. On terminal 3 with the key on there is 12bvolts, when cranking the voltage drops to 1 volt or less. That must mean something? To recap..
1. Power at the fp relay low circuit #2
2. Power at the fp relay high cicuit #4
3. The fuel pump turns on when jumping the relay or test plug
4. The computer is grounding the #4 wire at the relay
5. With the key on there are 12 volts at #3 wire but voltage drops when cranking.
1. Power at the fp relay low circuit #2
2. Power at the fp relay high cicuit #4
3. The fuel pump turns on when jumping the relay or test plug
4. The computer is grounding the #4 wire at the relay
5. With the key on there are 12 volts at #3 wire but voltage drops when cranking.
#10
03-22-2020, 02:40 PM
OK !
Hey Brandon,ya know what the penalty is for having 3 wives,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,3 mothers in law !!
So,,,,,the power that comes to terminal 3 comes from the fuel pump fuse at the fuse panel.. I would suggest you check that area for some possible corrosion .
Don't get hung up on that reading as long as the pumps run when the test terminal is grounded.
From what we have learned so far ,the pumps should run for the 2-3 seconds when you first turn the key on , do they ?
Hey Brandon,ya know what the penalty is for having 3 wives,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,3 mothers in law !!
So,,,,,the power that comes to terminal 3 comes from the fuel pump fuse at the fuse panel.. I would suggest you check that area for some possible corrosion .
Don't get hung up on that reading as long as the pumps run when the test terminal is grounded.
From what we have learned so far ,the pumps should run for the 2-3 seconds when you first turn the key on , do they ?