1988 F150 No Power to Fuel Pumps
#1
1988 F150 No Power to Fuel Pumps
I need help please... I have a 1988 F150 standard truck. The motor is a 300 six cylinder 4.9. It does not have air conditioning, no power windows or locks. It is a basic truck.
This fuel pumps in both tanks are not working.
All fuses under dash are working.
I replaced both relays under the hood with new ones.
I replaced the ignition coil and it is getting a good spark.
I removed all the connections on the solenoid and sanded each connection to remove any rust.
I confirmed the solenoid was working properly with my test meter.
I replaced the tank selection toggle switch on my dash with a new one.
Both fuel tanks are full of gas.
I used a rubber hammer to hit each tank hoping it would caused the fuel pumps to come on and did not work.
When I turn the key to the on position I can hear the high pressure pump cycle on for about 2 seconds but i cannot hear the pumps in either tank come on.
I can spray starting fluid into the throttle body and the truck starts with ease and runs very smooth until the starting fluid is completely used.
The past two mornings I went out to try to start it and when I turned the key to the on position I could hear the fuel pump in the rear tank come on. Yesterday morning the truck ran smooth for about 4 minutes and then shut down and would not start back up. This morning I could hear the fuel pump in the rear tank and started the truck and it ran pretty rough for less than 1 minute and would not start back up.
The fuel gauge shows empty when the front / rear toggle switch is on the front tank. When it's on the rear tank the fuel gauge shows full.
I tried to pull codes from the computer by jumping the EEC and the check engine light stayed on and would not work for me.
Question: If the tank selector valve under the truck was clogged.. would that prevent both tank pumps to come on?
I attached a picture of two connectors... Could anyone tell me what they are please?
Thank You Very Much for any help provided!!
This fuel pumps in both tanks are not working.
All fuses under dash are working.
I replaced both relays under the hood with new ones.
I replaced the ignition coil and it is getting a good spark.
I removed all the connections on the solenoid and sanded each connection to remove any rust.
I confirmed the solenoid was working properly with my test meter.
I replaced the tank selection toggle switch on my dash with a new one.
Both fuel tanks are full of gas.
I used a rubber hammer to hit each tank hoping it would caused the fuel pumps to come on and did not work.
When I turn the key to the on position I can hear the high pressure pump cycle on for about 2 seconds but i cannot hear the pumps in either tank come on.
I can spray starting fluid into the throttle body and the truck starts with ease and runs very smooth until the starting fluid is completely used.
The past two mornings I went out to try to start it and when I turned the key to the on position I could hear the fuel pump in the rear tank come on. Yesterday morning the truck ran smooth for about 4 minutes and then shut down and would not start back up. This morning I could hear the fuel pump in the rear tank and started the truck and it ran pretty rough for less than 1 minute and would not start back up.
The fuel gauge shows empty when the front / rear toggle switch is on the front tank. When it's on the rear tank the fuel gauge shows full.
I tried to pull codes from the computer by jumping the EEC and the check engine light stayed on and would not work for me.
Question: If the tank selector valve under the truck was clogged.. would that prevent both tank pumps to come on?
I attached a picture of two connectors... Could anyone tell me what they are please?
Thank You Very Much for any help provided!!
#2
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Join Date: Jan 2018
Location: Memphis, TN, Earth, Milky Way
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Why did you replace the relays? Why did you replace the coil? What solenoid are you talking about? We need to know the truck's whole history (everything YOU know) so we understand the whole situation. Click this, read the caption, and fill in your signature:
(phone app link)
ID connectors by their WIRE COLORS, using this & the NEXT few pages:
(phone app link)
Wiring diagrams are free at this site, but it requires an e-mail to access. It doesn't check if it's your e-mail, or even real.
http://www.bbbind.com/free_tsb.html
No, the switching valve (DFR) has nothing to do with pump power. This diagram shows how the fuel flows, and the caption contains a link to more info about your truck's early system:
(phone app link)
Unplug the HP pump on the frame so you can hear the selected tank pump. If it still doesn't run, check voltage at the tank pump connector using the information in these captions:
(phone app link)
(phone app link)
The captions in this album explain how to repair & test the fuel level senders:
(phone app link)
(phone app link)
ID connectors by their WIRE COLORS, using this & the NEXT few pages:
(phone app link)
Wiring diagrams are free at this site, but it requires an e-mail to access. It doesn't check if it's your e-mail, or even real.
http://www.bbbind.com/free_tsb.html
No, the switching valve (DFR) has nothing to do with pump power. This diagram shows how the fuel flows, and the caption contains a link to more info about your truck's early system:
(phone app link)
Unplug the HP pump on the frame so you can hear the selected tank pump. If it still doesn't run, check voltage at the tank pump connector using the information in these captions:
(phone app link)
(phone app link)
The captions in this album explain how to repair & test the fuel level senders:
(phone app link)