no power to fuel pump
01-28-2012, 09:43 AM
#12
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If you look at the schematic for the 1990, you'll see the pump circuit doesn't get its power from a fuse. It gets it from fusible link W.
While the Haynes manual is informative, the schematic I provided is specifically for a 1990 F series and is a Ford publication. Use what you want and good luck.
While the Haynes manual is informative, the schematic I provided is specifically for a 1990 F series and is a Ford publication. Use what you want and good luck.
01-28-2012, 11:29 AM
#13
November 2011 TOTM Winner
Check for 12vdc at the yellow wire in your fuel pump relay socket. It should be present all the time. If present the link is good. If not present then the problem is upstream in either the relay socket wiring, the wire itself, the link, or where it connects to the starter relay hot post on the right hand fender apron.
When you check for volts at the relay socket if not present give a good look to the contact and wiring at the socket. This is a known trouble point.
Fusible links are interesting little devices in that they are little links that go right into the wire harness that will open up like a fuse when its current carrying capacity is exceeded. If unfamiliar with it you could confuse it with a splice. They are widely available at auto parts stores and this particular link would be marked "20 guage blue". They require basic skills at wire stripping and splicing to replace.
When you check for volts at the relay socket if not present give a good look to the contact and wiring at the socket. This is a known trouble point.
Fusible links are interesting little devices in that they are little links that go right into the wire harness that will open up like a fuse when its current carrying capacity is exceeded. If unfamiliar with it you could confuse it with a splice. They are widely available at auto parts stores and this particular link would be marked "20 guage blue". They require basic skills at wire stripping and splicing to replace.
Last edited by 5Rangers; 01-28-2012 at 12:27 PM.
01-28-2012, 05:13 PM
#14
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Check for 12vdc at the yellow wire in your fuel pump relay socket. It should be present all the time. If present the link is good. If not present then the problem is upstream in either the relay socket wiring, the wire itself, the link, or where it connects to the starter relay hot post on the right hand fender apron.
When you check for volts at the relay socket if not present give a good look to the contact and wiring at the socket. This is a known trouble point.
Fusible links are interesting little devices in that they are little links that go right into the wire harness that will open up like a fuse when its current carrying capacity is exceeded. If unfamiliar with it you could confuse it with a splice. They are widely available at auto parts stores and this particular link would be marked "20 guage blue". They require basic skills at wire stripping and splicing to replace.
When you check for volts at the relay socket if not present give a good look to the contact and wiring at the socket. This is a known trouble point.
Fusible links are interesting little devices in that they are little links that go right into the wire harness that will open up like a fuse when its current carrying capacity is exceeded. If unfamiliar with it you could confuse it with a splice. They are widely available at auto parts stores and this particular link would be marked "20 guage blue". They require basic skills at wire stripping and splicing to replace.
01-28-2012, 08:36 PM
#15
Senior Member
Something else you need to remember you will only have power going to the fuel pumps for a few seconds after you turn on the key unless you jumper the data plug to ground or pull the pump relay and jumper a wire from a hot source to the output tereminal on the relay block. The best way being the data plug.
Last edited by Nitehawkjr; 01-28-2012 at 08:41 PM.
01-28-2012, 10:17 PM
#16
November 2011 TOTM Winner
True dat. With the relay installed the jumper plug takes the place of the EEC by putting a ground on the control circuit side causing the relay to switch and close putting power through the pump side of the relay. The Op should be testing with the relay out. It looks like the Op thinks he does not have any power coming from the battery buss side of the relay for the pump power circuit which is a straight shot over from the fusible link in the engine control harness near the starter relay.
Last edited by 5Rangers; 01-28-2012 at 10:22 PM.