Stalled, no FP hum. Hum when hotwired...
82Stang
07-08-2014, 08:13 PM
1993 S10 Blazer 4.3L Vortec 8th digit vin W auto 4 door 220K+, strictly a personal plow vehicle now, retired.
Driving the field a month or two ago, Blazer died. Upon trying to restart, noticed no FP hum. Prepared to do a FP replacement and opened the back floor for easy access to top of tank. 4 wires coming out of FP sending unit, 2 to somewhere underneath the vehicle and 2 to the plug. One of the underneath wires was disconnected, so I fixed it, no difference. Unplugged FP, hotwired plug to battery, FP works. Checked other side/car side of FP plug and got about 8volts on hot with KOEO. Prob only 8 because I've been cranking it and battery is getting worn on.
It shouldn't be a FP issue, as I verified it works. There could be a break in the line between the FP plug and up front at the relay. I assume the two plugged relays driver side front left of brake booster, are the proper relay set. I swapped relays side to side, no difference. I do not hear clicking of the relay when turning the key on. I heard there is an open terminal for directly powering the FP somewhere around these relays. If anyone has a picture of it, I'd very much appreciate it. Also heard the oil sending unit plays a part as well with the FP, but not checked.
I have another relay pack to swap in, but not convinced that will help. I checked the fuses and realized the ECMB was blown, replaced it and no difference. If I have a wiring issue, which is very possible with this old rusty truck, I have no problem running wiring right from the FP plug in back, to upfront and under the hood. I don't have to worry about being pretty or routing wires properly, as this is an old beater that just needs to work in the driveway.
The spider and under plenum works, I've attended too before so that is not an issue. Any ideas or pictures would be so appreciated. When I hotwired the FP directly to the battery, vehicle still would not start. As this is a work in progress, I welcome tips and pointers in the right direction. Thank you.
Driving the field a month or two ago, Blazer died. Upon trying to restart, noticed no FP hum. Prepared to do a FP replacement and opened the back floor for easy access to top of tank. 4 wires coming out of FP sending unit, 2 to somewhere underneath the vehicle and 2 to the plug. One of the underneath wires was disconnected, so I fixed it, no difference. Unplugged FP, hotwired plug to battery, FP works. Checked other side/car side of FP plug and got about 8volts on hot with KOEO. Prob only 8 because I've been cranking it and battery is getting worn on.
It shouldn't be a FP issue, as I verified it works. There could be a break in the line between the FP plug and up front at the relay. I assume the two plugged relays driver side front left of brake booster, are the proper relay set. I swapped relays side to side, no difference. I do not hear clicking of the relay when turning the key on. I heard there is an open terminal for directly powering the FP somewhere around these relays. If anyone has a picture of it, I'd very much appreciate it. Also heard the oil sending unit plays a part as well with the FP, but not checked.
I have another relay pack to swap in, but not convinced that will help. I checked the fuses and realized the ECMB was blown, replaced it and no difference. If I have a wiring issue, which is very possible with this old rusty truck, I have no problem running wiring right from the FP plug in back, to upfront and under the hood. I don't have to worry about being pretty or routing wires properly, as this is an old beater that just needs to work in the driveway.
The spider and under plenum works, I've attended too before so that is not an issue. Any ideas or pictures would be so appreciated. When I hotwired the FP directly to the battery, vehicle still would not start. As this is a work in progress, I welcome tips and pointers in the right direction. Thank you.
Automotive Network, Inc., Copyright ©2025