bad fpr?

3.0trd · 04-24-2008, 10:42 PM

so I did some very advanced testing (pulled fuel line off, jumped fuel pump) and, yeah, no fuel whatsoever... but with the jumper wire in, if I go to the filler neck, I can hear the pump working. apparently there is no flow though. could it be the pump? and still no noise under the hood when I jump the pump.

cre · 04-24-2008, 11:50 PM

You are aware that the fuel pump is IN the fuel tank, right? If you hear it from the filler neck it's probably not the problem unless the impeller broke free... in which case there's usually a little extra clatter.

If you're getting no fuel from the line your possibilities are:
Fuel pump (you could use an ammeter across FP and B+ to see if the pump is actually drawing power)
Clogged fuel filter
crush or blockage in the fuel line

If it's the filter or the pump it's usually easiest to pull the tank and replace both at the same time.

3.0trd · 04-25-2008, 12:04 AM

so, with the key on, the fp- b+ should have 12 v, or do I use an ohm reading?

cre · 04-25-2008, 12:18 AM

Nope... Across B+ and the battery's ground there should always be 12v with the ignition in the on position.

To read current draw you need to set the meter for 10A, connect the leads in the correct locations on the meter (it's usually got a different plug for the positive lead), set the meter to 10A (or higher if depending on the meter), then you place the + lead in the B+ position and the - lead in the FP location, the meter will act as a jumper. The pump should start up and the meter will display the amperage being drawn... if I mixed up the + and - positions it'll show the amperage as -5.3A (or whatever), it's not an issue though.

If the coil in the fuel pump is shot the amperage will be very little or 0. If the pump is seized the amperage will be high.

And of course, I don't recall what the specs are supposed to be if it's good... :P

04-24-2008, 10:42 PM	#1
3.0trd 3" Exhaust Join Date: Mar 2008 Location: Cali Posts: 76	so I did some very advanced testing (pulled fuel line off, jumped fuel pump) and, yeah, no fuel whatsoever... but with the jumper wire in, if I go to the filler neck, I can hear the pump working. apparently there is no flow though. could it be the pump? and still no noise under the hood when I jump the pump.

04-24-2008, 11:50 PM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	You are aware that the fuel pump is IN the fuel tank, right? If you hear it from the filler neck it's probably not the problem unless the impeller broke free... in which case there's usually a little extra clatter. If you're getting no fuel from the line your possibilities are: Fuel pump (you could use an ammeter across FP and B+ to see if the pump is actually drawing power) Clogged fuel filter crush or blockage in the fuel line If it's the filter or the pump it's usually easiest to pull the tank and replace both at the same time.

04-25-2008, 12:04 AM	#3
3.0trd 3" Exhaust Join Date: Mar 2008 Location: Cali Posts: 76	so, with the key on, the fp- b+ should have 12 v, or do I use an ohm reading?

04-25-2008, 12:18 AM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Nope... Across B+ and the battery's ground there should always be 12v with the ignition in the on position. To read current draw you need to set the meter for 10A, connect the leads in the correct locations on the meter (it's usually got a different plug for the positive lead), set the meter to 10A (or higher if depending on the meter), then you place the + lead in the B+ position and the - lead in the FP location, the meter will act as a jumper. The pump should start up and the meter will display the amperage being drawn... if I mixed up the + and - positions it'll show the amperage as -5.3A (or whatever), it's not an issue though. If the coil in the fuel pump is shot the amperage will be very little or 0. If the pump is seized the amperage will be high. And of course, I don't recall what the specs are supposed to be if it's good... :P