Fuel Pump

Timon · 09-10-2008, 08:07 AM

I think my fuel pump busted on me!

A few reasons I suspect the pump:
1. The car will start, idle for about 10-15 seconds normally, and then slowly start to drop from there until it hits about 300-500 in which case it barely keeps itself running - if left untouched it will die.
2. If, during the 10-15 seconds of perfect idling, I rev the engine up to say 3-4k and release the throttle it will instantly die.
3. Previously I could hear the fuel pump pressurizing the line coming out of the fuel filter when the key was turned on, but the car wasn't started - now there is nothing.
4. I just finished replacing the fuel filter during the troubleshooting process just to be sure it wasn't causing any issues.

Anyone have any objection to my theory of the fuel pump being bad?

muffinman · 09-10-2008, 09:41 AM

Have you tried getting a pressure reading?

Timon · 09-10-2008, 08:42 PM

Nope, how would I go about testing the pressure on the fuel pump? I believe someone mentioned something about testing the fuel rail, but where/how would I test the fuel rail?

muffinman · 09-11-2008, 11:44 AM

On pages FI-65 thru 67 of the downloadable BGB it gives you a couple test choices while still in the vehicle including pressure test. It says you need an SST but you can make your own but you will need a fuel pressure gauge.

Timon · 09-12-2008, 01:28 AM

Okay scratch that. It isn't the fuel pump.

Thanks to Aaron I was able to narrow it down to the 'AFM' or the 'Relay, Opening Circuit'.

I visually inspected the AFM for damage on the wires, but nothing. Where and how do I check the 'Relay, Opening Circuit'?

Timon · 09-14-2008, 10:48 AM

Update: Problem solved.

I finally got my hands on a multimeter and tested the AFM. I tried two and five, as Aaron from Lithia Toyota mentioned, and I got infinite resistance. He stated if terminals two and five did not get continuity when the flap to the AFM was open then the AFM was not working properly and needed to be replaced. The way I see it, if something breaks and has to be replaced it can't hurt to tear it apart.

To make a long story short: Terminal one has a flimsy piece of metal that is held back by a rod when the flap to the AFM is at rest. When the flap is moved open the rod moves out of the way allowing the flimsy piece of metal to straighten out and touch a hard piece of metal on terminal two - therefore linking terminals one and two and creating continuity. This action is what actually turns on the fuel pump.

Problem & Resolution: The flimsy piece of metal connected to terminal one did straighten out, but it was not reaching terminal two when the flap was open. From the looks of it, somehow terminal two was moved just a hair off and no connection was made. Terminal seven wasn't plugged in as well, but that is problem due to me taking the AFM apart.

09-10-2008, 08:07 AM	#1 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 628 Thanks: 13 Thanked 37 Times in 33 Posts My Google Map iTrader Rating: (0/0% )	Fuel Pump I think my fuel pump busted on me! A few reasons I suspect the pump: 1. The car will start, idle for about 10-15 seconds normally, and then slowly start to drop from there until it hits about 300-500 in which case it barely keeps itself running - if left untouched it will die. 2. If, during the 10-15 seconds of perfect idling, I rev the engine up to say 3-4k and release the throttle it will instantly die. 3. Previously I could hear the fuel pump pressurizing the line coming out of the fuel filter when the key was turned on, but the car wasn't started - now there is nothing. 4. I just finished replacing the fuel filter during the troubleshooting process just to be sure it wasn't causing any issues. Anyone have any objection to my theory of the fuel pump being bad?

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09-10-2008, 09:41 AM	#2 (permalink)
muffinman Brain Surgeon Join Date: Jan 2008 Location: Ft. Lauderdale Posts: 1,805 Thanks: 24 Thanked 102 Times in 99 Posts My Google Map iTrader Rating: (1/100% )	Have you tried getting a pressure reading?

09-10-2008, 08:42 PM	#3 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 628 Thanks: 13 Thanked 37 Times in 33 Posts My Google Map iTrader Rating: (0/0% )	Nope, how would I go about testing the pressure on the fuel pump? I believe someone mentioned something about testing the fuel rail, but where/how would I test the fuel rail?

09-11-2008, 11:44 AM	#4 (permalink)
muffinman Brain Surgeon Join Date: Jan 2008 Location: Ft. Lauderdale Posts: 1,805 Thanks: 24 Thanked 102 Times in 99 Posts My Google Map iTrader Rating: (1/100% )	On pages FI-65 thru 67 of the downloadable BGB it gives you a couple test choices while still in the vehicle including pressure test. It says you need an SST but you can make your own but you will need a fuel pressure gauge.

09-12-2008, 01:28 AM	#5 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 628 Thanks: 13 Thanked 37 Times in 33 Posts My Google Map iTrader Rating: (0/0% )	Okay scratch that. It isn't the fuel pump. Thanks to Aaron I was able to narrow it down to the 'AFM' or the 'Relay, Opening Circuit'. I visually inspected the AFM for damage on the wires, but nothing. Where and how do I check the 'Relay, Opening Circuit'?

09-14-2008, 10:48 AM	#6 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 628 Thanks: 13 Thanked 37 Times in 33 Posts My Google Map iTrader Rating: (0/0% )	Update: Problem solved. I finally got my hands on a multimeter and tested the AFM. I tried two and five, as Aaron from Lithia Toyota mentioned, and I got infinite resistance. He stated if terminals two and five did not get continuity when the flap to the AFM was open then the AFM was not working properly and needed to be replaced. The way I see it, if something breaks and has to be replaced it can't hurt to tear it apart. To make a long story short: Terminal one has a flimsy piece of metal that is held back by a rod when the flap to the AFM is at rest. When the flap is moved open the rod moves out of the way allowing the flimsy piece of metal to straighten out and touch a hard piece of metal on terminal two - therefore linking terminals one and two and creating continuity. This action is what actually turns on the fuel pump. Problem & Resolution: The flimsy piece of metal connected to terminal one did straighten out, but it was not reaching terminal two when the flap was open. From the looks of it, somehow terminal two was moved just a hair off and no connection was made. Terminal seven wasn't plugged in as well, but that is problem due to me taking the AFM apart.