Toyota MR2 Message Board - View Single Post - 4A-GE MK1 Engine mk1 mr2 fuel pump help

te51levin · 05-04-2009, 07:49 PM

First post, huh? Welcome to the board! Now on to business...

Whoa, wait, stop hold up! You're better off testing parts than replacing them.

There is no fuel pump relay, per se. The fuel pump gets its power from the circuit opening relay. This sends power while the starter is engaged and then, if told to, continues to send power to the fuel pump once the engine is running.

Is your airflow meter plugged in? If not, plug it in, because you need it in place. There is a switch inside it that sends power to the circuit opening relay when the engine is inhaling air, which allows the circuit opening relay to send power to the fuel pump. Check your manual (online BGB or a cheap Haynes manual from Half.com ) to see how to test the switch inside the AFM. Basically you're looking for continuity between two particular terminals at the AFM connector when the AFM door has been opened slightly.

If that is not the issue, run a jumper wire from B+ to Fp in the diagnostic connector (located in the engine bay). This bypasses the circuit opening relay and sends power directly from the battery to the fuel pump. Again, even the Haynes manual covers this in greater detail than I can go into here, from memory.

Where in Oregon are you? Anywhere near the Eugene/Springfield area?

05-04-2009, 07:49 PM	#2 (permalink)
te51levin LithiaToyotaParts.com Join Date: Oct 2005 Location: Copperhead Road Posts: 3,672 Thanks: 50 Thanked 317 Times in 261 Posts My Google Map iTrader Rating: (193/100% )	First post, huh? Welcome to the board! Now on to business... Whoa, wait, stop hold up! You're better off testing parts than replacing them. There is no fuel pump relay, per se. The fuel pump gets its power from the circuit opening relay. This sends power while the starter is engaged and then, if told to, continues to send power to the fuel pump once the engine is running. Is your airflow meter plugged in? If not, plug it in, because you need it in place. There is a switch inside it that sends power to the circuit opening relay when the engine is inhaling air, which allows the circuit opening relay to send power to the fuel pump. Check your manual (online BGB or a cheap Haynes manual from Half.com ) to see how to test the switch inside the AFM. Basically you're looking for continuity between two particular terminals at the AFM connector when the AFM door has been opened slightly. If that is not the issue, run a jumper wire from B+ to Fp in the diagnostic connector (located in the engine bay). This bypasses the circuit opening relay and sends power directly from the battery to the fuel pump. Again, even the Haynes manual covers this in greater detail than I can go into here, from memory. Where in Oregon are you? Anywhere near the Eugene/Springfield area?