mk1 mr2 fuel pump help

ctritr · 05-04-2009, 06:16 PM

so i have an 87 mr2 that used to start...but it sat over the winter with no gas in the tank, so the fuel pump got all rusty and stopped working. I had a Celica Fuel pump laying around so i put that in. It looked exactly like the mr2 one, so i decided it was ok to just use that. When i go to start the car, it starts for about 4 seconds and then dies. I put a test lamp to the positive lead of the fuel pump and for some reason it doesn't get power when the ignition is on the acc position, (i know my Honda does)...but it does get power when i turn the ignition to start it, then when it starts and i let the key go, (back to acc position) it no longer gets power. My first thought was the fuel pump relay, but i can't find it. Anyone know where it's located? I know i have one laying around somewhere cause i parted out an 85, so getting one is not a problem. I changed the ignition switch and i'm gonna change the fuel filter maybe later on today. Thanks for any 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?

ctritr · 05-05-2009, 03:43 AM

Quote:

Originally Posted by te51levin

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?

So earlier I took out my AFM and found that the flap was stuck in the closed position, so I got some MAF sensor cleaner and got it loose and working smoothly. I got home late tonight and read your reply...I checked the resistance when the flap is fully closed and fully open, and when it's fully closed I'm reading 400 ohms over the tolerance...so i guess that means i need a new AFM. Do you know anywhere i can get one for cheap? I'm a college student and my only income is the car parts i sell on ebay lol...but i will call LKQ tomorrow to see if they have any mr2's in the yard. Also, I might have a Corrola AFM laying around...I looked up the part numbers and they're just one number off. Do you think it will work if i use a Corrola one? From what i understand it should only change the gas mileage. Correct?

I live in Boring...so not near the Eugene area.

Thanks for all your help btw...

te51levin · 05-05-2009, 10:41 AM

Before you buy another AFM, isolate your test to the fuel pump switch within the AFM. Make sure that you have no continuity between the first and second terminals (E1 and Fc) with the AFM door fully closed, and full continuity (zero resistance) between them as soon as the AFM door is opened slightly. If this checks out OK, don't replace the AFM just yet. Test it, test the circuit opening relay, try the jumper, etc.

Good luck man!

ctritr · 05-05-2009, 03:52 PM

I checked the switch like you said, and it doesn't have continuity when the door is slightly open...what now?

te51levin · 05-05-2009, 04:01 PM

Well, since the AFM at least appears to be bad, you've got nothing to lose by cutting the seal and removing the lid. You'll see the little switch contacts inside, and with any luck you will find a broken wire that can be repaired.

Just for fun, have you tried starting the car with the jumper wire between B+ and Fp in the diagnostic box?

ctritr · 05-05-2009, 04:16 PM

yeah I used that to see if my fuel pump was working and it is...Now I started the car with the jumper wire in place and it stays started like it should.

te51levin · 05-05-2009, 04:23 PM

Oh, excellent. Then it's narrowed down to either the switch in the AFM or the circuit opening relay, or possibly an open circuit in the wiring (unlikely), with evidence that it's the switch in the AFM. If you're able to repair it, you can simply reseal the lid with silicon and be on your way...fingers crossed!

ctritr · 05-05-2009, 04:25 PM

i popped open the lid and everything looks good...no broken wires.

te51levin · 05-05-2009, 04:39 PM

Can you see the switch making contact when you open the flapper door a little? Might be worth poking around a little more.

ctritr · 05-05-2009, 04:47 PM

The switch only makes contact when the door is closed. When I open the door, it moves away and no longer makes contact. The funny thing is that FC is just hanging out there not touching anything...i put a test lamp to it and it's a ground. When i touch FC to E1 i hear the fuel pump come on.

te51levin · 05-05-2009, 04:59 PM

Oh, how embarrassing, I think I got it backwards. That's what I get for going off of memory rather than dissecting an AFM...

ctritr · 05-05-2009, 05:09 PM

I got it!! it works!...You were right, when the flap opens slightly, FC is supposed to touch E1...but somehow E1 bent (low temperatures maybe?) and the flap would hit E1 and never get to FC...hard to explain. But i fixed it...thanks a lot for your help.

te51levin · 05-06-2009, 01:37 AM

Excellent! Glad to hear it is working as it should.

05-04-2009, 06:16 PM	#1 (permalink)
ctritr slacker Join Date: May 2009 Location: Boring, Or Posts: 28 Thanks: 6 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	mk1 mr2 fuel pump help so i have an 87 mr2 that used to start...but it sat over the winter with no gas in the tank, so the fuel pump got all rusty and stopped working. I had a Celica Fuel pump laying around so i put that in. It looked exactly like the mr2 one, so i decided it was ok to just use that. When i go to start the car, it starts for about 4 seconds and then dies. I put a test lamp to the positive lead of the fuel pump and for some reason it doesn't get power when the ignition is on the acc position, (i know my Honda does)...but it does get power when i turn the ignition to start it, then when it starts and i let the key go, (back to acc position) it no longer gets power. My first thought was the fuel pump relay, but i can't find it. Anyone know where it's located? I know i have one laying around somewhere cause i parted out an 85, so getting one is not a problem. I changed the ignition switch and i'm gonna change the fuel filter maybe later on today. Thanks for any help.

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05-04-2009, 07:49 PM	#2 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,921 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (125/100% )	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?

05-05-2009, 10:41 AM	#4 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,921 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (125/100% )	Before you buy another AFM, isolate your test to the fuel pump switch within the AFM. Make sure that you have no continuity between the first and second terminals (E1 and Fc) with the AFM door fully closed, and full continuity (zero resistance) between them as soon as the AFM door is opened slightly. If this checks out OK, don't replace the AFM just yet. Test it, test the circuit opening relay, try the jumper, etc. Good luck man!

05-05-2009, 03:52 PM	#5 (permalink)
ctritr slacker Join Date: May 2009 Location: Boring, Or Posts: 28 Thanks: 6 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I checked the switch like you said, and it doesn't have continuity when the door is slightly open...what now?

05-05-2009, 04:01 PM	#6 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,921 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (125/100% )	Well, since the AFM at least appears to be bad, you've got nothing to lose by cutting the seal and removing the lid. You'll see the little switch contacts inside, and with any luck you will find a broken wire that can be repaired. Just for fun, have you tried starting the car with the jumper wire between B+ and Fp in the diagnostic box?

05-05-2009, 04:16 PM	#7 (permalink)
ctritr slacker Join Date: May 2009 Location: Boring, Or Posts: 28 Thanks: 6 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	yeah I used that to see if my fuel pump was working and it is...Now I started the car with the jumper wire in place and it stays started like it should.

05-05-2009, 04:23 PM	#8 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,921 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (125/100% )	Oh, excellent. Then it's narrowed down to either the switch in the AFM or the circuit opening relay, or possibly an open circuit in the wiring (unlikely), with evidence that it's the switch in the AFM. If you're able to repair it, you can simply reseal the lid with silicon and be on your way...fingers crossed!

05-05-2009, 04:25 PM	#9 (permalink)
ctritr slacker Join Date: May 2009 Location: Boring, Or Posts: 28 Thanks: 6 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	i popped open the lid and everything looks good...no broken wires.

05-05-2009, 04:39 PM	#10 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,921 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (125/100% )	Can you see the switch making contact when you open the flapper door a little? Might be worth poking around a little more.

05-05-2009, 04:47 PM	#11 (permalink)
ctritr slacker Join Date: May 2009 Location: Boring, Or Posts: 28 Thanks: 6 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	The switch only makes contact when the door is closed. When I open the door, it moves away and no longer makes contact. The funny thing is that FC is just hanging out there not touching anything...i put a test lamp to it and it's a ground. When i touch FC to E1 i hear the fuel pump come on.

05-05-2009, 04:59 PM	#12 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,921 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (125/100% )	Oh, how embarrassing, I think I got it backwards. That's what I get for going off of memory rather than dissecting an AFM...

05-05-2009, 05:09 PM	#13 (permalink)
ctritr slacker Join Date: May 2009 Location: Boring, Or Posts: 28 Thanks: 6 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I got it!! it works!...You were right, when the flap opens slightly, FC is supposed to touch E1...but somehow E1 bent (low temperatures maybe?) and the flap would hit E1 and never get to FC...hard to explain. But i fixed it...thanks a lot for your help.

05-06-2009, 01:37 AM	#14 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,921 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (125/100% )	Excellent! Glad to hear it is working as it should.