Bypass Fuel Pump Relay will car start?

[badger.]

If I bypass the fuel pump relay - essentially providing constant 12v to fuel pump, will the car start? I think it should provided nothing else is wrong, right?


(I bypassed the fuel pump relay by removing the fuel pump fuse, then taking a jumper wire from another fuse (+) terminal to the fuel pump fuse (+) terminal. Doing this, I can hear the pump kick on and stay running).

[emilio]

yes, iirc, the FP relay is directly controlled by the ignition (possibly even without a fuse). i don't think the computer is relying on any particular signal; i don't think the ECU is even aware of the FP relay.

- emilio

[q_dubz]

Yes but why?

[badger.]

yes, iirc, the FP relay is directly controlled by the ignition (possibly even without a fuse). i don't think the computer is relying on any particular signal; i don't think the ECU is even aware of the FP relay.

- emilio

wiring diagram No.37/6 fuel pump relay J17 one pin runs to ECM, Pin85 on the relay I believe.


From my understanding, on the relay:
Pin30 = always hot, direct 12V from battery
Pin86 = only hot when ignition is ON (comes from ignition/starter switch) - Think this is terminal 15
Pin87 = goes from relay to Fuse Panel to the fuel pump fuse, and will only see power when relay is Active (switch closed)
Pin85 = goes to/from ECM pin65 through a 17-pin connector(pin10) in the plenum chamber (under ECU I think).

I am trying to verify that the fuel pump relay won't close and power the pump unless the ECM sends a signal via relay pin 85, which will energize the relay and send power through pin87.

Basically, I think my Pump and Relay are OK, but they won't turn on because the ECM is not sending the signal to activate the relay and send power through the fuse to the pump. But I want to be sure.

edit: link to wiring diagram in this post
http://www.audizine.com/forum/showth...1#post12187943

[q_dubz]

The ECU is powered by the fp relay. So if you see a CEL then the relay is fine.

[MantanaB6]

If I bypass the fuel pump relay - essentially providing constant 12v to fuel pump, will the car start? I think it should provided nothing else is wrong, right?


(I bypassed the fuel pump relay by removing the fuel pump fuse, then taking a jumper wire from another fuse (+) terminal to the fuel pump fuse (+) terminal. Doing this, I can hear the pump kick on and stay running).

Were you able to successfully start you car doing this? My car currently won't start. Symptoms are as follows:

- A while ago (i.e. a couple months) I tried to start my car and nothing happened. Turned key, heard a 'click', then silence. I tried to start the car again, this time holding the key in the 'start' position for approx. 5 secs and the car started as normal. Continued to start with no issues.

- Today, car starts fine in the morning, car starts fine at lunch, go to Wal Mart () to get some odds and end, and when I try to start the car again, I get the 'click' then silence. Tried for about a half hour intermittently holding the ignition in the 'start' position, and get nothing. Replaced a bunch of 15a 'engine management' fuses (which appeared to be a little browned but not completely blown). Still not getting anything. Now the car is stuck at Wal Mart and I am looking for a temp fix to get it started so I can drive home.

[Durk]

My car was doing this my crank sensor was bad. I replaced that relay first, not the issue. Huge PITA you have to lay across the engine and blindly undo the sensor it is back below the oil filter housing.

[kabukie]

There are two relays under the ecu that are the same (iirc #395). Try replacing those

Were you able to successfully start you car doing this? My car currently won't start. Symptoms are as follows:

- A while ago (i.e. a couple months) I tried to start my car and nothing happened. Turned key, heard a 'click', then silence. I tried to start the car again, this time holding the key in the 'start' position for approx. 5 secs and the car started as normal. Continued to start with no issues.

- Today, car starts fine in the morning, car starts fine at lunch, go to Wal Mart () to get some odds and end, and when I try to start the car again, I get the 'click' then silence. Tried for about a half hour intermittently holding the ignition in the 'start' position, and get nothing. Replaced a bunch of 15a 'engine management' fuses (which appeared to be a little browned but not completely blown). Still not getting anything. Now the car is stuck at Wal Mart and I am looking for a temp fix to get it started so I can drive home.

[QIKRNU]

It's possible that your starter is trying to die.

[MantanaB6]

It's possible that your starter is trying to die.

That's my fear.


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[badger.]

I don't think I was ever successful, but that said I am pretty sure my no-start was not a fuel pump or FP relay issue.

Also, reading through your scenario, it sounds like a totally different issue. As QIKRNU mentioned, I think it is your starter. Search around for those symptoms. If it isn't even cranking, there is something in the starter solenoid that can crap out, or possibly the ignition switch I think as well.

[mrkubanftw]

Were you able to successfully start you car doing this? My car currently won't start. Symptoms are as follows:

- A while ago (i.e. a couple months) I tried to start my car and nothing happened. Turned key, heard a 'click', then silence. I tried to start the car again, this time holding the key in the 'start' position for approx. 5 secs and the car started as normal. Continued to start with no issues.

- Today, car starts fine in the morning, car starts fine at lunch, go to Wal Mart () to get some odds and end, and when I try to start the car again, I get the 'click' then silence. Tried for about a half hour intermittently holding the ignition in the 'start' position, and get nothing. Replaced a bunch of 15a 'engine management' fuses (which appeared to be a little browned but not completely blown). Still not getting anything. Now the car is stuck at Wal Mart and I am looking for a temp fix to get it started so I can drive home.

This is 100% starter. Solenoid is going bad and hangs up. The solenoid jumps out, tries to make contact, fails, and then is stuck in its current extended position. So you have to wait until it draws back (this is usually worse in winter) until you can try to re-fire the starter. In the case where you hold the key and randomly get a start... the solenoid is its struggling to hold contact position, and during that vibration/harmonics you get lucky and the contact fires. Starter will fix that all day.


Also i'm noticing a lot of these threads where people are having issues, people extend their help and knowledge, and then the OP fixes his issue and never comes back to the thread to update it with a final solution. These forums REQUIRE that extended feedback in order for any of these diagnosis to be successful. There's 5-10 threads specifically highlighting my current issues and in each one it appears the OP fixed his issue and took off never to be seen again. That stuff will render these forums useless, it doesn't help the next guy who has the same problem. Just a note- try to be responsible with this gents... especially the guys starting threads looking for help.

[MantanaB6]

This is 100% starter. Solenoid is going bad and hangs up. The solenoid jumps out, tries to make contact, fails, and then is stuck in its current extended position. So you have to wait until it draws back (this is usually worse in winter) until you can try to re-fire the starter. In the case where you hold the key and randomly get a start... the solenoid is its struggling to hold contact position, and during that vibration/harmonics you get lucky and the contact fires. Starter will fix that all day.


Also i'm noticing a lot of these threads where people are having issues, people extend their help and knowledge, and then the OP fixes his issue and never comes back to the thread to update it with a final solution. These forums REQUIRE that extended feedback in order for any of these diagnosis to be successful. There's 5-10 threads specifically highlighting my current issues and in each one it appears the OP fixed his issue and took off never to be seen again. That stuff will render these forums useless, it doesn't help the next guy who has the same problem. Just a note- try to be responsible with this gents... especially the guys starting threads looking for help.

Sorry for not following up; I agree these threads are essentially worthless if all the troubleshooting doesn’t end with a resolution. And I’ll be the first to admit I’m bad at following up. So here it is!

It was indeed the starter. Wasn’t too bad to replace in my driveway on a sunny Saturday. Put the car on ramps and used a jack to support the engine once I removed the engine mount. A couple hours of blindly finagling the old starter out and new one in, and she starts right up.


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