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Fuel Pump Relay Rapid Clicking? Crank No-Start

Old 05-12-2011, 03:08 AM
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Fuel Pump Relay Rapid Clicking? Crank No-Start

1989 305 TPI, 700r4 Iroc-Z28 Camaro

I have spark and compression.

I'm going to give you guys the whole run down what happened today so we rule everything as possible out!

So recently this is what has happened to me. I was driving down the road and out of no where my car's engine just shuts off. So I think maybe no gas (can't be, just put 5 gallons in). I have power, but I do not hear my Fuel Pump primping on for 2 seconds as I turn the key. So I went and bought a new Fuel Pump. Installed it and everything was good for about 2 hours... and then it just stopped working again... (I was stuck at Goodyear) they tested the 3 wires just above going to the fuel tank (Black, Grey, Purple). Black Read .00volts, Grey Read 4.6-4.7volts, Purple Read 4.6-4.7volts. So then they used some test thingy that put volts to the Grey Wire, Read 12.(something)volts and I could hear the fuel pump turning on. So we tried cranking the engine over while they put power to the pump (with the tool they used) and still nothing! (Tried that multiple times)

So I figured to myself... The fuel pump must be good since its working but its getting not enough volts... Because it needs around 12 volts to run... But it was only getting 4.6volts. So I figured it was the wiring in the fuel pump housing... So I warrantied out the fuel pump for a new one and decided this time to replace the wires that the new fuel pump always come with... So I had to place 2 connectors (The one on top of the fuel pump housing and the one that goes to the fuel pump) I replaced the Grey (signal/power "i think") and Black (ground "i think") wires. I had to cut the Black wire because it was grounded by solder. The wire (Black) that was grounded to a fuel line on the fuel pump housing I had to cut in 2 ends because of how it was like grounded in a split. So I had to solder (My first time soldering, it was a little clumpy but still the wires where stuck on, seemed like a good connection, also gave it a good tug and the wires are nicely on there. Heat shrunk it after) So I plugged the Black wire in the A Connector terminal on the connector that goes to the fuel pump. Thats what the instructions said. And the Grey wire into the B Connector terminal on the connector that goes to the fuel pump. Made sure that the Black wire is plugged into the right terminal on the fuel pump housing connector that has the floater unit (Purple wire) on it. And the Grey wire in its correct spot on that connector also.

Finally I'm happy, that **** to me 2 hours to do. So I put the fuel pump back it and instead of just twisting and taping the 3 wires that I cut to get the fuel pump housing off (wires coming out of the top of the fuel tank). I butt connected and heat shrunk them. Just to be nice and good Also I was checking the wires and connections on the fuel pump housing and they all appear good. FUEL PUMP IS IN! Also went and bought and new Fuel Pump Relay just to waste money and be on the good consious side! Everything is ready to go!

So I go to turn the power on waiting to listen for the Fuel Pump to prime 2 seconds telling me that I did an AWESOME job and... NOTHING HAPPENED!!

But what did happen... is this SUPER FAST CLICKING NOISE coming for the Fuel Pump Relay... It would stop for a second but then keep clicking fast. So... Now... this is all I am doing right now

I left it alone for a couple hours and came back and tried multiple times to start it... I HEAR NOTHING! It cranks but no start... and also makes that stupid Rapid Clicking Noise (frm the Fuel Pump Relay) w/ just the power on

What in the world can that be!!
Old 05-12-2011, 04:32 AM
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Re: Fuel Pump Relay Rapid Clicking? Crank No-Start

UPDATE!!!!!! So I left my car off for like 3 hours... Tried to start it like 3 times. Nothing, but the clicking. Also... I let it sit again for 2 hours... I turn the power on... I hear the clicking noise coming for the Relay... then like 5 seconds later... The Fuel Pump Primes... and then I crank it... and it starts!!!

But what about the clicking noise? Why did it do that?

Also I do not want to drive it again and have it fail somewhere on me... So what could possibly make it go out?

Could it of been that the wiring was bad that I replaced?

What about also... why did it take so many tries for the fuel pump to come on?
Old 05-12-2011, 09:34 AM
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Re: Fuel Pump Relay Rapid Clicking? Crank No-Start

The clicking noise at the relay indicates that the relay is bad, or that the wires to the relay and/or connector is bad.

A relay is an electronically activated switch. Inside is a coil. When 12v+ is applied to one end of the coil, and a ground is applied to the other end, the coil gets charged, creating a magnetic field. This magnetic field literally moves a metal lever from position A to position B. One end of the lever is attached to constant battery power. When coil not energized, the lever rests in postion A (which in the case of the fuel pump relay is feeding the battery power to an unused terminal). When the coil is activated, the lever moves to position B (which in this case is a terminal connected to your fuel pump wire). Thus, when the relay is activated, 12v+ is being directed from the battery to the fuel pump.

This fast clicking indicates that the relay coil is not getting a constant voltage supplied to it, thus the lever is moving back and forth between position A and position B - thus the clicking - it's like a windshield wiper that is hitting the cowl, then hitting the side molding ... back and forth and back and forth - thus the clicking.

So, either there is a wiring issue, a connector issue, or an internal issue with the relay.

The relay has 4 wires, black, grey, orange, green with white stripe.

black = ground
orange = battery = 12v+ always
grey = wire out to fuel pump (on some cars this wire is tan with white stripe)
green/white = signal wire from ECM

When key is turned ON, the ECM sends 12v+ out on the green/white wire to the relay for about 2 seconds - this activates the relay coil for 2 seconds, thus running the pump for 2 seconds (priming).

When the car is started, the ECM sees a constant ignition signal from the distributor, nd thus sends a constant 12v+ out on the green/white wire, thus activating the relay coil constantly, and thus running the pump constantly.

When car shut off, no more constant ignition signal, thsu ECM stops sending the 12v+ out on the green/white wire.

So, you can kind of test your connector ...

1) remove connector from relay
2) jumper a wire from the slot for the orange wire to the slot for the grey wire - fuel pump should run - wiggle wires to verify at connector
3) probe black wire slot with ohm meter - make sure black wire has constant ground - wiggle wires at connector

test relay ...

1) remove relay from connector
2) rig a ground wire to the tab that had the black wire when in connector
3) apply 12v+ to the tab that had the green/white wire - relay should click once and do this every time you apply the 12v+

That should help you track it down to either a connector problem, a wiring problem, or a relay problem.

One other thing - make sure that the fuse for all this is good - it's in a small weatherpack pass side, between the battery and the fender - will have a red wire in, and an orange wire out, with a 20 amp fuse inside the weatherpack. That fuse circuit feeds 12v+ to the ECM and the Oil Pressure Sending Unit (OPSU).

Also, assuming that fuse is good ... if you keep cranking the car constantly (may take 20 - 30 seconds of cranking), the OPSU will activate the fuel pump and run it. The OPSU is a back-up circuit for the fuel pump - when it senses oil pressure it will run the fuel pump if it's not already being run - but it takes time (20 - 30 seconds sometimes) for the starter to turn the engine over enough for the oil pump to start pumping enough oil to activate this OPSU fuel pump circuit. So, in theory - if stranded like that again - you can just crank and keep cranking and the car will start eventually.

Hope that helps!
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Old 05-12-2011, 06:05 PM
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Re: Fuel Pump Relay Rapid Clicking? Crank No-Start

Originally Posted by camaronewbie
The clicking noise at the relay indicates that the relay is bad, or that the wires to the relay and/or connector is bad.

A relay is an electronically activated switch. Inside is a coil. When 12v+ is applied to one end of the coil, and a ground is applied to the other end, the coil gets charged, creating a magnetic field. This magnetic field literally moves a metal lever from position A to position B. One end of the lever is attached to constant battery power. When coil not energized, the lever rests in postion A (which in the case of the fuel pump relay is feeding the battery power to an unused terminal). When the coil is activated, the lever moves to position B (which in this case is a terminal connected to your fuel pump wire). Thus, when the relay is activated, 12v+ is being directed from the battery to the fuel pump.

This fast clicking indicates that the relay coil is not getting a constant voltage supplied to it, thus the lever is moving back and forth between position A and position B - thus the clicking - it's like a windshield wiper that is hitting the cowl, then hitting the side molding ... back and forth and back and forth - thus the clicking.

So, either there is a wiring issue, a connector issue, or an internal issue with the relay.

The relay has 4 wires, black, grey, orange, green with white stripe.

black = ground
orange = battery = 12v+ always
grey = wire out to fuel pump (on some cars this wire is tan with white stripe)
green/white = signal wire from ECM

When key is turned ON, the ECM sends 12v+ out on the green/white wire to the relay for about 2 seconds - this activates the relay coil for 2 seconds, thus running the pump for 2 seconds (priming).

When the car is started, the ECM sees a constant ignition signal from the distributor, nd thus sends a constant 12v+ out on the green/white wire, thus activating the relay coil constantly, and thus running the pump constantly.

When car shut off, no more constant ignition signal, thsu ECM stops sending the 12v+ out on the green/white wire.

So, you can kind of test your connector ...

1) remove connector from relay
2) jumper a wire from the slot for the orange wire to the slot for the grey wire - fuel pump should run - wiggle wires to verify at connector
3) probe black wire slot with ohm meter - make sure black wire has constant ground - wiggle wires at connector

test relay ...

1) remove relay from connector
2) rig a ground wire to the tab that had the black wire when in connector
3) apply 12v+ to the tab that had the green/white wire - relay should click once and do this every time you apply the 12v+

That should help you track it down to either a connector problem, a wiring problem, or a relay problem.

One other thing - make sure that the fuse for all this is good - it's in a small weatherpack pass side, between the battery and the fender - will have a red wire in, and an orange wire out, with a 20 amp fuse inside the weatherpack. That fuse circuit feeds 12v+ to the ECM and the Oil Pressure Sending Unit (OPSU).

Also, assuming that fuse is good ... if you keep cranking the car constantly (may take 20 - 30 seconds of cranking), the OPSU will activate the fuel pump and run it. The OPSU is a back-up circuit for the fuel pump - when it senses oil pressure it will run the fuel pump if it's not already being run - but it takes time (20 - 30 seconds sometimes) for the starter to turn the engine over enough for the oil pump to start pumping enough oil to activate this OPSU fuel pump circuit. So, in theory - if stranded like that again - you can just crank and keep cranking and the car will start eventually.

Hope that helps!
Helps a lot! Thank you!

So I'm going to guess that is why it turned on for me last night was because of the OPSU sensed oil pressure... Because I was trying and trying to start it and will get nothing but click from the relay and cranking from the engine... I let it sit and came back to it and it clicked and then about 5 seconds later the Fuel Pump had primed up for 2 seconds and then it started. I let it run for like 5 mins... Shut it off (about 1 min) Then turned the power on... Heard the fuel pump prime for 2 seconds. I didn't heard the clicking from the FPR Shut if off again for like 10 mins. No clicking... GREAT! Starts up and everything.

Next... I let it rest over night and in the evening I wanted to see if it would start right up because I wanted to the oil pressure to go down... So I turned to power on and it primed for 2 seconds and started... Drove and made a couple stops... Everything seems good.

Now I didn't drive it a lot today because I don't want it going out on me again... So this is my question here... The first time when it went out... tried a couple times to start it and got nothing... No clicking and No prime... (10 hours later) Next, I switched the fuel pump and it started right up... No clicking from the FPR. After 2 hours of driving... It dies out again

No clicking, no priming, Black(ground) - 0.00volts, Purple(floater unit) - 4.6 volts, & Grey(signal/power) - 4.6 volts. So I'm thinking maybe it has something to do with the wiring somewhere... We also put 12.1volts to the Grey wire to turn it on and also no start. (Why didn't it start if we manually were primping the pump for pressure?) So I this time replaced the fuel pump and connectors in the fuel pump housing. Tried to start it and thats the first time when I heard the clicking from the FPR and no primp from the Fuel Pump.

I thought? What the Hell? I replaced the wires and the pump?

But it did start later after I let it sit like I explained in the "Updated post"

You said that the Black wire in the Fuel Pump housing gets grounded by the Relay from the ECM to get power... (or something along those lines)

Could it have been because I cut the Black(ground) wire and soldered a new black one on? (I don't have the best soldering skills but it was on there snug, it was a little lumpy but it appeared to be good)

So why did the first 2 fuel pumps go out? I don't want to drive it and have this one go out on me again? Could there be a short to ground or power somewhere on the Connector?

That fuse by the battery is good... and the Relay is Brand New.

Another "?" Why did it start right up today if there Oil Pressure was at Zero? (Like you said, The OPSU, it's a back up for the fuel pump if the relay isn't working properly and sense's oil pressure)
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