Fuel pump relay clicking. Help

oneblueyedog · oneblueyedog's Garage

After an alternator rebuild. My fuel pump relay has started to click.

I thought fixing the short circuit of the Voltage regulator was the problem.

Then I noticed something alarming when I was resetting my radio this morning turning the key. THE FUEL PUMP STAYED ON while the key was is Accessory mode. I went to the relay and switched it to a black one. The Puel pump went off when I turned the key to my relief. I started the car and it took a lot of cranking (feels like I might have a leaking cold start fuel Injector) then after it started,
THE CLICKING reoccurred. The relay gets hot understandably.

After I tapped on the red relay it functioned normally (fuel pump stopped running on) but began clicking again.

I have done nothing but R/R the alternator 6 times. The rebuild included a 75watt rectifier (had a 50 watt) and a Voltage regulator. The voltage regulator's blue wire was mismanufactured and shorted out on it's heat sink. I fixed that and the charging system works.

The wiring to the alternator is correct.

The clicking is in harmony with the RPM at idle.

What could cause this?

Jim Sims · 06-25-2006, 11:58 AM

Check that the CIS air flow switch connector is in place and properly connected. It's on the back of the airbox (towards the front of the car). It cuts out the fuel pump through the relay - open circuit allows the pump the run, closed circuit cuts the fuel pump. Fuel pump should only run while engine is turning over, i. e. inducting in air.

Jim Sims · 06-25-2006, 12:02 PM

Air flow switch connector is roughly rectangular in shape and should be painted green or have a green dot on it.

oneblueyedog · oneblueyedog's Garage

Jim,

I got a mirror and see that the air flow switch connector is blue. It's similar to the shape of connector on the wur and the Aux air valve. I felt back there to see if the assembly was loose. It's sturdy and tight. The engine is still a little hot! It's dusty but clean back there.

I read where there is a diode in the red relay. Does this smooth out voltage pulses?

Relay still clicks- red in now. Fuel pump is not running with key in accessory now.

Jim Sims · 12:42 PM

No the air flow switch is green or has a green dot on it; the cold start valve (CSV) connector is blue or has a blue dot on it and that is what you are probably seeing. Keep looking. Look for this green connector just below the fuel distributor.

oneblueyedog · oneblueyedog's Garage

I saw #1 on my SC. This is a picture from my rebuild before installation. It's realated to the metering plate right?

Jim Sims · 06-25-2006, 01:13 PM

Yes, number 1 is the air flow switch on the metering plate (connector should be green or have a green dot on it). No. 2 is the connector for the CSV and should be blue or have a blue dot on it. It is easy to mix up these two connectors when putting the engine back together.

oneblueyedog · oneblueyedog's Garage

Thanks Jim.

Just went around the block. On startup there is no clicking but after warmup it returns at anything below 1100 rpm. It's so odd that I can put my foot slightly on the gas pedal and it goes away.

The pump is still silent in accessory key position.

I could not see any dots on the terminal but when I restored the wiring harness 2 years ago I made sure that all of the terminals corresponded to the wiring diagram wire colors and the components that they plugged into. It's been running great for 2 years until I had the overcharging VR .

I'm going to pour over the wiring diagrams. The fuel pump has a diode for some reason. A search brought out that it smooths out pulastions of the relay. I might have fried at the 17+ volts that the circuits were seeing at 100°. It's hot in Texas.

Search also said it was some kind of safety item. I wonder in what way?

Jim Sims · 06-26-2006, 04:21 AM

The diode in the relay allows it to "free wheel" when breaking the circuit to an inductive load. This reduces damage to the contacts and voltage spikes. Something is causing the relays to operate in an intermitant manner (click). Try unplugging the air flow switch connector and see if the clicking stops (note the pump will then run whenever the key is in the on position).

oneblueyedog · oneblueyedog's Garage

I unplugged the Air flow switch lead and took a drive to full temp. NO Clicking!

Translation?

Jim Sims · 06-26-2006, 06:29 AM

Air flow switch or connector is bad or perhaps loose. Check the switch's mounting.

oneblueyedog · oneblueyedog's Garage

Will do. Thanks so much.

oneblueyedog · oneblueyedog's Garage

Sensor plate was adjusted high and I cleaned the connector. Set it back down to the correct level. Plugged back in and running fine now. It must have been barely lifting off the contact resting place or a dirty connector.

Thanks for your diagnosis Jim.