'89 Reatta, crank / no start, Fuel pump not priming

[Jess W]

I am a new owner of an '89 coupe and I've just replaced the fuel pump. The engine cranks, but will not start. The pump doesn't seem to be priming, and the schrader valve doesn't have any pressure or gas in it.

 

When the battery is plugged in, the park lamps are always on and I cannot turn them off - the security light on the dash also flashes and only the blower motor comes on when I put the car in accessory (not sure if this is relevant, but it could be possible that some anti-theft system is preventing my fuel pump from starting).

 

I've checked the relay for it, and I'm not hearing it click when I turn the car to accessory or to crank it. I've tried swapping in another relay that I'm fairly sure works, and still no click.

 

The tank has 4 gallons of gas that I just put in it, so I doubt it's a problem of the fuel pump not touching fuel.

 

I can't seem to hear the fuel pump making any noise either. I thought we would hear a hum or something when it primes, but all I'm getting is silence.

 

I'm completely out of ideas on why fuel isn't getting sent to the engine / the fuel pump is not doing anything. Is this a known problem? I know the fuel pump is a common part to fail on this car, but considering I just replaced it and all electrical connections / harnesses are new and should work, I don't know what the problem from here could be.

 

Any guidance to help me get this car moving would be greatly appreciated!

Edited October 17, 2023 by Jess W (see edit history)

[Ronnie]

Connect 12 volts from the battery to the green fuel pump prime connector shown in the photo and see if the pump runs and builds pressure.

 

[Jess W]

Will do, thank you for the quick response. I saw something similar to this on another post, but we're having trouble finding this green connector. Where under the hood is this located?

[Ronnie]

Driver's side toward the front. It might be tucked out of sight. If you dig around a little you will see it.

[Jess W]

Alright, we found the connector and sent power from the battery to it, and nothing happened.

 

Might there be more than one of these connectors in here? The one we found is on the driver's side close to the brake master cylinder.

[Barney Eaton]

You found the correct wire.

Next step would be to get to the connector near the gas tank and try power to the fuel pump there.  

At the same time you could test that you are getting 12v from the car to that connector.   

With some of the other issues you have,  this may take some trouble shooting. 

Look around the engine compartment for sign that wires have been cut and or spliced.  

[Jess W]

Here's an update: I followed Barney's advice and after quite a bit of head scratching, I was able to figure out why power wasn't getting sent. The ground for both the fuel pump inside the tank and the connector outside the tank had gone bad. The wires are just crimped directly onto the metal casing, and both crimps had rusted and corroded to the point that neither of them were conductive.

 

After finding that every other surface worked as ground, I soldered on new connections, applied heatshrink, and tested 12V from the battery again - the fuel pump primed! 

 

Now to get the fuel tank back in... my least favorite part.

[Jess W]

Alright, so this isn't entirely over. Tried powering the fuel pump using the green test connector and it started priming there as well (and sprayed fuel everywhere... no matter how tight we get the connection from the fuel hose to the tank, it seems to leak). The weird part here is that when I put the car into accessory or try to turn the engine over, the fuel pump won't prime then. No pressure builds and the pump won't start unless we use the green test connector.

 

What kind of problem could this indicate? I'm fairly certain that the relay should be fine, but I'll try swapping that too.

[2seater]

It certainly sounds like the relay is not functioning correctly. I do not believe it should prime in the accessory position in any case, only when the key is turned to run. The two second prime occurs when the key is first turned on. It is to provide fuel for starting and if the relay is not engaging, then the oil pressure sender has contacts inside that will energize the pump after oil pressure builds after extended cranking.

 

Connect a voltmeter or a test light to the green connector to observe the signal to the fuel pump directly. It bypasses all the interlocks and switches to connect directly to the fuel pump as long as the wiring is intact. If no power is indicated for a couple seconds upon turning the key to run, the relay is the most likely cause. I only have a 1990 FSM but I believe 89 is the same: Fuse #8 powers the fuel pump relay but it also powers the 12v feed to the injectors, so if they work, the feed is likely not the problem. The location of the fuel pump relay is different between 89 and 90, so there may be some difference.