Fuel pump cutting off right after startup

[paintdudeluke]

I dealt with this before but its been so long I forgot the trick. If I remember right, the pump gets power from the ignition when in "start" position and after it starts it then begins to get its power from the MAF unit. Is there a connection or relay in there that causes the "start right up and then die thing?" I can't remember. But if I keep bumping the starter it keeps running so I'm pretty sure I'm barking up the right tree.

[stuartrubin]

I had a similar problem which turned out to be a simple blown fuse. See http://www.fiatspider.com/f15/viewtopic.php?f=6&t=31806

I hope it's that simple for you!

Stuart

[paintdudeluke]

fuses are fine. Is there a relay between the MAF and the pump?

[johnsje6]

Not sure about FI Spiders, but a lot of cars run the fuel pump off the alternator once you let off the key, if your alternator has gone bad, it would do exactly what you are describing.

[GeorgeT]

fuses are fine. Is there a relay between the MAF and the pump?

The Double or Dual Relay; one side is for the injectors and the other side for the fuel pump.

[azruss]

The dual relay is on the relay panel below the glove box. it gets power from an in-line fuse behind the instrument cluster. It does not go though the fuse panel.

[paintdudeluke]

OK, the relays, I opened them up and they seem fine. I tested the green/blk output wire for the pump and it loses power after I let off start" position. I hot-wired the pump and the car runs really crappy. I suspected the MAF is not sending a signal to the relay. I opened up the MAF and when I pinch the little spring loaded tang that feeds power over to its connect point (image) I heard the pump kick on. When I manually move the slider thing I can keep it running but when I touch the throttle it craps out. Any way to double verify that I need a MAF before I buy one?

[paintdudeluke]

Actually if I bend that little point connection the pump stays on and the car runs but idles like crap (actually won't idle). I can hear the meter flap chattering closed. Is this a clear sign of a failed meter?

[spider2081]

The Fuel pump switch is either broken or modified by a previous owner. The area where your pointer is should be a longer piece of brass and reach the bright silver rod on the movable wiper. Hopefully the photo below shows that.



With the piece missing the contacts would be closed all the time and the fuel pump should run when ever the ignition key is in the "start or run" positions.

[paintdudeluke]

Thanks boss! That little piece was laying in there. I wondered how it was actuated. I guess I need a meter, or just pinch it together for a while.

[spider2081]

If you close those contacts so the pump runs continuously and it won't idle or run correctly there is additional problem. First I would check for an intake system for an air leak. Inspect for cracks or worn hoses. Next I would clean the connector for the temperature sensor in the coolant "T"

[KevAndAndi]

I won't pretend to be an expert; I'm only about a year into learning about these cars. But I will tell you this, and you can take it for what it's worth: It's my opinion that anyone buying an FI Spider that has the original, unrefurbished AFM should send their unit to these guys:

http://www.fuelinjectioncorp.com

There is no need to buy a new AFM. They are expensive. And any used AFM is suspect. Who knows what state the electronics are in? Who knows how the air bypass screw has been tampered with? The FIC guys will replace all the electronics, test and calibrate the unit (including setting and then plugging the air bypass screw), and media blast it, returning the AFM to you looking and operating like new.

Best $200 I ever spent on the car. This is not a paid endorsement.

As Brad Artigue mentioned in one of my threads, there's a progression that starts with the AFM air flap not opening properly. Because the result is the problem you have, the owner does a workaround by bending the contact in the AFM to get the fuel pump running. Now the car runs, but the fuel pump also runs before the car is started, when the key is in the pre-start, accessory position. That's not so good, especially in case of an accident. Also, this doesn't address the original problem with the AFM. In my case, the flap was not opening when the engine was idling; the engine was getting unmetered air elsewhere. My advice is: get the AFM refurbished if you can afford the bucks to do so, and chase down any air leaks.

I'm not sure if the problem I had would tend to lead to a too-rich or too-lean situation. But I can tell you that the odor and spark plugs indicated "too rich". I haven't yet replaced the plugs, so I can't say yet whether the refurbed AFM has eliminated that problem, but the odor seems to have gone away.

I can say for sure that: the fuel pump doesn't run until I start the car, the air flap opens during idle, and the car runs much better.

[paintdudeluke]

HACKED! I hacked the AFM and it worked great. 1st here was the problem. The pump contact strip broke off so the pump did not get power signal from the afm. Also, I think this piece limited the return in the meter so it never fell all the way closed. Either that or there is a physical "door stop" that might have broken off and when the flap started dropping all the way shut it eventually broke the tang off. This is why it was refusing to idle i guess.

Here is my hack around the problem:

1st thing] bend the pump contact to keep pump power on as long as the key is on. This loses the shut off safety feature, but it runs fine. So if you get in a crash, turn off the key Every other car I've had has an electric fuel pump that comes on with the key. Whatever..

2nd thing] bottom left from the dial / rotor /whatever you want to call it, there is a spring on a metal post and a smaller post next to the one with the spring on it. I chucked the spring, and then bent the small post forward until it limited the return of the meter to keep it slightly open. I epoxy'd a piece of rubber tubing over the post for some cushion so it doesn't get tapped back every time the throttle closes and the meter drops to zero. Look at the photos below. You can see the piece that was bent over to contact and the other photo shows the tubing on the post bent to limit meter closure. Anyway, it runs great and works for now. Bought a little time anyway.

[spider2081]

Great you have a running car.

You could remove the AFM from the car and then remove the 4 bolts holding it to the air filter box and separate the box from the AFM.
Then look into the AFM from where the box attached. Hopefully the flap stop is still there but bent. I have seen a number of them bent allowing the flap to pass beyond closed to slightly open. This allows the wiper on the white resistance board to rotate off the board. I remove the stop and straighten it and the over rotation is cured.
I think the stop bends from the car back firing in the intake system.

[KevAndAndi]

Regarding the immediately previous comment: In my comment I forgot to mention this very thing. My flap was also in the "beyond closed" (ajar in the wrong direction) position. So, some of the unmetered air that was getting into the system was actually going past the AFM flap, but with the flap open the wrong way and not moving. This, often due to backfire damage, is one reason why owners bend the fuel pump actuation post in the AFM, which is a workaround that doesn't address the root cause. Not having the AFM operate as designed is a source of many woes.