'81 FI Spider Ran 20 min. Now No Start. Help

[chastrialer41]

Hi gentlemen (and ladies)
I am new to the Forum. I recently bought my first Fiat 3 months ago after just accidently talking with an almost retired mechanic that used to be the top dog man at Fiat. He now owns and runs a small Fix-It shop in Memphis and had this baby sitting in the corner all covered up for 14 long years. A 1981 Spider. Anyway I got it and dollyed it home and has been at a friends shop for the last 3 months. After removing gas tank and having it professionally cleaned and reinstalled with NEW sending unit we then had no power to fuel pump. Replaced with new fuel pump relay under glove box and fixed that. We then had no spark. Installed new magnetic coil pickup and new control module--Problem solved. BRAND NEW injectors, cap, rotor, plugs, fuel filter, fuel pump. She cranked and would run for a minute then die. Found that the New Bosch fuel pump had locked up. After talking to a few Fiat friends was advised to instally secondary inline fuel filter just before fuel pump. So another brand new Bosch FP and new seconday fuel filter was installed (located right before fuel pump). Did that and bingo she cranked according to the mechanic and ran like a sewing machine for at least 20 minutes. He called and said come get her. I get to shop Friday and he cranks her up and it runs for 20 sec then dies. Recanked and ran but quickly died. Each time it would crank up but die. He put her back up on rack and removed the little seconday fuel filter and blew thru to make sure it was open which it was. We put 2 fresh gallons of gas in (even though new sending unit was showing that we had gas). Let her back down and same problem.
So we need any help you can give please. Mechanic plans to start again tomorrow. Thanks
Feel free to email also at calliscrew@hotmail.com.

[racydave]

http://www.italiancarclub.com/ FYI, good local club!

[So Cal Mark]

first, I'd get rid of the pre filter, but that isn't the problem. Your new sending unit should have a sock on it that is an adequate filter. Adding another pre filter just makes it harder for the pump to get fuel. Those pumps make very little suction, but lots of pressure so adding a restriction to the inlet isn't a good idea.
If the car runs for 20 seconds, you're either just running on the cold start injector or only the start circuit is supplying power to the pump. Check the injectors with a noid light to see if they're pulsing when the engine does run. You can check run circuit to the pump by opening the AFM flap with the key on. The pump should run then. I'd also check the integrity of the intake boot between the AFM and throttle body. An air leak will cause the problem you're describing.

[rlux4]

If after you've followed Mark's advice, the problem persists, try putting a resistor in the 300 ohm range (about 10 cents each at Radio Shack) on the connector to the temp. sensor at the coolant "T". This will simulate normal run temperature signal to the ECU. If you are running on the cold start injector only and the car dies when it times out, the resistor would give you the signal to the ECU to pulse the injectors. This will tell you if your temp. sensor is bad. Of the sensors related to the FI system, it is the most critical as far as the car running is concerned.
Ron

[So Cal Mark]

the temp sensor in the Tee doesn't operate the cold start injector, that injector is controlled by the thermo time switch in the bottom of the intake manifold. Putting a resistor in place of the coolant temp sensor will only freeze the fuel mixture setting

[rlux4]

I agree Mark, I think you misunderstood me. I didn't say the cold start injector was controlled by the temp. sensor. What I'm saying is if the car is running on the cold start injector only, that instead of dying when it shut off, the resistor would replicate a functioning temp. sensor. I'm not saying it should be a fix, it would only help diagnose a possible malfunctioning component (the temp sensor, as suggested in Brad Artigue's Fiat maintenance manual, in the chapter on FI diagnostics 5.13.3) The fuel mixture setting would be frozen, that's true, but it would be frozen in the normal operating temp range setting. At least that's my reasoning.
Ron

[narfire]

I had similar issues. My cold start valve was pooched somehow and the valve did not close up when warmed up. don't know if that is relevant to this problem but it did act like a leaking rubber hose from the afs to the plenum.