Intermittent Hard Starting 84 FI

[rridge]

30 psi is acceptable fuel pressure at idle with the vacuum line attached to pressure regulator. Fiat used a 2.5 Bar fuel rail. Most other L-Jet systems used 3.0 Bar. Some Fiat North American technical material cited higher incorrect pressures. Fiat abandoned the U.S. market in April 1982 before the errors were corrected. Technical support from Pininfarina or the U.S. importer for '83-85 Spiders was scant.

The fuel rail only holds pressure for 24 hours. If the check valve in the pump is clogged with rust and/or debris from deteriorating rubber fuel hoses, fuel rail pressure will leak down more quickly. It may not hold pressure at all once the engine is switched off. But the engine will still start and function until the pump finally burns out or the fuel filter is completely clogged.

It takes about ten minutes to remove the trunk cover over the tank, undo the six small nuts that hold the sending unit into the top of the tank, lift it out and inspect the bottom with a flashlight. There is nothing you can do in the engine compartment to fix the problems caused by a rusty tank.

Using a utility knife cut the old cold start fuel line lengthwise to get it off and replace it with a new piece of fuel injection hose. If you use too much pressure on the blade at the ends of the hose you will create notches in the hose barbs. Notches cause leaks. Be particularly gentle with the 40 year old blue plastic injector. Breaking the barb off will cause a hole in your wallet.

[AJgraham02]

Just to give everyone another update

I listened to all the injectors using my stethoscope and when I could get it running(Very poorly, sounding like a hit and miss engine) All four clicked in a very pronounced manner. I the proceeded to make sure my plug wires were seated and it immediately started running much better. I checked the wires(Which i replaced a month or so ago because the old ones were arcing) and the terminals inside didn't seem to be securely attached to the wires. I tightened them up with my crimpers and drove the car for about 30 miles, with no problems. I parked it back in the garage and figured i put a pin in it, but yesterday the problem came back again while it was very damp and rainy. Seems like that confirms its something in the ignition system, but I'm still going to take a few minutes and look into the fuel tank, and the hoses underneath just to make sure it doesn't cause problems later

[Andiamo]

Hi guys, I'm brand new here and by no means am I a FIAT expert. The one thing I read that really caught my attention here was the OP's comment, "...but when I plugged the ECU back in it ran great. It idled for 30 minutes plus. I restarted it 4 or 5 times no problems at all, But poor weather kept me from driving it." Not much was said about that, but wouldn't that be a sign of some sort? Bad ECU plug terminal connections perhaps?

My new acquisition is a '81 Spider 2000 and I have very similar problems so I've been reading a lot of forum posts searching for clues.

cheers,

Andiamo

[18Fiatsandcounting]

I think that's a very real possibility, Andiamo. Even on the older Fiats with regular old points and carbs, the ignition system could act goofy with excessive moisture or condensation under the hood. One issue that I used to have with my older cars was that moisture, plus the dirt and grease around the distributor cap and plug wires and plugs, would cause them to arc to ground (the engine) rather than across the plug gap as they should. Cleaning everything solved that problem. Sometimes plug wires that are bundled too close together can cause crossfires, but I think that's mostly with El Cheapo plug wires.

Describe your current symptoms and we'll go from there, with the disclaimer that the last time I had a FI spider with an ECU was in the late 1980s...

-Bryan

[pdx124]

I'm having very similar symptoms in my spider. Hesitant to startup. Sputters, dies. Try cranking again a few times. It will stubbornly start running but the idle is irregular for a few minutes. Eventually that smooths out and it'll drive fine.

Like you this seems to only happen when it's rainy or humid out. Temp might also factor in. It started happening last winter. During the hot dry summer the issue went away. Leaning towards thinking it's electrical problem.

[18Fiatsandcounting]

Like you this seems to only happen when it's rainy or humid out. Temp might also factor in. It started happening last winter. During the hot dry summer the issue went away. Leaning towards thinking it's electrical problem.

Possibly, especially with your note about humidity. Another thing I'd look at is the cold start mechanism on the fuel injected cars. I'm no expert on this, but if you search around for "cold start injector" or the like, you'll find that this is a common source of starting issues.

Or a combination of both: weak spark, and a too lean mixture when first starting that resolves itself as the engine warms up.

-Bryan