81 Spider Fuel Issue

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Gr8Panoz

81 Spider Fuel Issue

Post by Gr8Panoz »

Let me preface this by saying I am in no way mechanically inclined, and that after searching several similar threads haven't really found a topic that matches my ailments.
To the issue, my 81 Fiat Spider is having a fuel issue of this much I am certain. Purchased from my dad the car had sat for a couple years without running most likely turning all the fuel to turpentine. A mechanic stated that the fuel pump and 3 of the 4 injectors were plugged but he got them all working without replacing any parts. Car ran fine for a couple months but soon started to act like it was starving for fuel. The car turns over and idles just fine. Rev it up to 3k and it just cuts out completely. RPM's will drop but car remains running and returns to a normal idle. I've purchased some fuel line treatment and injector cleaner but am uneasy filling the tank in case I have to drop it. Without just starting to replace parts does anyone have any ideas on where to start. I'm quite strapped for cash and not expecting any windfalls any time soon. I should also state that the first few runs around the block went off without a hitch. Car revved just fine with no hesitation. 2 1/2 miles later I can't get her out of the drive.
Thanks in advance to anyone who takes the time to post on this issue and help me get this baby one the road. Cosmetically she's in great condition inside and out and not being able to drive it is really bumming me out.
majicwrench

Re: 81 Spider Fuel Issue

Post by majicwrench »

Well, ya gotta test stuff first. Test the fuel pressure at the cold start injector. Watch the pressure when you rev it up, see what it does.
Keith
wizard124
Posts: 752
Joined: Mon Oct 29, 2012 9:27 pm
Your car is a: 1980 124 spider FI
Location: Sheridan, WY exSan Rafael, CA

Re: 81 Spider Fuel Issue

Post by wizard124 »

Did the mechanic change the fuel filter? If not, that would be the first thing to do. It is located next to the fuel pump, under the car and forward of the fuel tank.
Not hard to change out, except for being on your back.

When you work/disconnect fuel lines, you should de-pressurize it first to minimize fuel from spraying. Connect a Mity Vac to the vacuum line that runs from the intake manifold to your fuel pressure regulator. By pumping with the MV, it relieves fuel pressure in the line. Go here to see what a MV is : http://www.harborfreight.com/mityvac-va ... 39522.html

I just tested my fuel pump and regulator by connecting a pressure gauge to the fuel line running to the Cold Start Valve. The CSV is located at the forward end of the intake manifold; it has a 4-5 inch fuel line leading up from the fuel rail. The pressure regulator is that circular looking device connected in the fuel rail; it has the vacuum line on top and the fuel return line attached to it.

With the fuel line dis-connected at the CSV, test for volume output. Dis-connect the coil wire at the distributor (you don't want the engine to run). While holding a container with the fuel line pointing into it, have someone engage the starter. My result was about 2 cups of fuel in 20 seconds of cranking. I don't know what the spec is supposed to be, maybe you can find it with a search. Anyway, this seems like plenty :)

If you obtain a pressure gauge, connect and clamp it onto this same fuel line. Re-connect the vacuum line to the regulator. Plug in the coil wire and start the car. The gauge reading will vibrate some but it should read about 28 psi. It should read the same/close at all steady engine speeds. When you quickly accelerate the engine, the reading should jump higher (around 40) but quickly recover to the steady reading.

If you don't get these numbers, test the fuel pump pressure prior to the fuel rail. The spec is 39-45 psi.
So Cal Mark

Re: 81 Spider Fuel Issue

Post by So Cal Mark »

changing the filter is a good suggestion and you may also have a restricted sock filter on the pickup in the tank. But, I'd also check the intake boot for cracks as it can cause the same symptoms
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