A mechanical puzzle

[CHEROKEE1]

I have a mechanical puzzle for all of you Fiat Whizzes out there. I have a 1980 Fiat 2000 that starts up just fine. I can go and drive it for 20 miles with out an ounce of trouble, then it will just die. No warning, no cough or sputter, it acts like it's completly out of gas. Usually the (new) electronic fuel pump is ticking like a hyper time bomb. I have a (new) glass fuel filter that is full and clean, I also just had the filter in the tank replaced though it was relativly clean. Here's the kicker, when I'm dead on the side of the road, if I go back to the gas fill-up nozzle, cup my hands and blow really hard into the tank, the clicking from the pump goes away and the engine will start. I might get 1/4 mile down the road when it does it all over again. After three or four times it runs fine and I can usually get home. Another odd thing is that if I'm stopped with the hood up and the car is off, all of the sudden the gas in the filter drains to the carb, I turn the pump on and watch the filter fill and I'm good to go. Do I have a sticking float in the carburator, and if so, is it something I can fix myself without goofing up the carb? I've tried a cleaning additive in the gas and have sprayed carb cleaner on it as much asI could. I hate to take it back to the shop (again) and I'd really like to work on this myself, any comments?

[mbouse]

one comment

carbureted 1980 Spiders came stock with a mechanical fuel pump powered by the auxillery shaft. if you have an electric fuel pump i would suspect it's installation until proven otherwise. first off, is the pump the correct pressure for a carbureted engine, and secondly, is it correctly wired for power, or is there an intermittant short? third, the location of the pump...front or rear?

and, is it connected to the correct fuel line from front to back (being certain that the fuel return line is not accidently feeding fuel to the carb)?

[So Cal Mark]

electric pumps are noisy when they are starved for fuel. It sounds like you may be creating a vacuum in the tank after 20 mins. Try driving with the fuel cap loosened. As Mike suggests, the pump installation or condition of the hoses could be a factor. The pump should be back as close to the tank as possible. the hoses to the pump need to be in good shape and tight.

[CHEROKEE1]

Thanks for the info, this site is really great. A couple of other things about the car,this is the second electronic fuel pump, the first one lasted about a year. It's located about a foot forward of the gas tank. It seems that that the fuel return lines have been disconnected, the mechanic (whom I have great trust in), said that the fuel pump "pumps against pressure". The first thing I'm going to try is to loosening that filler cap, that's also the cheapest! Thanks again.

[mbouse]

umm... that is a classic comment "pumps against pressure" i think all pumps do that to some extent.

what pressure is your pump rated for? BIG problems if the pump is not rated for a carb'd engine. you use the word electronic, which leads me to think you may have the wrong pump in addition to the other discussed issues.

[CHEROKEE1]

OK, so now you know I'm no mechanic, but I did stay at a Holiday Inn Express last night.

I just went out and started the car. After a minute the fuel filter completely empties of gas, the in another 30 seconds fills back up from what looks like the pump side. All the while the fuel pump continues to click away. Please noe that the filler cap is on but loose.

Don't worry, I'm sticking with my day job.

[baltobernie]

When the filter appears empty, does the car continue to run? Have you tried to disconnect the line at the carb and run fuel into a container?

This new fuel pump you have ... does it look like this?

[CHEROKEE1]

Yes for both questions. The fuel pump is a Facet Electronic Automotive Fuel Pump but thats all I can read on it.

[baltobernie]

No part numbers, huh?

Well then, I guess we'll have to hope that a PO installed the correct one; p/n 40104, which produces 1.5 to 4 PSI, NOT p/n 40106 at 4-6 PSI. Weber carburetors don't work with fuel pressures above 3 PSI.

Try "pumping gas into a container" (outdoors) from my previous post. Also, I've re-read your original post, and don't see any mention of emissions items. Do you have any attached evaporative equipment; under-hood charcoal canister, trunk-mount separator, one-way valve in the tank well or under the car? I'm wondering if the guy who disconnected the return line (why would you do this?) plugged it somewhere, as others have suggested. The plumbing on these cars is not terribly sophisticated, but if modifications are not documented, there can be problems. I think there are only two ways you can plumb a carbureted Fiat; (1.) as it left the factory, or (2.) one fuel line to the carb; everything else blocked off and a hole in the gas cap.

[Schnauzer]

I experienced the "runs great with sudden crap out" sydrome. This on my son's 79 2000 carb'd. After many pushes home in the middle of the night we found that the fuel pickup filter inside the tank had decomposed and that the tank had that material along with a lot of rust in it. Removed the tank, cleaned and flushed and installed a fuel screen from Napa. This pickup sock works great. If you go this route contact me. I will get you the Napa part number. I sorted through 50 or 60 of these things to find one that works. Son's Spider has not had an issue since.

Good luck,

Jim

[mbouse]

I'm wondering if the guy who disconnected the return line (why would you do this?)

depending on the carburetor used, it may be necessary... the 32/36 DFEV has no return line.

[CHEROKEE1]

Thank you for the great tips, I took the car out this weekend for a nice cruise in central Virginia without a problem. I'll be sure to keep up with this forum.


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