fuel line air lock.

[pottsthomas]

I have a 79 spider. It had the hard starting problem related often on the site. I replaced the card with a 32/36 weber a couple years ago and voila- no more problem. This spring, after a winter hibernation I started up and took it to a Fiat group outing. Ran great on the way out, but wouldn't start when it was time to leave. 15 Fiat experts descended on the car, and after replacing the fuel filter, was off and running. Diagnosis: crud in the tank. Stocked up with spare filters, and resolved to seal the tank after a quick trip to an Italian car show two weeks later. On the day of the show, went to the bank to get cash and no start in the bank lot.
Later that afternoon (after the show) went back- checked the filter (ok) and pulled the sender/float unit from the top of the tank. Blew through it, swished it around in the tank, put it back together and it ran fine, but no filter sock on the bottom of the suction tube. So, took it to the shop for inspection, rigged up a filter sock, and while it started several times in the couple weeks at the shop (needed front wheel bearings) again no start after sock installed.

I have a Saab v-4 with a 38/38 weber that was experiencing similar issues. Typically we took off the fuel line to see if anything was coming through. It was, put it back together and it ran fine. The final diagnosis was an air lock was forming in the line, and the fuel pump (saab was electric) wasn't strong enough to push through it. When we opened up the line the vacuum broke, and you are running again. The Saab solution was to put in a bigger fuel pump, and the issue never resurfaced. I'm thinking that's the route to take with the Fiat. The Fiat guru last spring also said without a doubt get rid of the mechanical pump and put in an electric one. He was going to do it on the spot after a quick trip to autozone. Any comment on that? What is creating these air blocks in the fuel line? Does storage in a moist environment have anything to do with it.

[azruss]

I think you are still looking at a crud problem. Get the tank replace and even think about the fuel lines as well.

[So Cal Mark]

sounds like your 15 "experts" are self-proclaimed. A filter won't prevent your car from starting. The float bowl holds enough fuel to start and drive a couple of blocks. A hot restart issue can be attributed to flooding, caused by heat soak after the engine is shut down

[bluespider262]

I just went through something similar.

If you are seeing any crud in the filter (buy clear ones) you'll have no end of intermittent driveability issues. I had issues getting the car over 40 mph originally. Tried a bunch of easy stuff that didn't work then finally pulled the sender when I realized how quickly it would trash a new filter. The sock was so clogged with rust I couldn't blow through it after letting it dry. Yet it would still start and drive pretty good under 40mph.

At this point I figured I'd try trapping some stuff with a filter or two, but it would end up killing filters after just a few miles, so that wasn't practical. I had two choices at this point - replace the tank w/ a repro, or try pulling the tank and cleaning it myself.

So I drained/pulled the tank. First I filled it with water until it was full, then tumbled it a bit and tipped it over to drain, and then shook it as empty as I could. Did this probably 5-10 times - lots and lots of junk came out but I could still hear stuff in there. The internal baffling makes it really hard to get all the stuff out of one of the two holes you have to work with.

So I let it dry in the sun a couple of hours before attacking it with the air gun @ 120 psi. I essentially blew compressed air into both larger openings, alternating them, at all sorts of angles and depths. I had a small air gun and a larger 12" wand one, and I alternated between those. Believe me it made a big brown cloud and a crazy amount of sediment would blow out the other hole for a bit. Every few minutes, once it settled down and not too much appeared to be coming out any more, I'd stop w/ the air. I would then tap the outside with a mallet all around a couple of times, then repeat the air gun treatment for another 5 mins. or so until it stopped spewing rust. It took about an hour of repeating this, and I had to get it just right to get that final tbspoon of dust out, but finally I hit a point where all the junk was gone and I couldn't hear *any* stuff at all in there when I shook it after hammering on it and rolling it around the yard a bit.

The pile of stuff that came out was surprising. Probably enough to fill a gallon jug - and that was after getting the big stuff out with the garden hose! My arms still hurt from shaking that thing around. But I haven't seen even a single flake in my filter since then.

Don't know how long it will last, but I keep the tank full now, so hopefully this will prolong me needing a new tank for a while.

-Dave

[bradartigue]

You need to fix the problem - the tank.

Put on a glass filter in between the tank and pump. From now until well after you replace the tank monitor the crud in the filter and replace or clean the element when needed. I would also put a filter in between the pump and the carburetor. You also need to inspect the filter in the carburetor itself, which is behind a brass cap on the float bowl where the inlet is.

[pottsthomas]

I saw Vick had repro tanks for less than what I paid to seal a tank the last time I had it done. Out of stock though. It has no baffles they say. Any thoughts on the no baffle tank? Thanks for the comments. My Buddy Charlie has a Lancia Beta that had the same issues until he had his tank coated, so I'm sure this is the right advice, though I'm still wondering about my Saab experience. That had the tank out and sealed when it had its problem. What is the input on an electric fuel pump?

[azruss]

i'm running an unbaffled tank from AR. Only once i got a momentary starvation and that was pushing the car hard with a 1/4 tank.

[So Cal Mark]

avoid VAS, get a tank from Auto ricambi

[bobplyler]

A filter won't prevent your car from starting.

I had a completely blocked filter once. The car ran for about 20 feet, then stopped.