1977 Spider Runs rich

[davefrancisco]

My fiat runs very rich and was wondering what ideas you folks may have. The car idles well, an occasional miss, but otherwise runs smoothly. No noticeable issues like hesitation during acceleration either.

What I have done already;

1. New Plugs & Wires
2. New Electronic ignition including Coil.
3. Set the idle mixture and idle speed.
4. Removed all emissions BS, air pump and electro valves. (perhaps this is the issue )

There is also an after market electric fuel pump that was on the car when I bought it, and I have seen posts that mention fuel pressure and the issues they may cause.

Any advise/wisdom appreciated.

Thanks

Dave

[18Fiatsandcounting]

When you say it's running rich, what are the symptoms? Gas smell? Poor gas mileage? Black soot coming out the exhaust?

If your car idles well, accelerates smoothly, and gets low to mid 20s mpg, you've got a normal running Fiat! But, if you smell gas or have black soot coming out the exhaust, there might be some things going on due to the removal of the emissions stuff.

-Bryan

[davefrancisco]

Thanks Bryan. Its the smell of gas that is the issue, The car runs well, so not going to worry about it.

Dave

[Nut124]

Excessively rich running will quickly wear out piston rings.

The problem is assessing how rich is too rich to do this. If the smell of unburnt gas is such that it burns your nose, then for sure rings are hurting.

Back in the -90's, when I fired up a Fiat engine for the first time after a rebuild, with new twin webers, the idle mix was way too rich. I was happy to get it started. It was running way rich and I did not realize that early enough. The engine actually seized while idling and stopped, ring end gaps closed, due to gas washing oil off the bores.

It did start and run again after cooling down, but there was always more blow by than I wanted.

Found idle screws open over 6 turns when 1/2 to 1.5 is typical after adjustment. These carbs came "adjusted for my application".

[18Fiatsandcounting]

A gas smell can be from running rich as Nut124 described, but it could also be from a missing EVAP system on the car, old fuel hoses that "weep" gas, loose or open connections to the tank or carb, etc.

Might be good to check your gas tanks and fuel lines/carb for any issues.

-Bryan

[davefrancisco]

Idle mixture was set. about 1.5 turns open. Certainly not at a point where the exhaust burns my nose. I'll find a local shop with a Co2 measurement capability and see what the emissions look like.

And yes, some of the hoses for fuel/evap system are old. I cannot see any cracks, but that does not mean much.

Thanks

Dave

[18Fiatsandcounting]

Yes, it would be helpful to find out if the gas smell is coming out the tailpipe (running rich), or gas is leaking (seeping) from somewhere else like an old fuel line hose. If the car smells like gas when it's just sitting there, that's a pretty good sign it's the latter, but it's not conclusive as the hose might only start to leak when it's pressurized from the fuel pump or the like.

Also, if the engine really is running rich, the spark plugs should have a sooty appearance. Normally, they should be tan or grey.

Another sign for running rich is gas mileage. If you are getting less than 20 mpg, something's wrong. For the 1970s cars, fuel economy was somewhere in the mid 20s.

Oh, and I forgot to mention: These 40-50 year old cars do tend to smell like gas and oil; that's just part of the charm of owning an older car! So, I'm not saying you don't have an issue, but a faint smell of gas under certain conditions may be "normal".

-Bryan

[davefrancisco]

The PO installed an electric fuel pump that comes on once the key is in the start position. So turned on the fuel pump with the car not running to pressurize the system and after 10 minutes no gas smell.

Aside from the #4 spark plug, the rest look fine. #4 may have a valve seal issue or oil ring problems. That's a project for the winter. I just clean that pug from time to time.

To wrap this one up, I think this is simply the charm of an old car.

Thanks as always

Dave

[wubie317]

The PO installed an electric fuel pump that comes on once the key is in the start position. So turned on the fuel pump with the car not running to pressurize the system and after 10 minutes no gas smell.

Aside from the #4 spark plug, the rest look fine. #4 may have a valve seal issue or oil ring problems. That's a project for the winter. I just clean that pug from time to time.

To wrap this one up, I think this is simply the charm of an old car.

Thanks as always

Dave

I know I'm late to the party, but just had this same experience...and I solved it to pass my smog test in CA with flying colors. The trick? The old 'Italian Tune-Up'! 2 miles with RPMs at 5500 steady blows out all the crap (nice billow of gray smoke at the end of the run). Ran a bottle of Seafoam additive too which might have contributed. Had to reset the mixture screw afterwards, but now everything is running great.

[18Fiatsandcounting]

Ran a bottle of Seafoam additive too which might have contributed.

Wubie, did you add the Seaform to the gas tank, or bleed it directly into the intake through a vacuum line or the like?

I don't usually recommend snake oil, but Seafoam really does seem to help to pass emissions tests. I sometimes run a can directly into the intake, being VERY careful to not add too much at once as it can do serious engine damage if it's added too quickly. Just bleed in a can over the course of a couple of minutes with the engine running at 2000 rpm or so. It coughs and sputters, but it's powerful medicine.

-Bryan