Troubleshooting

[boogiedude]

So I've been having some some power issues with my car lately. In all gears,I have virtually no power under 2000 rpms. In gears 2-5, it is basically like a switch. Once i fall below the 2000 line on the tach the car bogs down and refuses to get up and go, but as soon as the needle passes the mark, it takes off and is very peppy. In first gear it isn't as severe, but it is still noticeable. I've been dismissing it for several weeks, but my annoyance with it has finally caught up with me.

And that isn't all of the problems I'm having. Every morning i go to start the car, it takes a good 15-20 seconds of turning the engine over before it finally fires up. If I pop the hood and check the filter before trying to crank the engine, i can see that it is bone dry. Not sure if the filter is supposed to retain fluid over night or drain, but figured it would be worth mentioning. Do all fiats take a while to start after sitting over night? a friend of mine has a 73 and 76 bmw and the 73 takes just as long to start but the 76 starts immediately.

And now on to problem number three, once i get my car started, the engine is extremely prone to choking and backfiring out of the carb. And it takes quite a while to get past this point. usually 3-5 miles of driving until i can safely give the car a good amount of juice. Once again, is this normal for fiats?

And the last problem. When the car is not yet at the 190 mark, the car will sometimes develop a speedlimt. Basically, if i hit that speed, regardless of gear or rpm, the car will lurch violently and refuses to get past it. I've only had this happen at night, and its happened at 4 different speeds. The first was approximately 60mph, the second was 50mph, then 55mph, and the most recent was 30mph.

I know that i haven't provided the best info, but if there's anything else you need answered, feel free to ask away and i'll fill you in as best as possible.


Thanks in advance for the help!

[kilrwail]

Do you have a mechanical fuel pump? If so, that would at least partially explain the need to crank the engine for several seconds after it has sat overnight. But in addition, it souncds like maybe the acceleator valve diaphragm is faulty, resulting in poor low-end and cold fuel delivery. Have you checked its condition?

[boogiedude]

I do have a mechanical fuel pump. How would i go about checking the accelerator valve diaphragm?

[ventura ace]

Pump the accelerator linkage while looking down the throat of the carburetor (engine off). You should see a little spray of fuel from the pump jet every time you pump the linkage. If not, the diaphram could be bad, the pump jet could be plugged, the check valve could be malfunctioning, gaskets sealing the pump jet could be compromised. But if the pump jet spray is good, then all of the above is probably healthy.

Alvon

[So Cal Mark]

it sounds like you have a couple of issues, probably all carb related. You could have an accel pump diaphragm that is leaking and causing the carb bowl to empty overnight. It also sounds like your low speed jet is plugged up. Choke may not be working either

[boogiedude]

I just did the test suggested by ventura ace, and it appears to be functioning correctly.

Manoamatt rebuilt the carb about 2-3 months ago so i hope that the carb isnt the issue. And i'm pretty sure the choke does work, it does open and close depending on the temp.

[kilrwail]

If it's not fuel-related - and we're not 100% sure of that yet - it's likely ignition. Please remind us what year, engine and ignition system you have. If it's points, have you checked the gap/dwell? Is it dual or single points? Have you checked the distributor advance? Timing?

[boogiedude]

It's 78, 1800 engine, and it is a points ignition that we converted to single points. As far as I'm aware, Matt has the timing and distributor advance set to where it should be. He adjusted it not too long ago(withing 2-3 weeks) when we changed out my exhaust.

[kilrwail]

Same as my car. When you converted to single points, did you run a wire directly from the coil to the distributor? Or are you still using the wire in the harness? Have you personally checked the points gap today? Or the timing? These settings can shift inexplicably. Was the condensor on the distributor changed? Have you checked all electrical connections at the coil and distribtor?

[boogiedude]

Yes, we did run the wire directly to the coil. As for the timing and gap, i don't have a timing light, nor the knowledge to check the points gap. The condensor was not replaced, and yes i have gone through and checked connections and everything is solid.

[kilrwail]

Have a look at this thread:
http://www.fiatspider.com:16080/f08/vie ... sor#p51029

Your problem might be the condensor or the plugs. You really ought to buy a timing light, because you'll need one as long as you have the car ($40 max). Do you have feeler gauges, which are required to set the points gap (~$7)?

[boogiedude]

how would i check the condenser? what should i look for? and no i dont have feeler gauges either, i'll look into getting my hands on a light and feelers

[kilrwail]

Well, I suppose if you were to disconnect the condensor and the problem doesn't get any worse, that would be a clue. A better approach would be to buy a new one, along with a new set of points if they weren't changed either. I replace both of mine every spring, although it's recommended every two years. It's cheap insurance.

[So Cal Mark]

still sounds more like a carb problem to me. But it's always wise to check the point gap. And that is pretty easy to do. The gap should be about the width of a matchbook cover (.016) when the rubbing block of the points is on dist cam

[majicwrench]

I'm with Mark, sounds like the low speed jet. My '72 plugs on a pretty regular basis, and give the symptoms you describe. Even if the carb was just re-done, plugging happens. Very tiny jet.
I hate to see people start grasping at straws, not that is COULDN'T be the ignitions, but I often see folks start messing with something else, then something else, and end up with a bunch of problems as well as the original problem.
Not sure what type of carb you have, but if you can tell us, someone can likely point out where the low speed jet is.
Keith