Carb/Fuel Filter/Cleaning Tips

[joelbert2k]

That engine is awfully noisy. I think I'd check valve clearance and try to figure a way to get the cams properly timed. A compression test might show something as well.

I agree with Mark about the tools.

Joel

[So Cal Mark]

okay, I listened to your first video. Get someone to help you. Start the car and have your helper floor the gas pedal while you're behind the car. Using a towel or shop rag to cover your hand, feel for the amount of exhaust coming from the tailpipe.
If the volume is low and super-heated you probably have a restricted catalytic converter. Try loosening the exhaust pipe at the manifold and see if it will rev. If the exhaust volume seems good, you probably have the cam timing off.

The video sounds like exhaust is coming back up through the carburetor

[majicwrench]

Yup, check the exhaust. Does it have a converter??

The way I check for exhasut restriction, drill a 1/8 hole in exhaust pipe up by engine. Now go get one of those cheapy vacuum/pressure gauges, they are about 3" across.. Get some short rubber hose to make a reasonable seal, press up against hole while someone revs engine. SHould be less than 2 PSI. My bet is yours will be up around 5psi. Even if you don't have the gauge, drill the hole, have someone rev it up. With a good exhaust system, almost nothing will be coming out. ON a plugged one, like yours, hot exhaust will come blasting out the hole like the jet stream, under pressure.
Dropping exhaust is always so iffy, they are so much louder then is hard to tell what is going on, and it gets really subjective.

Another spot you could check exhaust is that air check valve on top of the head, the valve would have to come off, as it is a one way valve. On many cars, don't know about Fiats, my 72 aint' got one, but removing the valve is TOUGH on a lot of cars, so be careful.
Video a big help, you done good. IF exhaust check proves unproductive, might be fun to watch you restrict air flow as engine is at 4000rpm,

Don't bother with clear fuel filter, it will never be full. I would bet ignition fine, check exhaust before anything else.
Keith, call if need be, 406 293 9277

[maytag]

If y'all are thinkin' restricted exhaust, how do you account for the first part of the original post:

Hello Everyone...
Here goes:
Coming home the other day, off a freeway off-ramp, car died as if it had no gas. Just coasted to a stop, dead. Had about 1/4 (little less?) of a tank left. No start, nothing. After letting it sit, checking to see if all hoses, condensors, fuses and everything else was proper, it started up and limped/sputtered home. Getting some gas and filling her up, now idles fine, but sputters and shudders horribly under load, as if it's starved for fuel.

How does restricted exhaust fit these symptoms?
Possible that what you're hearing as restricted exhaust is really the exhaust coming back through the carb, 'CUZ the CAM TIMING IS OFF? I think it's very plausible that he down-shifted coming off the freeway off-ramp and jumped the exhaust cam a tooth (or two?). the fact that the cam marks do NOT LINE UP might point that way too. To me, chasing a restricted exhaust is something he could do ONCE HE FIGURES_OUT WHAT THE REAL PROBLEM IS!!

[So Cal Mark]

you're assuming the engine ran perfectly just before this was noticed

[maytag]

you're assuming the engine ran perfectly just before this was noticed

But you're assuming that it wasn't.

The truth is probably somewhere in between. I suspect it did NOT run perfectly before. But I also suspect that if he were now experiencing the same symptoms as he was before, he probably wouldn't have started the original post the way he did. Even if the symptoms were now worse (which would not really seem to be related to the event either), I would expect he would've started with "I noticed it was doing this before, but now it's worse...." or something like that.

But the original post describes an event, with no symptoms "Pre-Event", and then a specific set of symptoms it is experiencing "NOW", "Post-Event". In my opinion, All of those symptoms (and perhaps even the video) point at a problem of either ignition-timing or cam-timing.

YRMV.

[majicwrench]

Not sure what happened with cam timing issues, thus all my ???????? marks.

But watching video, I see cars that sound like that all the time and they have..... plugged exhausts. Is easy to check exhaust, that needs to be next step.
But I too would still like to know why cam timing issue was dropped, although like I have already posted, I am not convinced that is an issue.
As for the original post, there has been a LOT of general misinformation and misunderstanding in this thread, I gotta go with what I can see/hear in the video, again, having that video is a neat diagnostic aid, I would have never thought of that!!
Keith

[So Cal Mark]

since most drivers don't routinely push their cars, many symptoms aren't apparent to them as they develop until the tipping point is reached. If the car has a honeycomb cat, they can become plugged "just like that" once the media breaks up or melts. We don't know anything about the exhaust on the car.
As for this thread, we still have no idea if the basics are right. He might as well have asked us to guess the color of his house. Trying to diagnose potential ignition problems without a scope is a crapshoot; what is the resistance of the plug and coil wires? What output does the coil have? What is the fuel pressure? Is the cam timing correct? what is the compression? What is the vacuum reading at idle and when break up occurs? What is the ignition timing both static and at break up? What is the air/fuel ratio at idle and cruise?
Answer these questions and I'll post my diagnosis in one line

[OaklandSpider]

Fellas-
again...thanks for the info (guesses?)
wish I had more time to spend on it this weekend, but life gets in the way sometimes. Thus, I haven't been able to perform some of the diagnostic tests y'all have suggested.
As for the CAT, yes, it does have a CAT...no idea of it's effictiveness. The one thing I can say about the CAT is that there was a crack right by where the CAT is connected to the exhaust section. That was recently welded shut, and the car was running better/quieter that before. Ddin't even think of mentioning that due to the fact that I was chasing fuel lines, timing belts, etc.....
Another symptom...if you watch the video (might be hard to make out) the is an almost wheezing / sucking sound coming form the CARB area (maybe out of the carb?) that I didn't notince before.
I'll get back to you on the compression / other timing issues when I have the chance to check them.
Also, is it normal for a car to be running 'fine', as mine was (good power, no issues to speak of, fired right up, etc.) and all of a sudden NOT? I have check condensors, points, all wires to / from iginition and all appears to be proper...
The plot thickens....
Peter

[OaklandSpider]

...feel for the amount of exhaust coming from the tailpipe.
If the volume is low and super-heated you probably have a restricted catalytic converter.
The video sounds like exhaust is coming back up through the carburetor

Mark- exhaust volume does appear to be low...not 100% if 'super heated'...it's hot, yes, but super-heated? Not sure how to quantify that...
Agreed with the 'sound like exhaust is coming back up through the carb' comment...SOMETHING is coming buck up / out of the carb...
To be continued...
Peter

[majicwrench]

From my point of view, the plot is becoming clearer.
Either drop the exhaust or drill a little hole in pipe and check backpressure. That sound coming from the carb is what you get when the exhaust is struggling to get out the back, and can't.
Checking at tailpipe is very subjective unless you spend a lot of time checking your tailpiple to know what it is normally doing.

Convertor can fail in an instant like Mark said, simply falling apart inside.
Drop pipe, or drill hole. Eliminate one thing at a time.
Keith

[OaklandSpider]

Fellas-
Hopefully we are getting closer to the issue at hand. I hope to have time this weekend to get at the CAT issue. I'll report back as time allows.
Thanks again.
Also-
How about good (i.e. cheap) sources for a CAT? I've done some research and got some prices-$200+ at most places...can anyone direct me to something cheaper / and of good quality? Another type of CAT that would work and is readily available?
Thanks
Peter

[majicwrench]

Hmmm, how about we run some tests and decide what is at fault first. Mufflers can collapse and restrict exhaust just like cats can.
Drill hole, test, or drop exhaust and see if it will rev past 4000rpm.
Keith

[OaklandSpider]

wrench-
of course. Just looking / doing some homework in case this proves to be right.
Had I bought / done all of the things suggested, I'd be broke by now.
I may be a relative novice, but I'm not foolish (oh...wait...I bought a Fiat, didn't I?)
Thanks for your help, by the way.
Peter

[maytag]

Okland!
How about an update? did you ever get to the bottom of this?