Runs and drives, but not tuned quite right yet...

Keep it on topic, it will make it easier to find what you need.
Post Reply
User avatar
KalamazooJohnny
Posts: 147
Joined: Tue Dec 28, 2010 12:09 pm
Your car is a: 1976 spider 1977 spider 1965 1100D
Location: Kalamazoo, MI

Runs and drives, but not tuned quite right yet...

Post by KalamazooJohnny »

Well, I have it running and have driven it around the yard, but I just can't get it right on. I got it to quit backfiring, I adjusted the timing a bit an that seemed to fix that, but I still have trouble with it stalling. I start it, and if I am real careful, it will accelerate and once it runs for a bit, its not quite as touchy, but if I hit the gas quickly, or try to rev it up too quickly it stalls. I have never had it running better than it is now, but that one thing is stumping me. I have yet to rebuild the carb, I am trying that on on extra one I have first for experience, but thought I would just throw that out to see if anyone knows exactly what the fix is to what I am describing.
Image
"Get used to people calling it an MG. Hardly anybody recalls Fiats, but people remember MGs because they once saw one on fire." -Corey Farley, Autoweek January 20, 2003
76spider
77spider
65 1100D
So Cal Mark

Re: Runs and drives, but not tuned quite right yet...

Post by So Cal Mark »

a common cause of stumble on acceleration is a bad accelerator pump and/or leaky or clogged accelerator pump discharge nozzle
mdrburchette
Posts: 5754
Joined: Wed Jan 25, 2006 5:49 am
Your car is a: 1972 Fiat 124 Sport
Location: Winston-Salem, NC

Re: Runs and drives, but not tuned quite right yet...

Post by mdrburchette »

That could also cause backfiring and sptting through the carb.
1972 124 Spider (Don)
1971 124 Spider (Juan)
1986 Bertone X19 (Blue)
1978 124 Spider Lemons racer
1974 X19 SCCA racer (Paul)
2012 500 Prima Edizione #19 (Mini Rossa)
Ever changing count of parts cars....It's a disease!
User avatar
KalamazooJohnny
Posts: 147
Joined: Tue Dec 28, 2010 12:09 pm
Your car is a: 1976 spider 1977 spider 1965 1100D
Location: Kalamazoo, MI

Re: Runs and drives, but not tuned quite right yet...

Post by KalamazooJohnny »

Well, I did replace that diaphram, but with a used one because the one I had on there was leaking, but I didn't clean anything. Do I need to run a pipe cleaner through there or something?
"Get used to people calling it an MG. Hardly anybody recalls Fiats, but people remember MGs because they once saw one on fire." -Corey Farley, Autoweek January 20, 2003
76spider
77spider
65 1100D
User avatar
kilrwail
Posts: 1100
Joined: Wed Mar 04, 2009 6:49 am
Your car is a: 1978 Fiat 124 Sport Spider
Location: Perth, Ontario

Re: Runs and drives, but not tuned quite right yet...

Post by kilrwail »

The accelerator pump discharge nozzle is on the opposite side of the carburetor from the diaphragm, below the throttle plate. Try to find it on your spare carb; then you'll see how hard it would be to remove it for cleaning without disassembly. The right way to clean it is with compressed air. A complete carb disassembly may be in your future!
_____________________________________________________________
Peter Brownhill

1978 Fiat 124 Sport Spider - original owner
1977 Porsche 911S - track car
2022 Ram 4 x 4 - hauler
PCA National Instructor and Motorsport Safety Foundation Level 2 Instructor
So Cal Mark

Re: Runs and drives, but not tuned quite right yet...

Post by So Cal Mark »

the discharge nozzle is above the throttle plate. You have to remove the carb top for access. Besides the possibility of the nozzle getting plugged, the o-ring on the nozzle can leak. That lets fuel bypass the nozzle and just seep up around the nozzle. A used diaphragm may not be the best solution
User avatar
kilrwail
Posts: 1100
Joined: Wed Mar 04, 2009 6:49 am
Your car is a: 1978 Fiat 124 Sport Spider
Location: Perth, Ontario

Re: Runs and drives, but not tuned quite right yet...

Post by kilrwail »

Sorry - quite right. I should have said "choke plate". :oops:
_____________________________________________________________
Peter Brownhill

1978 Fiat 124 Sport Spider - original owner
1977 Porsche 911S - track car
2022 Ram 4 x 4 - hauler
PCA National Instructor and Motorsport Safety Foundation Level 2 Instructor
User avatar
KalamazooJohnny
Posts: 147
Joined: Tue Dec 28, 2010 12:09 pm
Your car is a: 1976 spider 1977 spider 1965 1100D
Location: Kalamazoo, MI

Re: Runs and drives, but not tuned quite right yet...

Post by KalamazooJohnny »

Ok, I bought a different carb, completely tore it down, and rebuilt it. Then took off my carb and replaced it with the one I just rebuilt. Started right up (with a spray of starter fluid). But its still stalling out when I stomp on the accelerator. I don't know if its any better than with my old carb. Any other suggestions? I have a new mechanical fuel pump on it, and a new fuel filter, removed the gas tank, cleaned it out completely and ran all new fuel lines the entire length of the car. Spark plugs and wires are new. I don't have an air filter on it, the carb is just sitting open.
"Get used to people calling it an MG. Hardly anybody recalls Fiats, but people remember MGs because they once saw one on fire." -Corey Farley, Autoweek January 20, 2003
76spider
77spider
65 1100D
User avatar
manoa matt
Posts: 3442
Joined: Thu Oct 26, 2006 4:28 pm
Your car is a: 1978 Fiat 124 Spider 1800
Location: Honolulu, Hawaii

Re: Runs and drives, but not tuned quite right yet...

Post by manoa matt »

Regarding the distributor: How are the condensers? Points gap within specification? How about the Dwell angle?

I like your tag line at the bottom of your posts.
User avatar
KalamazooJohnny
Posts: 147
Joined: Tue Dec 28, 2010 12:09 pm
Your car is a: 1976 spider 1977 spider 1965 1100D
Location: Kalamazoo, MI

Re: Runs and drives, but not tuned quite right yet...

Post by KalamazooJohnny »

Thanks, I liked that article, and I found that quote pretty amusing, so I thought I would use it.
Sounds like I should find a timing light an dwell meter. Not sure how to use it, but I got a book
to help me once I locate one.
Anything else?
"Get used to people calling it an MG. Hardly anybody recalls Fiats, but people remember MGs because they once saw one on fire." -Corey Farley, Autoweek January 20, 2003
76spider
77spider
65 1100D
koadoa

Re: Runs and drives, but not tuned quite right yet...

Post by koadoa »

If your distributor has centrifugal advance, you may want to check the springs. Sounds like what was happening to my 850 and that was the fix.
User avatar
KalamazooJohnny
Posts: 147
Joined: Tue Dec 28, 2010 12:09 pm
Your car is a: 1976 spider 1977 spider 1965 1100D
Location: Kalamazoo, MI

Re: Runs and drives, but not tuned quite right yet...

Post by KalamazooJohnny »

Absolutely amazing. Sheer stupidity. Went to remove the distributor cap, and noticed the wires are numbered. Started wondering, if they were numbered according to the order of the spark plugs. Looked in the book. Looked at my 76 which runs fine. Switched plug wire #2 with wire #4. Starts up, idles alot faster, but runs. Sounds better, but smoking a bit. Hesitation on acceleration gone. Turned idle down and adjusted timing a little by ear. All this time I had 2 plug wires switched?! I didn't think it would run if you did that! I am sure when I changed the plugs, I did not switch the wires, which means the old wires from the previous owner were like this. So who knows for how long. I know I have been starting and letting it run occasionally since I changed the plugs and wires a year ago. Now a new question, what kind of damage may this have caused?
"Get used to people calling it an MG. Hardly anybody recalls Fiats, but people remember MGs because they once saw one on fire." -Corey Farley, Autoweek January 20, 2003
76spider
77spider
65 1100D
Post Reply