New issue with 1275/ sputter stall

[Mike]

About every 10 miles or so at low idle I go into a sputter that will stall unless I rev up. Only sputters at low idle not at higher rpm. After several revs (30 seconds or so) everything returns to normal. The carbs have plenty of gas in the the bowls so I would assume this is not a fuel line issue. Took it by a mechanic and he didn't think I was losing spark. I wondering if I need to rebuild the carbs or is it a intermittent short that occurs at low rpm and the short is stopped by higher revs. Any suggestions.

Thanks,

Mike
1958 Bugeye

 

[Woblynne]

Hi,
Do the carbs have waxstats or similar, when pulling up after a run the temp in the engine bay may rise quite a bit so it could be the waxstats or just fuel evaporation, does your fuel line run near to your exhaust and do you have a carb heatshield fitted?

HTH
Mark

 

[Billm]

Check your float level, you could be running too rich and fouling the plugs (possibility only)
Bill

 

[SilentUnicorn]

WAG- check jet alignment?

m

 

[nomad]

Whats the fuel pump doing while this is happening? Could be a balkey SU fuel pump. Had one act like this.
KA

 

[Mike]

Re: New issue with 1275/ sputter stall 2nd posting

Well, I started her up cold this morning and we went thru the sputter session for a bout 4 minutes until it stopped. I believe this rules out a heat issue of any kind (fuel line near exhaust or carb heat shield). How do I go about testing the fuel pump other than replacing? My mechanic said that the bowls had fuel in them when this occurred, would this eliminate a fuel pump issue. Could this possibly be an alternator issue? It has squealed occasionally when I have gone into the sputter.

Thanks,

Mike

 

[texas_bugeye]

Re: New issue with 1275/ sputter stall 2nd posting

sounds like its loading up - running a little rich "dusting the plugs"
May turn in a flat or lower the float hieght.

 

[jlaird]

Re: New issue with 1275/ sputter stall 2nd posting

Yep, carbs for sure.

 

[bugimike]

Re: New issue with 1275/ sputter stall 2nd posting

Certainly something to check for with these symptoms is vacuum leaks. Make sure all manifold nuts are tight and gaskets are good!! Vacuum leaks can be very temperature-sensitive!

 

[Sarastro]

Re: New issue with 1275/ sputter stall 2nd posting

You might want to take a look at https://www.nonlintec.com/sprite/fuel/. It describes my experience with a very similar problem.

 

[bugimike]

Re: New issue with 1275/ sputter stall 2nd posting

Nice write-up there Steve :thumbsup: !! Very similar to what I wound up doing!!

 

[Mike]

Re: New issue with 1275/ sputter stall 2nd posting

Great article Steve!

The symptoms are identical. One thing I have noticed though is my problem can occur on a cold start (How cold can a start be in 100 degree texas weather?). Being a novice at this stuff can be very frustrating but I do enjoy the learning curve. I'm thinking of rebuilding my carbs and going thru the whole fuel system to make sure everything right.

If I'm loading up in the bowls and the symptoms are getting much more frequent, what do I do? Could their be a piece of something lodge somewhere in the carb? What make the bowls load up? Why was this an infrequent issue and now It's on every start up? I am getting fuel to the bowls so I believe I can rule out a fuel pump/line clog or failure.

Thanks,

Mike

 

[texas_bugeye]

Re: New issue with 1275/ sputter stall 2nd posting

what I mean buy loading up is if its running a little to rich and as hot as its been here in dallas you could have a little carbon buildup and blipping the throttel is enough to clear the rich state for what.. 10 minutes of idle until it happens again.

Maybe leaning the mixture slighty would help.
Maybe your plugs need a heat range change.

 

[Sarastro]

Re: New issue with 1275/ sputter stall 2nd posting

Thanks for the comments on the article.

Of course, it could be other things; I just described what happened to me and what fixed it. Problems like this can be awfully sticky--just keep trying things that make sense, and eventually you should get it. I do think it's a fuel problem, though.