Losing performance after about 10-15 minutes

PeterBo

PeterBo

Junior Member
Have just fitted a new carburettor, and checked the manifolds for leaks etc. All appears good, no leaks and car runs beautifully. I have stripped distributor and redone timing and again appears to run at idle and speed with no problems.

So, after idling correctly and running properly up and down local hills, I then find I lose power after about 10-15 minutes. It is as though it is is running too lean and when pushed may backfire. It loses power to the point it may stop altogether but will start and run immediately after albeit with no power. Fuel feed appears OK and after it cools down, performance returns.

Suspected issues could be:

- Bad distributor capacitor
- Bad high tension coil or lead
- Something I haven't thought of but which is temperature affected...

Any ideas???? I am running out of them.

Thanks, Peter
 
Your suspicion of the capacitor and coil are spot on. I do not subscribe to the "throw parts at it until it's fixed" method of troubleshooting but in this case, there really isn't a more efficient way to diagnose either of the two components. R&R the cheapest item first.
 
When your car acts up, do you leave it running at an idle and feel the temp of the coil. Is it hot. Had almost the same problem, coil got hot wouldn't run. Cooled down ran fine. Replaced coil, problem gone.
 
At my age any loss of performance is concerning...

Oh, and losing power is the spelling as defined by the Queen's English (Aussie, Aussie Aussie !!!!)

Thanks for the help guys....

PeterBo
 
True story: How about the biker guy who had "Born to Loose" tattooed on his arm? I wonder if he meant he was born "to lose" or that he was born "too loose"? Maybe the tattoo "artist" didn't know the difference? How many people would know the difference in spelling? Or would care to point it out to the biker? :)
Pooch - Don't get me started on the always-to-be-seen misapplications of loose/lose, they're/their/there, its/it's (there is NO SUCH WORD as a possessive pronoun! That is spelled "its" without an apostrophe, just as "his" and "hers" have none.), whose/who's, then/than in the comparative, and so on. These "gotcha's!" are why the English language can be difficult for foreign speakers to learn. Heck! We have very little grammar to master. So, we gotta' do SOMETHING to make English difficult to learn! I know! Let's have multiple spellings of words that sound the same, but have different meanings! That'll fix those foreigners trying to learn our language! :)
Did you know that because of phonetic spelling, the simple word "fish" can be spelled 76 different ways? Jeez! No wonder little Bobby and Jane can't spell!
Marshall
 
Dad takes those special blue pills, they turn the top of his head red.:eek:.. Don't tell anyone:D

SA sonnoutt
 
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Hmm I would try the coil as its easy to get to and cheap but I helped repair an A that was doing what you described:

Stone cold it would start and run beautifully but after 5-10 minutes it would start to cough and occasional backfire and slowly loose power till it eventually died. Would not restart or cough till it cooled down.

We did the whole electrical system, carb, etc nothing changed. Ended up doing a leak down test after we got it hot and it shutdown on its own. Leak down test is where you supply a regulated 10 lbs of air to each cylinder at TDC on compression stroke and see where the air leaks out. You must remove the radiator cap, oil fill cap, and all 4 plugs. In theory it shouldn't leak out anywhere but after a few seconds it will blow by the rings and you will hear air escaping thru the oil fill - thats normal unless its immediate then you got stuck/broken rings. If it escapes thru the carb you have an intake valve not sealing, thru the muffler its exhaust valve not sealing, if it sounds like its coming from the neighboring cyl then the headgasket is blown between them. Repeat on each cyl turning each one to TDC. BE AWARE THE AIR CAN HAVE ENOUGH OOMPH TO MOVE THE CAR! so dont do it with your legs between the bumper and the garage wall...parking brake and blocks are a must with car in gear.

In our case it was not sealing from cyl to water jacket so when we applied air it was like old faithful out of the radiator neck! New headgasket, decked head, and no more problems. It must have only decided to leak when things got hot and resealed when things cooled down a bit.

So like I said IF a different coil fixes it then yay your back in business for only a little $ and repair time. BUT be aware it could be the headgasket - the leak down test doesnt take much time to do at all and really tells you the health of the engine.
 
Marshall V. Daut said:
True story: How about the biker guy who had "Born to Loose" tattooed on his arm? I wonder if he meant he was born "to lose" or that he was born "too loose"? Maybe the tattoo "artist" didn't know the difference? How many people would know the difference in spelling? Or would care to point it out to the biker? :)
Pooch - Don't get me started on the always-to-be-seen misapplications of loose/lose, they're/their/there, its/it's (there is NO SUCH WORD as a possessive pronoun! That is spelled "its" without an apostrophe, just as "his" and "hers" have none.), whose/who's, then/than in the comparative, and so on. These "gotcha's!" are why the English language can be difficult for foreign speakers to learn. Heck! We have very little grammar to master. So, we gotta' do SOMETHING to make English difficult to learn! I know! Let's have multiple spellings of words that sound the same, but have different meanings! That'll fix those foreigners trying to learn our language! :)
Did you know that because of phonetic spelling, the simple word "fish" can be spelled 76 different ways? Jeez! No wonder little Bobby and Jane can't spell!
Marshall
Click to expand...

I confused my neighbour the other day by trying to explain English spelling and pronunciation using just four words, red; read; read; reed. I didn't have the strength to try to explain plough; tough; thought or go onto bough; bow; bow; beau.
 
Cornishman -
You are right/wright/rite about that! :)
Marshall
By the way, Cornishman, I have always been impressed by your command of the English language, which I am guessing by your location is a second language to you. Articulate, the correct words chosen and properly spelled, and very, very few grammar errors, certainly no more than the rest of us make. Are you native French or an American/Englishman living in France? I suspect that because of the "Cornish" part of your Fordbarn name, you are from Great Britain? I wish I were as fluent in my chosen foreign languages of German and Russian as you are in English!
 
PeterBo said:
Have just fitted a new carburettor, and checked the manifolds for leaks etc. All appears good, no leaks and car runs beautifully. I have stripped distributor and redone timing and again appears to run at idle and speed with no problems.

So, after idling correctly and running properly up and down local hills, I then find I lose power after about 10-15 minutes. It is as though it is is running too lean and when pushed may backfire. It loses power to the point it may stop altogether but will start and run immediately after albeit with no power. Fuel feed appears OK and after it cools down, performance returns.

Suspected issues could be:

- Bad distributor capacitor
- Bad high tension coil or lead
- Something I haven't thought of but which is temperature affected...

Any ideas???? I am running out of them.

Thanks, Peter
Click to expand...


How did it run before you changed carb, and worked on dist. Did you check the spark when it was not running right. If so what color was it.
 
Marshall V. Daut said:
Pooch - Don't get me started on the always-to-be-seen misapplications of loose/lose, they're/their/there, its/it's (there is NO SUCH WORD as a possessive pronoun! That is spelled "its" without an apostrophe, just as "his" and "hers" have none.), whose/who's, then/than in the comparative, and so on. These "gotcha's!" are why the English language can be difficult for foreign speakers to learn. Heck! We have very little grammar to master. So, we gotta' do SOMETHING to make English difficult to learn! I know! Let's have multiple spellings of words that sound the same, but have different meanings! That'll fix those foreigners trying to learn our language! :)
Did you know that because of phonetic spelling, the simple word "fish" can be spelled 76 different ways? Jeez! No wonder little Bobby and Jane can't spell!
Marshall
Click to expand...

The one that I have noticed on The Barn lately is using 'and' in place of 'an'. Changes the meaning of the sentence completely. :p:p

And please don't get me started on the use (or lack of) capital letter and periods at the end on a sentence. I see that and I just skip the post. Too hard to read. :cool:
 
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Capital letter with an "a". ;) A capitol with an "o" is a building and is generally where a state's legislature holds its sessions. Iowa's capitol is in the capital city of Des Moines. 'See why English is so hard for foreigners to learn???
I know, I know: Everybody likes a little *ss, but nobody likes a smart*ss. :)
Marshall
 
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