Low rev stutter under load

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Joe_bury
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Joined: 28th July 2016 - 4:26am

Low rev stutter under load

Post by Joe_bury » 16th February 2018 - 6:26am

Hi all,
My fasty has been running well however developed a low revs stutter but not originally on every drive. Needed a bit of a tune up so took it to my mechanic and told him. He just reset the carbs, valves, timing and has driven perfect all week then started up to drive home from work today and was stuttering again. Drives fine through the revs but low down in slow traffic very annoying! It’s popping on the exhaust more than normal and notice the idle drops when it’s like this too when it normally more positive when ok.
Going to give it a rest for a few days and be interested to see if it runs normal again. However just seeing if anyone has any suggests as to what it can be or has experienced this before?
Any help would be great. Thank you :)

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937carrera
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Location: North Yorkshire

Re: Low rev stutter under load

Post by 937carrera » 16th February 2018 - 12:22pm

Sounds like it could be an excessive gap on the plugs. Do you know if the points were checked prior to adjusting the timing ?
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

Joe_bury
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Joined: 28th July 2016 - 4:26am

Re: Low rev stutter under load

Post by Joe_bury » 16th February 2018 - 8:10pm

Hi 937, yes points were checked too. Points and condenser only 2 weeks old and all ok. Possibly thinking could be a fuel filter problem but doesn’t seem like it..

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937carrera
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Location: North Yorkshire

Re: Low rev stutter under load

Post by 937carrera » 16th February 2018 - 9:25pm

How are the spark plugs ?
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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broady_6
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Re: Low rev stutter under load

Post by broady_6 » 18th February 2018 - 11:03pm

Just because a condenser is new doesn't mean its ok. I've had a couple of knackered ones out of the packet. Always worth revisoting newly installed parts
The sultan of swing

Joe_bury
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Joined: 28th July 2016 - 4:26am

Re: Low rev stutter under load

Post by Joe_bury » 19th February 2018 - 3:47am

It actually started to do it briefly before I changed the points and condenser thinking about it. It’s inconsistent drove it yesterday for a short trip after being sat for 2 days and had no problems at all but know before long it’ll start hesistating again.
Sorry 937 the mechanic didn’t check the plugs so think that’ll be my job tomorrow check the gaps etc. Just one of those annoying ones, must be a minor issue creeping in somewhere!

Joe_bury
Posts: 41
Joined: 28th July 2016 - 4:26am

Re: Low rev stutter under load

Post by Joe_bury » 22nd February 2018 - 2:40am

So update on this. Checked spark plug gaps and all were fine. Looked at fuel filter and it pretty dirty was some rusty fuels swishing around in it. Changed it over and seems to be all good and idling as it was. However looked under to see if any leaks but noticed a bit of rusty fuel had already spirted into the filter not much though. So maybe some rust from the chassis line has dislodged as fuel tank has been recoated who know. Will keep and eye on this and might replace again soon.

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937carrera
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Location: North Yorkshire

Re: Low rev stutter under load

Post by 937carrera » 22nd February 2018 - 8:15am

Was the tank re-coated on the inside - more likely to be corrosion on the inside of the tank than pipes, especially if the car has been stored for a while with little fuel in it.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

Joe_bury
Posts: 41
Joined: 28th July 2016 - 4:26am

Re: Low rev stutter under load

Post by Joe_bury » 22nd February 2018 - 8:51pm

Was sat for a long time before I bought it hope recoated tank on the inside, I’ve had it running for a year or so now. Kept original metal fuel as seemed fine after blowing it out so need to see where this is coming from..

Joe_bury
Posts: 41
Joined: 28th July 2016 - 4:26am

Re: Low rev stutter under load

Post by Joe_bury » 24th February 2018 - 2:30am

Stumble has come back, drives great through the rev range never had trouble with this before!!&))!&@!! In the process of emiliniation. Cheers

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937carrera
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Location: North Yorkshire

Re: Low rev stutter under load

Post by 937carrera » 24th February 2018 - 10:33am

Getting into an area that's not my strong point...carbs. Could there be bits of grit causing blockages in the idle jets ?
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

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purplepeter
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Location: Bath, Avon

Re: Low rev stutter under load

Post by purplepeter » 24th February 2018 - 2:19pm

Check the connections to the balance pipe are all nice & tight
Also, whilst You're there, check the vacuum pipe to distributor
And also, Check the connections & that the Cut off vales are tight

Joe_bury
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Joined: 28th July 2016 - 4:26am

Re: Low rev stutter under load

Post by Joe_bury » 26th February 2018 - 8:19pm

Right you’re proberly getting sick of hearing from me but quick update. Changed spark plugs in lunch break from Bosch to Ngk’s runs better, checked connections etc all seems ok wriggled them a bit tighter. Anyway still stuttered 90% of the drive home then suddenly came good again and stayed good whole drive to work next day so starting to think a bit of dirt was/is floating around the carb and blew itself out so that next step if that happens again will clean carbs. Thanks for all your help guys

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937carrera
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Re: Low rev stutter under load

Post by 937carrera » 26th February 2018 - 8:50pm

Sounds good :)

Have another check on the fuel filter and change again if it's looking dirty, try to stop the problem recurring.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

Joe_bury
Posts: 41
Joined: 28th July 2016 - 4:26am

Re: Low rev stutter under load

Post by Joe_bury » 26th February 2018 - 9:59pm

Will do, thanks again 👍

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