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Car is spluttering above about 4000rpm...?


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Hey guys.

This is the story. I've got a 2002 *non ti or tii) that's been running fantastically well since the day I bought it a few years ago (the engine at least). In the beginning the engine still felt quite 'tight' and wasn't too keen to rev up, but over the weeks and months I kept pushing it further and further up the rev range to the point where it was running beautifully all the way up to about 5000rpm (maybe a little higher), and then I lost the balls to rev my 42 year old car any higher.

ANyway, it's been running like that for several months now, no issues. The other night I took it for a drive and at about 4000 rpm there was a bit of a 'cough'. I had just pulled out of a fairly sharp left hander and wrote it off as fuel surge. Then last night it happened again, so I powered through it. After the initial 'cough' (at about 4k) it went back to sooth revving and then at about 5k it began spluttering again :( This time I eased off and now it's standing in my garage.

It must be said that aside from this, the car is running beautifully. It starts up first time, it idles smoothly (cold or hot) and it revs beautifully smoothly up to the said 4k or 5k mark where it then starts spluttering.

Any ideas? My guess would be fuel delivery is lacking at those engine speeds or timing. If it was timing though, I'd imagine it to be out all through the revs and not just high up.

What do you guys think...where to start looking?

Thanks guys!!

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learn where the secondary jets are in your carburetor

remove the carb top half, clean all jets, adjust the float level,

adjust the dwell and ignition timing and reset your idle speed

and idle mixture, check to be sure when the gas pedal

is at the floor that the linkage and carb are at the STOP

full open at the carb.

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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It's most likely fuel supply, as above

(it's not the secondary jets, tho it COULD be the power valve diaphragm)

I've had pump problems do that, and having the fuel filter before the mechanical

pump can make it do that, too- it forms an 'air spring' that reduces

the effectiveness of the pump,

as can having the short pushrod on the long pump, blah blah blah...



"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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