Hi There,
Hopefully i can point you in the right direction mayeb even offer a solution,
Generally i have foudn that when this happens its mainly due to a vacuum leak somewhere in the system. Check all the small rubber hoses in and aroudn the intake manifold.
If they are all non perrished and in good condtion it coudl be something else such as a clogged injector, However there are soo many possibilities and problems that it could be.
With cars the main problem is that sometimes its a few different things causing the one problem.
Has the car been tuned recently/Serviced.
Generally if air filters /fuel filters are blocked and dirty they can also help cause hunting in engines.
It could also be that you throttle linkage is sticking. This is common in older cars as dirt grease and oil builds up on the engine and can stop linkages moving correctly,
You coudl try following the wire that runs to the accelerator/gas pedal to the butterfly and try cleaning and lubricating with a reputable spray on lubricant that wont attract dust on all the linkages carefully and see if this helps .
Other common problems may be timing chains/belts, If they need replacing they tend to cause spiraddic idle as well although generally it would be really bad all the time,
Sometimes however it can be a problem with the cars onboard computer, be aware that if your cars battery is running low on charge or is long past needing to be replaced this to can effect the computer and cause spiradic idle as the car trys to compensate revs to push more charge through the alternator.
I know its not really a definitive solution but i hope it helps save you takinng it to the mechanic.
Cheers
Steve
Hi there ,
Generally one wouldnt think that a new pump wouldnt effect the rpms,
However if your model has a computer adjusted timing and fuel table it may be re-learning.
A lot of the newer cars today have this setup, howver it may be that you might of got a bit of dirt in there while changing pumps. that may be an issue clogging up something.
Remember injector nozzles are very small and it only takes a little bit to partially clog one up,
You could also try a fuel injector cleaner in case it just needs a good clean.
I almost forgot, when you changed the fuel pump did you change the fuel filter? As generally if the old one was clogged up it might of been the reason why the last pump died from not being able to pull enough fuel through? Not sure if tis relevant to your case but Allways stay away from fuel in drums as rust particles can live in drums and are a common problem here where i live.
Hopefully it gives you more of a hand there,
If need be comment back again and ill get back to you.
Cheers
Steve
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steve, thks for the infor.i did changed the fuel pump recently , will this affect the rpm shoot up?
steve, thanks again. i have solved the problem.a loosed rubber hose around manifold was the cuprit.ttks
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