Cuts out on full throttle
Turbo Mini Forums

Hi guys getting to a bit of a wits end now with the wifes motor.

Been restoring her 89 rose 998 over the last 2 years now everything is done it just wont run right.

Replaced all the usual things plugs points condenser leads etc.

The problem i'm having is at full throttle it will sit and rev full throttle quite happy but as soon as you drive it and try and give it the beans it just dies then runs like a pig chucking out blue smoke.

It will run quite happy under 1/4 throttle but nothing more without getting the hump.

So today took the hif38 apart to check that all ok there and even replaced the fuel pump as thought that may have got to pot wilst it was sitting. Put it all back together and was the same. Got the correct oil in the dash pot. i was thinking maybe wipping the head off to have a look at the gasket as cant think of anything else.

Thanks Tony.

I'd be inclined to think it was the head gasket. As the pressure increases with the increase in throttle, it can force the gases through a hairline crack in the gasket. On lower throttle the pressure isn't as high so could run normally.

Edited by Mini_the_minx on 22nd Oct, 2010.

This is what i was thinking but hearing someone else say it just backs it up.Well suppose the head comes off tomorrow..

Have you checked the timing? Is the vac advance connected and free to move inside the dizzy housing?

sounds like a fueling issue to me. Is the engine standard and are you using a standard needle in the carb?

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i 2nd bens diagnosis

Jack Jones

Engine is standard apart from a stage 1 kit and a hif 38 carb. timing checked all ok. but is getting worse. there seams to be enough fuel getting up and misfire is slighty worse today.

if it was head gasket it would run ok higher up but be rough low down, been there many times
im with the fueling, try pulling the choke out just as it starts to missfire if it revs through there is the answer,
also the needle in the carb should be an AAM or AAU both made mine run good but with a high idle co ( ie didnt pass mot with that needle)

Yes i moved to the darkside

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Dont seam to want to run with choke in or out this morning when trying to move it on the drive just fire's up pop's a bit smeels massivley of fuel but no bang. Plugs out cleaned checked still nothing the time it takes i think the head is coming off aint been off in 4 or more years.

what colour where your plugs before you cleaned them?

Change the condenser again - there are lots of very poor ones out there.
Then try substituting a different coil.

Instead of debating about the head gasket, just do a simple compression test.

Whilst lots of the other answers re. fuel, ignition etc. could be correct, I allways start with a basic compression test - especially if you think it may be the head gasket anyway - why pull it apart to look when a compression test will tell you most things. :)

Schrödinger's cat - so which one am I ???

Sounds like over fueling to me not under, so pulling the choke out will make things worse.

This could be all sorts of things, but have a look at the float bowl needle. If this is not sealing then that could be the problem.

I agree with Rod though if you think it is the head gasket then a compression test is a must before you start pulling it apart.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

Im going with either:
split vac advance pipe
faulty coil
faulty condenser