cavalier hesitation - Anthony Oliver
hi , i posted a topic a few weeks back about my cavalier hessitating on a low fuel tank, i had since been through every option and its not fixed, although i have heard of something called a charcoal canister whish evaporates fuel.

can somebody tell me where this is located as the diaphram might have gone or the purge valve.

i have no idea even if it has one.

Cavalier sri, 2.0 8 valve, j plate, 91 (change over year),
cavalier hessitation - Ellis
if you have no joy try, or

both vauxhall sites

cavalier hessitation - Dynamic Dave
How low on fuel before it hessitates?
Never heard of a charcole canister.
When was the last time the fuel filter was changed? Should be every 18,000 miles, but if you run the tank low on fuel a lot, you might have prematurely aged it by drawing sediment from the bottom of the tank into it. For reference, it's situated under the back end of the car on the OS of the spare tyre well, or on the tank fixing strap, if it's a later model.
cavalier hessitation - Anthony Oliver
Yeah there is definately a charcoal canister on injection cars so i've been told, and a search in yahoo on charcoal canistor, returned a pictures and lots of hits about what it does etc.

its not the fuel filter its been changed.

dunno if breather is blocked, but took petrol cap off and drove about and its still the same, so that rules that out.

cavalier hessitation - Anthony Oliver
forgot to mention, its a quarter of a tank, when it gets to that its starts giving me jip
cavalier hessitation - Dynamic Dave
Anthony, Re: Charcoal canister,

This was only fitted to cars built after 1993 with cat convertors. It was fitted to minimize the escape into the atmosphere of unburnt hydrocarbons. So this won't apply to your 1991 Cav.

Back to your original question, daft question, but is the fuel filter fitted the correct way around?
cavalier hessitation - Anthony Oliver
lol yep the filter is fitted the proper way round, and it did it with the old filter anyway.

One other thing it might be is,
the tank as a few dents as if it has been scrapped along a ground or hit something to dent it in a few places, it doesn't leak or anything,

could it be the sender unit , as it was dented it bent the pipe up inside and the fuel when low sits around the dent, thus the pipe not getting the fuel it requires, its ok when its high because the fuel covers pipe.
cavalier hessitation - Dynamic Dave
Anthony, you might have hit the nail on the head. If it only does it when you've less than ¼ of a tank, and combined with the dent, then it sounds possible. In that case the only solution is to not run the tank down to less than a ¼ full, which is a lot cheaper than replacing the tank.
cavalier hessitation - prm
I had this same problem a few years ago on a Granada 2.0, which I lived with for a year. The battery needed renewing due to dying on me, and the problem dissapeared,car ran better as well.
cavalier hessitation - Anthony Oliver
did your granada do it all the time, or only when the fuel tank was low like mine?
cavalier hessitation - prm
No, not all the time only when the fuel was low.
Hessitation Fixed - Anthony Oliver
sometime ago u might recall, i posted a message about hessitation missfire etc, when the tank hit quarter mark.

After a year of being fed up i decided to whip out the fuel tank and give it a good ole wash out see if it was that, that was giving me jip. nope nice and clean, i then took off the sender unit,

problem found.

the return pipe on the sender unit that goes in the tank and connnects to the round bowl type thingy wasn\'t connected, dunno how it came off , or was a new unit and they couldn\'t be bothered to connect it, took me about 1 hour, all back together fired in a can full of petrol and way hay, idle lovely no hunting etc, can blow away some saxo\'s with quarter tank now, hehe

just thought i\'d let u all know incase it happens to u.

swearwords deleted/edited. You might feel it is acceptable to use words like that in your everyday language, but please refrain from doing so here DD.
Hessitation Fixed - Railroad
This problem of hesitation on the 20NE engine with Motronic 4.1 or 1.5 fuel injection is often easily cured.

On the side of the Air Flow Sensor is a screw which when new would've had a black or blue tamper proof cap over it. This is the CO potentiometer. Turning the screw clockwise increases the CO pot voltage, and the engine will run richer. Use a voltmeter into the CO pot wire on the 5 pin AFS plug, (sorry can't remember which terminal it is off hand) and earth. If the voltage reads about 2.5V it is too low, increase it to about 3V - 3.5V.

Beware though if you increase it too far, you will go outside the ECUs parameters and it will recognise this as a fault and store a trouble code. The ECU will then be in Limp Home Mode, the engine management lamp will be on, and it will restore the CO pot voltage to it's default setting, thus you will have your hesitation problem back. Setting the CO pot to 3V - 3.5V should cure your hesitation and cause no other problems.

Hope it helps.

Value my car