Idle problem

[mav 1]

I've got an idle problem with my Chim 400.

Just had it serviced (12k service). Drove fine for a few days but it seems that when the fuel tank is <1/2 full the engine starts hunting for revs and occasionally cuts out on idle. It's fine with a full tank, and ok when I press the accelerator.

So i've been holding the revs up when stationary which isn't great.
I took the stepper motor out and cleaned the cone on top - seemed fine.
I also took it back to the garage where they loosened the idle screw a bit, but in true TVR form the problem temporarily went away while at the garage.

Any thoughts? I'm thinking fuel pump, but the car does start OK every time.
Back to the garage anyway.....

Cheers,
Mav.

[Bodmin]

Try slackening the fuel cap incase your carbon canister is not working properly resulting in the fuel tank not venting properly. Usually shows up more in warmer weather like now.

If you slacken the fuel cap you will feel it has a second 'catch' point before it comes off. When in this position the cap will feel springy but fuel cannot escape.

Worth a try

Bodders

[spend]

Don't overlook trapped pipes (fuel feed & return + vent). Its easy enough to kink them or pull up a tie wrap when working underneath..

[GJOSDDLO]

I would have said it's a damaged stepper motor, but the >1/2 tank solution throws my theory out of the window.

I had a similar problem a while back when starting from hot - but a good clean of the stepper motor fixed it.

Hope you get it sorted.

G

[Symonab]

Fuel temp may be an issue? With a full tank there is suffieicent volume of cool fuel. Once you get lower temp rises. Is this problem there when you start off with a full tank or does it only occur when you have been out and the tank has lowered?

[mav 1]

The problem occurs any time that the fuel is <1/2 a tank.
The car always starts fine, but when idling will hunt and then die.

The fuel pump has been whining for a few years now, but as I said the car starts properly so it can't have died completely. I'll take a look at releasing the cap and checking the pipelines.

Cheers.