Hi, just been out for a blast and had a problem with my Indybade which I would appreciate your thoughts on.

Car was running fine for about 5 or 6 miles and was pulling hard, but then started to die under load. When I dipped the clutch it would rev OK but then wouldn't. pull with clutch out.

I pulled over and had a quick look around the simple things like coils, leads etc. and these seemed fine. Car ticked over OK.

Started off again and car was OK for another mile or so then same think happened, no power. Slowed down and revved engine, again it would rev but not pull under load.

Once again after taking it steady it seemed to run OK for another 3 or 4 miles but the problem came back and car would only run in short bursts, ie. dip clutch rev. engage clutch, some progress, dip clutch again etc.

Also noticed that car alo seemed to then backfire.

Managed to limp home, though engine did actually stop when trying to pull up a short hill, though started again OK.

Car will still start OK and seems to tickover fine.

Any thoughts? Is it a fuel starvation problem or an ignition one?


Thanks,

Simon

agree, maybe air getting in after carbs too.

Certainly does sound like a fuel problem - had exactly the same symptoms with a bike a few years ago. In my case, it was a blocked vent on the fuel cap causing a drop in pressure as the fuel went out, until the pump couldn't pull any more out.

I'd look at fuel tank venting, filters and all associated stuff.

David

Carbs icing up ? typical symptoms. Try running a preheat pipe into your airbox from the exhaust

Thanks guys, I thought that it would be more likely a fuel problem. I'll give the fuel supply system a good going over tomorrow and report back.

Simon

Ditto - fuel starvation

Hi all, had a look at fuel pipes etc. today.

Replaced fuel filter (between tank and pump) and increased the radius of bend between tank and filter in case this was causing a blockage.

Again car started fine so tried a test run. Got two hundred yards down the road and problem returned.

Car will start and tickover, but will not pull, it is as if you use up the fuel in the carbs. and once this has gone, the fuel pump will not keep up with the demand.

The fuel pump seems to be OK, you can hear it click when you turn the ignition on and stop when pressure built up. When we fitted the new filter it ran fast until pressure was built up.

I think next step is to pull fuel pipe off at carbs. and check the pump flow rate.

Any further thoughts?

Thanks,

Simon

"Fuel pump wont keep up with demand" ?

Have you checked the fuel pump ? What does it pump like too an open end and also whats it pump like when it as a bit of work too do, ie restrict the open end, can it cope ?

Is the pick up in the tank ok ? Not pulling air in somewhere, ie pickup pipe split inside tank and drawing air ?

Edit too add not sure if its been posted above but have you a breather in the tank and if so is it clear ? Usually takes a fair few minutes of running for that one too cause starvation probs though.

[Edited on 26/11/06 by Jon Ison]

as others have said, pull pipe off at the carbs and check it there, should flow nicely, then check tank venting.

Also bear in mind that a failing coil gives almost exactly the same symptoms, but usually only when it gets hot.

You could try the same driving test with the filler cap a bit loose (with care, of course!). If it runs OK, you have a venting problem; if it still fails then that's one possible cause that can be discounted.

David

Hi all, latest update.

Just tested fuel pump and it seems OK. We disconnected fuel pipe at carbs. and then turned ignition on. Pump ran quickly and pumped in excess of 225cc in 15 sec. (according to an old post from Shortie this should be OK). Then tried increasing back pressure by throttling the pipe down and the pump slowed down as you would expect.

We then noticed that there was a petrol leak form the connector between carbs 1 & 2, see photo.

Could this leak be the cause of the problem? Would such a leak give the symptoms we are seeing?

Your thoughts would be appreciated.

Thanks,

Simon



Description

[Edited on 27/11/06 by asn163]

It could do. Could mean that half the engine is running out of fuel, and holding back the rest as those two carbs could run out of fuel.

unlikely unless its either a big leak or letting air in, both of which are doubtful.

While you are looking at the carbs, take to float bowls off and check there is no dirt in there, but it sounds to me like you are having a coil failure.

Get a spare pair of coils if you can and try swapping them over.