Fuel Pump Or Carby?

[Xon]

Hey all, just to be up-front I'm still fresh in the world of carbys, so if I sound retarded please go easy :D

 

I took my new KE20 for it's first proper drive in 12+ years last night, and it drives like a dream, mostly. It idles like a new car, and in traffic skips along without complaint, but under load (going up a hill, or merging onto a highway for example) it picks up good for a few seconds, and then chuggs a bit (violently!), and then just cuts out completely. If I ease up, sometimes it will come back to life, but as soon as I give it even a tiny bit more throttle, it cuts out again.

Once I pull over and let it recover for a minute or two, it drives fine, but if I put it under load the same happens again.

 

To me this screams fuel starvation, and I'm leaning towards a dud fuel pump - perhaps the diaphragm has cracked after sitting dry for so long? But a lot of the posts I read describing similar (but not identical) problems suggest the float level may be off. I'm leaning more towards the pump, because I would think that if the float was off I'd have more issues with regular driving?

 

Any suggestions K motor gurus?

[Banjo]

Hi Luke,

If you are pretty confident the issue is fuel, (although I would never rule out ignition issues under load), you can quickly eliminate the fuel pump with a quick test. Disconnect to outlet pipe from the fuel pump at the carby, & stick a piece of plastic hose onto the end & feed into a container.

 

Remove spark plugs so the engine can spin freely on the starter. Disconnect the ignition coil wire at the distributor or coil, so it won't try to fire.

 

Turn the engine over and see what sort of a discharge you get from the fuel pump. If you can get hold of a fuel pressure guage then attach it to the end of the plastic hose.

 

Typical pressures are 3-4 PSI. Sometimes a automotive vaccum guage acts as a fuel pressure guage working backwards.

 

If that checks out OK, then I would be doing a full tune up, starting with ignition; plugs, leads, points, timing etc. If still no joy, then off with the carby & a full clean. Rubber tipped needle & the seat in the carby can often cause issues for engines that have been left sitting for long periods.

 

Hope that assists.

 

Cheers Banjo

[Xon]

Thanks Banjo, that gives me somewhere to start!

[altezzaclub]

Before you buy anything just pull the carb off, strip the jets out and hose petrol through all the drillings leading to them. I get a 5ml syringe to do it, but a can of carb cleaner with a long nozzle on it would do fine. Do the jets too of course.

 

When fuel evaporates it leaves a sludge through the carbs.

[Xon]

Thanks Altezza, I'll give that a go too. I figured the jets should be ok since it runs fine otherwise, but I guess if they're partially clogged it'll only be an issue under load?

[Kirill]

Put a kit through the carb I recon

[ke70dave]

A new fuel filter would be a good idea too.

[Xon]

Thanks for the advice guys but I've discovered the problem: the fuel tank is rusted to shit! It looks like an undersea wreck in there.

Anyone have any advice for a replacement? :-D

[CREEDY]

someone on here probably has a spare one, i've had motorbike tanks reconditioned so surely there's a mob out there to do car tanks?

[Xon]

Thanks for the suggestion Creedy, I thought about a wrecker tank but figured they would all be rusty too.

 

In the end, I found POR-15 fuel tank restorer - it's a 3 step process to clean and treat, and then seal the tank. Seems like it's done a good job, just need to let it cure for a few days before I fill it up and go for a drive. Cost about $110, and took many many hours to finish!

[CREEDY]

i add a litre of methylated spirits to the tank every now and again especially if running ethanol fuel. it soaks up excess water and allows it to go through the fuel system and not sit in the bottom of the tank.