Engine idling and driving fine then won't take throttle??

[70-CA-Panel]

Hey guys,

I made it to Germany after three days of driving and several stops for repairs.
Drove like a dream through England till I got to Dover. Changed the generator pulley as the other one had eaten into itself (two tabs).
Got a squeek in Belgium on the front right wheel sounds like the backing plate rubbing on the drum.

Here is the main issue though:
Drove up a hill in Germany and all of the sudden the throttle cut out and wouldn't take anymore gas.
Checked the throttle cable it was still attached. Rolled it to a flat spot down the hill and it started up again. Thought it was lack of fuel so filled tank up, drove up hill again and got past the last spot it stopped thought we solved it only for it to happen again a few hundred meters later. A guy who races busses stopped and pulled us up to the next pull off. He thought it might be the carb float or needle valve. Also found that one tire had spit out its wires through the sidewall so changed that. Started engine again and it took us all the way home along flat roads. So the next day I head off on the road for it to stumble again, but this time on flat roads. I can start it again and it'll drive fine for another 20km it so and then stumble and does not want to take the throttle again.

Took off the carb to check the float and cleaned it out, it was very clean inside had a couple small black 'pellets' in the bowl (probably from the new petrol resistant filler hose), cleaned out what I could get to and replaced the needle valve. The intake manifold was hot right below the carb so thought it's getting too much hot air from the oilbath preheater hose so disconnected and plugged this.
The fuel filter is clean only has a small black line before the filter element, but clear otherwise.
I changed the coil, checked the spark leads for ohms all same except the short one from coil to dizzy. Changed the short one, thought it might be the electronic ignition in my 205T dizzy, so replaced the whole dizzy with a working 009 (checked timing full advance at 28 BTDC).
I did all these things at the different times the engine stopped. still to no help.

I'm thinking it might be the throttle accelerator pump on the carb as it almost touches the generator, so doesn't have much room to work. Weird thing is though that once it happens I can start it right up again and it mostly drives like normal again, sometimes it won't and keeps on bogging down.

On a side note the generator (newly reconditioned) the halfmoon key has worn on the shaft and enlarged the hole in the shaft! could it have anything to do with the generator or fanbelt being too tight?

I'm a bit at a loss here as the fuel system seems to work (haven't checked the fuel pump) and the sparking seems to work.

What else can I check?
Its a single port 1600.

Thanks for reading to the end :shock:

Andy

 

[70-CA-Panel]

I can change the filter and see if that makes a difference, weird thing is it idles fine, drives fine until I think it gets hot, but even then I can either stop the engine and start it right back up again to drive normal again or have it turned off for 5-10min and it'll drive fine for another 20km...

To note also this is the first trip besides to the MOT station that I have done with this engine set up...

 

[Trikky2]

Try this.
Take the top off the carb, remove and clean the needle valve. Before replacing the needle valve, with the coil disconnected, get someone to turn the engine over while you hold a container under the carb top to collect the fuel.

This will do two things. It will allow you to see if the fuel pump is delivering fuel nicely and it will also flush out any bits trapped in the pipe that may be causing the needle valve to block intermittently.

If there was any dirt in the fuel chamber then remove and clean out the idle jet. It's normally the first one to block.

 

[70-CA-Panel]

Hi Lee and Trikki thanks for your replies.

I've already removed the carb by the time I read your msgs.
I still turned over the engine with the fuel line from pump to carb in a jar. The pump pumped nice even fuel into the jar, no dirt came out.
Next test would be to clean carb fully and maybe dissasmble fuel pump.

So if it isles fine and runs fine for 20 min and all of the sudden starts to play up is this a sign of a plug somewhere?

 

[70-CA-Panel]

Good ideas Lee,

I've already changed the brand new blue could with my previous blue coil, same old story.
U haven't checked the fuel pump filter yet, yes it can be dissasmbled.
A local mechanic also mentioned that the fuel pump rod sometimes used to stick so will check that as well.

Cheers

Andy

 

[Trikky2]

A local mechanic also mentioned that the fuel pump rod sometimes used to stick so will check that as well.

Cheers

Andy

True. I didn't think it could happen - until one day on a friends engine, it did.

Used to stop pumping when the engine got hot enough. In fairness, he had replaced the pushrod guide not long before. Found the fault by doing the same thing you did, checking the pump - but immediately after it had stopped on the side of the road. Bit strange though.

One other thing - have you checked the tank breather is clear?

 

[70-CA-Panel]

Hi Trikki,
Don't think I'll see that the pump pushrod will be sticking as the engine is cold. Might just change it my old one if I have it with me.

Regarding the fueltank breather, there are ne pipes installed, how do I check them with engine installed? Blow into the pipe next to the filler and below wheelarch?

Cheers

 

[70-CA-Panel]

Alright connected hose to the pipe next to the filler and blew through, air came out of the filler cap gasket. Then blew through the pipe below the wheelarch and it came out the hole below the filler.
There is defo also a petrol smell coming from the breather Pipe next to the filler cap.

Don't have gaskets for the fuel pump so was reluctant to open it...

 

[jonboylaw]

Andy, do you think going up the hill you got some gunk cover the fuel outlet causing the original stalls, this in turn has sucked crap into the system?

Well done on the trip so far.


Sent from my GX64 SatCom phone using Tapatalk

 

[Resto-raider]

SOunds a bit like the problem I had/have. I cleaned out and coated the tank, bought a reconditioned carb, bigger fuel lines and an electric fuel pump only to find out that the carb probably freezes...
It will run fine untill it freezes, then after a short wait it will fire up and run perfect again because it heated up. Some days it runs without issues, some days it happens after a couple of miles.