Mk2 8v on Bike Carbs, annoying problem.

[DreXeL]

OK, looks like it's not related to engine temp at all. Went out and started it this morning from cold and it fired up first turn of the key, (in fact it starts from cold better than the old engine on k-jet). It only ran for about 20-secs before dying again, so it didn't even get a chance to get warm. I'm starting to think it's electrical now, I've ordered a new dizzy cap, rotor arm and HT leads, lets see if they help.

[Wayne]

Is the fuel pump still running when it cuts out.

[DreXeL]

No, the stock pumps switch off as they should (I can hear them switch off just after the engine cuts out) and the R1 pump automatically shuts off when the float bowls are full. The R1 pump is still running up until it cuts out, then switches off just after.

[Wayne]

I am sure and maybe someone else will confirm but the pump should run all the time, if so that is why it is cutting out.

[DreXeL]

Which pump are you referring to? The R1 pump isn't designed to run all the time, it runs until the float bowls are full then stops, then starts again to keep the bowls 'topped up'. I did try bypassing the R1 pump and connected the carbs directly to the t-piece. Still the same result.

[Wayne]

Which pump are you referring to? The R1 pump isn't designed to run all the time, it runs until the float bowls are full then stops, then starts again to keep the bowls 'topped up'. I did try bypassing the R1 pump and connected the carbs directly to the t-piece. Still the same result.

Main fuel pump from memory should prime on ign then run all the time the engine is running.

[DreXeL]

Main fuel pump appears to be running all the time the engine is running, the fuel filter between the t-piece and the R1 pump is still full of fuel when the engine cuts out.

[DreXeL]

Here's a pic of the fuel circuit:



It's set-up like this: Stock fuel pump is in place, the stock feed and return under the bonnet are connected to a t-piece, this t-piece feeds the R1 fuel pump which in turn feeds the carbs. The R1 pump is designed so it only delivers what the carbs need, it shuts off when the float bowls are full.

Could it be that the stock pump is still forcing fuel through the R1 pump, even when off, thus flooding the float bowls?

[rubjonny]

pull the plug off the lift pump and see if that helps?

[danny_p]

bypass the K jet injection pump thats under the rear seats,   it moves WAY to much fuel, there will be excessive pressure at the T if useing that pump, just use the lift pump to feed the bike pump.