K301 fuel starvation?

[Mickwhitt 4,881]

this is 1 to 2 psi so should be OK. I can just bypass the mechanical pump and see what happens. 

[Mickwhitt 4,881]

I guess this size of relay will do the job, I'm no electrician so I will be asking questions like a dummy.

Lol 

[pfrederi 18,181]

I do not see the current draw in the specs for your pump.  The ones i use only draw about 1.5 amps (the have an internal 3.5 am fuse so that would be the max)    I know a lot of people use relays i do not. Have at least 4 electric pumps for several years now no issues.  Your ignition switch handles 3-4 amp for the ignition and  6 amps or more for lights with out a problem.  to me adding a relay just introduces another electro mechanical device that can fail .   Put a fuse in the feed line.  wire it to Acc..

[squonk 41,941]

Those relays will out last 10 ign switches. Simple to hook up. The instructions are in my threads. Yes the pumps don't draw a lot but the ignition switches have crappy contacts when new. I installed relays and contactors on all kinds of equipment. They handle loads much better than the switches and controls things come with now days. Do what you want. I have a drawer full of these relays so they don't cost me a thing. 

[Stormin 9,983]

Just a tip, Mick. Before you spend any cash, as I know what you Yorkshiremen are like, have a look in the tank. As already mentioned you'd be surprised what can get in there. I found leaves, bits of rubber plus other debris in my C-125's tank when I got it.

[ranger 1,770]

Try operating the primer bulb when it plays up Mick, if you have any form of blockage in the tank/fuel tap etc, the bulb will collapse and be very reluctant to resume it’s ‘Inflated’ state. If you want to fit a relay, p.m. me an address, and I’ll send you a few, 25amp ‘micro’s, I’ll fish out some of the smaller spade terminals as well, the larger ones are 1/4”. I think I may have some inline fuse holders also. 
Doug.

 

 

Edited February 1, 2022 by ranger

[ranger 1,770]

5 hours ago, pfrederi said:

Some have luck with cheap electric pumps... i did not.  and when it fails a long way from your shop and you have to drag the tractor and front mount mower home the $15 or so bucks I saved suddenly weren't worth it...

At the price some of them are, you could fit two in tandem with a change over switch, (Rally car style), almost, “Aircraft” 🛩 grade reliability! 😂😂😂

 

Edited February 1, 2022 by ranger

[Mickwhitt 4,881]

First chance I've had today to do some investigation. 

I tried the condenser but that didn't seem to make any difference. 

Fuel tank clean as a whistle and I can see the fuel outlet is clear.

Breather is clear too so nothing on the tank side of things.

I was going to strip the carb but decided to just check the jet settings as the plug is a bit sooty, bear in mind he hasn't had very much running.

Idle jet is pretty easy to set but I'm finding the main jet harder to deal with. 

I done seem to have two distinct positions where engine bore changes. Screwing it in results in the engine dying, obviously too lean, but screwing it out doesn't seem to make much difference. 

I've tinkered with it a good bit and he runs a bit better. I'll have a butchers at the plug and see if its still running rich.

Mick 

 

[Handy Don 13,085]

My instincts on this are that when adjusting the needle seems to have no effect, then there is something impeding the fuel flow through that needle or else the needle is broken and non-functional!

[ebinmaine 69,711]

38 minutes ago, Handy Don said:

My instincts on this are that when adjusting the needle seems to have no effect, then there is something impeding the fuel flow through that needle or else the needle is broken and non-functional!

I've had carbs that made little to no difference on the upper side like that. 

I'm thinking I tore them apart and cleaned em out again. 

 

Forgive my memory of you've mentioned this Mick... Have you sprayed the exterior to check for vacuum leaks while running?

 

 

[Mickwhitt 4,881]

Not done any kind of vacuum check. What do I do to carry such a check out? 

Mick

[ranger 1,770]

11 minutes ago, Mickwhitt said:

Not done any kind of vacuum check. What do I do to carry such a check out? 

Mick

If you spray WD40 or Carb/Brake cleaner around the carb/engine flange with engine running and the rpm’s increase momentarily it’s a pretty good sign that you have a vacuum leak. This could be due to a warped carb flange, a failed gasket, etc. thick or multiple gaskets, heat insulator spacers, anything like this can cause warping if over tightened. If you try this Mick, Please do it outside for safety reasons!

Doug.

[Mickwhitt 4,881]

Had a look on you tube and I will have a go tomorrow at some point.

 

The low speed jet seems sloppy in the threads but I'm not sure ifvthat would make a difference.  

 

I did a little video so I will post it see if I'm being picky lol. 

[Mickwhitt 4,881]

It does it a few times on this short hill climb. Its just like I've cut the throttle for a beat then opened up again. 

[RED-Z06 2,379]

One thought from the video...it seems to be bump related, maybe the float drops for an instant and lets in too much fuel causing a momentary rich condition?

[ranger 1,770]

Does it behave the same coming down the hill?

I was always taught that 90% of carburettor problems were actually ignition problems! As @RED-Z06 commented, it could be ‘bump’ related. Check for any wiring that could be loose or chafing. Especially grounds. Disconnect the ignition live to the coil and run a temporary lead from the battery + to the coil, drive the same route and see if it’s the same. If it’s better than before, check your wiring. 

Edited February 8, 2022 by ranger

[Mickwhitt 4,881]

Well by way of an update.

Checked for vacuum leaks and everything OK.

Tried the original main jet back in the carb, no real difference.  I had replaced it with a spare one in slightly better condition but from a different carb. This one worked fine despite the difference. 

Messed with the ignition wiring, tried a wire from positive to coil positive, made no difference. 

Seemed to run fine at tick over but acted up when at running throttle,  even standing in the drive.

Tried a new capacitor in place of the automotive condenser I had fitted new with the ignition coil. 

Hey presto seems to run a lot better just parked up. No time for a test run today but I will run him under load on Friday and see if it has cured the problem. 

Hoping that Ranger is right and the fuel problem is an ignition issue.

If so this new jury rigged capacitor will be made permanent and resilient.  

[Mickwhitt 4,881]

This is the capacitor simply fitted between coil and earth.

[Jeff-C175 7,203]

1 hour ago, Mickwhitt said:

the capacitor

 

What value is that capacitor Mick?

[ranger 1,770]

Many years ago my ‘service’ van was a B.L. Sherpa, visiting a customer in Croydon, South London one day, the engine, (2ltr “O” series) cut out. Quick check at the side of the road showed no spark. Coil had a suppressor, (capacitor) fitted on + terminal for radio ‘noise’, swapped it to - terminal, spark returned and away I went. I’ve lost count of the number of condensers I’d renewed during my time as an RAC patrolman in the late 70’s.

[squonk 41,941]

Seems odd that a capacitor would fix an ignition issue caused by bumps unless the bump issue is a coincidence. I had an engine stumble just like that on bumps on my C-160. Turned out the fuel baffle gasket was missing in the carb. Kohler # 2504102 S

 

 

Edited February 9, 2022 by squonk

[ranger 1,770]

 I’d be inclined to check and clean the ground connections, especially ignition components. On rebuilds it’s easy to not remove paint, or grease a connection point, leading to problems later on, (corrosion / oxidation), especially if left unused for an extended period. Having said that, the reliability of ’New’ ignition components available nowadays leaves a lot to be desired. (In my opinion). So vibration and ‘Jolting’ over rough ground could possibly be a factor.

Edited February 9, 2022 by ranger

[Mickwhitt 4,881]

The condenser i put on with the new coil is on the left, you can see the insulation on the wire has cracked. Its not the best bit of electronic engineering. 

The capacitor I used is 0.22uF I believe, its on the right.

Old motorcycle forums provided information about condensers and gave the value to try. I can only look at the points to see if they are burning to tell if I'm in the right ball park.

 

[Jeff-C175 7,203]

14 minutes ago, Mickwhitt said:

0.22uF I believe,

 

S'what it looks like to me, 224 = 0.22uF

 

And 630V ?  hard to read with the glare...  that oughta be enough!

 

Now ya got me curious to measure the ones on my machines and see what the value is.  Maybe I'll do that tomorrow if'n I remember!

 

If the cap is too large, you get deposits on one side, if too small, on the other... I can't recall which side is which though.

 

[Mickwhitt 4,881]

I have that in the article I read, I'll post tomorrow.  

Hoping that it runs good now, if that's the cure I will see how long this capacitor lasts. The other one was brand new and died after only a few hours. 

Mick