Author Topic: Cold starting issue  (Read 277 times)

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Flash

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Cold starting issue
« on: July 07, 2020, 05:46:33 PM »
Hi Fellow Mokers,

Now that I've got the Moke running really well with it's new distributor, I'm in need of some advice and guidance to solve another irritating issue.

When the Moke is parked overnight I really battle to get it started. I pull the choke out fully and crank the engine over but it takes forever before it will fire. Yet if I pull off the air cleaner lid and spray a bit of quick start into the neck of the SU it fires right up. From the look of my plugs I think I've got my fuel mixture set pretty good at the moment and I also know that the choke cable is moving the little enrichment cam on the SU.

During start ups I currently don't touch the accelerator at all. I have tried tapping the accelerator but it has made no difference.

Subsequent start ups during the day work perfectly and the Moke usually fires up on the first flick of the key. Then next morning its back to a long crank.

Is there a trick to cold starting ?

The other thing that is in the back of my mind is that I could be experiencing a fuel vaporization issue when the Moke sits for a long period of time. Does this sound feasible ?

I'd really appreciate some advice from those in the know.

Thanks in advance.
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Fruit flies like an apple.

Steam

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Re: Cold starting issue
« Reply #1 on: July 07, 2020, 07:27:16 PM »
If you gat the chance pull the fuel float chamber lid off before trying next time and see if there is fuel in there.
There should be about 2 thirds full of fuel.. 3 screws and make sure the gasket doesn,t fall off.
I assume you have a mechanical fuel pump.
If there is fuel in the float chamber you will need to ensure the choke is fully operating as even if it is only just shy of full it will struggle to start.
I usuallly pump the accel pedal about half its travel while cranking, it is a habit but I do not know if it does anything productive.
Cheers, Dave

Flash

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Re: Cold starting issue
« Reply #2 on: July 07, 2020, 08:28:29 PM »
Good suggestion Dave. Thanks !

I'll pull the float bowl and report back. Yes, it has a mechanical fuel pump
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Terry

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Re: Cold starting issue
« Reply #3 on: July 07, 2020, 08:46:33 PM »
Hi,

you should also check that you have the breather in the fuel tank exists and is not blocked. What can happen is you drive it around fine all day but the fuel tank is pressurising because it can't get fresh air and then overnight it draws the fuel back from the carby, pump and filter.

Before you try to start it in the morning, inspect the float bowl(as per Steam) and the filter and see if they have fuel in them. It is sounding like you have to pump fuel up from an empty pump and filter.

Terry
I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is.


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Steam

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Re: Cold starting issue
« Reply #4 on: July 07, 2020, 08:57:11 PM »
Also make sure the choke is increasing the throttle via the fast idle screw and the choke cam.
Cheers, Dave

moemoke

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Re: Cold starting issue
« Reply #5 on: July 07, 2020, 10:14:16 PM »
pumping the accel pedal doesn't do anything, it's just a habit we pick up from have cars with an accelerator pump which su's don't have.

check float level like others have suggested, it may be low and a cold start is just to much for it.
also check the choke is working correctly, the jet holder should move down as the choke is pulled out.
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Flash

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Re: Cold starting issue
« Reply #6 on: July 08, 2020, 08:31:37 AM »
Thanks for all of the suggestions thus far.

The Moke has been standing overnight and I've just pulled the top of the fuel bowl off.

The bowl measures about 59 mm deep and there is currently around 33 mm of fuel in the bowl so just over half full.

Does this sound about right ?

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Steam

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Re: Cold starting issue
« Reply #7 on: July 08, 2020, 08:38:37 AM »
Sounds about right, at least it isn't empty. you could dribble a bit more in to see if it will then start.
Once you get it going recheck the level.
Time to check the choke is fully operational, both fast idle and mixture enrichment,
« Last Edit: July 08, 2020, 08:45:19 AM by Steam »
Cheers, Dave

Steam

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Re: Cold starting issue
« Reply #8 on: July 08, 2020, 08:43:43 AM »
pumping the accel pedal doesn't do anything, it's just a habit we pick up from have cars with an accelerator pump which su's don't have.

check float level like others have suggested, it may be low and a cold start is just to much for it.
also check the choke is working correctly, the jet holder should move down as the choke is pulled out.

I have always wondered if it allows a little more fuel/air into the manifold.
Cheers, Dave

Flash

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Re: Cold starting issue
« Reply #9 on: July 08, 2020, 08:51:11 AM »
Thanks for confirming Dave.

Just looked at the fast idle mechanism on the side of the carb and it looks like it is doing what it should when I pull the "choke" out.

I'll pop the pot and see what the enrichment side of things is doing when I next get a gap.

Cheers, Gordon
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Steam

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Re: Cold starting issue
« Reply #10 on: July 08, 2020, 09:31:35 AM »
The mixture enrichment is the lever arm from the choke pivot to the jet holder. It is on the outside of the carb so you can see it without removing anything although depending on which air filter you have, removing the filter may give a clearer view.
Cheers, Dave

Flash

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Re: Cold starting issue
« Reply #11 on: July 08, 2020, 09:41:28 AM »
Thanks for the info Dave.

I'll let you know what I find.
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Flash

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Re: Cold starting issue
« Reply #12 on: July 09, 2020, 01:40:22 PM »
I managed to spend a bit of time on the Moke this morning and made an interesting discovery.

With the air filter housing off I was able to lean over and watch the cable action on the carb when I pull the "choke" knob out. The fast idle cam turns as it should but the cable stops moving before the mixture lever enrichment lever starts to operate.

I then got the missus to turn the key whilst I moved the mechanism on the carb by hand until the enrichment lever moved all the way and the Moke started like a dream. So for some reason the cable is not moving the mechanism far enough (it looks to me like it needs to pull an extra 10 to 15 mm).

My first thought was that maybe the cable was at fault so I removed it for further inspection. But the inner cable moves freely in its outer sleeve, so it doesn't look like that is the issue.

I re installed the cable and tried playing around with the slack on the cable to see if it would improve matters, but no such luck.

I'll need to do a bit more investigation.

I disconnected the cable is lifted.
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Terry

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Re: Cold starting issue
« Reply #13 on: July 09, 2020, 02:13:31 PM »
Hi,

can you provide a photo of the side of the carby showing the choke cams and linkages and also how the cable is held into the carby.

Terry
I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is.


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Flash

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Re: Cold starting issue
« Reply #14 on: July 09, 2020, 02:37:04 PM »
First picture

Time flies like an arrow.
Fruit flies like an apple.