Choke

[Ian Cooper]

Hi folks.

I'm suffering start-up embarrassment and hoping someone out there can throw me an idea, or two.

Mk2 GT6.

My engine was rebuilt some 350 miles ago. It runs on unleaded, the ignition system is electronic, fuel pump and lines are new, tank has been cleaned and treated, carbs have been refurbished and the whole system has been rolling road tuned and from five seconds after start-up is actually 'awsome', as described by the rr tuner. It runs beautifully and sounds great but start-up is embarassing.

On turning the key she initially sounds like she wants to start and then......nah!

I've tried no choke, half choke full choke and back again and it's usually at least four or five attempts before she fires, at which point she says, come on lets do this, I was just teasing there.

Is there a foolproof method to get her started please?

Thanks

Ian

[Gary Flinn]

A couple of questions, is your car fitted with the standard CD150 Stromberg Carbs and a Mechanical Fuel Pump?

Also, is the problem when starting from cold or is it the same when its fully warmed up?

On my Standard Mk2 Vitesse (Mechanically the same as a standard Mk2 GT6) if I left the car for any length of time, a few days or more you get the fuel draining back or evaporating.

I always used to prime the mechanical fuel pump using the lever underneath to fill up the carb float bowls with fuel, or it would take several sessions of turning the engine over before it eventually fired, when the engine was hot/warm it would start first time?

Regards

Gary  

 

[Ian Cooper]

Hi Gary.

Standard CD150s, from cold, if she's run for any time at all she'll go first pull for hours afterwards. I was wondering if it was garage related, i.e., the garage may not be cold enough to merit choke, but as I say i've tried no choke, full choke and half choke🤔🤨

cheers Gary

[Gary Flinn]

17 minutes ago, Ian Cooper said:

Hi Gary.

Standard CD150s, from cold, if she's run for any time at all she'll go first pull for hours afterwards. I was wondering if it was garage related, i.e., the garage may not be cold enough to merit choke, but as I say i've tried no choke, full choke and half choke🤔🤨

cheers Gary

The Choke mechanism on the CD150S carbs is not the best set up in my opinion, an SU carb is a far simpler arrangement which works better.

I had to be careful not to flood mine when using the Choke from cold, one thing to check is that the fast idle set up is adjusted correctly to give a tick over of around 1,200 to 1,500 RPM when on Full choke.

Full choke should only be needed in the depths of Winter, half choke should be ok this time of year.

Priming the fuel pump helped with starting mine from cold, but it didn't always start first time then?

Regards

Gary  

[Pete Lewis]

is this lack of start after a period of lay up or not starting when ever youre out ??

its common for floats to evaporate and it take a long crank to refill and fire , short busts on the key wont work 

its best to flip the bonnet and hand prime the pump to refill then pull choke   a cold engine should need choke to fire up 

thats why its there .

can be solved by fitting an electric pump but that has other things like a cut of inertia switch to make it safe 

but laid up for a week may need 30 seconds of continuos cranking to get her alive   its quite normal 

Pete

[Paul H]

What starter do you have . I fitted a high torque to my mk 2 Vitesse and the starting difference was significant. I’ve also fitted a Huco fuel pump and this makes for easier starting . The pump is by the  battery . 

[Colin Lindsay]

1 hour ago, Ian Cooper said:

On turning the key she initially sounds like she wants to start and then......nah!

I've tried no choke, half choke full choke and back again and it's usually at least four or five attempts before she fires, at which point she says, come on lets do this, I was just teasing there.

The initial 'almost' start may be the very last of the petrol in the carbs, just enough to kick but not enough to run the engine for long. The rest of the fuel has probably run back down the fuel pipe, as the gang here have said already, and needs pumped back up again. 

[Ian Cooper]

I thought about fitting a non return valve, what do you reckon ??

The puzzle seems to be that she'll start for hours after she's run once, so my guess is not evaporation. I have a one way filter just before the pump would that not inhibit run back??

Cheers

Ian

[NonMember]

46 minutes ago, Colin Lindsay said:

The initial 'almost' start may be the very last of the petrol in the carbs, just enough to kick but not enough to run the engine

This.

My Mk3 GT6 does this when cold. It needs full choke. It kicks on the first turn of the key but never starts. Sometimes it disengages the Bendix in the process. But then it's completely reliable - it will churn on the starter for some tens of seconds before bursting into life, at which point the choke needs to be fettled down to the happy point for the ambient.

[Clive]

The filter is directional, but not a one way valve.

These days there is a lot to be said for (Huco) electric fuel pumps....

[Ian Cooper]

Hi torque starter.Problem occurs with 'overnight' starting no better or worse with a short layup.

Glad you seem to be saying it's 'normal', but surely this must have driven customers mad when they bought to cars new????

Ian

 

[Pete Lewis]

its quite probable the old fuel did not evaporate as quickly as this modern stuff

there again most were daily drivers so time periods to cause a crank up didnt happen 

if you use the car daily it will be fine if you leave t for a couple of weeks it needs aprime or a crank up 

ignore any thoughts of drain back there is no way the supply can syphon fuel back from being well below the float needle valve 

unless its a magician 

Pete

[PeteH]

I note you refer to a "new" fuel pump?. It has been noted on the Forum before that there is a "quality" issue with non O/E replacements?. Also dirt, debris, Pete`s Slivers?, holding the valves open would have effect.

Reminds me of My old Mini Van, 60`s Vintage, which would try to start, Cough, Fart and stop. The answer was to grovel under the van with a heavy object and persuade the old SU electric pump back to life!!.

Pete

[Stratton Jimmer]

Both my GT6 which has HS4 SUs and the Sixfire which now has CD150 CDSE Strombergs are reluctant starters after being out of use for several days. Once going though, they both restart easily. Both have Hi Torque starter motors. The simplest solution I have found is to put a two second blast of Bradex into the air filters. This results in instant starting as the Bradex keeps the engine running until the fuel gets through to the carbs. It's a compromise but...!

[Pete Lewis]

doesnt matter what carbs you have if the fuel has evaporated then it needs some sort of priming 

from a aerosol , the starter or hand prime the pump if it has a lever fitted .

then pull choke and she fires up

Pete

 

[Chris A]

Look on the bright side. The delay in starting while petrol gets to the carbs gives the oil pump time to pressure the system and avoid 'The Death Rattle'.

[johny]

ha yes I purposely dont pull choke initially just to avoid the possibility of an immediate and rattley cold start!

[68vitesse]

My technique with the Mk1 Vitesse 2L is to turn it over a few times on full choke then leave it for a minute. Always seems to work if left overnight or a week or so, standard mechanical fuel pump and lumination electronic ignition.

Regards.

Paul.

 

 

[johny]

Is that to get it to start Paul or to avoid a rattley start? Then do you leave it on full choke for the actual start? That would surprise me as I reckon I only need full choke when its below freezing....

[68vitesse]

To start, leave on full choke and startsup straight away but have to push choke in while it clears its throat then a small bit of choke for the first me or so.

Have a geared, hi-torque, starter fitted.

Regards

Paul.

[Wagger]

The mechanical pump has a one way valve in it anyway. As others have stated, it is just evaporation when left standing. Priming should work if your pump has the lever. I have fitted an electric pump purely for priming in the past, but that is now used for draining tanks.

You could fit low pressure electric pump in series or parallel with the mechanical one if necessary. Mine ran fine with this setup and I connected the electric one to the start solenoid so it operated with the starter. It means a bit more plumbing and even more joints that could cause problems.

[Nigel Clark]

3 hours ago, Chris A said:

Look on the bright side. The delay in starting while petrol gets to the carbs gives the oil pump time to pressure the system and avoid 'The Death Rattle'.

+1

I like that approach.... My GT6 starts slowly after a lay up of a few days.  Turning the engine over on the high torque starter primes the carbs from the mechanical fuel pump and ensures a bit of oil pressure before she fires. I'm not tempted to go the electric pump route. 

Nigel

[johny]

50 minutes ago, 68vitesse said:

To start, leave on full choke and startsup straight away but have to push choke in while it clears its throat then a small bit of choke for the first me or so.

Interesting. My idle cam gap is set pretty small which I do to get sufficient idle speed with little choke and it runs great while still cold. However the downside is that if I did give it full choke the revs would be too high and I risk getting the rattle. Maybe my carbs runs richer than yours as mine would bog down very quickly on full choke unless as I say theres arctic conditions...

[Chris A]

4 minutes ago, Nigel Clark said:

I like that approach...

I'm happy with it now that I am used to it. I suspect my neighbours think the car has starting problems, but who cares what the neighbours think 😁

[Peter Truman]

Nigel I run electric pump mounted in the boot but with an isolation switch and light in the cabin.

I turn the engine over on the hi torq starter with the pump isolated ie off then turn pump on letting it prime the carbs ie pump changes sound then spin the starter and she starts in a couple of secs NO RATTLE!