starting

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kevin s
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starting

Postby kevin s » Fri Sep 20, 2019 9:14 am

I have a strange one, most of the time our 1098 saloon starts very easily from cold, but a couple of times lately it has been difficult to start from cold, Pull the choke out turn it over nothing, put choke in a foot flat to the floor and after a while it splutters into life on what sounds like 2 or 3 cylinders, add a bit of throttle and slowly pull the choke out a little and it then revs up a bit smoky (black not blue) and is then absolutley fine again.

To me it seems like it is flooding when parked, the only way I can think this is happening is if the float chamber is over filling and pushing fuel up through the main jet. Has anyone any better ideas, or seen something like this before?

I have already changed the float valve for a viton tipped one because the original leaked badly.

Monty-4
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Re: starting

Postby Monty-4 » Fri Sep 20, 2019 12:12 pm

I'd check the float height to see if your theory is correct!

Then work your way around the ignition system. Dirty points can make starting harder, for example.
68' 4-door Saloon, another 'Monty'.

oliver90owner
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Re: starting

Postby oliver90owner » Fri Sep 20, 2019 12:47 pm

Does the fuel pump continue clicking too regularly? Does it make a difference if you start immediately after turning on the ignition? If a regular affair, starting without the fuel pump connected might sort if it is flooding before starting.

As per Monty-4, a check on the carb might be good. I would expect crud in the inlet valve or a worn out needle or seat in same as the most likely culprit. Could be a perforated float, even.

Until the fault becomes too serious one can only check bits carefully and sequentially. Assuming here that it is otherwise serviced to the usual maintenance specs?

kevin s
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Re: starting

Postby kevin s » Fri Sep 20, 2019 1:25 pm

I had a look at it at Lunchtime, its got a new viton tipped float valve and a plastic float for which looks like the height can't be adjusted, there is no fuel in the float and with the top of the bowl removed the fuel is aprox 20mm down from the top. (mind you it started perfectly Ok when I put it back together so perhaps the problem wasn't present anyway).

The pump knocks 2 or 3 times when I turn the ignition on and it is a plastic aftermarket copy of the SU one. The ignition is an A+ electronic distributor.

Strangely it has done it twice when parked in the garage at home for a couple of days but when left outside at work for a couple of days it has started fine.

my thoughts are:

- Next time it does it take plugs out to see if they are flooded or the dash pot off to see if the carb is full of fuel.
- Check there is a spark at all 4 plugs, it always kicks on one or 2 cylinders so there must be some spark.
- perhaps check the ignition timing in case the advance is sticking(though it's not kicking backwards)

Myrtles Man
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Re: starting

Postby Myrtles Man » Fri Sep 20, 2019 5:17 pm

"- Next time it does it take plugs out to see if they are flooded or the dash pot off to see if the carb is full of fuel."

Before you go to that sort of trouble, get yourself round to the back of the car and have a sniff near the exhaust pipe. You'll soon know if flooding is the problem, then take things from there. 8)

King Kenny
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Re: starting

Postby King Kenny » Fri Sep 20, 2019 7:15 pm

Check the oil in the dashpot.
1969 Traveller in Almond green.

kennatt
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Re: starting

Postby kennatt » Sat Sep 21, 2019 7:11 am

You have check the float ,but have you checked the mixture setting when hot with the lift pin (assuming yours has one) under the carb body. It could be too rich and with the choke out on cold start simply over enriches the mixture ,choke in and throttle fully open is the classic way to clear mixture out of engine when flooded.

Edward1949
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Re: starting

Postby Edward1949 » Sat Sep 21, 2019 2:07 pm

kevin s wrote:
Fri Sep 20, 2019 1:25 pm


Strangely it has done it twice when parked in the garage at home for a couple of days but when left outside at work for a couple of days it has started fine.

Could be a clue here. Mine needs full choke after a cold night outside, but only half choke if garaged, otherwise it can flood (although this is easily remedied with full throttle/no choke and a quick churn on the starter, whereupon it staggers into life, then clears itself and runs smoothly after a few seconds). Minors tend to be excellent starters even in sub-zero conditions, maybe full choke over-enriches the mix for milder cold starts.

myoldjalopy
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Re: starting

Postby myoldjalopy » Sat Sep 21, 2019 2:17 pm

Have you checked the plugs after a run? If sooty, then probably mixture too rich as 'kennatt' suggests.
Are the plugs new(-ish) and in good condition - and are they gapped properly (0.025 inch)? I assume the plugs are the correct type? Champion N9YC or equivalent is recommended.

kevin s
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Re: starting

Postby kevin s » Sat Sep 21, 2019 11:53 pm

Plugs are the correct ones and have done around 200 miles, gaps were correct when I fitted them.

I'll see if its flooded while its standing as its now been in the garage for a couple of days and if its not then try starting it with no choke and see what happens.

oliver90owner
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Re: starting

Postby oliver90owner » Sun Sep 22, 2019 9:29 am

The last few posts have simply (I think) just reinforced the last bit in my post ( Assuming here that it is otherwise serviced to the usual maintenance specs?

Valve leakage or a tiny leak developing between two adjacent cylinders could make starting more difficult. With only a couple of instances of this happening, i could be one of many faults developing.

‘One swallow does not make a summer”, as they used to say. Neither might two. Iis going in the right direction, but not there yet!

kevin s
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Re: starting

Postby kevin s » Thu Nov 21, 2019 9:12 am

After a spell of starting Ok ish it would not start this morning, it's kicking enough to knock the starter out but doesn't pick up. I tried retarding the ignition timing which made no difference, so this evening i will pull the plugs out and see if any are wet with fuel or water It runs really well once it has started, I am wondering if there could be a head gasket leaking to coolant as suggested above , crack somewhere in the head or a valve sticking I had to top it up with a litre of coolant last week, Once I get it going I will also stick the radiator vent in a clear bottle, lots of bubbles will tell me if there is a gasket or head issue. I think I have a usable spare head and a gasket set so it wouldn't be the end of the world.

It's Just time, the Lotus also wont start (this is an issue it has always had, polished ports, twin 40s and cold weather means it floods ever so easily, a squirt of ether will get it going) and the Range Rover is in bits repairing chassis rust (rear X member so fuel tank out), The TR still starts instantly on SU's though which is what I am expecting from the minor.

oliver90owner
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Re: starting

Postby oliver90owner » Thu Nov 21, 2019 6:46 pm

‘Kicking’ will stall the starter, firing in the correct direction will release the bendix.

One should know, by the rhythmic starter motor sound, if one cylinder (or more) has no compression.

You will only get bubbles if the combustion chamber is leaking to the coolant passages. A failure between two cylinders may not leak to the cooling system.

If it is losing water it certainly needs investigating, but could be a rad, water pump, or hoses as well as losses internally.

Poor starting could be a damp distributor cap, with this weather we have been having.

kevin s
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Re: starting

Postby kevin s » Thu Nov 21, 2019 9:11 pm

Took a look tonight, all 4 plugs were wet with petrol, as nobody else wss home I dried them out on the cooker, the colour looks pretty good.
rps20191121_210314.jpg
rps20191121_210314.jpg (58.71 KiB) Viewed 1353 times
Then I did a compression test between 9.5 and 10 bar in each cylinder, with a fairly flat battery and closed throttle, so nothing wrong there.

Then I took a look at the ignition, it is a 1990 to 96 electronic distributor, spark seemed a bit weak, There were 2 obvious issues, the cap was loose, one of the threads in the body had stripped and the center electrode seemed a bit weak, I tapped the thread out to m6 and drilled the cap to match, then stretched the spring on the carbon electrode, put it all back together and bingo it started first pull, new cap and rotor arm are on the way to make sure but it looks to be fixed.

Doesent seem to have lost any more coolant so it might have been the air bleeding out of the heater like I first thought.

kevin s
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Re: starting

Postby kevin s » Fri Nov 22, 2019 11:12 pm

It's not fixed, went to start it this morning, it did start but it was clearly flooded again so it's flooding when parked. Clearly its something in the carb, I'm thinking it might be to do with fuel pressure, it has a non standard aftermarket fuel pump and when I first got it going I had to resort to a viton tipped needle to stop it flooding.

Tommorow I will start it up make sure it's warm then pull the fuel line off the carb and see if it starts in a few days.

mobylette
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Re: starting

Postby mobylette » Sat Nov 23, 2019 9:03 am

Seems that your non standard pump has too much pressure for the SU carb float valve. Surely fitting the correct SU fuel pump would resolve your problem?

philthehill
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Re: starting

Postby philthehill » Sat Nov 23, 2019 9:21 am

The fuel pump line pressure to the carb should be 2.7 lb/sq inch.

Use a fuel line pressure gauge to check.

https://www.ebay.co.uk/itm/Gunson-G4103 ... XQVT9TFuJp

See this link for additional information:-

https://www.mgexp.com/article/su-fuel-pumps-101.html


StillGotMy1stCar
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Re: starting

Postby StillGotMy1stCar » Sat Nov 23, 2019 11:18 am

Phil,
The AUA66 as originally fitted is a Low pressure 1.5 lb/sq inch pump.
2.7 lb/sq inch is the High pressure version not fitted to the standard car.
Regards John

philthehill
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Re: starting

Postby philthehill » Sat Nov 23, 2019 11:55 am

John

Many thanks for pointing that out.

Phil


Edward1949
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Re: starting

Postby Edward1949 » Sat Nov 23, 2019 4:01 pm

kevin s wrote:
Fri Sep 20, 2019 1:25 pm
......and with the top of the bowl removed the fuel is aprox 20mm down from the top.
Doesn't sound as though the float needle is being overwhelmed by too much pump pressure if the petrol level is below the top.


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