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Car won't start low pressure (very confused!!)

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jacob.cob.young Jacob Young
HORSHAM, WEST SUSSEX, UK   GBR
I'm very stuck here. I'll explain how my car stopped working and then I'll give a list of everything I've tested or tried.

On a longish (30 miles?) journey, the car lost power. So fast and briefly though, it was more like someone stomped the brakes. As it went on it became more frequent. Then as I came off a dual carriageway it cut out at some lights. And didn't start.
I played for a bit and finally after playing with the king lead connection I got it running. But by the time I was home the problem restarted.
After that I can't get it to start.

Some bits about the car
-new Peter Burgess econotune head in January (new payan gasket too)
-new points and condenser
-new fuel filter

WHAT I HAVE TRIED
-new coil and king lead
-fuel lines to carbs from the back of engine bay including deleting the filter
-spark test lights on all plugs look fine
-dizzy where it was when I tuned it a few weeks back
-engine earth checked
-cleaned plugs (smelled fuely so definitely fuel is coming from carbs)
-starter turns engine (the fan moves when I turn the key)
-new condenser
-compression test- 100 psi which is even lower when you consider the new head
-retorqued head
-tappets are set correctly (at least they are as I set them when the car was running fine)

If anyone has any ideas I'd be very grateful.
Thanks in advance !!



Edited 1 time(s). Last edit at 2019-03-13 05:57 PM by jacob.cob.young.

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rocannon Avatar
rocannon Platinum Member Frank .
Clairvius Narcisse Township, Bokor, St. Kitts and Nevis   KNA
1967 MG MGB GT "GT From Hell"
1980 MG MGB "Restored By Photoshop Inc."
Water still in radiator? At proper level?



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jacob.cob.young Jacob Young
HORSHAM, WEST SUSSEX, UK   GBR
I haven't checked it since the breakdown but it was fine a few days before the journey. Could that be linked if not do you think?

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sweep Avatar
sweep Gold Member Chris W
Gosford, NSW, Australia   AUS
1966 MG MGB "Basil"
2013 Volkswagen Tiguan
2015 Audi A3
Taken in conjunction with the lowish compression results, I would be looking to rule things out, so, IMO, yes it could be linked. What you smell and see on the plugs may not be all fuel.

In reply to # 3908271 by jacob.cob.young I haven't checked it since the breakdown but it was fine a few days before the journey. Could that be linked if not do you think?



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ingoldsb Avatar
ingoldsb Silver Member Terry Ingoldsby
Calgary, AB, Canada   CAN
1971 MG MGB
The compression is definitely low - that may or may not be the problem.

I would always check ignition first. What rotor do you have? The good "red" one?



Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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jacob.cob.young Jacob Young
HORSHAM, WEST SUSSEX, UK   GBR
The rotor arm is indeed a red one. I didn't think to change that only because the test lights show the HT leads are getting spark.

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ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Do a complete leakdown test.
Get back to us with the results and where the compression is exitingeye popping smiley



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bev sleet Avatar
bev sleet Bev S
Raunds, Northamptonshire, UK   GBR
what is the oil pressure ?

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allanreeling ALLAN R
RANDLAY, TELFORD, Shropshire, UK   GBR
Jacob,
1. There are red rotors and red rotors, as I have recently found out. There is still rubbish out there and some of it is red/orange.
2. Spark "lights" only tell you there is HT. A weak HT will break down in the combustion chamber, causing loss of power and incomplete combustion.
3. Have Peter's ecotune heads got bronze valve guides? Sticking valves would explain the loss of power and the low compression readings. There are posts about this.



soonerv8

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tvrgeek Avatar
tvrgeek Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Symptom sounds electrical but you verified you are getting spark. Did you check with a timing light it is at the proper time? I kike to put a bit of tap at about 180 on the damper so I can check the timing on all four cylinders. I have found bad plugs and wires that way.

Have you checked for corona off the plug wires at night?

The low compression would have me pulling the head to look at the gasket. Maybe more than one problem.

I caution about swapping parts and not swapping them back. It is easy, especially with some parts quality, to swap in an additional problem making it worse.



Cogito ergo sum periculoso

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jacob.cob.young Jacob Young
HORSHAM, WEST SUSSEX, UK   GBR
In reply to # 3908428 by allanreeling Jacob,
1. There are red rotors and red rotors, as I have recently found out. There is still rubbish out there and some of it is red/orange.
2. Spark "lights" only tell you there is HT. A weak HT will break down in the combustion chamber, causing loss of power and incomplete combustion.
3. Have Peter's ecotune heads got bronze valve guides? Sticking valves would explain the loss of power and the low compression readings. There are posts about this.
1) is there a way to tell without replacing it?
2) that's really useful to know thank you
3) the valve guides are bronze according to his site but I've emailed to double check

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tvrgeek Avatar
tvrgeek Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Basically, the rivet is an issue and the black plastic has too much carbon becoming conductive, both shorting your spark.

I found a weak spark will tend to show up as more scatter on the timing light. I have not thought about the physics much, but I think it would be that too low a voltage would take longer to ionize the gap so it would delay the spark some erratic amount. Timing light sees current, so until there was flash-over, no strobe. Drop out is even worse.



Cogito ergo sum periculoso

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jacob.cob.young Jacob Young
HORSHAM, WEST SUSSEX, UK   GBR
In reply to # 3908453 by tvrgeek Basically, the rivet is an issue and the black plastic has too much carbon becoming conductive, both shorting your spark.

I found a weak spark will tend to show up as more scatter on the timing light. I have not thought about the physics much, but I think it would be that too low a voltage would take longer to ionize the gap so it would delay the spark some erratic amount. Timing light sees current, so until there was flash-over, no strobe. Drop out is even worse.
Thanks for your response
I'm not sure what you mean by rivet?

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allanreeling ALLAN R
RANDLAY, TELFORD, Shropshire, UK   GBR
Jacob,
1. Rotor arms are cheap enough, get one from The Distributor Doctor, at least he has the confidence to put his initials on them!!.
3. Ask Peter what clearances he uses on his bronze guides.
He installed Bronze guides for me and there was never a problem. Did he supply the valves too?



soonerv8

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rover100rich richard gurner
tipperary, Ireland   IRL
i just posted my experience of my car not starting,remove the hose to the brake servo and plug it to ensure that there is no possibility of air being drawn in here instead of the carbs,this was the problem with my car anyway,it would seem odd that if the car was running ok then suddenly not that the compression on all cylinders would be the cause,rich



Edited 1 time(s). Last edit at 2019-03-14 08:24 AM by rover100rich.

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