Mystery non-start issue. Help needed!

[tjcmus]

Hi all,

Looking for a bit of help from the Morris Minor hivemind..

Have had a '68 Minor 1000 2dr for the last 12 years or so. Bought as a bit of a passion project, and enjoyed many years of driving it all over the country, giving it small tweaks and upgrades etc. Sadly due to changes in circumstances, the car has been off the road for a good few years now, and until recently kept under a car cover on the drive. Could never bear to sell it as it's become part of the family.. A recent move to somewhere with a garage means I can start tinkering again with a plan to get it back on the road, but I've run into issues that surpass my (admittedly basic) spannering skills:

The last time the car was running was a couple of years ago, as I made sure to at least start it up and let it get to temp a couple times a year while it was sat outside. Idiot that I am, I was doing it at dark and put the battery in the wrong way round. Cue smoke and a fried alternator. Sourced new one from ESM and despite some slightly different brackets, and with much swearing managed to get the new one in and belt on.

The issue is that ever since that, when trying to start the car it has turned over, and over, spat back out the carb, backfired hugely, and simply refused to start. I have checked the following:

. There is spark to all 4 plugs, that seems strong and regular
. The fuel pump is running and delivers fuel correctly
. AFAIK nothing on the carb has been changed since it last ran perfectly
. Plenty of compression on all cylinders, and no stuck valves

I assumed therefore that it was a timing issue, as it was acting as if the timing had been knocked way out. I admit here that I'm reaching the ends of my knowledge/ability but I knew that I could at least set the static timing by checking when cyl 1 was just before TDC with the plug out, checking where the rotor is pointing and then ensuring the HT leads were then put in the right order following on from that. Did that and seemed to make no difference at all.

So I'm all out of ideas. The engine is a standard 1098 with the exception of a 1275 head, 1.5'' SU and pancake filter, and has never had this much trouble getting going. Any thoughts/ideas are very welcome, with the caveat that I'm no expert and can only do the best I can.

Picture for attention - during better times..

Many thanks in advance,

Tom

[oliver90owner]

Possibly stale fuel?

[liammonty]

Totally agree re the possibility of stale fuel. Fuel goes off much more quickly than it used to!

[tjcmus]

Good thought, but sadly I had already checked the fuel getting to the carb, and it's not stale, no sediment. Just to make sure I popped a couple of quids worth in a jerry can at the local garage and chucked that in the tank, too.

[Bill_qaz]

Does it have electronic ignition, possible damaged from inverse polarity ?

[svenedin]

This does sound strange especially the backfiring out of the carburettor. It suggests the timing is way out if the spark is being delivered when the inlet valve is open. Is there any chance you have the HT leads in the wrong order? The firing order is 1,3,4,2 and the leads are counted anticlockwise around the distributor cap.

Stephen

[tjcmus]

Appreciate the responses, thanks.

@Bill - still running points & condenser. In fact just to rule them out I changed them over for a new set from a service kit just in case one had been fried/otherwise by the alternator messup.

@Stephen - I wondered the same. Hence checking where cyl 1 TDC was, then putting the leads in 1342 order going round the distibutor. I will double check this tomorrow and report back, but it is a weird one.

How would I know if the timing was completely out, like 180 degrees out?

Thanks for the help

[svenedin]

Appreciate the responses, thanks.

@Bill - still running points & condenser. In fact just to rule them out I changed them over for a new set from a service kit just in case one had been fried/otherwise by the alternator messup.

@Stephen - I wondered the same. Hence checking where cyl 1 TDC was, then putting the leads in 1342 order going round the distibutor. I will double check this tomorrow and report back, but it is a weird one.

How would I know if the timing was completely out, like 180 degrees out?

Thanks for the help

Well that is what I am thinking, that the timing is 180 degrees out. Perhaps you set the timing with cylinder 1 at TDC on the exhaust stroke and not the compression stroke. You would know it is the compression stroke because if you take the spark plug out and turn the engine over on the starting handle you can feel the compression with your finger over the spark plug hole. However, the original problem could not have been caused by this because accidentally connecting the battery reverse polarity is not going to mess up the ignition timing! I just wonder whether you introduced another problem whilst trying to rectify the first.......Remember 1342 around the distributor ANTICLOCKWISE.

Stephen

[Bill_qaz]

Take off the rocker cover, with number 1 at tdc firing both valves would be closed (freeplay @rockers)
Number 4 cylinder valves on rock. Now you know number 1 firing and follow Stephens plug lead position advice

[jaekl]

Another simple test, put your had over the carb inlet while the starter is on to feel for vacuum. Critters may have stuffed your exhaust pipe.

[tjcmus]

Update:

Had a chance today to have a tinker. Followed advice and did the following:

Plugs out, rocker cover off, dizzy cap off
Rotated engine on starting handle until could visibly see piston rising in no.1 spark plug hole. Checked if it was intake or exhaust stroke by very slightly wiggling 2 front rockers, which had a very small amount of play as you all mentioned.
Assigned next post on dist. cap as cyl 1, and then went round anticlockwise following 1 3 4 2
Retached rocker cover, plugs in and leads correct to above order.

And? Still the same. Builds oil pressure while cranking, which is good at least, but just cranks, and one muffled pop. Under bonnet smelt a bit burnt-fuelish (I think?)

Here's the current carb setup just in case there's something staring me in the face that I've not spotted.

IMG_20241030_152229.jpg (1.39 MiB) Viewed 2843 times

(scuse the mucky engine bay..)

Otherwise, any other ideas? Or does anyone know an A-Series friendly roving mechanic in the Chester/Wirral area?

Appreciate all the help so far.

T

[svenedin]

It's a bit different under there to a standard configuration. The fuel pump is not a type I recognise but you say it does pump fuel in your first post. Did you actually remove the hose and check the fuel flows out with the ignition on? Be careful doing this. No sparks or naked lights!

When you pull out the choke does it correctly move the jet downwards? It doesn't look like a standard HS2 carb. Is there fuel in the float bowl? Is the float bowl full of crud?

Is there any chance that the carburettor piston is stuck (you said the car was left a long time). Is there oil in the carb?

The air filter looks very grubby and may be restricting air. Have you tried without the filter in place?

Stephen

[Peted7202]

What's the lower hose behind the pancake filter?

[svenedin]

What's the lower hose behind the pancake filter?

I think one hose is fuel into the pump and that silvery hose with the metal braiding is going from pump outlet to the carb float chamber in a loop (we can't see the float chamber)

Stephen

[Bill_qaz]

When you say
"Assigned next post on dist. cap as cyl 1, and then went round anticlockwise following 1 3 4 2"
You do mean the distributor cap post it's just passing as you are at tdc. You haven't inadvertently started from the next one, putting one out for the start of your firing sequence?

[tjcmus]

Carb is indeed non-standard. A few years back a mechanic friend of mine swapped on a 1275 head and this 1.5'' (HS4?) SU for a bit more poke. Have never had to fiddle with it at all and always ran fine.

Silver braided hose is fuel inlet into carb. I've removed it to check fuel trickles through, but will try and find a mug and see if the pump (which was just an electric one to replace the original iirc) fills it with fuel when the ignition is on.

Fair point re the air filter, it's mostly surface rust I think. Will whip it off and see if it makes a difference.

What kind of movement of the carburettor piston should there be? I seem to remember there being oil in the dashpot but just in case, what's best to top it off with?

I may have to take the carb off entirely to check for things like float bowl full of muck etc, but only as a last resort.

Happy to snap any other pics of the carb setup. This is the only other one I took earlier

IMG_20241030_152239.jpg (1.38 MiB) Viewed 2811 times

Thanks

[svenedin]

Carb is indeed non-standard. A few years back a mechanic friend of mine swapped on a 1275 head and this 1.5'' (HS4?) SU for a bit more poke. Have never had to fiddle with it at all and always ran fine.

Silver braided hose is fuel inlet into carb. I've removed it to check fuel trickles through, but will try and find a mug and see if the pump (which was just an electric one to replace the original iirc) fills it with fuel when the ignition is on.

Fair point re the air filter, it's mostly surface rust I think. Will whip it off and see if it makes a difference.

What kind of movement of the carburettor piston should there be? I seem to remember there being oil in the dashpot but just in case, what's best to top it off with?

I may have to take the carb off entirely to check for things like float bowl full of muck etc, but only as a last resort.

Happy to snap any other pics of the carb setup. This is the only other one I took earlier

IMG_20241030_152239.jpg

Thanks

You can use engine oil in the carb dashpot. When you take off the air filter you will be able to see in to where the piston is. You should be able to lift it with your finger and it should automatically come back down with a metallic clunk.

If you direct the pump outlet pipe into a bottle you can check the flow rate and then pour the fuel back in the tank. Have a look at that fuel and check it looks OK.

Bill's point about which distributor cap post did you call number 1 is important. Number 1 post is the post that the rotor was in contact with when you set your engine to TDC number 1 cylinder on the compression stroke.

If we get to the point where we know the timing is correct and there is a good strong spark it can only be fuel related. However, just because fuel is coming from the pump doesn't mean it is necessarily getting to the carburettor jet.

Stephen

Stephen

[myoldjalopy]

On the subject of fuel,OP says "I popped a couple of quids worth in a jerry can at the local garage and chucked that in the tank, too." £2 is not a lot of fuel these days and might not be enough to make a difference if the tank had a lot of stale fuel in it. Be better to manually fill the float chamber with fresh fuel and see if it starts then....

[Myrtles Man]

When you take the filter off try giving it a squirt of this up its trumpet https://www.ebay.co.uk/itm/363303192653 ... UN6im-zbZA and then see if it starts.

[tjcmus]

Definitely confirmed fuel pump running fine as directed the input to carb into half a Coke bottle which it filled at a good rate. Fuel looks a little yellow but certainly seems petrol-like.

Having taken air filter off, carb piston does seem to have a bit of a buildup of black gunk on the side, I've run out of time today to take any more photos but will have a look tomorrow when I get a chance and snap some more pictures, as well as try and get the float bowl off to check for crud. The carb piston does seem to move up and down, albeit a small distance.

Will also snap some pics of the distributor side to check I've not been an idiot again. As far as I could tell earlier, when no.1 piston was at TDC, the rotor wasn't exactly on top of where one of the distributor lobes should be, but just before one (which I assumed was 1 and then set the rest up following on)

I do appreciate all the help here, I'm doing what I can but admit the limits of my own spannering quite freely.

Updates to follow