Stuttering after a few miles then slows down and stalls.

[BenDixon2002]

Hi everyone. My Morris has been struggling and I‘m not sure what to look for . Hopefully it’s something simple. My Morris is my only car and daily driver, so I hope I can get it sorted out soon.

I’ve been driving my Morris since March and almost everyday since September, and it’s ran perfectly until recently. Just over a week ago when driving home, about 40-50mph, my Minor started jerking as the engine stuttered and the car quickly slowed down and I had to pull up at the side of the road. As the car was stuttering the fuel pump was ticking very fast and continued to do so for about 3-5 minutes when I parked with the ignition on. Of course usually it ticks for only about 30 seconds at most when I first turn on the ignition before a drive. When the fuel pump stopped ticking I was able to set off again and the car drove fine for about a mile until the same happened again. I managed to get the car home by driving for a mile at a time and stopping until the fuel pump finished ticking, again about 3-5 minutes.

The next day I looked through my manual and it said that it’s most likely a sticking float valve needle. I cleaned the float bowl and the float isn’t leaking, but the float needle was indeed worn, so I ordered a replacement needle and seat. I also tested the fuel pump and it was pumping fuel when I disconnected the fuel hose from the carburettor.

When the replacement needle and seat arrived I replaced them and gave the car a short test drive about 2 miles and the car was fine. The next day I drove to Sixth Form and got about 6 miles until the same stuttering happened as before . I got to Sixth Form using the start stop method as before. Out of interest, one time when it did stop, I turned off the ignition and opened the float bowl and it was half full. I don’t know if that’s a clue into diagnosing my problem, but I hope so. Also, when I opened the float bowl, the new needle definitely wasn’t sticking.

The RAC came when I’d finished my day at Sixth Form, and he took the lid off the float bowl and removed the carburettor dash pot and cleaned the inside of the carburettor and float bowl with compressed air, but they looked clean inside anyway. He drove behind me on the way home to see if it was fixed, but I got about 2 miles until it stopped, so I was able to pull over and he pulled it home with his van.

Some other info is that my distributor has been converted to electronic ignition and my fuel pump has been changed at some point to an electronic HARDI pump. My fuel gauge read 1/2 when it happened the first time and is at 1/4 now. Also one day previous when I got home from Sixth Form, I’m not sure if it was day before problems started, but definitely the same week, I noticed my fuel cap was off when I got home . Don’t know how if I’d somehow forgot to put it on or even if it’s related, but might be important.

Thanks for reading my long message. I just wanted to provide as much information as possible. Any help and replies are greatly appreciated . This is my only car, so I’m quite anxious to get it going again.

Regards,
Ben

[kevin s]

Sounds like you have either got muck in the fuel tank blocking the pick up , there is some sort of contaminent in the fuel or one of the valves in the the pump is playing up.

I would try taking the fuel pipe off the carb sticking it in a can and turning the ignition on, it should pump fuel through freely, pump a litre or 2 trough to see if anything goes wrong, if theres not much in it it might be worth draining it all out and putting fresh fuel in ( if the caps been left off is there water in there?).

Unfortunately if there is muck blocking the pick up in the tank you may have to change the tank because you can't get to the filter on the end of the pick up. Blowing backwards may help for a while.

Also double check it has got fuel in it, my son was driving his today heard the pump knocking and realised the fuel gauge hadn't moved for a few days, gave it a tap and it dropped to empty! Fortunatelly he had a can of fuel.in the boot.

[mike1864]

The other thing to check is the filter that unbolts out of the bottom of the pump. If crud has been sucked out of the petrol tank, the state of this mesh cylinder should give a clue. If so, cleaning it might help. But maybe the pump innards will still be bunged up.
With all the dismantling to get to the float and needle, I assume the bottom of this bowl - and especially its outlet pipe - is clear of debris.

[kennatt]

you say that on stopping you have checked the carb bowl and found it half full with petrol (Thats about correct accounting for the displacement of the float)The pump is ticking so thats ok. You have replaced needle valve,so eliminated that.
Try getting a known good second hand coil,and doing a swap,older original coils very rarely fail,but if there has been a replacement fitted at some time ,they are known to pack up. They run for a while until hot then fail,leave it standing to cool then its ok for a few miles.Dont think its fuel related ,from what you have said, Thats if you are sure there was fuel in the bowl on checking after stopping .SU carbs are very basic , rarely give trouble ,If there petrol in the bowl they work,no tiny jets to clog etc. fuel cap off,nothing to do with fault.

Im not a great fan of electronic dizzys ,If it was mine I would be putting the original back on but others will disagree ,Bit set in my ways .

[BenDixon2002]

Thanks for the help and advice everyone. I’ll inspect and clean the fuel pump filter and then swap the coil. If that doesn’t work maybe converting my distributor back to points will show if the electronic ignition is failing. Hopefully something out of that fixes the problem before I have to look at the fuel tank.

[oliver90owner]

The continued fast ticking of the fuel pump clearly indicates a fuel supply problem. What it is, exactly, needs to be ascertained and then remedied. No amount of other “remedial” work will actually make this fuel supply issue go away. The pump should only tick occasionally, once the carburettor is filled, while the ignition is switched on without the engine running.

[BenDixon2002]

The continued fast ticking of the fuel pump clearly indicates a fuel supply problem. What it is, exactly, needs to be ascertained and then remedied. No amount of other “remedial” work will actually make this fuel supply issue go away. The pump should only tick occasionally, once the carburettor is filled, while the ignition is switched on without the engine running.

Okay, yes like you said, the ticking fuel pump is probably the best clue. Does that indicate the problem is probably somewhere before the carburettor on the fuel’s path?

[ManyMinors]

I agree with Oliver. It is often quite difficult to establish whether a car which is running poorly has an ignition or a fuel problem but if the pump was running quickly/loudly at the same time as the car was stuttering then the problem is pretty clearly fuel related and might simply be a failing fuel pump. I wouldn't at this stage worry too much about the ignition but check through the fuel system. Maybe (carefully) pump some fuel out into a glass jar and see if it looks clean? Check the filter (if a Hardi pump has one?) as others have suggested. Do you know another local Minor owner who might lend you a different pump to try?

Good luck. It WILL be something straightforward once you find it

[BenDixon2002]

Hi all. Just saw this and I wonder if an air leak sounds plausible? I will test soon and post my results.

00AD4742-47C9-4824-829C-08A25D83BD13.jpeg (302.24 KiB) Viewed 3094 times

[BenDixon2002]

Hard to tell in the picture, but what I did what disconnect the fuel hose end from the carb and I put the end in a glass jar. As the fuel pumped and the end of the hose was fully submerged, lots of small air bubbles appeared. I suppose does this mean I have an air leak between the tank and the pump? Also the fuel is slightly red because of Redex cleanet additive.

F33AC86A-6A9B-4172-B6C4-67C75959D4A3.jpeg (237.39 KiB) Viewed 3085 times

[jaekl]

The Hardi pump could be the cause. I used one many years ago and had similar problems. Symptoms indicate a leaking diaphragm.

[BenDixon2002]

The Hardi pump could be the cause. I used one many years ago and had similar problems. Symptoms indicate a leaking diaphragm.

Hi, thanks for your reply. Do you know how I could test for a leaking diaphragm? I don’t have access to a replacement pump without buying one.

[jaekl]

Mine would be fine until it warmed up a bit. Probably the first thing to do is disconnect the inlet and plug it with your finger. If it ticks it is either the diaphragm or the valves leaking. The bubbles in the output also points to a leaking diaphragm. Although the fuel could be vaporizing in the vertical run of the fuel line. Ambient temperature may be low, but fuel will also vaporize when the pressure drops. A highly restrictive fuel line could cause too much vacuum in the line. The pump is most likely the issue. What style of pump body are you using. I had my Hardi mounted to a SU pump body.

[BenDixon2002]

Mine would be fine until it warmed up a bit. Probably the first thing to do is disconnect the inlet and plug it with your finger. If it ticks it is either the diaphragm or the valves leaking. The bubbles in the output also points to a leaking diaphragm. Although the fuel could be vaporizing in the vertical run of the fuel line. Ambient temperature may be low, but fuel will also vaporize when the pressure drops. A highly restrictive fuel line could cause too much vacuum in the line. The pump is most likely the issue. What style of pump body are you using. I had my Hardi mounted to a SU pump body.

Okay. I’ll check now.

[BenDixon2002]

Mine would be fine until it warmed up a bit. Probably the first thing to do is disconnect the inlet and plug it with your finger. If it ticks it is either the diaphragm or the valves leaking. The bubbles in the output also points to a leaking diaphragm. Although the fuel could be vaporizing in the vertical run of the fuel line. Ambient temperature may be low, but fuel will also vaporize when the pressure drops. A highly restrictive fuel line could cause too much vacuum in the line. The pump is most likely the issue. What style of pump body are you using. I had my Hardi mounted to a SU pump body.

Just tested it. I disconnected the inlet pipe from the fuel pump. Of course I’m not able to plug the pump inlet with my finger and turn the ignition on at the same time, so what I did was unplug the earth terminal from the pump, then turn on ignition, then plug the inlet, and then touch the earth pump terminal with the earth wire. I hope that’s clear . The pump did indeed tick fast for about 3 - seconds, and then stopped. I removed my finger from the inlet and it still didn’t tick. That’s similar to the normal time it ticks when I first turn on the ignition for a drive. Just a bit quicker, because I’ve just moved the car to give it a wash and I put it back in the garage a few minutes before testing. Does this mean the pump’s faulty? Oh, and the pump is a HARDI 12V 1112-5. It was on the car when I bought it. Many thanks

07F2F90A-2665-475C-ABCC-BBA326FEA930.jpeg (300.62 KiB) Viewed 3035 times

[BenDixon2002]

Mine would be fine until it warmed up a bit. Probably the first thing to do is disconnect the inlet and plug it with your finger. If it ticks it is either the diaphragm or the valves leaking. The bubbles in the output also points to a leaking diaphragm. Although the fuel could be vaporizing in the vertical run of the fuel line. Ambient temperature may be low, but fuel will also vaporize when the pressure drops. A highly restrictive fuel line could cause too much vacuum in the line. The pump is most likely the issue. What style of pump body are you using. I had my Hardi mounted to a SU pump body.

Just tested it. I disconnected the inlet pipe from the fuel pump. Of course I’m not able to plug the pump inlet with my finger and turn the ignition on at the same time, so what I did was unplug the earth terminal from the pump, then turn on ignition, then plug the inlet, and then touch the earth pump terminal with the earth wire. I hope that’s clear . The pump did indeed tick fast for about 3 - seconds, and then stopped. I removed my finger from the inlet and it still didn’t tick. That’s similar to the normal time it ticks when I first turn on the ignition for a drive. Just a bit quicker, because I’ve just moved the car to give it a wash and I put it back in the garage a few minutes before testing. Does this mean the pump’s faulty? Oh, and the pump is a HARDI 12V 1112-5. It was on the car when I bought it. Many thanks

07F2F90A-2665-475C-ABCC-BBA326FEA930.jpeg

Picture is upside down, sorry I don’t know why

[jaekl]

You probably should let the output discharge freely to complete the test. You must have had pressure in the hose to the carb and that stopped the pump. The pump runs until there is a 3psi or so pressure differential between inlet and outlet. Do it again with the discharge to an open container. The warmer the diaphragm is the more conclusive will be the failure.

[BenDixon2002]

You probably should let the output discharge freely to complete the test. You must have had pressure in the hose to the carb and that stopped the pump. The pump runs until there is a 3psi or so pressure differential between inlet and outlet. Do it again with the discharge to an open container. The warmer the diaphragm is the more conclusive will be the failure.

Hi. I think the problem is either the fuel pump being faulty or the fuel pipe between the pump and tank leaking air. I don’t want to replace the fuel pipe yet incase it’s the pump that is faulty, as it’s not a quick job to replace the fuel pipe. I’ve ordered a Standard Type SU Pump from ESM, I wanted to get one anyway as I don’t like the look of the HARDI. If I still have problems I’ll replace the fuel pipe. I’ll keep updating the thread. Thanks everyone for the help so far

[mike1864]

Even if it transpires the fault is not the pump, it's a good idea to keep one in the boot as a spare.

I also keep a small square of fine Emery paper taped to the adjacent bulkhead, so that I can easily wipe the points in situ (dirty/pitted points being the most common cause when these pumps stop pumping). The old wive's tale of taking the points out and wiping them on a nearby kerbstone strikes me as daft, and fraught with problems.

[BenDixon2002]

Hi everyone. Just posting an update on my car troubles. I can safely eliminate the fuel pump from the potential problems I hope. I've replaced my HARDI pump with a brand new SU standard type pump from ESM. I gave it a test drive on Tuesday and I'm afraid I managed 10 miles until tick, tick, tick, tick and I had to stop the car. I've got the car home safely. Now my suspicion is on the fuel tank, as some of my responses have said. My theory is either dirt or rust in the tank gets sucked up eventually and blocks the fuel flow out the tank. This could explain why it takes a few miles until I experience problems, and why I can manage to drive further when the car has been stood still longer. I have done the air bubble test and my new pump is pumping some air bubbles with the fuel as it idles. I am replacing the fuel pipe, but I'm worried that maybe there is a leak in the pick up pipe in the tank, sucking air when the tank is less than half full. I guess in that case I would need a brand new tank. I've taken off the fuel pipe and I've drained the fuel in the tank. I blew compressed air down the fuel filler to blow some more residue out. On Saturday I'll take the tank off and flush it as best I can. Hopefully that will fix the problem when I put everything back together with a new fuel pipe. Should that not work I guess I'll assume I need a fuel tank, but I'll really try to save this tank if I can.