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MG TD TF 1500 - Engine Stalls, fuel problem???

I had a problem yesterday I thought I would run by everyone to seek advice. I had my TF out for a drive and was in line waiting for the light to change. The engine suddenly died. I noticed the idle dropped by about 400rpm then stopped. On restart the engine seemed to turn over normally but no start. This was on the SU pump. I switched to my backup facet pump but still no start. Naturally this was in the fast lane of heavy traffic and I could not hear if either pump was clicking normally. I managed to push the car into a parking lot (with help) and tried again. It was still very hard to really hear if the pumps were doing their normally thing but I think they were. After about 2-3 minutes the engine started normally. I do not remember which pump I was using. I drove in the lot about the length of a city block when the engine quit again. I went through the same routine on trying to restart. I did look at the float bowls (at least the rear bowl) and it was full of fuel. After a few minutes the engine started normally. Again I drove about the same distance when the engine again quit. By this time I was running out of four letter words! Once again the engine seemed to want to start but didn't. After a few minutes it started again normally. This time I drove almost in a circle in the somewhat quiet street and all seemed OK. I kept the engine at idle for perhaps 15 minutes and it seemed OK. I did not want to get stuck on a busy street but I finally decided to try it. I drove perhaps a mile and a half to home and the car ran fine.
I am suspecting the fuel filter. What do you all think? The filter has been on the car for perhaps 5 years and is the type that attached to the facet pump. It is solid so I cannot look at it to see if there is anything that might be clogging it. Putting on a new filter is easy enough but do you think there could possibly be another issue causing the problem?
Maybe electrical?

Any thoughts would of course be appreciated.

Larry

PeeEss-- The layout of the fuel system is from the tank the fuel line goes to the facet filter, facet pump then forward to the SU pump. Also, then the engine stalled, after the first time, there was no sputtering or gradual loss of rpm, just the engine quitting.
LD Kanaster

Could be a blocked fuel filter. There is one in the tank, another in the SU pump, and another at the carbs (plus any other that may have been added).
Dave H
Dave Hill

Larry, the attached pic is of the inside of my Moss billet fuel filter (I just like the bling). This brought me to a complete and immediate stop but a quick rinse out had me going again with no further problems.

In addition to the filter that you have installed ahead of the Facet pump, you also have a filter inside of the SU pump and a filter in each SU carb. All of these require periodic inspection and cleaning. I think there's also a filter screen in the fuel tank but I don't know anything about it.

Several people smarter than me recommend against the extra filter in the fuel line. They are probably right in that the SU pump and carbs can handle a substantial amount of junk but I like the bling and the extra filter even though it means one more periodic maintenance item.

Jud


J K Chapin

Pretty easy to test if its a fuel flow problem. Get a bucket that you can put the fuel into. Remove the pump to carb line at the pump and put it into the bucket. Turn the ignition on and see how much fuel goes into the bucket (rate).

I don't have the number handy but the WSM has a figure for you.

The one thing this won't test is back pressure. But first things first.
Christopher Couper

Does not seem a blocked fuel filter. Because you were waiting at the light. Engine idling for seconds. So a very low fuel consumption. The full carb bowl can idle an engine for minutes. Clogged filter mostly appears at high speed, when consumption is high.
I'm thinking of electrical failure. Maybe the coil. When it fails it often apears when hot. And restart when cooling.

Laurent.
LC Laurent31

I forgot about the other filters. I checked the carb filters and both were clean. I let both pumps move some fuel into a jar and the fuel was perfectly clean and the pumps seemed to be working normal. I haven't looked at the filter in the SU pump (for that matter where is it? I presume in the fuel line going into the pump?)
Regarding the possibility of a coil problem, if the coil was the issue (or some other electrical issue) would the engine start as it did and then die after a couple minutes (for a couple of times) and then run fine going home? In other words, intermittent?

Larry
LD Kanaster

Nobody has mentioned the condensor. It sounds like that.
The moment it stops open the bonnet and check if you have spark at the plugs.
Sanders

An old mechanic mate passed on these words of wisdom:

"The most common failing amongst people diagnosing why their engine stopped is to believe it is lack of fuel, 90% of the time it is lack of ignition".

This is where I would be looking.
G Evans

Larry,

We are fortunate in having a rapid (less than 10 seconds) means of checking if the fuel system is functioning correctly. When you have the problem all you need to do is check the float levels by pressing each carb tickler pin. This assumes that you still have these pins installed. I have kept mine for this reason.

John
J Scragg

A simple ignition tester that goes in series with your plug lead will tell you a lot.

They are $5 at Harbor Freight.

Peter
P G Gilvarry

I'll add to the conundrum. Modern fuel (with lower boiling point due to ethanol content) and it's apparent more frequent cause of vapouization- a problem I'm currently trying to sort on my TF1500.
JK Mazgaj

We can get ethanol free fuel here in the USA, can be 30% more.

Easy to find, especially near boating communities. I have 2 stations within 5 miles. Also use it in all my gardening engines.

Peter
P G Gilvarry

I agree with Sanders. Bad condenser, I have seen these same symptoms on a number of T series cars. It was the condenser each time. Install a known good condenser. Keep us posted.

Ed
ECS Stanfield

Oops, I posted the following on the wrong thread:

It's sounding like a fuel blockage is not your problem but, FWIW, the SU fuel pump filter is in the back of the bump and is accessed by a big brass bolt at the bottom of the pump.

Jud
J K Chapin

Well, here is an update. I checked everything I could regarding the fuel system, i.e. filters, pumping petrol into a clear container to check for contaminants, carbs, and anything else having to do with gas. All looked great. The ignition seemed (operative word there, 'seemed') to be OK. I figured the easiest thing to do would be change the condenser. I did this and also the points (though the points were fine). I tried to start the engine and nothing happened. It turned over but did not start. At that time my brain kicked into gear. Did y'all know that the engine runs better with the rotor installed? Anyway, it fired right up. Today I did a test drive and it seemed fine. I only wish I knew conclusively what the problem was (another operative word there, 'was' and hopefully not 'is'). The only left would be the coil. During the drive I stopped after awhile to feel if the condenser was hot and it was perfectly normal.
I have another coil purchased from someone at sometime. I think my next step is to swap the coils to make sure the thing works and carry it, at least for awhile, as a back up.
Thanks to everyone for the suggestions. If anything new happens I will certainly do another thread.

Larry
LD Kanaster

Hi Larry. Agree that the condenser was probably the culprit. I guess you meant the coil when you stopped to check it if was hot and not the condenser? Glad it's running again. Cheers
Peter TD 5801
P Hehir

Larry, check the live voltage to the SW terminal on the coil. It could be fine with the engine, and dynamo, running at revs, but drop due to voltage loss when stationary, leading to cut out and then refusing to start.

Took 18 months to track mine down. Cause was corrosion on one of the ammeter terminals, tucked away under the dash of course ... And I blamed absolutely everything else.

David
David Wardell

Problem happened on 8/2/2020. What was the ambient temp? Ours was in the mid 90F range close to your latitude. You stopped for a spell with a hot engine and it quit. Sounds like classic vapor lock these cars are prone to on a hot day. While stopped, heat can overheat the fuel line. Alcohol in gasoline exacerbates the problem, as JK mentioned. I've used a thermocouple to check temps in the engine compartment and have seen 250F at the fuel line on the firewall.

As you related, streets can be noisy, and yes, the sound of the fuel pumps would've been a very important clue. If they clatter rapidly instead of just click periodically, they're trying to pump vaporized fuel.

This subject has been discussed at great length frequently and those arguments can be in the arhives.

Insulating the fuel line with wire loom can add a touch of insulation if it recurs frequently.

Where are your pumps mounted? I installed a pair of fuel pump below the tank for gravity priming of pumps and they only push fuel to the carbs, never try to suck it uphill where negative pressure can create vapors.

If I get around to it, I plan the reroute the fuel line to the cooler left side of the TD engine instead of directly behind the exhaust.

Might even add a return to the tank so there's constant circulation. Ironically, this old '50 had a return line when we got it twenty some years ago but I eliminated it after installing a supercharger.
JIM N

This thread was discussed between 23/08/2020 and 29/08/2020

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