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MG MGA - MGA Losing Power

I have a '62 MGA 1600 MK2 with a frustrating problem!

It intermittently loses power. Most recently after adding some fuel to the tank. It starts to lose power, feels like it is about to stall but with load will not pick up speed easily. Dipping the clutch and pressing the accelerator causes the engine to rev freely but immediately the clutch is released the car struggles to move forward. Once switched off and left for a while the problem disappears…..until it happens again. I did wonder if this could be due to debris in the tank blocking (temporarily) the fuel line. Any thoughts or suggestions gratefully received.

Paul
Paul Bowens

I had a similar problem a few years ago Paul and it was as you suggest a blocked fuel line.

I traced the lack of fuel by removing the fuel pipe at the carb end and with the ignition on (pump operating) noticed very poor fuel delivery. I ended up removing and cleaning the tank which had not been cleaned properly after being shot blasted.
John Bray

The similar problem I had a few years ago was caused by a partially blocked after market fuel filter in the fuel line near the tank. It would let a trickle of fuel through, enough to fill the float chambers when the engine was stopped but a mile or two down the road it would gradually splutter to a halt.
Fuel starvation is distinctive in that the engine drops first onto 3 cylinders, then onto 2, then 1 and then stops.
Hope you find the problem quickly.
Colyn
c firth

I once had this as a self inflicted problem caused by using sealant on the sensor screws. It partly got into to the petrol and then built up in the pipework.

Pasul
Paul Dean

Could it be a brake fluid expansion problem? Not too familiar with MGAs but isn't there an expansion escape hole in the master cylinder which an incorrect MC seal can cover when things get hot. Brake fluid is then expanded down the lines thus putting the brakes on. Leaving it for a while, fluid cools down and car feels OK again.

David
David Wardell


Thanks for the comments and suggestions. I have check the fuel pump filter which is clean so still suspecting tank may have debris which, when disturbed blocks the fuel draw off.

Interestingly I have had the car out twice this weekend one run was nearly 40 miles without any problem, the car was running beautifully!

Thanks again for the advice, I will let you know when I find the problem.

Paul
Paul Bowens

Misfiring under load but revving ok without load can be a symptom of poor spark or failing coil, especially if it is worse when the engine is hot but better when cold.
Try replacing your coil with a good known one. Also check to make sure you have a good spark. Finally, check your point gap and ensure that they are indeed opening properly.
Getting back to fuel, there are small conical wire mesh filters on the inlet side of the fuel bowls in H series SU's. These can be accessed by removing the fuel banjo connector. It's another possible spot for fuel flow to be impeded.
A Bowie

Paul, an easy way to check the fuel flow is to simply remove the fuel supply hose from the carbs and hold the end into a measuring jug.
With the ignition switched on you should get a minimum of 1 pint per minute if the fuel supply is good.

Colyn
c firth

Paul, you may have some flotsum in your fuel tank. It floats around until it gets sucked into the pickup tube leading to a reduction in fuel flow. Once fuel pump is turned off, the flotsam is released and it continues to float around until next time. Ask me how I know!
Nick Kopernik

Its strange that you should post about this subject just now Paul because my car has just begun to have an intermittent misfire again. Just goes onto 2 cylinders momentarily and then runs fine for the rest of the day.

So I decided to have a quick luck at the usual culprit, the aftermarket in-line fuel filter that the previous owner fitted down near the fuel tank.
It entails removing the Rt rear wheel to make access easier.
The filter is inside a glass tube and it didnt look too bad but I decided to remove it to make sure.

Have a look at the picture and see why I was so surprised.

Colyn


c firth

It was a piece of silicon sealant, gone slightly gooey after being immersed in unleaded petrol and it was about one and a half inches long.
You can see it better in this second picture after I had dissembled the filter.

On the one hand Im glad the DPO fitted this extra filter, but on the other hand Im not so happy that he used silicone sealant to try to seal the weird non standard tank filler hose he used.

I have recently replaced this with a proper MGA type hose.
Hopefully this is the last piece of sealant left in the tank, time will tell.

Colyn


c firth

JR Jack

This thread was discussed between 24/07/2015 and 02/08/2015

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