MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Enging quits while driving!

Ok here's the problem and my observations when it happens. While driving my 75 B the engine quits. All dash instruments (tack, oil, water, gas) continue to read. If I take the car out of gear and turn the key it starts. If I slow down some and "pop" the clutch it starts. The engine makes no funny noise before dying. I have noticed a slight "jump" when the engine first quits but this may be a result of going down the highway at speed. My first thought is a short some place although I guess it could be a gas filter problem. Although I did get the car home and let it idle in the drive for 15-20 min and the engine did not die. The only thing I did before this started was top up all fluids before going for a drive. Any suggestions would be appreciated.

George
George Logan

Easy stuff first. Next time it happens remove the gas cap and listen for a "whoosh". If so tank is not venting properly.

Mike
'79B
Mike Janacek

As Mike says "easy stuff first" I would also replace the fuel filter.
A cheap fix and an easy way to eliminate that as the potential source of the problem.
Bruce

Also look for a broken wire or bad connection at the coil.
Chris Betson

George. I would tend to think of a fuel problem first. The fact that you mention the tach does not, immediately, drop to zero, tends to rule out a low tension (LT) circuit problem. This is the wire to the coil, the "primary windings" of the coil, the wire from the coil to the dizzy and the points and condensor. In every case I have seen, a problem in this area is immediately noticable by the dropping of the tach.

Hence, I suspect fuel as the most likely problem. Within this area, there are several possiblities. As Mike notes, stopping and removing the fuel filler cap is a basic check. If you hear the "whoosh" he mentions, you have a clogged vent line. This is the line that runs from the fuel tank, through the "vapor seperator" and forwards to the charcoal canister. I have seen this line become plugged one time with results similar to what you have experienced. I have also had a somewhat similar problem when a fuel filter became plugged. But, in that case, the car would only restart and run for a few minutes. Still, replacing the fuel filter is a very good idea. I like the clear fuel filter from Spectre which allows you to see the junk building up. When I had my problem, this is what allowed me to quickly diagnose the problem. Others do not like this type of glass fuel filter. I did a thread about it and it should be in the archives. Read it before you make a decision on the type of filter to use.

Other fuel related areas are a plugged line. (You need to check the fuel pump pressure--1 psi min, 1.75 psi max.) The volume (should be about a pint a minute as a minimum--from memory, may not be correct). These tests will also give you an idea of the condition of the fuel pump. If the readings are low, disconnect the output line from the pump and retest. If bad, it is a pump problem. If good, it is a line problem.

Fuel pick up line. I only own a 68, 77 and 79s. On the 77 and 79's there is a filter on the end of the pick up tube. If this filter becomes clogged, it can restrict the volume of fuel that the pump can bring forward. Relatively easy to check on my RB cars, but I have no experience with the 75 model.

Fuel pump. In additon to points going bad, the diaphram can go bad and the pump is not capable of delivering the desired pressure. Also, check the electrical connections. A loose connection can lead to intermitatant operation.

Carb fuel bowl. A sticking needle valve or a float that does not drop properly can lead to running out of fuel.

High tension circuit. If you have a bad coil, secondary windings or a bad rotor or cap (the carbon bushing in the top where the rotor connects) this could cause such a problem.

Sorry, I do not have a definitive answer, but, if you check out these areas, we can focus more accurately on what the problem may be. Les
Les Bengtson

Thanks for your comments and suggestions. I'll give all a try this weekend and let you know what happens.

Thanks again!

George
George L. Logan

This thread was discussed between 15/10/2002 and 17/10/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.