Moss Motors, Ltd

my 1977 MGB has had some issues having no power when you are getting up to speed the engine just kept cutting in and out, I thought it was the fuuel pump but I tried replacing that, and it did not fix the problem, so I then found the vacuum line to the distributer was loose so I tightned the hose and everything was fine, but now the problem is back, I cant even keep it past 40mph because of it loosing power, does anyone know what to do?

We need some more information on your car and the circumstances before offering suggestions ...

Any modifications to your car (ignition, fuel, carbs, cylinder head, etc) from a standard '77 B?  Does the engine response vary when it's just fired up (below normal temp) or only when at temp?  Will it "cut out" only under load, or if rev'ed to higher rpms in neutral while parked?  Try to describe what it sounds like when it "cuts out" - backfire?  Does it run "rough" above a certain rpm?  Problems when accelerating, or if steady speed, or coasting? 

Also, details on last tuneup, age of ignition components, fuel filters, any recent work on fuel or ignition parts, etc.

Check out John Twist's MG web site at University Motors  http://www.universitymotorsltd.com/.

Lots of Q and A on all models of MGs and how to solve assorted problems.

Repost with as much detail as you can.  Good luck! 

 

Good find on the vacuum hose, but this may be unrelated.

Let's start with the basics, how are the spark plugs? Pull and examine each one. Perhaps your not hitting hard enough on all cylinders. How old are the plugs and wires anyway? Perhaps it's time to renew?

Put a timing light on her and check that.

Fuel, spark (timing), air, and compression.

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On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"

'68 Sprite 1275
'76 Midget 1500

I have not modified the car it is pretty much original other than taking off the smog pump, I got the car from a guy in California who got it from an auction, but before that I know the car had been parked in the late 80s without being touched, so the car has only 28k original miles on it. This is what I know what looks like has been done to it, new plugs, new plug wires, new distributor cap, new alternator, new water pump. The car always fires right up does not like the cold so much but it still starts, when the loss of power occurs is when the car hits about 2500 – 3000 rpms and it does not matter if you are driving or parked, it happens it at the same point, the best way I can describe it is like when you run out of gas and you push the pedal and nothing happens. Other than losing power at the higher rpms there is no backfiring, running rough, or smoke, and I tried replacing the fuel pump and the problem remained so I put the old one back in. my only other thought is the vacuum advance on the distributor?

 

Any suggestions?  

"new plugs, new plug wires, new distributor cap,"

Did you install a new condenser and rotor along with the above parts?  If so, put the old ones back in and see how the car runs.  There is  a known issue with the rotors available today.  Jeff at Advanced Distributors http://www.advanceddistributors.com/ has good rotors that don't cause problems.  A new condenser, regardless of wher you get it is always suspect.  If the old condenser was not causing problems, don't replace it.  Condensers usually fail in the first hundered or so miles if they are going to fail.  Once past that point, they usually will last a lifetime.

Cheers,

Dave

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Cheers,
Dave
http://homepages.donobi.net/sufuelpumps/

alexu,

Just a hunch. These symptoms sound suspiciously like a plugged exhaust. How long was this vehicle sitting?....I wonder who's living(was living)in there. Break away the rearmost muffler and try it again. Also, check to see if you're getting full throttle.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

It might be good to check the fuel level in the float chamber, too.

I have had a similar problem, & then I found a clogged in-line fuel filter (not OME)...

I think that I fixed the problem for now, I found and place on the distributor to adjust the advance so I tried turning it a few times and the problem seems to have gone away, the only thing now is that it idles a little higher now, thank you for all your here guys.

Sounds like what that car really needs is a methodical step-by-step tune-up.  These little motors run pretty good, but only if everything is carefully dialed in as per the shop manual tune-up instructions.