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MG MGB Technical - HIF carb issue

I have a 73 B with HIF carbs. A few weeks ago, I had a problem with the car flooding. I removed the carbs and replaced and adjusted the floats and float valves. After reinstallation and tuning the car ran perfectly. Yesterday, when running at speed on the highway, I experienced a sudden loss of power, and the car stalled. I can restart the car with choke all the way out, but if I ghen release the choke to the normal 1/4 out position, it stalls. If I keep the choke all the way out, the engine initially revs quite high - about 2000 rpm, but then stalls out. If I wait a couple of minutes I can restart the car, but same thing happens. I am planning to pull the carbs again and check float chambers, but wanted to check to see if anyone had any idea what the issue might be. Thanks for any information you can provide.
DJ Shaw

How many miles over those few weeks? Time is probably not relevant if the car is only used occasionally. If only a few dozen miles I'd say it is almost certainly something you did inside the carbs. If a few hundred then perhaps not. But before diving into the carbs again, which probably means removing them, I'd do the simple stuff like check the throttle cable, linkages, idle and fast-idle screw, remove the dashpot covers and check the needles and pistons, check the damping, and look at what is happening in the carb throats with the air filters removed.
PaulH Solihull

Sounds like it could be the fuel pump.
darnoc31

Thanks Paul. I have driven the car a number of times, but you are right, not that many miles. Maybe a total of about 120. Thanks for the checklist of simple stuff. I did take a quick look at most of these, but will look harder at them before removing the carbs again.
DJ Shaw

DJ-
So, the car ran well and then suddenly went into what appears to a lean running condition? You might have developed a serious air leak.

Let's start with the easy, simple stuff first: With the engine running, spray some carburetor cleaner onto all of the joints in the system (Intake manifold/cylinder head, Intake manifold/carburetors, Throttle shafts). If the engine's idle speed changes, then you've located the leak.
Stephen Strange

I just swapped out a set of HIF, completely rebuilt, that started pumping gas out the o'flow through the cannister and on to the pass side cockpit floor.
I thot the viton jet was the problem and swapped out a Grosse Jet. While reinstalling the float, I noticed it was 1/2 full of gas! It would never rise to close the jet, and the gas just kept pumping through the overflow, the cannister,and the engine bay.
Check both carb floats for leaks.
How many turns on the mix screw? Should be about 3.5-3.75 turns out ( to the lefty lean: CC) from all the way in for sea level.
Did you catch the screw when you reinstalled the jet wedge using the sprung screw? Sounds like this is the area of focus...always go back to the last thing you did. Vem
vem myers

DJ,

It must not be completely reponsible to your problem, but often when HIF run rich and are non-adjustable it is that cold start enrichment device the problem. It is a 3 seals-O-rings job/carb....

Chers,

Jean G.
Jean Guy Catford

You all ain gonna believe this one: I swapped out the leaking float in the front HIF with another from a brand new rebuild set I had. 3 days later, that float leaked and filled with gas so it wouldn't rise to close the jet, and gas again pumped through the cannister and into the cockpit. Jeez, I gotta get a better religion.
One guy I talked to said the gas chemistry in California is such it can eat the floats?!? I say, really? in 3 days time???!????

VEM
vem myers

Have you tried Scientology? It's worked great for Tom Cruise. RAY
rjm RAY

wow, gonna go back to the HS4. At least I can get to the float bowls on the freeway shoulder if it happens again. I'll let Tom and Kate revel in their immortality while I try something proactive.Putten 'em on right damn now. Cheers, Vem out 11:50 AM 7/7/12
vem myers

VEM-
Tell Joe Curto about this. I think he has made new deal plastic floats for the HS that are said to be indestructo. And Burlen. Maybe he and/or Burlen can connive to fix this V annoying problem.
Besides, where is this crap coming from? Hard to believe anybody except Burlen is making HIF floats.

It put me off HIF for the same reason, as
I told you elsewhere.

FRM
FR Millmore

This thread was discussed between 16/06/2012 and 07/07/2012

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