HELP! I hate carbs - weird SU leakage problem

Major Ledfoot

See the tiny red arrow, pointing to the tiny little hole on the side of that object?

Well, it's spraying raw fuel all over the place. When I put my finger over this hole to try and stop the spray of fuel, the engine stalls.

I've just changed the mechanical fuel pump for another mechanical fuel pump, because I didn't want problems...

I need to fix this, or getting to Benalla without getting crispy is gonna be a problem.

What is going wrong? How do I fix this? Or how can somebody fix this?

(cue panic voice)

HELP!

jrhendo

It's a long time since I played with SUs (my 140s have webers or strombergs) but that looks like an overflow hole. If it's overflowing, by guess your float or needle valve is jammed open, letting the fuel pump do what they do best - pump fuel continuously.
SUs are pretty simple. Take off the top of the float bowl. That's the main object in your photo, below the red arrow. Clean out any gunk and replace the needle valve if you've got one, check the float isn't jammed in its movement.
Put it back together and fingers crossed it should be ok.
If you need a needle valve, CSC in Burwood is pretty good.

jrhendo

PS loads of info on the net on SUs

egads (she/her)

The floats leak and fill up with fuel jamming open leading to an overflow.

Major Ledfoot

Thanks gents. Maybe is is just crud and crap in there, if I am lucky.

A_Volvo_Driver

Crush it

Vee_Que

My bet on needle valve also. Did the same thing on my 122 a while back.

Major Ledfoot

A_Volvo_Driver;120048 wroteCrush it

Never. Not after the pain of losing the previous 73.

1971_144GL

I've had this. The probablem turned out to be that the newer fuel pumps have too high a pressure. A thicker spacer on the fuel pump mount helps, not as much lift from the cam then. I the end I cracked it with the replacement mechanical pumps and fitted a fuel flow electric pump and fuel pressure regulator for good measure. Carbs have never run so well, engine smoother instantly on the 1800. A fuel pressure regulator also improved an over pressure mechanical pump, and low end versions are easy to get at Auto shops.

I still ove carbs still, in part because most people have already given up and it is fun to see mystified looks. Twin su sounds great in anger too.

egads (she/her)

I have a carb appropriate adjustable FPR if you want it? Can express post later today.

Major Ledfoot

1971_144GL;120090 wroteI've had this. The probablem turned out to be that the newer fuel pumps have too high a pressure.

Arrrgh, CRAP. This is not what I wanted to hear, but it seems to be the problem. :( Have taken the top off of the float bowl, checked the float (looks okay and not full of fuel) and removed the little axle, removed the slidey-plastic and metal doohickie and gave the lot a blast with carby clean, reassembled... and it's still doing the same thing.

It appears there's two types of lids, according to the MG forum from which I've pinched this pic.

(pic: Gerry Adams)

According to Gerry Adams on that forum, the good type of cover is on the left.

As luck has it, I have the type on the right....

I hate carbs.

Thank for offer @egads (she/her), but package won't arrive in time for our departure.

Vee_Que

A regulator shouldn't be too hard to find.

egads (she/her)

Space out the fuel pump with a thick homemade gasket?

Major Ledfoot

I wonder if the needle and seat arrangement are cactus, or if it's a dodgy cover?

I'm wondering why the front SU is spewing fuel, but the rearward one isn't. I got to thinking - ~~Shirley~~ surely if it's a pressure issue, both of them would be spraying gas?

Out of my very limited range of expertise, gonna have to find a pro-spanner - have to be in Yass on Thursday night and Benalla on Friday.

egads (she/her)

Any MG blokes local?

Have you tried the Hail Mary of swapping them back to front? If the pressure is relieving ok by one perhaps not building up in the second?

Major Ledfoot

The thing is running at the moment, albeit spewing fuel. Therefore I am very reluctant to fiddle further with it in case it won't run at all, meaning I won't even be able to drive it to a shop for repairs. So I am going to rig up a "catch tank" and try and get it to a shop.

Hassle is finding a shop that isn't inundated with work - I've tried several shops and they're flat out after the long weekend.

The nearest MG place in is Penrith and the guys are pretty busy there - I've made inquiries about float bowl covers already.

Major Ledfoot

Update:

Whipped the float bowl cover off again and checked the float level figure as per secret advice given - it seems to be okay. Having doubts if the float is any good.

Will try MG place in Penrith tomorrow for new float, needle and seat, and top cover.

Vee_Que

Good idea. If both leaked I'd like pressure more.

nickm

I have had that happen.It was 30 years ago.
Fuel pressure or float valve I can't remember which one.

Major Ledfoot

I'll get both, then. :)