SU float chamber sflooding

[mitchelltjohn]

I have as std UK spec 2.0 FHC. Over past couple of months car started sounded liek runnign on two cylinders. I found SU float chamber for bulkhead-side SU was flooding and squirting petrol ou tof overflow tube. I removed chamber top, cleaned gunge out of chamber, lubricated float hinge, checked float not sinking adn fitted NEW float valve & seat. All well until same problem with float chamber on camchain-side SU. Did same maintenance procedure as above and again all well.
Now after a few weeks both float chambers are flooding are same time making car completely undrivable under any circumstances.
I am at a loss to know what to do next. I also fitted a fuel filter between fual lien and fual pump incase some debris was being picked coming from fuel tank, not no difference. Where should I look next - fuel pump?
Any ideas / suggestions?

1979 FHC pageant blue
1981 DHC triton green

[supercass]

In my experience sometimes the float itself becomes distorted and jams on the side of the chamber. This is not always obvious.There are new etahanol resistant floats that may work better. Floats aren't cheap for a tiny bit of plastic, so first take the existing float out and give it a good polish with metal polish or similar, the resultant shine I have found can be just enough to prevent it sticking. Regards, supercass

[gaz]

Also if you have acsess to a commpresor blow out any crap in fuel rail the one between the float chambers and renew the rubber fuel lines there only cheap make sure there a very clean cut as any minscule bit of rubber from a rough cut could be enough take you back to square one.

To be pefectly honest since i got my TR7 on the road in 2006-07 this has been the only thing that has had me reaching for the toolbox at the side of the road.
I used to drive around with spare floats, chamber tops screws & gaskets that was until i got the new tank a couple of years ago.
Then I had the same problem the other week...... happy days

http://mytr7.weebly.com/blackpool-lights-run-2012.html

1981 DHC 2.0 Litre
1980 DHC pedal car
1976 FHC 2.0 Litre

[Hasbeen]

If the floats are not full of fuel & sinking, either you have faulty float valves, dirt getting in them & stopping them shutting properly, or your fuel pressure is too high. Your symptoms sounds like classic excess fuel pressure to me.

Have you done anything with the fuel pump recently? If you have had it off the engine, you may have removed some of the packing between the pump & the block, which increases the operating pressure.

First I'd do as gaz advises, perhaps replacing all the fuel hose after the in line filter, & making sure no junk is in the solid lines.

If the problem persists find a low pressure fuel gauge, or someone with one, & check the pressure. It must not exceed 2 PSI with our SUs. Adding packing between the pump & the block will reduce the pressure.

There are about 4 float valves being marketed for SUs today. I have has flooding problems with the one with a ball at the valve end.

Hasbeen

[mitchelltjohn]

The new float values I used are red cone tipped items (from. RIMMERS) - is experience of these ok from others?
Only had car a few months so dont know all the history of engine rebuild or fuel pump status.
I willl look into pipeline clean out and polishing/renewing floats first.

[gaz]

there is even a video on youtube with me attending to my float chambers on one of the tr drivers club runs.
Just after driving under a bridge at billing, cant find the anymore

http://mytr7.weebly.com/blackpool-lights-run-2012.html

1981 DHC 2.0 Litre
1980 DHC pedal car
1976 FHC 2.0 Litre

[nervousnewowner]

float chamber was overflowing on mine and i pulled the float out and dropped the needle which was sticking, was crud in the chamber, cleaned it out and not had problem since, just crap running....lol.... see other posts from me.......


Dave...

the project at birth, watch it evolve...I hope...

[Hasbeen]

If the car is new to you, check that fuel pressure. Too high fuel pressure is the usual cause of our flooding, as the most often supplied replacement pump operates at too high pressure, when fitted to a slant 4 engine.

One advantage of buying parts from a company that does mechanical work on the cars, is that they have experienced most if not all the problems with replacement parts, that are not quite right, & know how to overcome the problems.

I have never known of the fuel to run, let alone squirt out the overflow, unless the pressure is too high, although a bit of rubber from a hose, blocking the valve wide open, could do it I suppose.

Hasbeen

[saabfast]

I have had the problem on the front carb. Checked it all - float etc looked OK. Tried removing and cleaning the float valve, and then fitting one out of an old spare carb, all to no avail. Only stopped when I fitted a new valve and its been OK since.

Alan
Saab 9000 Stg 1
Saab 9000 2.3 FPT Auto
Saab 2.3 LPT Auto
'81 TR7 DHC