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MG MGB Technical - Fuel not getting to block

Ok. my 1970 mgb roadster has sat for like 8 years with all the fluids in it. Just now we have gotten to draining and cleaning it all out. When we try to start it the car turns over.. gets spark, all that, but doesnt start. Fuel drains out somewhere between the floaters and the carbs. I took the floaters off and they are perfect... so I am pretty sure its the carbs. They are the original SU carbs and I was just wondering, should I just do a good cleaning/inspection and hope it was just clogged or something? Anything else it could be?

Thanks
BC Corey

BC,
Need some clarification here. What do you mean about the fuel draining out between the floaters (assume you mean the side-mounted float chambers) and the carb. The HS4 carbs have a line from the bottom of the float chamber to the jet base- is there a leak there? Do the float chambers have fuel? Regardless, after so long a good cleaning would be in order. Jim
james Burkhart

BC. As Jim notes, the lack of adequate technical description can cause a problem. Using the descriptive terms in the workshop manual or a parts catalog would help. Not everyone here is a native English speaker and, even among those who are, there can be some confusion. Hence, we try to use the standard, factory terms for most things. When you say, "Just now we have gotten to draining and cleaning it all out", exactly what do you mean? Did you drain and clean the fuel tank, strip and clean the fuel pump and strip and clean the carbs? If so, what is your fuel pressure at the line from the pump to the carbs? Should be at least 1 psi and not more than about 1.75 psi. With your "floaters", does this mean the fuel shut off floats in the float chambers? If so, is the fuel getting into the float chambers? If not, look at the needle valves being stuck due to residue from old gas/petrol. As the gas/petrol evaporates, it forms a thick varnish which is re-disolved by the new fuel (expecially the mixed fuel common today), then it is carried forwards into the small passages of the carbs and can cause needle valves to stick, passages to clog, the needle to stick to the jet, etc. Probably the entire fuel system needs to be throughly cleaned and the carbs stripped, cleaned and re-assembled. Otherwise, you will continue to have problems. Les
Les Bengtson

Ok. sorry about the lack of information. I am used to my other VW BBS that is a lot more lax on that stuff. Anyways. Yes, we just started to drain the fuel tank, drain the old oil, drain all the fluids. We are very intent on getting it running. At first, I thought that it was a floater problem (yes, the floaters off to the side of the carbs) because the fuel just drains off the bottom of those. I took the tops off of them though and there is no clogs in the tops of them... and there didnt seem to be a hole in the bottom for the fuel line you all are talking about... but I believe there is a fuel line of sorts coming off the bottom. Im sorry for the lack of technical terms, since I dont have a shop manual yet. Please bear with me for the time being. Thanks all
BC Corey

BC. You need to take the hex nuts with rod attached (internally) off the carb suction chambers, then remove the suction chambers, the pistons (be careful not to bend the needles) and look into the jet. The round, brass object on the center of the "bridge". It will probably be setting downwards about .060" below the bridge. Then, remove the tops from the float chambers and use paper towels to remove all the gas. Once it is all out, use a can of the compressed air, used to clean computers and electronic gear, to blow through the jet and into the float bowls. That should show you if the line to the jet is clear. If it is, that is not your problem. Perhaps the pistons are not rising properly. Re-assemble and see if, when lifted upwards about 1/2", they fall back quickly and without binding. If there is fuel getting to the jets and the pistons are not binding, old fuel and lack of choke are the most probably fuel related problems. Use the electric fuel pump to pump the tank dry, refill with fresh gas, pull out the choke and see what happens. But, in the long term, you are going to need to drop and clean the tank and clean the carbs to ensure everything will work right. Les
Les Bengtson

BC. I believe you said fuel is leaking out the bottom of the float chambers. If so
the leaks should to be corrected before doing anything else. You can try tightening
the jam nut where the fuel jet line attaches to the float chambers. If that doesn't
stop the leak you will need to replace the jets. As Les said you are going to need
to rebuild the carbs on a car that has been idle for years.
Clifton
Clifton Gordon

This thread was discussed between 18/03/2002 and 19/03/2002

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