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Su Carbs. Flooding out ,A real problem for the Experts..

Last post 05-12-2009, 12:29 PM by Peter W. 5 replies.
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  •  08-21-2008, 7:48 AM 15873

    Su Carbs. Flooding out ,A real problem for the Experts..

    Here is my problem I restored the car completely , At the time I bought a replacement pump from Moss (made in Canada) it had a 1/4 inch outlet the new pipes I also purchaced matched perfectly . The carbs sometimes were flooding so I switched jets to grosse and fixed it for a while . Started to smell gas while driving.. (sometimes).I found carbs were still flooding out intermittently. Changed out Fuel pump to Rebuilt orig type with lever primer. installed new gas tank due to rust problem , installed new outlet pipe 5/16ths to match fuel pump outlet. The Problem still came back. installed fuel press reg.(broke my heart to put in Non orig. part) solved prob. but would only work if I put it on 5lbs as the engine would starve for gas. Changed out Carbs with New SUs from Moss. removed pressure reg. Problem came back. I read somewhere that the float level can be adj. to just 3/8ths of an inch above the bridge .instead of the 7/16ths as set in the manual.  so I adj.my float level. to that.. The prob. went away . finaly I  have fixed this nagging prob.I said.  I went to start it the other day and Yep. front carb dumping gas like it was on sale.. Getting Real disgusted here.. I am now continplating changing out the fuel pump again and also going with New Gross jets.       Help me the Gremlins are killing me
  •  08-21-2008, 12:04 PM 15877 in reply to 15873

    Re: Su Carbs. Flooding out ,A real problem for the Experts..

    Jag,

    Wow, you've thrown a lot of money at this problem, but it seems that each time you disturb the fuel system you solve the problem temporarily. Therein, I think, lies the clue we need to heed. New fuel tank aside, there may be crap in your fuel system which is getting stuck in the float valves.. You state that the car was completely restored. Did you replace all the fuel lines front to rear, hard and soft?

    Also, modern fuel contains alchohol which degrades standard rubber fuel lines, breaking off tiny little chunks and sending them downstream. We now use nothing but fuel injection grade hose, which is formulated to hold up under these conditions. SOMETHING is getting stuck in your float valves.


    Motorbill
    From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon
  •  08-21-2008, 2:00 PM 15881 in reply to 15877

    Re: Su Carbs. Flooding out ,A real problem for the Experts..

    Ah I wish it were that easy. I have replaced everything in the fuel sys. Lines hoses, Cked the jets right after they flood out and find them absolutly clean and operational holding down the arm and blowing through the pipe they seal well however as soon as I put them under pressure from the pump they overflow I have tested the pump and it puts out 2.5 lbs press.  It is possible that I have aTR4 engine but I don't know if that would make a diference in fuel pressure , I even though about fuel cam through . Do  all Pumps have the same arm?
  •  08-21-2008, 3:14 PM 15883 in reply to 15881

    Re: Su Carbs. Flooding out ,A real problem for the Experts..

    Jagawar, somewhere along the line I've heard that shims (spacers) between the pump and the engine block can adjust the throw of the pump's arm and affect the pressure. I have no experience doing this, just something I've heard.
  •  08-21-2008, 3:42 PM 15884 in reply to 15883

    Re: Su Carbs. Flooding out ,A real problem for the Experts..

    I have heard the same thing.. However I just went out and fooled around starting from the basics and found my pump pressure is 1.5 lbs not 2.5 at crank speed,  I also found that I had changed out the rear jet to Gross jet (had one kicking around)after the carbs flooded out the last time , It must have gotten stuck from sitting. and I changed it to the orig. one that came with the carbs. engine started right up and ran  perfect. now that I am up and running again .. I still know this flooding prob will not end..  I am still looking for the right solution on the fuel pump issue.. I am planning to purchace a small pressure gauge and install it just before the lead carb so when it floods I can get a glimpse of the pressure.. I think I have all but rulled out the carbs as a problem.  If I indeed have a TR4 engine I need to cypher the numbers and maybe find out that that engine requires the spacer block I keep hearing about..
  •  05-12-2009, 12:29 PM 19400 in reply to 15884

    Re: Su Carbs. Flooding out ,A real problem for the Experts..

    H There

    Have you checked that the float chambers are horizontal ie level with the ground?

    We had a problem like this years back and it turned out to be a weird inlet manifold that looked just like the TR3 log manifold but had its carb mount faces machined at a steeper angle than a real TR3 manifold.  We guessed the manifold to be from a TR engine Morgan that would have used a different type of carb. It had TR3/4 H type carbs fitted and the float chamber tops were not horizontal so setting the float level was a pointless excercise, as we guessed the floats were sticking as they rose on the incoming tide of fuel. Gravity not being sufficient to let them drop on the fuel in the chamber.

    The replacement of the manifold with a TR4A item cured the problem. I do recall tho that with the TR4A inlet manifold the air filters fouled the inner front wings (fenders)

    Hope this is of use and gets another TR out on the road where it should be.

    Peter W