Overfuelling problem

[paulv]

I have a Subaru Sumo 4WD with Hitachi carburettor. After being layed up for some time I came to restart the vehicle and found that it runs so rich and the fuel sight glass shows that the float chamber is too 'full'. I have to remove the carb-to-airbox boot and place a spanner in the carb throat to hold the primary valve flap open. Thinking that this was due to the carb I tried a spare carb and found that it does exactly the same. Is there something extraneus to the carb that controls fuel pressure? My local Subaru agent wants me to leave it with him for repair but it's only worth around £300 and I don't want to scrap this old friend. Can anyone help please?.

[gbrand]

Not sure what a Sumo is, but I had a 1980 4wd wagon with a Hitachi carb. On mine the fuel pump had a pressure sensor in it so that the fuel pump would "pulse" when the pressure dropped too low, then shut off until the pressure dropped again. If this regulator some how screwed up then too high a pressure could be feeding too much gas into the carb. Check with a guage and compare to specification.

 

I have been bitten by too many stuck/defective floats with carbs letting too much gas in that i would not rule out the spare carb might have the same problem, esp if has been sitting. If the fuel pressure checks OK then a quick check of the float is in order.

 

Let us know what you find out, hope it is a simple fix.

[SUMO NUTT]

wow this is amazing, i have had the same problem exactly, on a 1991 uk sumo 1.2

 

 

i have been trying for months to fis it, 2 experts have told me its the carb thats at fault, but reading ur post i am not sure now. hte newest clue i have to solving the problem is that on mine, the bob weights in the distrib is fauty.

 

if u do get an answer please email me asap, and if i sort the problem i will do the same.

 

also if you have a working complete carb would you be interested in selling it, i am desprate for one at the mo, my one has been broken beyond repair.

 

also i herd that sometimes the jet at the bottom of the float chamber wears funny, and so allows to much fuel through.

 

although i should add that this did not solve the problem for me. happy drivn dude.