Car drinks Petrol !

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Dumindu
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My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
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Car drinks Petrol !

Post by Dumindu » Fri Aug 02, 2019 1:17 pm

My car is a 1987 Toyota Tercel DX Wagon RHD 1452cc manual driven car. It has a Aisen 2 barrel carburetor.

Car gas mileage is very poor now. It runs 4 km for 1 liter of petrol.

I connected a bottle with two tubes to the petrol pump instead of tank lines. It is the same. So problem should be with either petrol pump or in carb.

I tested fuel pump with a vacuum gauge. It can withstand a around 30 inHg vacuum pressure. So It seems pump is not bad.

AAP pump of the carb also can withstand the vacuum pressure. It seems it is also good. Both Jets were newly replaced and are having 105 size.

I checked the pistons by removing plugs. They are flooded with fuel.

Engine oil doesnt have a petrol smell. But it is too dark and has a burned smell.

My questions are:

1. Can fuel pump still bad and leak fuel to engine over the 30 inHg pressure level?

2. What are the other locations in a carb where such a huge fuel leak can happen?

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Petros
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Re: Car drinks Petrol !

Post by Petros » Fri Aug 02, 2019 8:35 pm

the float valve in the carb, it it is bad it will flood the engine. when it is running normal, you should be able to look into the sight glass window on the front of the carb. you should see the fuel level in the sight glass, if not, it usually means the float or needle valve is bad. you have to carefully remove the top and either clear, or replace then needle valve.

it is not likely you would get flooding in the engine if fuel pump was leaking. Nor if fuel line was leaking. only a few things can cause that much fuel from getting into the engine, either the carb has stuck valve, or the AAP is bad. you might also check if your fuel pressure is too high coming from the fuel pump, if too high it will also cause engine flooding.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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Dumindu
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Re: Car drinks Petrol !

Post by Dumindu » Fri Aug 02, 2019 9:07 pm

Thanks a lot.

Is this means if the other check valves (3 or 4) in the carb in addition to float valve if got stuck also can cause flooding?

xirdneh
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Re: Car drinks Petrol !

Post by xirdneh » Sat Aug 03, 2019 10:01 am

Its always the carb
Rebuild it or find another one to try
Love those Tercell 4x4 wagons but they sure suffer from road noise.

xirdneh
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My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
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Re: Car drinks Petrol !

Post by xirdneh » Sat Aug 03, 2019 3:20 pm

Check the usual mpg eaters
1. Low tire pressure
2. Brake dragging
3. Roof rack
Love those Tercell 4x4 wagons but they sure suffer from road noise.

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Dumindu
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My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
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Re: Car drinks Petrol !

Post by Dumindu » Sat Aug 03, 2019 7:45 pm

Thank you Mr.Xirdneh.

I am running with a 1 L petrol bottle with two hoses connected to the fuel pump instead of tank lines(to check the gas mileage). Even at idle, bottle empties rapidly (without running). Vacuum hoses in the carb are having a thin lining of gas. Certain places vacuum line connections are also wet from the gas.

I checked with my older carburetor which was rebuild recently to use at emergency. I replaced it to check. Same figure is for that carb too.

I disassembled the removed new carb.

I noticed fuel pump pressure is somewhat high but not affect for abnormal bowl filling. I connected the fuel pump outlet to the disassembled carb fuel inlet tube and held the float needle valve closed by holding the floater up by hand. Fuel not coming out beyond the horizontal level of the float. I checked by placing the float on water. Upward thrust on the float is enough to keep the valve closed.

Other valves are to be checked. I will use my vacuum gauge with thin tubes. I will update with the findings.

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Dumindu
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Re: Car drinks Petrol !

Post by Dumindu » Wed Aug 07, 2019 5:52 am

Finally I could correct the problem with your help.

AAP pump was directly connected to manifold vacuum since the TVSV valve was removed. It was the major cause of the fuel loss. After corrected that and capped the pump vacuum connection, 80% of the problem solved.

Instead of that throttle plate was not closing totally due to the poor spring tension in the accelerator connection. It caused a rough idling leading to fuel loss at idling.

Thank you for your great help.

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