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My truck(B3-B) engine is a IND-251.I adjusted its tappets valve clearance months ago.It is very with a very good development now,but these days ago I did a consumption media.First I ran 59 kilometers,refill the tank with 31 liters.Media of=1,9 km/l.Today I did another consumption media.I ran 23 kilometers,refill the tank with 14 liters.Media of=1,6 km/l.Why?Which is the normal 251 consumption?Thanks for the inputs. 

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If my calculations are correct that would convert to around 4.47 miles/gallon and 3.76 MPG. That would be terrible fuel economy. I get around 15 mpg or approximately 6.4 km/l.

I think Jeff may be on to something. You may have a carburetor issue.

Edited by Merle Coggins
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Yes guys I will check my not original carburetor.My carburetor is a DFV.I remember one time I change a jet in its bowl put a number 28(big hole).I withdrew this jet from my WWII GMC CCKW 270 engine.Merle my odometer is for km/h.It marks until 140 km/h.

10 hours ago, Jeff Balazs said:

Better check to see if flat valve is working. You must be smelling the gas pretty bad.

Jeff,after I adjusted valve tappet clearance my truck  is excelent running super ok,strong development.

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7 hours ago, Jeff Balazs said:

Sorry should have read Float valve. You are absolutely using too much fuel. I would think that you are just pouring fuel into it and this could cause some real problems. 12 miles per gallon is probably the lowest you should ever see. Sounds like you need to find the correct carb.

Jeff I red my B3-B archives now and saw that in october'2013 I changed the following jets:low speed 12 to14(GMC) and high speed 20 to 28(GMC).My DFV six cylinders carb is similar to the Zenith(GMC).Today I re-torque all the diaphragm pump screws,because it was wet.

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On 25/01/2017 at 9:01 PM, Fernando Mendes said:

Jeff I red my B3-B archives now and saw that in october'2013 I changed the following jets:low speed 12 to14(GMC) and high speed 20 to 28(GMC).My DFV six cylinders carb is similar to the Zenith(GMC).Today I re-torque all the diaphragm pump screws,because it was wet.

I learned this weekend that if the venturi is 27,for example,I have to put a principal jet  number 27 too.(in my DFV carburetor).

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On 25/01/2017 at 9:01 PM, Fernando Mendes said:

Jeff I red my B3-B archives now and saw that in october'2013 I changed the following jets:low speed 12 to14(GMC) and high speed 20 to 28(GMC).My DFV six cylinders carb is similar to the Zenith(GMC).Today I re-torque all the diaphragm pump screws,because it was wet.

I learned this weekend that if the venturi is 27,for example,I have to put a principal jet  number 27 too.(in my DFV carburetor).

I noticed too this days ago that the intake manifold center hole of my PU is not the same diameter of my carburetor to inlet manifold.Then I did two gaskets.One gasket for the intake manifold and other gasket to my carburetor to inlet manifold.It is very good now.

Dodge DFV recuperado e limpo 006.JPG

Dodge DFV recuperado e limpo 007.JPG

Dodge DFV recuperado e limpo 008.JPG

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Not completely familiar with that carb, but if it is similar to the carter it should have a vacuum path from the intakemwnifoldthrough gasket to the base of the carb.  That vacuum signal functions to control the step up /power jet.  This jet provides for extra fuel after the initial squirt from the accelerator pump. High vacuum at cruise and idle keeps the valve closed against spring pressure, no or low vacuum lets it stay open. Your carb is mounted off center, plus you have mismatched gaskets, one or both of those items could be causing a total or partial blocking of the vacuum signal, leaving you power jet open all the time.  I have seen a car (54 Plymouth station wagon with OD) go from 9 or 10 miles per gallon to 17 to 19 mpg, by assuring this valve and vacuum signal are operating correctly.

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19 hours ago, greg g said:

Not completely familiar with that carb, but if it is similar to the carter it should have a vacuum path from the intakemwnifoldthrough gasket to the base of the carb.  That vacuum signal functions to control the step up /power jet.  This jet provides for extra fuel after the initial squirt from the accelerator pump. High vacuum at cruise and idle keeps the valve closed against spring pressure, no or low vacuum lets it stay open. Your carb is mounted off center, plus you have mismatched gaskets, one or both of those items could be causing a total or partial blocking of the vacuum signal, leaving you power jet open all the time.  I have seen a car (54 Plymouth station wagon with OD) go from 9 or 10 miles per gallon to 17 to 19 mpg, by assuring this valve and vacuum signal are operating correctly.

 

Scan0010.jpg

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Greg and Jeff.Thanks to you have watched my stuff.In these drawing we can see in Fig 89 letter H is similar to metering rod(high speed circuit) and Fig 89 letter I is similar to same high speed circuit,only a reinforce.The canal of the carburetor base that gets the manifold vacuum is not clogged.I already ran in my PU and it is ok.I will try to find a pic of the gaskets I did.

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Greg G or Jeff I bought these two fuel pump repair.Question 1)In pic 001 why the gaskets are differents(rubber and leather)?Question 2)I never saw this type of valves.I do not know how to mount them.This diaphragm is not correct,it is not CARTER model.Thanks.Regards.

Reparos bomba de gasolina 001.JPG

Reparos bomba de gasolina 002.JPG

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They are likely check valves to prevent fuel from flowing back under gravity when the fuel pump stops with engine off. Probably have a captured ball min the casing.  The ball will fit into a soft stopping flow.  You will need to determine the direction the ball moves to be open when the pump is working and install the proper one for the inlet  and the out let.  When to take the pump apart make note of which one is where and what gasket is in which position on the pump. 

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12 hours ago, greg g said:

They are likely check valves to prevent fuel from flowing back under gravity when the fuel pump stops with engine off. Probably have a captured ball min the casing.  The ball will fit into a soft stopping flow.  You will need to determine the direction the ball moves to be open when the pump is working and install the proper one for the inlet  and the out let.  When to take the pump apart make note of which one is where and what gasket is in which position on the pump. 

But can I put for example:the rubber gasket in inlet and leather gasket in outlet or rubber in outlet and leather in inlet?This is my doubt.Thanks.Regards.

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3 hours ago, greg g said:

I would use the rubber on the inlet and fiber on the outlet, but what is on the pump now?  The rubber will be a better seal against an air leak on the suction side.

My CARTER(?) pump(B3-B) is still with OLD rusted valves.Now I discovered who sells them here.I will change them.I bought a new original diaphragm too.

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Hi Greg G.Here are some pics showing the circuits of DFV:1)Float circuit,2)Low Speed circuit,3)High Speed circuit,4)Power Speed circuit,5)Pump circuit.(gasoline is represented by black color and white arrows).Regards.

Carburador DFV circuitos 001.JPG

Carburador DFV circuitos 002.JPG

Carburador DFV circuitos 003.JPG

Carburador DFV pistão vácuo 001.JPG

Pump circuit 001.JPG

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  • 2 weeks later...
On 15/02/2017 at 4:17 PM, Fernando Mendes said:

Greg G or Jeff I bought these two fuel pump repair.Question 1)In pic 001 why the gaskets are differents(rubber and leather)?Question 2)I never saw this type of valves.I do not know how to mount them.This diaphragm is not correct,it is not CARTER model.Thanks.Regards.

Reparos bomba de gasolina 001.JPG

Reparos bomba de gasolina 002.JPG

Today disassembling fuel pump,cleaning with solvent,puting new valves.I will try to change the lever.My pump is a Carter MO-644.Its two valves were very old(rubber,spring).The engine was failing when climbing the road.

DSCN3897.JPG

DSCN3895.JPG

DSCN3891.JPG

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On 2/12/2017 at 5:26 PM, greg g said:

Not completely familiar with that carb, but if it is similar to the carter it should have a vacuum path from the intakemwnifoldthrough gasket to the base of the carb.  That vacuum signal functions to control the step up /power jet.  This jet provides for extra fuel after the initial squirt from the accelerator pump. High vacuum at cruise and idle keeps the valve closed against spring pressure, no or low vacuum lets it stay open. Your carb is mounted off center, plus you have mismatched gaskets, one or both of those items could be causing a total or partial blocking of the vacuum signal, leaving you power jet open all the time.  I have seen a car (54 Plymouth station wagon with OD) go from 9 or 10 miles per gallon to 17 to 19 mpg, by assuring this valve and vacuum signal are operating correctly.

I have seen this many many times and on almost all makes.  The wrong gasket or a gasket which is wrongly installed keeps the "power " valve open and  mileage is cut almost in half.   A vacuum leak will do this too. Look for a crack in the middle intake runner between the manifold and the block usually on the underside.

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There is no need to prime it.   If you want to keep it on the shelf for awhile, spray some WD 40 in it.

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