Fuel Pump Replacement

[LancerL]

Dear Members, as I feel my fuel pump has gone bad hence I need to crank few turns of engine to start after parking it few hours.

My engine is Mitsubishi Orient 4G12 and has mechanical pump.

Kindly advice me on following areas.

1. Possibility of repairing the current one.
   
2. Fixing a new mechanical pump or electric one which one is best.
   
3. Does electrical pump comes with a stop valve?
   
4. Rough cost for the project.
   

Thanks in advance.

[Davy]

LancerL,

1. The mechanical fuel pump in your engine is a sealed type pump, so the answer to your first question is, No.

2. If I were you, I'd buy a brand new mechanical pump to avoid messing with the engine & electrics. They're quite reliable as well. If you're going for an electric pump, you will first of all have to seal off the place (on the valve body) to where the fuel pump is fixed via a push rod.

3. Not sure about this but there are electric fuel pump conversion kits that are available with a stop valve mechanism implemented by tapping into the oil pressure switch.

4. The mechanical fuel pump cost me about 2500 at Panchikawatta in 2010. Maybe someone else with experience installing electric fuel pumps will be able to shed some light on rough conversion costs.

[Sylvi]

Dear Members, as I feel my fuel pump has gone bad hence I need to crank few turns of engine to start after parking it few hours.

My engine is Mitsubishi Orient 4G12 and has mechanical pump.

Kindly advice me on following areas.

1. Possibility of repairing the current one.
   
2. Fixing a new mechanical pump or electric one which one is best.
   
3. Does electrical pump comes with a stop valve?
   
4. Rough cost for the project.
   

Thanks in advance.

First of all any mechanic has sorted out that the pump is defective. Because you think the pump is defective and you want to change.

Get a second opinion before you change the pump.

As for advice given to you by member Davy it is best to buy a new mechanical pump and get it fitted because you cannot repair sealed type pumps satisfactory by any mechanic. Even if he does same it will be temporary.

If you want to do a conversion with a (Morris minor type) electric pump that is also good, as you switch on the Ignition switch, electric pump supply wire is connected to Ignition coil supply side. Pump will pump fuel into the carburetor unlike the engine has to crank few turns to operate the mechanical fuel pump.

Compare the cost of both pumps with labour cost for fixing and time.

As I have done mechanical pumps converting to electrical pumps there is nothing to worry on converting to electric pump because the float of the carburetor will control the flow of fuel to carburetor, connect in of the mechanical pump to inlet and out let according to electric pump, Electric fuel pump too will stop pumping fuel when the carburetor is full, unlike the electric high pressure pumps fitted inside the fuel tank in modern EFI engines.

It is left for you to decide the advantages on fitting both pumps.

Sylvi Wijesinghe.

[LancerL]

First of all any mechanic has sorted out that the pump is defective. Because you think the pump is defective and you want to change.

Get a second opinion before you change the pump.

As for advice given to you by member Davy it is best to buy a new mechanical pump and get it fitted because you cannot repair sealed type pumps satisfactory by any mechanic. Even if he does same it will be temporary.

If you want to do a conversion with a (Morris minor type) electric pump that is also good, as you switch on the Ignition switch, electric pump supply wire is connected to Ignition coil supply side. Pump will pump fuel into the carburetor unlike the engine has to crank few turns to operate the mechanical fuel pump.

Compare the cost of both pumps with labour cost for fixing and time.

As I have done mechanical pumps converting to electrical pumps there is nothing to worry on converting to electric pump because the float of the carburetor will control the flow of fuel to carburetor, connect in of the mechanical pump to inlet and out let according to electric pump, Electric fuel pump too will stop pumping fuel when the carburetor is full, unlike the electric high pressure pumps fitted inside the fuel tank in modern EFI engines.

It is left for you to decide the advantages on fitting both pumps.

Sylvi Wijesinghe.

Dear Sylvi,

Thanks for your valuable advice, BTW can I fix a check valve separately to the fuel line between pump and Carb instead of replacing the fuel pump, hence my issue is returning fuel back to tank when engine stop.

Thanks

[Sylvi]

Dear Sylvi,

Thanks for your valuable advice, BTW can I fix a check valve separately to the fuel line between pump and Carb instead of replacing the fuel pump, hence my issue is returning fuel back to tank when engine stop.

Thanks

'LancerL',

You mean to fix a non return valve Did you check that carburetor is below the required level to start the engine after few hours of stopping the engine.

You have to check the fuel pump pressure to fix a non return valve.

Because the valve has to open when fuel pump operates opening pressure of the valve is more than the pump pressure valve will not operate.

Sylvi Wijesinghe.

[LancerL]

'LancerL',

You mean to fix a non return valve Did you check that carburetor is below the required level to start the engine after few hours of stopping the engine.

You have to check the fuel pump pressure to fix a non return valve.

Because the valve has to open when fuel pump operates opening pressure of the valve is more than the pump pressure valve will not operate.

Sylvi Wijesinghe.

Dear Sylvi,

Yes, I meant was to fix a non return valve.

You’re correct. Yesterday I fixed a transparent extension tube to the fuel line and start the engine. I observed that after few cranks only the fuel reached Carb and as soon as fuel enters engine started!

When I stopped the engine it went back to the tank without remaining on the tube.

I couldn’t check the pressure of the fuel pump.

Anyway if it is giving a bad pressure, fixing it in between tank and the pump also will solve the matter? Am I correct?

Thanks

LancerL

[The Don]

Dear Sylvi,

Yes, I meant was to fix a non return valve.

You’re correct. Yesterday I fixed a transparent extension tube to the fuel line and start the engine. I observed that after few cranks only the fuel reached Carb and as soon as fuel enters engine started!

When I stopped the engine it went back to the tank without remaining on the tube.

I couldn’t check the pressure of the fuel pump.

Anyway if it is giving a bad pressure, fixing it in between tank and the pump also will solve the matter? Am I correct?

Thanks

LancerL

LancerL, just a little idea in using the cohesive properties of liquids (not sure if it will work on Petrol but it works in water) is to lift the petrol line a little higher than the entry point to the carburetor in a small arc and see if this will leave enough petrol in the carburetor to start next time. My only fear is it might flood the carburetor.

[Sylvi]

The Don,

Your idea some times will work like the good old days cars had no pumps instead they had vacuum tank with petrol get in to canister and carburetor gets filled with petrol on gravity fed. Still carburetors had a float to control the level of the carburetor.

LanceL. If you want to try that method which Thedon had said do give a try, with a little longer tube clipped to body so that Petrol will not come back to gravity because definitely the tank petrol level is below the carburetor level. Petrol will come back for gravity.

If you want to fix a non return valve you can buy a non return water valve have to modify same fix on to small tubes it will be a complicated project for a person like you. Even if you inform a mechanic he will not like to do that type of a job because time taken for that and the cost.

I have non return valve with plastic tube connections which I want try out for a different project cannot give you the cost.

Will be under rupees 1000.00 with two nipples for tube connections all Brass. Purchasing was done by another worker of mine who will here on Friday.

You need to buy 1/2 inch water pipe non return valve with two brass adapters for 3/8 inch hose to connect to your petrol pump.

Or turn out small ball valve on a lathe with free ball moving up and down to petrol pump pressure.

When you stop the engine ball will close the inlet of the unit and.Control the back flow of petrol.

Ball has to be seated very well for the ball to the adapter inlet line so that petrol will not go back to the carburetor same way floater control works.

Any further clarifications you can contact me on my mobile or land line 0712222420 / 2573690.

look into the cost and time taken for above this and fitting a new original mechanical pump or electric pump.

Sylvi Wijesinghe.

[Sylvi]

LancerL,

log into the web page below you will get a compete working principle of the Vacuum tank petrol filling the carburetor, in early day automobiles had patented.

Now present day mechanics I don't think this type of thing existed.

http://www.allpar.com/fix/fuel/vacuum-tank-fuel-pump.html

Sylvi Wijesinghe.

[Sylvi]

LancerL,

I manage to get my worker on his mobile he told me the 3 units cost were rupees 900.00.

If you want to tryout that NON RETURN valve you can try out at my residence I will gladly help you.

Sylvi Wijesinghe.

[The Don]

Sylvi, what do you think is the actual problem with LancerL's carburettor ? What is the mechanism which keeps some petrol in the carburettor so help with starting after a while.

Sorry, my experience is mostly in fuel injection so haven't really taken a carburetor apart and studied it well.

[Sylvi]

Sylvi, what do you think is the actual problem with LancerL's carburettor ? What is the mechanism which keeps some petrol in the carburettor so help with starting after a while.

Sorry, my experience is mostly in fuel injection so haven't really taken a carburetor apart and studied it well.

'The Don',

Normally carburetors keep petrol level for two days or more. If it is evaporating off in no time that shows the carburetor area is too hot that temperature evaporates the petrol. Then he has to operate starter motor for little longer time to fill in the required amount of fuel level to carburetor to start the engine.

As for my knowledge there is no way that float control jet will allow to return petrol back.

Fuel returning on the line back I have not heard or experienced in carburetor engines. I have to examine and give a diagnosis of the problem.

I do not know who gave the idea of fixing a non return valve on the line.

That is the reason I offered him to help on the matter to give my non return valve so that I can examine the problem what he has.

Not to expect a fee as I am no more in that section of Automobile repair.

I know he has posted another thread about carburetor repair on 24tht September requesting help for repair of his carburetor.

Above is what I can think of his problem.

Sylvi Wijesinghe.

[The Don]

'The Don',

Normally carburetors keep petrol level for two days or more. If it is evaporating off in no time that shows the carburetor area is too hot that temperature evaporates the petrol. Then he has to operate starter motor for little longer time to fill in the required amount of fuel level to carburetor to start the engine.

As for my knowledge there is no way that float control jet will allow to return petrol back.

Fuel returning on the line back I have not heard or experienced in carburetor engines. I have to examine and give a diagnosis of the problem.

I do not know who gave the idea of fixing a non return valve on the line.

That is the reason I offered him to help on the matter to give my non return valve so that I can examine the problem what he has.

Not to expect a fee as I am no more in that section of Automobile repair.

I know he has posted another thread about carburetor repair on 24tht September requesting help for repair of his carburetor.

Above is what I can think of his problem.

Sylvi Wijesinghe.

Sylvi, rather than jumping the gun for solutions, I think it might be best we help Lancer L with his actual problem. Because what Lancer L is trying to do is treat the symptoms rather than the illness.

Somebody should take his carb apart and observe it's operation and then propose a fix.

[Sylvi]

Sylvi, rather than jumping the gun for solutions, I think it might be best we help Lancer L with his actual problem. Because what Lancer L is trying to do is treat the symptoms rather than the illness.

Somebody should take his carb apart and observe it's operation and then propose a fix.

'The Don',

Yes Don that is the best. I think some member should propose who Owens or owed a similar model car to a good Carburetor mechanic to get his problem sorted out.

Sylvi Wijesinghe.

[LancerL]

'The Don',

Normally carburetors keep petrol level for two days or more. If it is evaporating off in no time that shows the carburetor area is too hot that temperature evaporates the petrol. Then he has to operate starter motor for little longer time to fill in the required amount of fuel level to carburetor to start the engine.

As for my knowledge there is no way that float control jet will allow to return petrol back.

Fuel returning on the line back I have not heard or experienced in carburetor engines. I have to examine and give a diagnosis of the problem.

I do not know who gave the idea of fixing a non return valve on the line.

That is the reason I offered him to help on the matter to give my non return valve so that I can examine the problem what he has.

Not to expect a fee as I am no more in that section of Automobile repair.

I know he has posted another thread about carburetor repair on 24tht September requesting help for repair of his carburetor.

Above is what I can think of his problem.

Sylvi Wijesinghe.

Sylvi, rather than jumping the gun for solutions, I think it might be best we help Lancer L with his actual problem. Because what Lancer L is trying to do is treat the symptoms rather than the illness.

Somebody should take his carb apart and observe it's operation and then propose a fix.

'The Don',

Yes Don that is the best. I think some member should propose who Owens or owed a similar model car to a good Carburetor mechanic to get his problem sorted out.

Sylvi Wijesinghe.

Dear Sylvi/The Don,

Thanks for your valuable inputs.

Sylvi, if the carb is perfect, do you think the amount remain on carb is enough to run engine at lease 4-5 sec till it pumps fuel from tank? What is your observation on this?

Ok, let’s assume that the carb is defected! But still can the fuel pump let fuel to return back to the tank once the engine stops?

Special thank to Mr. Sylvi for offering me a free consultation on his work shop!!! Really appreciate your kind support.

LancerL

[Sylvi]

LancerL,

According to my knowledge yes the carburetor should have a minimum level to start the engine.

This text below may be not to the topic and your Question.

I remember a friend of mine had used a injection syringe small amount of petrol every morning to inlet manifold for a better and quick start on Austin Cambridge car. He too had a small brass nipple on the inlet manifold with a butterfly tapered bolt. I questioned what is this extra fixture on the manifold.

Explanation was that he had to crank the engine about 10 to 15 seconds in the morning and after few hours of not running difficult start.

Then I asked him the person who gave that advice he informed me that was Mr. Senvratna who was the works manager at M/s, Walker sons who was a racing car driver and a very good at tuning double SU carburetors and modifying to SU carburetors of cars which had different make carburetors.

I was a good friend of said engineer later He too advised me to start to change carburetors to SU not to try to repair the other carburetors are complicated with various operating systems and their working was not that simple as SU carburetors.

I followed his advice and did plenty of cars modified to SU carburetors.The the modified cars did not complain any drop of petrol consumption or problems.

Then new SU carburetor was Rupees 800.00. Entire modification I used to charge Rupees 1500.00 with the new carburetor.

Today you can buy at Panchikawatthe Morris minor spare dealers they SAY are rebuild in UK I do not know the truth of that. Price Quoted recently to me was Rupees 8000.00.

I am not rambling but I have to post my experience, opinion, facts on carburetors, on to the question what you have raised and, because you have tried to repair your carburetor with on a norther thread. Therefore I with good intentions posted this extra text on the same post.

Sylvi Wijesinghe.

[Davy]

Right, so your problem is not in the fuel pump, it's in your carburetor. And as The Don said, you're trying to treat the symptoms rather than the actual issue here. My advice would be for you to first get a good mechanic to overhaul your carburetor. There should be something very trivial wrong with your carburetor and a competent mechanic should be able to figure it out.

The workshop manual below will have everything you need to know about your specific type of carburetor (there were 4 types). Print the manual and take it with you to the workshop and carefully identify what's wrong. I have helped diagnose many carburetor issues this way.

4G Series Fuel System - Carburetor - Workshop Manual

If you're thinking of converting the fuel pump to electric because of this issue, you might want to think again.

Hope this helps. Good luck!

[LancerL]

Dear Friends,

After a busy week I was able to attend to my carburetor issue. After several diagnoses I found that there are three lines connecting to carburetor relating to fuel supply.

1. Primary fuel supply from pump.
   
2. Secondary fuel supply from pump.
   
3. Return line from Carb to Tank.
   

Primary fuel supply from pump has connected to top of the Carb and Secondary fuel supply from pump and Return line from Carb to Tank has connected together at right back corner of the Carb. Also there is a float level visibility glass fixed on to the carb body where I can see the float level.

Once I start the engine, float fills with fuel and running engine without any issue, but as soon as I stop it I’ve seen the fuel level goes down slowly.

After playing with fuel lines few minutes and taking off the carburetor top cover I found that there is a hole on bottom of the floating chamber which internally connected to return line from Carb to Tank.

When engine stops, the return line giving a considerable vacuum due to gravity, where it sucks out remaining fuel from floating chamber back to tank and theirs no enough fuel remaining to start on next time. So I have to crank engine few times to fill it with fuel.

I’ve taken off the entire carb from car to inspect and sort out this matter and planning to do little by little on working days nights.

Please share your knowledge on this and help me to identify the problem.

Thanks in advance.

LancerL

[Davy]

I have a quick question: Have you changed your fuel filter by any chance? The default fuel filter comes with a non return valve inside and looks as follows:

[LancerL]

I have a quick question: Have you changed your fuel filter by any chance? The default fuel filter comes with a non return valve inside and looks as follows:

Dear Davy,

Thank you for your reply.

Their was no fuel filter when I brough the car.

Thanks,

LancerL

[The Don]

Dear Davy,

Thank you for your reply.

Their was no fuel filter when I brough the car.

Thanks,

LancerL

Sounds like that's your problem Davy is quite a resource when it comes to Lancers!

All this time I was trying to make sense of this problem as to how the carburetor was supposed to retain some fuel for the next start, if a no return valve was not integrated to the carburetor itself.

Edited October 15, 2012 by The Don

[LancerL]

Sounds like that's your problem Davy is quite a resource when it comes to Lancers!

All this time I was trying to make sense of this problem as to how the carburetor was supposed to retain some fuel for the next start, if a no return valve was not integrated to the carburetor itself.

Dear Don,

Thank you for your reply, as I observed this return line from Carb to Tank is not going through a petrol filter, it is directly connected to the metal line which driven back to tank.

So then how this fuel filter stop returning that in to tank.

Please help.

Thanks

LancerL

[The Don]

Dear Don,

Thank you for your reply, as I observed this return line from Carb to Tank is not going through a petrol filter, it is directly connected to the metal line which driven back to tank.

So then how this fuel filter stop returning that in to tank.

Please help.

Thanks

LancerL

Hmmm..... after looking at the fuel filter again, I see what you mean. The fuel filter has only 2 connectors so the no return valve on that relates to petrol coming into the carb not petrol being returned to the tank.

I am guessing here but perhaps the mechanism is one made out of fluid mechanics. I mean think of how a water seal works. The outlet line (the rubber line) is suspended slightly above the exit from the carburetor and then goes through a bend down to the copper line to the tank.

So if there is no actual device inside the carb which regulates this, it is likely this is how it works. Also your breather valve needs to work very well, else the loss of pressure inside the tank will cause the petrol to be sucked back in through the only method available, the return line, because the no return valve in the fuel filter prevents petrol returning that way.

But as I said this is a guess.

[LancerL]

Dear Members,

Sorry for the late update, hence I was too busy with last couple of weeks.

I found the problem!!!

As I mentioned on my last post I’ve slowly studied the mechanism of the Carb and the internal lines going here and there, you’ll might remember that I’ve mentioned a hole on my previous post which is sucking out fuel from bottom of the floating chamber.

Actually what that hole really does is to supply fuel to “secondary manual” pump based on Carb body to spray out fuel in to intake manifold for quick pickup when sudden paddling the accelerator.

According to the design of this, the secondary fuel line coming from fuel pump and return line going to tank both are inter connecting through the body of this. (I don’t know why the hell this Japanese has put this on such a way)

What happen is due to corrosion or some odd reason, this body of the “secondary manual” pump based on Carb has wear off and the pump is leaking fuel on to the line back to tank. So once the engine stops it sucks out entire thing including fuel on floating chamber.

Initially what I’ve done was to apply some glue and closed that hole on the floating chamber to stop leaking fuel through the pump.

I cleaned everything with kerosene and fixed properly.

I was half away successful, engine started without any issues and I’ve tuned it well.

But due to unavailability of the secondary pump on Carb, I cannot quickly pickup, engine gets stall when I push the pedal fast. Other than that everything is alright. It just starts in one turn after keep stop for even two or more days.

I’m planning to takeoff the Carb again and burnout glue on hole.

Then take off of both secondary fuel line and return line from Car body and apply alternative way of interconnecting both.

Will update the status soon after I’ve done.

Thanks for all the support guidance given by everyone in many ways.

Cheers!!!!

LancerL

[The Don]

Sounds like an excellent piece of detective work there

[Davy]

Happy to hear that you isolated the issue. And most importantly, I'm glad that you didn't go for the electric pump solution as the workaround.

Good luck on this LancerL, I'd love to see some photos of this!