Turbo Engine rebuild 20HC85

[Jeff Turbo]

Plumbing the fuel in the wrong way round will not cure your issue I'm afraid. You could try welding a pipe into the fuel filler pipe as per DR Diesel if it's working correctly in a canister. But I would test under load first. You could route the return pipe into a fuel canister in the boot securely and drive it up the road and see how that goes. Your issue may also keep going back to to the wrong ECU on the car though.

[Juanmacandel]

In the photo you can see two hoses: a thicker one, which is the supply line, and a thinner one, which is the return line. I swapped them, making the smaller one the supply and the larger one the return. It improved slightly, but I still have some overpressure and the carburetor is overflowing. Any ideas? Is it possible that the pump has too much flow

[Doctordiesel77]

Yeah Lee bow did that and blocked off the tank return tube in the tank. Worked too but best to find the issue first?

Very true, a proper repair is always best and if the return pipe is full of slime it could be because the tank is in need of a proper clean out....

[Jeff Turbo]

It wouldn't count as a 'proper' repair, but in the old days when we were converting petrol vehicles to diesel we usually fed the return into the fuel tank breather pipe that goes to the filler neck, all you need is a suitable t piece, cheaper and easier than taking the fuel tank off.

Yeah Lee bow did that and blocked off the tank return tube in the tank. Worked too but best to find the issue first?

[Doctordiesel77]

It wouldn't count as a 'proper' repair, but in the old days when we were converting petrol vehicles to diesel we usually fed the return into the fuel tank breather pipe that goes to the filler neck, all you need is a suitable t piece, cheaper and easier than taking the fuel tank off.

[Jeff Turbo]

Hi Jeff, yes, there are three lines in total coming from the fuel tank. One is the pump’s supply line, another is the return line, and the last one is for the tank vapors going to the canister — that one can’t be used because it has a check valve.


Yes, the car runs fine with the regulator’s return line connected to an empty container.

It maybe that the return in the tank is blocked, swirl pot is rusty or has some sort of restriction. The size of the return shouldn't make much of a difference unless it's tiny as the return isn't a large tube anyway, only about 1/4 inch and is smaller than the other pipes. Have you tried to blow into the return to clear it, with a near empty tank for safety?
Using a better fuel pump has created more pressure so will now highlight any restriction, if you can't clear it you may have to drain it and have a look in it with a camera to find out what's going on. This is getting quite common these days on old petrol tanks getting rust inside them

[Juanmacandel]

Hi Jeff, yes, there are three lines in total coming from the fuel tank. One is the pump’s supply line, another is the return line, and the last one is for the tank vapors going to the canister — that one can’t be used because it has a check valve.


Yes, the car runs fine with the regulator’s return line connected to an empty container.

[Jeff Turbo]

With the cat fuel return into the petrol tank. How many pipes are on the return on the petrol tank as sometimes there are more than one? its being restricted at the moment which is causing the carb to over fuel. If you put the return pipe into an empty canister does the car run better and stop over fueling ?

[Juanmacandel]

I’ve found the problem. It seems to be the return line — it has too much restriction for the flow that the new pump delivers. I figured it out thanks to a post you sent me a few weeks ago. I’m using an EFI CAT fuel tank. I’ve noticed that the hose and the tube on the tank where the fuel returns are thinner than the fuel outlet. I’ve tried bypassing the pressure regulator and the pressure is still the same.

When I disconnected the return from the regulator, the pressure dropped and the car started running well. Can I swap the pump’s suction to the return port and send the return fuel back through the port where the pump originally draws fuel from?

[Juanmacandel]

The other day I swapped the carburetor fuel pump for an injection pump, and the gasoline started overflowing from the carb completely. I took the carburetor apart and adjusted the float to close a bit more, then tested it again without the bowl, closing the float by hand. The problem is still there. Fuel pressure is not higher than 7 psi. The float is set tighter than what the manual specifies. Should I close it even more? Do you know why this is happening?

https://youtube.com/shorts/dZK91k2xg...0cSOAA-CZU6aEU

[Jeff Turbo]

Thanks for your reply. Right now the car is complete. I’ve bought a programmable ECU and soon I’ll start tuning it to get the most out of the carburetor.
Later on, my intention is to install the EFI manifold along with all the sensors and turn it into a turbo fuel-injection setup, which is why I was asking.
Most likely I’ll have to make a custom exhaust manifold. I’ve done things like downpipes and full exhaust systems before, but this is a bit more complicated, haha.
We’ll see how it goes — until then I’ll stick with the carburetor and the programmable ECU.

Ah right, good luck with it

[Juanmacandel]

Thanks for your reply. Right now the car is complete. I’ve bought a programmable ECU and soon I’ll start tuning it to get the most out of the carburetor.
Later on, my intention is to install the EFI manifold along with all the sensors and turn it into a turbo fuel-injection setup, which is why I was asking.
Most likely I’ll have to make a custom exhaust manifold. I’ve done things like downpipes and full exhaust systems before, but this is a bit more complicated, haha.
We’ll see how it goes — until then I’ll stick with the carburetor and the programmable ECU.

[Jeff Turbo]

Hi Jeff, you’re absolutely right. I was a bit impatient to finally take the engine out for its first drive. I think I’m going to take the opportunity and go straight to a programmable ECU. The tuner would charge me a fortune and no one can guarantee that the MAP sensor only reads atmospheric pressure, which would mean I couldn’t adjust the ignition properly. Also, since my plan is to adapt the injection system from my EFI engine, that’s work I already have halfway done, haha.

Do you know if the intake manifold from an EFI fits directly, or does it hit the exhaust manifold? The fuel pump issue is already sorted, but I’m not risking going over 4000 rpm so I don’t damage the engine.

Why do you ask about the manifold as i thought you had one on the car?
Efi manifold is different and won't fit if you have a turbo on it as it's a completely different shape unless you're going down the efi/turbo route as i know a couple of guys have in the past. I wouldn't know how they achieved that though. You would have to move the turbo possibly to the front of the engine
It's an old mate of mine https://maestro.org.uk/forums/forum/...he-mad-maestro

[Juanmacandel]

Hi Jeff, you’re absolutely right. I was a bit impatient to finally take the engine out for its first drive. I think I’m going to take the opportunity and go straight to a programmable ECU. The tuner would charge me a fortune and no one can guarantee that the MAP sensor only reads atmospheric pressure, which would mean I couldn’t adjust the ignition properly. Also, since my plan is to adapt the injection system from my EFI engine, that’s work I already have halfway done, haha.

Do you know if the intake manifold from an EFI fits directly, or does it hit the exhaust manifold? The fuel pump issue is already sorted, but I’m not risking going over 4000 rpm so I don’t damage the engine.

[Juanmacandel]

Hi Jeff, you’re absolutely right. I was a bit impatient to finally take the engine out for its first drive. I think I’m going to take the opportunity and go straight to a programmable ECU. The tuner would charge me a fortune and no one can guarantee that the MAP sensor only reads atmospheric pressure, which would mean I couldn’t adjust the ignition properly. Also, since my plan is to adapt the injection system from my EFI engine, that’s work I already have halfway done, haha.

Do you know if the intake manifold from an EFI fits directly, or does it hit the exhaust manifold? The fuel pump issue is already sorted, but I’m not risking going over 4000 rpm so I don’t damage the engine.