Fuel Pump upgrade

[alec.e]

Hello, I have recently upgraded the turbos in my CL500. Everthing is straightforward, howenver the stock fuel pumps are clearly not up to the job.

I have purchased a CL63 AMG fuel pump, but sadly not a straight swap.

Is it possible to add a regular inline fuel pump after the stock one, or add another running parallel in tank with the stock one?

If so what is the best way to wire the new pump in?

I have tried specialists and no-one seems able to help...

Any pointers greatly appreciated
Thanks!

[GreenV8S]

Running in series is unlikely to give you any benefit. Either replacing the original or running a pair of pumps in parallel seem to be your best options. However, you'd need to find a way to get a free flowing supply to both of them. That might involve modifying the tank. The electrical side of things would be the least of your problems. Is it a dead end supply on that car, or a return loop?

[alec.e]

GreenV8S said:

Running in series is unlikely to give you any benefit. Either replacing the original or running a pair of pumps in parallel seem to be your best options. However, you'd need to find a way to get a free flowing supply to both of them. That might involve modifying the tank. The electrical side of things would be the least of your problems. Is it a dead end supply on that car, or a return loop?

Cheers, it is a dead end system as far as I know

[anonymous-user]

GreenV8S said:

Running in series is unlikely to give you any benefit.

Not true at all. The volumetric flow of a pump depends on it's speed, and it's speed depends on the torque required to drive the pumping element. If you reduce the deltaP, you increase the speed, and hence get a greater flow. You could use a second pump in series, with a pressure regulator set at say 2 bar on the inlet of the existing pump.

Alternatively, there are systems that can "Overvolt" the pump temporarily at high fuel flow conditions, (WOT peak power rpm) but run it at normal voltage most of the time to avoid too much wear.


What you do need to do is to measure the current pumps supply voltage to see if it is in fact being driven "flat out"

[stevieturbo]

alec.e said:

Cheers, it is a dead end system as far as I know

Depending on the nature of that system...could affect options.

Is it dead end with the pump PWM'd and no mechanical regulation, or is it a basic system with a regulator out back near or in the tank ?

I'm sure if you had the pump out, it wouldnt be too difficult to figure upgrade options.

[alec.e]

Here is a photo of my existing pump:






If anybody knows an expert to undertake the upgrade for me, let me know

[Penelope Stopit]

How about a simple modification?

Use the hole where the pump fits as a fuel pick-up (no motor) and fit an external pump

[stevieturbo]

That photo is largely of the bucket...not the actual pump.

It's small enough to be a very basic pump, bound to be plenty of Walbro type options out there that should be relatively easy to fit depending on what flow range you need.

Or as Max suggested, if it is simple control there are voltage boosters out there that will offer a decent gain without having to go near the pump itself.

[GreenV8S]

alec.e said:

If anybody knows an expert to undertake the upgrade for me, let me know

If there isn't a drop-in replacement and you don't want to deal with the engineering yourself, you could look for small independent motorsport race teams in your area. They'll be used to doing this sort of job on their race cars, and may be interested in taking on small easy jobs out of season. The people tuning your new setup for you may even be able to recommend somebody suitable.

[stevieturbo]

Although the AMG pump setup with 4 terminals on the pump...isn't looking it will be an easy option anyway, unless they're just using some sort of separate controller or something.

Just take the pump out, look at it, measure it etc. It'll be easy enough to do something

[E-bmw]

alec.e said:

Hello, I have recently upgraded the turbos in my CL500. Everthing is straightforward, howenver the stock fuel pumps are clearly not up to the job.
Thanks!

On what evidence are you basing that statement?

[alec.e]

Thanks again Chaps...
The stock pump has 4 terminals like the AMG pump, not that clear from the photo

There are a number of explanations why I think the current pump isn't up to the job:
1. Engine is pulling back at certain rpms and under heavy load
2. Other who have swapped turbos on these say the fuel pump isn't good enough
3. Acid from MSL Performance says the fuel pump isn't good enough
4. Look at the dyno graph:

Power drops off from about 5.5k

[PositronicRay]

alec.e said:

Thanks again Chaps...
The stock pump has 4 terminals like the AMG pump, not that clear from the photo

There are a number of explanations why I think the current pump isn't up to the job:
1. Engine is pulling back at certain rpms and under heavy load
2. Other who have swapped turbos on these say the fuel pump isn't good enough
3. Acid from MSL Performance says the fuel pump isn't good enough
4. Look at the dyno graph:

Power drops off from about 5.5k

Which pump do MSL use?

[alec.e]

As this conversion is a first for Acid, he can't offer any advice sadly. He is in the same boat with his Wiestec supercharged C63 Black!

[anonymous-user]

what? Why not actually just look at the one thing that will tell you with 100% certainty that the pump is not capable? Namely, fuel rail pressure? It's reported in real time on the data bus, so just log that, and see if it tails off at high power conditions?

[stevieturbo]

alec.e said:

Thanks again Chaps...
The stock pump has 4 terminals like the AMG pump, not that clear from the photo

There are a number of explanations why I think the current pump isn't up to the job:
1. Engine is pulling back at certain rpms and under heavy load
2. Other who have swapped turbos on these say the fuel pump isn't good enough
3. Acid from MSL Performance says the fuel pump isn't good enough
4. Look at the dyno graph:

Power drops off from about 5.5k

So they haven't done the obvious thing of checking fuel pressure and AFR's ? and injector duty cycle ?

Weird

[Boosted LS1]

Once they check the obvious this could be a good place to read. Lots of in tank and out of tank pumps to consider if it's fuelling issue.

https://www.realstreetperformance.com/blog/fuel-pu...

[alec.e]

Guys, Acid data logged the whole time he had the car on the dyno. As the leading Mercedes tuner in the UK, I am sure he is well qualified to comment, hence telling me I need a better fuel pump. So I have no reason to doubt what he says.

[GreenV8S]

alec.e said:

As the leading Mercedes tuner in the UK, I am sure he is well qualified to comment,

If so, he should be well qualified to recommend a suitable pump or refer you to somebody who can.

[stevieturbo]

alec.e said:

Guys, Acid data logged the whole time he had the car on the dyno. As the leading Mercedes tuner in the UK, I am sure he is well qualified to comment, hence telling me I need a better fuel pump. So I have no reason to doubt what he says.

And as the leading Mercedes tuner in the UK....he cannot supply you a suitable pump ?