2.0 8v Race Motor fuel issues. Advice Needed

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Mk12doorlover
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2.0 8v Race Motor fuel issues. Advice Needed

Post by Mk12doorlover »

Hi All

I'm running a 2.0 8v, race ported head, 298 cam, ITB's with 12.5 compression ratio on 102 Octane race fuel.
I'm having some inconsistent fuel surging issues only while driving. On the dyno the car runs well, seemingly without any issues and makes expected power.

After a lot of time trying to solve this issue, I have come to the conclusion that the problem is between the tank and the fuel pump, with the pump not getting enough fuel. I still have the citi.com FI fuel tank with external 4bar cti pump. So I just want to hear from the guys with a similar motor setup if this can still work or if it is necessary for a fuel cell with a surge tank?
What is your fuel setups??

Thanks in advance
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by alfaquad »

Is it getting surge when going through corners or what? In general, if the fuel level is low in a stock tank, you will get slosh and surge in corners. Easiest way to deal with this is to install a surge tank along with the standard tank. Wire in a low-pressure Facet pump from the tank to the surge tank and then pipe the surge tank to the high-pressure pump to the motor. Fuel return line goes back to the surge tank as well.

The standard tank's pickup sits on the front right side of the tank, so right-hand corners with low fuel are more prone to surge.

My race car doesn't have a surge tank in yet, so I always have to run with a lot of fuel in the car to prevent surge. Basically running the same setup as you - 2.0 8v with 298 in a race head with 45mm ITBs and over 13:1 compression. I'll be putting a surge tank in before my next race in July.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by Mk12doorlover »

Thanks Alfaquad
The surge is really very irregular. the car is undriveable when tank is below quarter, even on a straight line.
Seemed to be gone when tank is half, but the other day it even started surging when the tank was half as well.
I would have to take the tank out and check what's going on there and hopefully get the issue resolved.

Is your surge completely resolved when you keep the tank full with the stock tank and only the external fuel pump?
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by PaKiMoNSTeR »

We busy installing a surge tank setup on the Jetta. But our problem is not so much surge, rather that the stock pump is running out of oompf higher up in the rev range. So we will run a caravelle pump from the tank to the motor. Could this not also be your problem? Also check the fuel rail. We had a leak in ours which we didn't pick up for months until it broke completely.

There is a smaller pipe in the fuel rail that leaks into the larger one or visa versa. Can't remember the feed direction. This will cause all your pressure to go back to the tank.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by Mk12doorlover »

Thanks for the advise guys. The return on the fuel rail are blocked off and replaced with a broken FPR.
The fuel filter and 4Bar FPR is one unit (Polo fuel filter), so this cancels out a leaking or cracked fuel rail.
I decided to redesign the fuel system, will run a 20L Fuel cell to a surge tank with a Bosch 044 pump inside the surge tank.
Only reason for running the fuel cell are due to space issues trying to fit the surge tank...

I would like to run a Fuel Pressure gauge to monitor the Fuel Pressure at all times. Any advise on doing this and where to shop? this gauge needs to be 100% accurate.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by panic-mechanic »

you have an entire empty spare wheel well and i is a race car stripped out - how can you have a space issue to fit a surge tank?.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by Mk12doorlover »

Hi Panic
Forgive my ignorance, it is still a street car with a full interior. It would probably solve the issue if I just install a surge tank, but I would rather prefer having the fuel system outside the car, thus having the issue of where to fit a surge tank with the stock fuel tank...
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by panic-mechanic »

AH I assumed race car. There is still enough space to fit a surge tank. Talk of fuel cells etc I simply assumed race car becuase basically nobody runs small fuel cells on road cars. There is space on the left under the area where the fuel pump sits on the right.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by alfaquad »

You can also run a surge tank in the tray on top of the firewall in the engine bay. Super Stu used to run his there in his Challenge Golf.

I don't get any surge in the race car with more than around 20 liters in the stock tank and don't think my pump is a higher pressure one than standard either. I never have issues with it.

It could be that your piping to your tank is wrong. Main feed pipe to the pump and the engine has to be the lowest one on the tank; return and breather sit higher.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by AlexTDi »

Mk12doorlover wrote: I would like to run a Fuel Pressure gauge to monitor the Fuel Pressure at all times. Any advise on doing this and where to shop? this gauge needs to be 100% accurate.
Speak to Miggz from FSU Development, he is shipping in some Glowshift digital fuel gauges, I have one in my race car and it's 100% accurate, sensor sits on the fuel line with a t piece so it's simple to install.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by Mk12doorlover »

Thanks everyone.
@Panic. yes sorry for that one luckily it is only short distances on the street. I noticed the space on the left hand side. how would one go about doing this then, running two pumps one to fill the surge tank and second one to feed to the engine? sound like something I would investigate. would be awesome if I had an in tank pump to work with and not just the external pump.

@alfaqaud I think this can work nicely again if there is an internal pump. if the fuel pump does not receive enough fuel now it sound like systems which potentially will have the same issues of current fuel pump not receiving enough fuel and therefore not able to pump anything...

Also after removing the tank I saw everything inside there are plastic and way above my knowdledge to know if there is maybe perhaps issue with the pickups/baffles etc. are there places were one can get tanks tested to have all checked out and make sure it is all sound.
Was also thinking running this Race Fuels/ Eth, meth, avgas etc. the standard tank were not designed for this use, whats the changes that this could maybe cause issue to the tank itself, with all the plastic bits inside?

@Alex thanks will have a look at them.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by panic-mechanic »

The are no pickups in plastic etc. nlet's take a step back. Exactly which body and tank are we talking about here. Are you not running an efi setup on a carb tank?
But anyway yes you use a diapraghm(facet) pump the feed the surge tank and out of the surge tank it feeds your efi pump.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by Mk12doorlover »

1997 citi golf. when converted from carb to FI, a MP9 fuel tank from a newer citi golf were installed, definitely efi tank.
Will have a look at that options of running the surge tank with Facet pump on relay, it will be a cheaper way to do it.
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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by BlueBlob »

Plenty space in a mk1 to mount a surge tank. In my opinion, always better to try and get it as close to the engine as possible.

In my drag car, my fuel cell had a surge tank built in, in the back of the car, but I still had surge issues from time to time.

This is where my current one is mounted (in the rain tray). Makes the piping much simpler/cheaper.

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Re: 2.0 8v Race Motor fuel issues. Advice Needed

Post by Mk12doorlover »

Just an update if someone is interested. The issue has been resolved.
I am now still running the stock FI tank with the 4bar CTI fuel pump direct from the tank.

Firstly I replaced the 6mm carb hard fuel lines to new 8mm fuel lines (the old return line had a small bent in it as well).
Then the return were for some reason routing via the fuel level gauge on the top of the tank (like the carb setup). It now returns into the "swirl pod" like factory setup from the side of the tank. Since these changes I have been racing with the car, as well as driving to and back from the strip, 50km's +, and driven around the neighbourhood, with the tank below half, and not one single fuel surge or stuttering so far. Fuel pump is also running quiet and fuel pressure stays constant at 4 bar.
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