Can anything else look like a fuel surge problem?

I believe I have a fuel surge problem in my 69E historic race car (2.1 litre mfi motor).

The car has a plastic RS style tank and even with 60 litres of fuel on board it has power losses coming out of turn/braking zones. All the gauges stay on, tach drops a bit, loses power, then a second or two later all is well again. Almost feels like a giant flat spot.

I've just pulled out of a 2 day meeting after just one race as I was at risk of being hit from behind. Car is unsafe to race as is.

The solution seems to be a surge tank near the motor, fed from a lift pump near the main tank, and a second fuel pump from the surge tank to the mfi.

Before I do so, has anyone ever had a similar problem that wasn't fuel surge? For example, would a failing or shorting fuel pump act like this?

Crap, sorry to hear you had to cut the meet short.

Is this a 'new' problem? Before setting up a surge tank, I'd positively identify the problem doesn't lay elsewhere such as a fuel pump or pump wiring short, or even something like a crimped fuel hard line (from a rock) etc...

Not new, but getting worse - hence the failing fuel pump comment. Used to happen near 1/4 tank now at 3/4.

Don't really want to add a surge tank (one more thing to fail, weight etc) but need to get this sorted. Very hard to diagnose as it doesn't happen on a dyno and tough to recreate on the street.

ryan,

maybe best to start with the plastic tank.

i just had my 40 year old plastic tank chemically cleaned also removed the microfilters, then had the filters ultrasonically cleaned.

regards

peter kaufmann

Hi Peter,

Who cleaned your tank?

And what microfilters are you referring to?

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Originally Posted by obrut

Hi Peter,

Who cleaned your tank?

And what microfilters are you referring to?

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i will find out who it was sent to and get back to you , but any good radiator repairer can hot wash it. they could not get mine 100% clean,

but pretty close. the filters are on the the inlet and outlet nozzles.the surface area of the filters on mine were 80% blocked with krudd.

i had this tank cleaned about 20 years ago,but no where near as thoroughly as this time.

this the first time the filters were removed and ultrasonically cleaned,this was done in house, so to speak.

they came out clean ,although once again not 100%

regards

peter

thanks peter, very helpful.

i would be grateful if you could let me know who cleaned your tank.

did you look into replacing the filters? or they available?

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Originally Posted by obrut

thanks peter, very helpful.

i would be grateful if you could let me know who cleaned your tank.

did you look into replacing the filters? or they available?

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ok , i will find out for you and let you know.

i am pretty sure you can get the strainer/filters, as i have seen them on e-bay, bit pricey for what they are.

can't remember who vendor was, maybe serria madre...? i would try sunset porsche first for example as they are probably available still.

i would throughly clean and inspect the strainer/filters you have first.......

although after doing all this , i did go out and buy another new plastic tank , and kept this one as a spare and/or for later use on the other

car.

Hi Ryan, that's a good call by Peter.

Aviation industry use poly fuel tanks in a lot of aircraft, maybe someone in the Bankstown area can help?

If you can't find someone down there, mail the filters to me and I'll put them through my ultrasonic cleaner... I also have one or two spares to make sure you get the cleanest ones back.

NEWS FLASH!

"Wakefield may be back on the race calendar for Curnick"

John - Thanks for the offer. I'll let you know.

Alex - Thanks for the support, but lets not jump the gun...

I had a similar problem and it was due to incorrect connections at the fuel console, double check this from a few sources. I believe there is some erroneous diagrams of fuel flow about. Steve

With 3/4 of a tank I can't imagine it is a fuel pickup problem. I agree that there must be a clogged filter although it's hard to understand how cornering would affect this. Could be something is moving and crushing a hose.
I know this is classic racing, but from a safety standpoint running a plastic tank on a racetrack is very, very, very dangerous. You should look into getting a proper fuel cell in the car. I'm sure any organization would gladly grant the exemption.

My MFI race car had a similar problem. I have a fuel pressure gauge attached to the fuel filter console where the cold start valve would be screwed in. I noticed a miss while racing that my fuel pressure was at "0". I had water in my fuel which swells the paper element and shuts off the fuel. It takes a little while for the water to get stirred up to swell the paper. When people say they have a performance problem, we always ask hows your fuel pressure? Gled

Thanks for the feedback guys. Dropped the car at the mechaincs last night and will not be racing it again until this is sorted.

Quote:

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Originally Posted by chiroracer

I had a similar problem and it was due to incorrect connections at the fuel console, double check this from a few sources. I believe there is some erroneous diagrams of fuel flow about. Steve

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Very interesting, did your car otherwise run fine most of the time? I dropped off a copy of the incorrect and correct digrams with the car.

UPDATE: fuel pump checked out ok (pressure and flow), CDI checked out ok, tank was clean, mesh screen in tank fittings were clean, lines were good.

The culprit appears to be the original, and now brittle, wiring to the fuel pump. My mechanic was able to recreate the problem by pulling and wriggling the pump wiring harness.

The fuel pump has been rewired. CDI has been rewired too (while you're in there)

I'm racing next weekend and have my fingers crossed that its sorted once and for all.