mk1 - mk1sc fuel pumps

[squeezebox]

anyone know if the fuel pump is the same for a mk1 and mk1sc?

[LimeyMk1]

I don't think they are.

For a cheaper alternative for shelling out for an uber rare SC one you could fit a Mk2 Turbo pump, they're more than up to the job (works for my V6).

Chris

[MartG]

Different pumps. The SC one has a higher flow rate

[LimeyMk1]

Different pumps. The SC one has a higher flow rate

Do you know if the flow rate is much different to the Mk2 Turbo one Martin?

[MartG]

Not sure Chris - I know the AW11 GZE pump flows 116 l/hr ( AE92/101 ones are 125 l/hr ) but I don't know what the NA or Mk2 Tubby flowrates are.

My GZE converted 1a trackcar has a Walbro aftermarket pump in it, which was advertised as a replacement/upgrade for the Tubby, and flows around 200 l/hr

[squeezebox]

thanks guys

[MartG]

And if you want to avoid dropping the tank to swap pumps, an external inline one can be used to boost the output of the NA pump. The NA pump can flow enough fuel for an SC, but NOT at the required pressure - using an inline pump produces the required pressure

[squeezebox]

oh ok, well i guess it'll give me a chance to clean around the fuel tank area anyway. just those damn connections that can be a bit of a pain.

[Lauren]

Or just fit an adjustable fuel pressure regulator and get it setup and you can leave the fuel pump alone.

[PW@Woodsport]

Or just fit an adjustable fuel pressure regulator and get it setup and you can leave the fuel pump alone.

So what happens under high load/RPM when the stock pump cannot meet the fuel demand and the pressure drops?

Very dangerous, going lean under WOT is not something you ever want.

Also 25 year old Mk1 pumps won't be running at their best, most are well past their prime and need replacing anyway, i personally wouldn't risk a regulator on an old pump, without a wideband gauge fitted you have no way of knowing what's happening at high loads.

Keep it safe and do it right.

[Lauren]

Paul, I tested this at length on a rolling road. It didn't go lean under WOT and the stock pump can keep up.

Was no issue in 30K, 30+ trackdays etc.

[PW@Woodsport]

Yes, i know Lauren, but that was on your car, like i said on 25 year old Mk1 pumps you cannot trust them for a second that they are as fit as they were when new, they fail all the time.

There is no way to know what your fuelling is doing at WOT under load without a wideband fitted or on a rolling road.

For me it simply isn't worth the risk gambling on wether the pump is good or not. I accept that if the Mk1 NA pump is as fit as new then a FPR will do the job no problem, but it's that big "if" i have a problem with.

Therefore, change the pump, it's the only safe way.

[Lauren]

Fair enough to an extent, guess mine was 13 years old when I did that conversion originally, then again on another car two years later which was 14 years old. Obviously I had the benefit of a full rolling road setup on numerous occasions.

Are they really prone to failure then? Just not heard of many failing.

[PW@Woodsport]

God yes, Mk1 pumps failing are perhaps one of the biggest causes of them breaking down these days, the pumps are just getting too old now.

[elbon50]

God yes, Mk1 pumps failing are perhaps one of the biggest causes of them breaking down these days, the pumps are just getting too old now.

Oh ohh ! Another job I'll need to get done then

The list is endlesss

Never have time to get into any mischief these days

Peter

[Fab4MR2]

The SC and turbo pumps are the same. I discovered this when ordering a new Denso pump for my SC a while back.

I am currently using a used SC pump in my NA right now with no ill effects. As long as the fpr does its job there should not be much to worry about, I would guess.

[PW@Woodsport]

Like i said, unless you have it rolling roaded or a wideband installed you are never going to know if it is doing its job, and you're right, it would be a guess.

I don't have enough faith in 25 year old fuel pumps and then on top of that upping its workload and asking them to provide more pressure, not when my engine depends on it.

As Lauren says, a fit Mk1 pump and a FPR will do the job though, but i do think just fitting a FPR and setting the pressure at idle and hoping it's maintaining that pressure during WOT under load is a big gamble without proper monitoring.

Not for me sorry