Finally! on the road!

[khughes]

Well guys,

yesterday i finally got the charity rally beast on the road, all bluslip'd and insured

Finally got to give the thing a blast around the streets, the brakes are still a bit dodgy (the front disks are still rusty, i havn't got them machined yet), the car is pinging it's nuts off and the fuel pump seems to be struggling to keep up.. but apart from that it is awesome

My friend spent some time playing around with the tune last night, and it is apperantly so much better (havn't drivin it since), though the fuel pump is really having a hard time keeping up now..

for some reason, the pump doesn't seem to be pumping enough to keep enough fuel in the fuel filter, and the engine dies.. off to search the forums!

Interestingly, i got full comp. insurance with the NRMA for it (it was going to be around $60 more than 3rd party!), believe it or not, they wouldn't insure the car for $2000, they said with the current k's (65,000) they couldn't insure it for less than $2900 (it took me a while to realise what they were actually saying!), makes me feel good about paying $500 for it (mind you after repairs etc. it isn't far off $2k!)

paint still looks crap, but hopefully that will be fixedx up in 3 weeks time!

[Alfadog]

Hi Kent - the fuel pump is the one thing that I've had a lot of problems with with my car. Bastard of a thing, I'd highly recommend converting to electric if you can (I would if I had the money/knowhow).

Insurance for cars older than 30 years is great

Good to hear its well on its way Sounds exciting now!

[khughes]

i was thinking about that too, i have a VL fuel pump i was thinking of hooking up, but i am just not 100% sure if it is that simple? can i just hook it up inline, and provide power? not sure if the pump will flow too much, and perhaps overflow the system (esp. if the return can't flow enough back perhaps?)

it also seems that air bubbles are being sucked up not sure how though as the fuel tank is full (and surely it would be easier for it to suck up fuel than air through possible split hoses?), and i have replaced the 2 hoses at the rear, i guess i may need to replace the front ones too.

[Cuong Nguyen]

You cant use a fuel pump that is designed for EFI on carby engines. I think the ideal fuel pressure for carbies is around 4 psi if IIRC.

Cuong

[khughes]

bugger.. thanks! i would have found out the hard way otherwise!

we pulled the fuel pump apart today and cleaned out a little gunk.. seems to be behaving itself for the moment. Fingers crossed this will last!

[440k]

Kent,

Looks like most has been answered so far, but just make sure there are no blockages on the suction side of the pump (will have a buch bigger impact than a blockage on the delivery side)

Also, a small split in a suction hose WILL suck air in - no doubt about it. Specially if it's close to the pump.

Might be worth re-kitting the pump. A split in the diaphragm will mean she no work, and could allow petrol to mix with the oil.

As Lachlan said, throw an electric pump in there. It's not that hard. Just mount it in the boot. route the first suction hose from the tank to the pump, then put another hose from the pump discharge to the metal fuel line (where the original hose was connected). Make sure you use good quality new hose, and connectors at all times, and the hose is correctly sized for the tails.

Then in the engine bay, you bypass the fuel pump and route the hose directly from the filter to the carby. Simple.

Although, if you're not mechanically inclined, then a car's fuel system is not the place to teach yourself mechanics 101, if you know what I mean. :eek:

[Alfadog]

If you dont convert, you'll carry a spare pump though wont you! Easy to change if you need to. I've done it 3 times now

If you do decide to convert, see if you can check with the rules and regulations first. My mechanic told me its a bit difficult because you need to set it up to run for 3 seconds before ignition or something - like modern cars do. And I know you want the car to be strictly legal!

[440k]

I think that the mechanic was confused with an EFI car. EFI cars are designed to run the pump for 2-3 seconds to build up the fuel pressure, then the pump cuts out till the engine starts cranking. This saves dead-heading the fuel pump.

On a standard carby engine, the fuel pump doesn't pump until you start to crank the engine. An electric pump would be set up to come on with the ignition, so it would always prime the fuel lines for a second or so anyway. I used to turn on the ognition and wait for the pump to build up pressure (you can hear it happen) then start the car.

Besides, if your carby is in good condition (ie no leaks) then the fuel won't drain out, and there's no need to build up any pressure / prime the system.

[Alfadog]

Peter - yes that was the point! He was saying the pump had to be set up to run like an EFI car. Now I'm not saying what he says is gospel, but I'd go by his word as he's done it before with the Datsuns he races

[440k]

I can't for the life of me see why you would have to do that. As I said before, the mechanical pump doesn't start to build up pressure until the engine's actually turning over, and the car runs fine without it, why would an electric pump be any different?

Sorry, but I think in this case the guy's telling you porkie pies - simple as that. (I'm not trying to discredit him - if it's the guy I'm thinking about, then he knows a lot about Datsuns)

If his race car needs to be primed before he can start it, then as I said before, it's a simple matter of turning on the ignition and waiting 2-3 seconds before cranking the engine. I did that for 6 years in my Datto rally car and road car. Note that the car didn't actually need it, as it would always start without the fuel pump running. I just liked to hear it build up fuel pressure before starting (and I could tell by the fuel pump sound whether there was a fuel leak, or suction blockage or some other fuel delivery problem)

[khughes]

Thanks guys,

after a bit of investigation, it seems that one of the hose clamps between the fuel filter and metal line was a bit stretched and not clamping enough.. once i replaced this clamp, there are no noticable bubbles in the filter now.. although i havn't taken the car for a long drive yet.

The VL pump that i would use i think runs at 37psi (100L/Hr).. I assume that this increased flow, would fill the fuel filter, fill the carb, which should then (once full), divert the remaining fuel back to the tank, letting the engine suck from the carb.

so really it would only be the delivery and return path that would be under more pressure? is this a correct assumption?

[g72s20]

If you must use the EFi pump, you'll also need to install an inline fuel pressure regulator to ensure the line pressure does not get high enough to upset your carby (needle and seat, float bowl venting, gaskets....).

I have a (modern) electric pump from the Prince project you can try until you figure out the best option. It's a simple boot mount setup, and is used in conjuction with the mechanical pump.

Jim.