Engine Problems

[Matthew]

Sorry about the long post but I thought I would try to include info as possible.

Last night I parked my car on a downward hill and in the morning there was petrol leaking from the carbies.
I went to start the car and the engine seized up.
Took the spark plugs out and cranked the engine over until all the petrol shot out the spark plug holes in 3 & 4 cylinders.

My question is why would this happen? I has happened to my car one other time with similar circumstances.

I do have twin side draft delortos with the fuel return line plugged. The fuel vapour and crank breather are connected but just to my air filter and do not think it actually does anything. I also have problems with my fuel tank pressurising.

What do you guys reckon is causing this??

[9EMI]

hello, doubt this reply will solve your problem, but just a few things to consider: what type of fuel pump are you using?, i assume electrical, what may be happening is some form of gravity feed from the fuel tank due to the car being on the down hill slope. why are you not using the return line? in an attempt to get maximum pressure from the fuel pump to the carburettors? if you have the standard in-tank electrical fuel pump, or an aftermarket electrical fuel pump, i would reconnect the return line and monitor any changes. if your car still drives the same when its opperational i doubt it is a faulty float/needle. i realise this doesnt conclude anything, but just some ideas.

[Matthew]

Thanks for your imput,
Yeh I am running the std electric fuel pump. No reason why
I don't have the return line connected. Would I just insert a 'T' connector to the line going to the carbies and connect this to the return line?? If I did do this, wouldn't the fuel just bypass the carbies all together and not fill the fuel bowl??

I don't want this happening again in case I bend some rods.

[Fastgem]

The return line should be a little smaller than the fuel line which keeps pressure up for the fuel to enter the carbies. They only need about 3.5psi max and i think the electric fuel pumps run about 5-7psi so a regulator might be a good idea too if you dont have one. If the fuel pressure is to high then it can push the needle valve off its seat and cause and excessively rich air/fuel mixture and possibly flooding. Does that sound familiar?

[Matthew]

My car does run a bit rich, but my carbies have never been properly jetted to suit my particular motor. I was quoted around $400 which I could not afford. I have just put up with excessive fuel consumption. Plus it is likely that I put a 2L in soon and then I would need to get them jetted again, so I will probably just wait. What does a fuel regulator cost??

[Ben Wight]

Sounds pretty simple. Your fuel tank has presurised, this in combination with parking on a downward hill has caused the fuel pressure to be higher than the maximum the needle and seat on one or both of the dellorotos could handle.

DCOE webers are only supposed to handle about 5psi, so I assume DHLA dellortos to be the same.

With your return line blocked, you might also be running a bit rich with these carbs as the std pump with blocked return line runs almost to 5psi, so this will slightly raise the level of fuel in the bowl. You could conuter this by adjusting the float level, but you could also simple reconnect your return line.

If it runs fine, then you know that you are still getting enough fuel flow to feed the carbs under full load. If not, then I would be performing a few fuel pump mods, including blocking or further restricting the fuel return line.

I would also look into why your fuel tank is presurising. There is a black platic tank in the boot next to the fuel tank. Disconnection both rubber hoses off this and blow through them to make surer they are not blocked. There is also a vent line that must be blocked or kinked. This is attached to the top of the fuel tank. Make sure this is not blocked. I think the tanks use a vented cap as well. But just the cap alone should not make the tank presurise in the sun.

Cheers!
Ben Wight