So I recently redid all the mechanics on my 1971 240z and everytime I go an start it (which is approx every week) It takes awhile to turn over! Everything is brand new on it!? Its like it take a while for the fuel to get to the carbs after its been sitting for a few days. After of turning for awhile it finnally starts. It runs great when its running! just takes awhile to get it going......Whats the problem i want it to start on the first turn!!!

Please help!

Keith

Its like it take a while for the fuel to get to the carbs after its been sitting for a few days.

Yup, you pegged it. That's exactly what's happening. If you need it to start quicker, you'll need to add an electric fuel pump.

Two questions. Where are you located, and do you have a choke?

*edit*

Good call, Arne, you are quick on the draw, er, type!

I'm no expert on the 240's, so I'll let someone else help out in more detail...

.. but if I recall, there's a choke lever that's supposed to help more gas make it into the combustions chambers when the engine is cold. Are you using this correctly, is it hooked up properly?

When you replaced the mechanicals, did that include the fuel pump? Is that working properly?

'might be good places to start looking...

Good luck

Yes I replace the fuel pump! (Its OEM type pump). Yes I am running the SU carbs and they have the choke cables connected properly. Even with the choke it takes a while for it to turn over! Would an electric fuel pump solve my problems? Will it turn on the first key?

AHHHH

Keith

Also I am located in Redding Ca

If you suspect the fuel, why not check the level in the float bowls prior to cranking the engine?

They should be full from the last time it ran.

If they are empty then the fuel is draining away somewhere.

That would introduce a time delay until the carbs. re-filled.

[An electric pump would still need time to do what the mechanical pump is doing now, you just won't be cranking the engine]

At the same time you could disconnect the fuel pump outlet hose and check that the pump spews out fuel when you crank it.

Needless to say,

TAKE CARE AND NO SMOKING

From what you describe, it does appear to be a fuel issue.

Just totally random thought, but could an issue with incorrect spark plug gaps cause something like this?

they have the choke cables connected properly. Even with the choke it takes a while for it to turn over! Would an electric fuel pump solve my problems? Will it turn on the first key?

AHHHH

Keith

Are you sure the chokes are working properly? Check that with the lever in the car pulled fully back that the nozzles underneath the carbs are pulled down. Some adjustment on the cable ends may be required. Even after a week there should be enough fuel in the carb float chambers to start the car. Fitting an electric pump won't make any difference.

Keith,

It's normal for SU's to need several seconds of cranking on cold starts, especially after sitting several days. If they're in good condition and adjusted correctly it ain't gonna fire on the first turn. You need EFI or a downdraft carb with an accelleration pump for that.

With no accelleration pump there's no way for SU's to prime the manifold before the engine turns over, you have to have to do that by cranking it at full choke. A week between starts is long enough for some of the most volatile ingredients in the gas to evaporate from the float bowls, so makes it take a bit longer to get a flammable mixture to the cylinders.

If it's really hard to start you may not be getting full mixture enrichment in both carbs. With the "choke" lever all the way back the cables should pull the levers on the carbs all the way to a built in stop, which should expose about 9 mm of the nozzle shaft below the adjusting nut.

Air leaks into the manifold also cause hard starting along with problems getting the idle RPM and mixtures balanced. Vacuum advance diaphrams fail suddenly and throttle shafts wear (were the SU's rebuilt?). Just a thought.

An high voltage ignition system & the wider plug gaps it allows will fire a lean mixture more reliable, so make cold starts a bit faster.

Starting technique makes a difference, too. 3-4 seconds of cranking followed by a pause of about 5 seconds to let the gas in the manifold evaporate, seems to work best. Just crank and pause 'til it fires. Very light, quick pats on the gas pedal while it's cranking also seem to help.

All an electric fuel pump can do is top up the float bowl levels before cranking starts. A mechanical pump in good condition will do that in in the first second or two of cranking, so the e-pump buys very little. The new gas goes in on top and the discharge is from the bottom, so fresh gas doesn't reach the engine until after it starts.

Dave's explanation is great, and better than my advice.

FWIW, neither of mine start immediately either, it is the nature of the beast.

Does anybody here have an SU carbed engine that fires on the first turn of the key on a cold engine? Mine takes about five seconds with full choke. I never understood why it would take so long, I knew my float bowls were not going dry, but I accepted it as normal.

Thanks for the explanation Dave, that make sense.

Steve