Several problems with my 1972 240z

[jalexquijano]

Recently found a reliable mechanic to tune my Hitachi twin SU Carbs. He managed to set the car to 1,100 RPM at idle due to the fact that i have a FAR 311 Race cam and the RPM needle will never keep steady. However after driving the car the following symptoms came out:

1. Car has power but is not running smooth it tends to choke when shifting from 1st to 2nd gear;

2. After 10 minutes of driving the RPM started lowering from 1,100 RPM to 500 RPM tending to stall;

3. Finally when arriving at the shop the electronic fuel pump fuse was blown and there was no fuel present at the fuel filter.

4. Replaced fuse and the car threw a flame from the exhaust when started.

Now i am all confused. Is the problem the mechanics here in Panama, the Hitachi su carbs that i ordered from EBAY supposedly remanufactured, the electronic fuel pump or what?

I was finally recommended to a mechanic that has a fine shop and has fixed Porsche with 2 carburetors. I will strive for that one even though i have to wait for 2 weeks so he can see my car as his shop is full.

Any advice on how to solve these problems provisionally so i can take at least take the car to the other mechanic.

[240260280z]

Sounds like too much fuel. The needles may not be right or the jets too low.

What is fuel pump pressure?

[Zed Head]

I don't think that you can generalize all mechanics in Panama from the work on one modified old 240Z.

You didn't really define a problem in your post. Does the fuel pump fuse keep blowing? Does the car start now? What is the current state of the car, you've only described something that happened in the past.

Have you looked in the FSM at the basic adjustments for the SU carbs? Pretty sure that there are some simple things you can check.

[Stanley]

Suggest wait for the guy with the "fine shop" if he said he can fix your Z. Sounds like the guy that worked on my dual carb 73 VW in the eighties. He was from Germany, his shop was so clean you could eat off the floor, and he got my Type 3 running perfect the first time.

Even better for a Z if he was from japan.

Edited June 25, 2014 by Stanley

[siteunseen]

My '72s don't have electric fuel pumps, they both do good with twin SUs. Have you tried just the mechanical pump? My Dad always told me too much fuel will wash the oil off your bearings and could cause the motor to seize up. Does your oil smell like fuel?

[jalexquijano]

I don't think that you can generalize all mechanics in Panama from the work on one modified old 240Z.

You didn't really define a problem in your post. Does the fuel pump fuse keep blowing? Does the car start now? What is the current state of the car, you've only described something that happened in the past.

Have you looked in the FSM at the basic adjustments for the SU carbs? Pretty sure that there are some simple things you can check.

Why did the fuse blew?? Having replaced the fuse the car started once again!

[Zed Head]

So the main question is how to keep the fuse from blowing. Fuses blow when they get too hot, usually from too much current but sometimes from corroded connections in their vicinity. Clean up the connections to the fuse and around it to make sure it stays as cool as possible. Look for short circuits on the fuel pump power circuit.

[jalexquijano]

Mechanic solved the problem and now the car is back in commission even though he left the Choke cable slightly misadjusted as the yellow light is turning on. He said the problem was i was using standard NGK BP6ES spark plugs. My car has a Pertronix PerTronix Ignition Kit with new coil and i should use NGK-R spark plugs and not normal ones. The ones it had were all burned black.

Is this correct?

[madkaw]