72 240Z hard to start and run

[miker]

Having trouble starting my 1972 240z, just got it about 6 months ago and it had set for 8 years. Everything is original motor, transmission, differential, etc. Engine runs a little rough once it is warmed up. Drained the gas and refilled tank and included new fuel filter. New plugs, plug wires and air filter. The SU carburators round top could use some cleaning I guess, but not too experienced to do this myself. I have to turn the key to get the fuel pump working before I try to start it. Then I have to pump the gas until it finally turns over. Seems like the carburators are starving for fuel. Strong gas order like it is running to rich. I have to leave the choke fully open longer than necessary I think, before the engine will run without coughing so much. Any help is appreciated.

[dimitri_zee]

Is the choke cable hooked up and working fine? I'd recommend a good going over of the ignition/fuel system. Have you installed an electronic distributor? Theres several things to check..

[miker]

Thanks, tomorrow I will look at choke cabling. Do you recommend spraying carb cleaner into the carburator somehow to possibly clear out some crud.

[manny1973]

Miker, 72 does not have an electric fuel pump. Just turning the key on won't help. It's a mech. pump only pumps fuel when the engine cranks.

[miker]

Thanks Manny, but when I turn the key just before start, I hear a sound like something is working by the gas tank, I thought it might be the fuel pump. Could the previous owner have changed to an electric fuel pump. I will know more tomorrow. Also, I didn't want to add any additives to the fuel tank, afraid that it would break alot of crud loose and really cause problems with the carburators. The car runs and I was hoping that after a 100 miles it would run better, well it does run better but not by much.

[miker]

The choke cabling looks to be fine, but I did find a electric fuel pump. I noticed on the fuel filter air bubbles when the engine is running. I am going to buy a new electric fuel pump since this one is making noise. Question, should I go back to the mech. pump? This electric pump is set up from the gas tank thru the filter and thru the mech. pump.

What do you guys think, should I by-pass the mech pump with the electric fuel pump or should I replace with mech. pump? Also, should there be air bubbles in the fuel filter?

[d240zx2]

No, there shouldn't be air bubbles. There can be air in the filter, though. Bubbles are generally caused by cavitation in the pump. I agree with your replacement of the pump if you find it low on pressure, volume delivery or if it draws excessive amperage.

I have a Stewart Warner clicker pump I installed over 35 years ago, and it's still pumpin' gas.

[miker]

Thanks Frank, I am going with a new electric fuel pump, Stewart Warner if I can get one. Thanks for the input everyone, I will let you know the results.

[beandip]

Before you change the electric pump. If the PO installed the electric correctly there should be a in line fuel filter between the tank and the electric pump. Replace that filter and the one mounted on the inner fender up by the front of the engine bay. If this does not cure your problem then a pump could be in order. Make vary sure there are no small cracks in the rubber hoses. And the clamps are tight and not allowing any air to enter the line or gas to leak. Running both fuel pumps is no problem if the mechanical is not leaking. I have been running RX-7 fuel pump for 8 years and they are great. $15.00 at the u-pull-it . you just need to be sure it is NOT a fuel injected pump. I use only the electric.

Gary

[beandip]

Miker you do realize that these engines are cold blooded and need to have a rich mixture to run until at normal temp or close to it. Also SUs do not have accelerator pumps so pumping on the gas peddle does nothing . If fact it may cause the engine to be harder to start.

Gary

[miker]

I bought the electric and mechanical fuel pumps and will install in the next few days. Will let you guys know what happen. How do I include a picture of my ZmikeR in this post?

[Redraider]

I am having the same problem gentlemen. I have a 1971 Datsun 240Z with what appears to be a 73' or 74' SU Carb system. The previous owner rigged an electric fuel pump and I can hear the pump working when the ignition key is turned. I pull the hose off of the carburetor and I could feel a bit of pressure but I doesn't seem to be pumping enough to keep the car running. I am going to purchase another electric pump tomorrow and see if that does the trick! I also am going to try replacing the carroded wires and cracked hoses that make up the fuel delivery system. I bought the car at 12:30 PM and after hauling it on the back of a trailer for about 120 miles. The car would not stay running. I concluded the starter works, the air filter is not clogged nor the air lines, and the battery is good. I the last thing I noticed are the fuel lines are bone dry. Is there a way to put fuel in the lines other than the pump to make sure that it is the fuel pump that is broken? Or am I better of spending the money on an electric pump?

<IMG SRC="cid:http://hphotos-snc3.fbcdn.net/hs172.snc3/19943_784327439528_16705162_43917983_5019186_n.jpg" >