Houston we have a problem!!!

[bigd652]

OK here is the back story.... I drove the car for a full summer about 4 years ago. Since then the car has sat with about a 1/4 tank of gas. Last summer i started to tinker with it again. The car which is a 76 280Z 2+2 would run when still but when in motion after a few miles or alittle longer would just out of no where start to spit a sputter and die. If I would let the car sit for alittle bit it would start back up again and go another 5-10 miles and do it again. Plugs and cap and rotor have been changed along with the coil. The car sat again until this spring. Now I will get this thing running good again. Last year I did fill up the tank with gas but after it sat again for a year I pumped out as much of the gas as I could. Now I'm thinking the bad running is due to crap in the tank getting sucked up so I would like to drop the tank. Is there a drain plug on the tank and how hard of a job is it to take the tank off? Any other thoughts on why it would sputter out when in motion and not when it idles would be great. Sorry this is so long. Any other questions for me please ask and I will reply. Thanks for your time.

Derick

[GunnerRob]

When's the last time the fuel filter was changed? If it doesn't need changing and the gas tank needs draining/cleaning, you might want to think about cleaning out the fuel lines as well.

[bigd652]

Oh yes its a new filter as well. If i where to change the lines what would I need to use for new lines?

Derick

[GunnerRob]

Oh yes its a new filter as well. If i where to change the lines what would I need to use for new lines?

Derick

From what you've said so far, it sounds like your lines are ok. Have you determined your existing lines need replacing? If so, do you mean the hard lines, the rubber fuel lines, or both? If you need new hard lines, you might want to see what you can find at your local salvage yard, or ask if anyone here has a spare set to sell you. As far as rubber fuel lines go, you want to buy a good quality hose that is designed to use for fuel injection. Fuel injection systems operate at higher pressures than non-injected systems. I believe our 280Z's run at about 60 psi.

[e_racer1999]

could the fuel pickup be clogged?

[sblake01]

.... I drove the car for a full summer about 4 years ago. Since then the car has sat with about a 1/4 tank of gas......

I'm afraid your answer lies somewhere in that statement. When I bought my Z, it had been sitting for 'about four years' according to the PO. The gas tank was so full of crud, that it was a lost cause. I replaced it and the problem (same one that you describe) dissappeared. There are baffles, chambers, nooks and crannys in a fuel injected car's tank. They are virtually impossible to clean out with any kind of chemical, additive, etc. Believe me, I tried! Your tank will either need to be professionally cleaned, or replaced.

[bigd652]

Well then if i need to remove the gas tank thats fine. If somebody out there could please tell me how to get it out as easy as possible. And any tips. Thanks

Derick

[dogma420]

sblake01--

You say that fuel injected car's gas tank has baffles/nooks and crannies...

Quick question--is this gas tank any different from my 72's gas tank? I though 70-78 was very similiar....

I just bought the POR15 gas tank sealer, and enough POR15 to coat the outside of my tank. I had very minor surface rust when I pulled it out to replace the vent hoses and sending unit.

I am going to do a full write up with pictures on how to do the por15 tank treatment. I am having a radiator shop dip the tank right as we speak for 3 days to get all the crud off of it inside and out...I'll let everyone know how it goes.

[dogma420]

Well then if i need to remove the gas tank thats fine. If somebody out there could please tell me how to get it out as easy as possible. And any tips. Thanks

Derek--

Taking the tank out is very easy actually. I just did it 2 weeks ago...

1. Lift up the rear with jack stands...you will need to remove the passenger rear tire so do this as you're lifting the rig

2. Remove the access panel in the rear of the passenger rear wheel well..this gives you great access to the filler hose clamp and getting that hose off is easier. You can also see the wires for the sending unit through this and the inlet/return fuel lines that go to the motor.

3. (this step describes my 72 so it might be different for yours) There's 3 vents...one on the driver's side by the muffler (goes to the filler hose), one near the sending unit in the front passenger side (goes to the motor in the front), and one on top in the rear (went to my expansion tank), on the passenger side next to the wheel well...this is the one that more than likely will have a 180 degree turn in it...some tanks don't have this, but most do...my does.

4. when you're dropping it, make sure all gas is removed...either drain from drain plug or if you don't want to risk the plug being a source of a future leak, use your electric pump, by turning on the ignition and draining at the front of the car (you may have to hook up a make shift 12v lead to it)....

5. remove the 2 bands that hold the tank in place...if its empty of gas, the fuel lines/vent lines are going to hold it in place....carefully take all of them off one by one and it will slowly lower down the more of the hoses you take off, and I left the filler hose attached and removed it last, so when all other hoses were removed, the vent was holding it at a 45 degree angle. Read my caution below regarding do this however.

6. With the tank out, I would recommend what I am doing--replace all vent lines--the 180 degree hose is too expensive (80+ bucks) so I am doing a 180 degree copper piping (like a plumber would do)(thanks to Scanlon and Beandip for this idea)...I am actually getting rid of the expansion tank, but still have a vent to the filler and a vent going to the front to burn gases for the environment...I am replacing both pickup and return rubber lines, and I am replacing the sending unit with a new nissan one from MSA (it was $40 I believe)...my wires were all screwed up to the sending unit, so I am soldering the wires to the sending unit as I don't have the original connectors, and once this is done, I don't want to have to do it again. After soldering them they will get a liberal amount of liquid electrical tape to seal them from moisture.

One more word of caution--my filler hose is in REAL GOOD SHAPE...if it appears to be brittle at all or not in good shape, I wouldn't recommend dropping the tank with this being the thing that holds it in place---but if it isn't in good shape, it must be replaced....getting rid of all fuel problems associated with leaks and smells is something that you should all do at once if you're pulling out the tank. Once the inspection door is off in the wheel well, feel and squeeze your filler hose...you can tell if it is in decent shape or not by doing this and also how the outside of the hose looks...leaks are going to look like stains, etc on the outside.

good luck, and remember, pulling the tank is easier than you might think at first thought. To me it was.

Let us know how it goes!

[TomoHawk]

Fuel injection systems operate at higher pressures than non-injected systems. I believe our 280Z's run at about 60 psi.

You are correct about the elevated fuel pressure, but the spec on the 280Z is 46 PSI. I have a pressure guage on my engine, and it shows about 40 PSI with the engine running mid-range RPMs, and about 30 PSI at idle.

Fuel hoses rated higher than the 46 PSI won't hurt you tho. The size is 7-8mm, NOT 1/4 inch, which is what VB sent me when I ordered their F.I. hose.

[oldroaddog]

This is a timely thread.

On the way to a body shop to have new frame rails welded on I experienced very much the same sputtering which came and went and finally completely stoped the engine. So I'm thinking it's clogged fuel filters and will replace both before trying to drive the '75 280Z home from the body shop. The large canister filter in the engine compartment was easy to find locally but no dice on the small filter by the tank. So I puchased just a generic in-line to get the car back to the house and order the real deal. While working on the console a few weeks back I was able to get the red fuel indicator light working. What does this indicate? Fuel level in the tank or fuel pressure? I noticed when the car was sputtering it looked like this light was pulseing faintly.

[TomoHawk]

The red fuel light is the warning light to get you to fill the tank. Most newer cars haver them. What did you do to hget the warning light to work? It has one leg always +12V and is hooked up to the level sender in the gas tank, which breaks the ground leg for the light when you have some gas in there (how much?)