jimbolo619

Im Stuck.... I recently bought a 78 280z non Cali model. The car turns on perfect. Idles not to good and when i accelerate it the engine stumbles.
I have researched a lot and asked a few mechanics and all told me it was the Air Flow Meter. I changed the airflow meter and it helped out a lil bit but problem remains. Any helP please... I know some stuff but this is frustrating ThanKs

NismoPick

What's the timing set to? Does your car have an O2 sensor?

jimbolo619

I checked the timing and it is off. Don't know how? If I had left it at the 0 spot. I didn't find an O2 sensor so I'm guessing it doesn't have one. Thanks for the help man. I will put it bak in time and see how it runs.

NismoPick

You set the timing to 0? The stock timing should be about 8 degrees.

jimbolo619

Yes well it was the 0 mark. What mark is 8 degrees on/ is It 4?
Thanks.

NismoPick

What the??? 8 = eight = ocho = eight = 8

Eight is eight, not four.

Look on the timing mark... find 0 (zero) and then look below it for the next number. Maybe you need to clean it to see the numbers / marks???

Setting the timing to zero will kill all power... timing is set to spark BTDC (below / before top dead center).

jimbolo619

Gotcha... needa probably clean then I only saw 2 and four haha.
Thanks for the help.

theramz

check your vacuum advance too.

jimbolo619

Already did but there's barely a difference, Thanks .
Still need to change that timing to 8 degrees. Does anyone of you know if there's a timing difference when the z model has AC? I was reading the Haynes repair manual and it mentioned something bout that.

theramz

I bought a timing light from Harbor freight. It has a dial you can set to what ever advance and when you point it at the timing mark it shows "0". Very handy and easier to read. There is a relay that kicks up the idle when the AC comes on. Have you down loaded the FSM from carfiche.com?
Hmm, I just tried it and it won't load. Hopefully it's only temporary.

jimbolo619

Kool!! I will look into that timing light. The fsm? I think I've tried to but the website was under construction kinda. Thanks for the info.

NismoPick

^^^ www.xenons30.com/reference

jimbolo619

Thanks for the link NismoPick I got the manual.

jimbolo619

Okay I adjusted the timing and is still stuttering. Im thinking It might be a fuel pressure problem because when I stick it to 2nd it no longer wants to gas or accelerate. Should I check the fuel injectors?

theramz

You need 35 psi for the injectors to work right. Check the little screen filter inside the pump inlet port. Auto Zone may have a fuel pressure gauge you can rent. When you bring it back they refund all your money.

jimbolo619

I finally had time to check these things and all are good. The pressure was exactly at 35psi. The fuel pump is good no leaks or none of that. However, I read that the fuel pump should only stay on for a couple of seconds, and it does not. Not only that but a relay also starts making a short-circuit noise.
I have a feeling is an electrical problem????Any suggestions?
Appreciate all the help

theramz

The relay is in a very tough place to get to so replace that as a last resort. A relay will bounce if it has a weak coil or a bad ground somewhere. Does it maintain pressure at say 4000 rpm for a minute or so? A bad fuel pressure regulator will allow the pressure to drop at higher rpm too. The fpr restricts the flow back to the tank. Any variation will cause the pressure to drop to where the pump can't keep up. At idle it will cycle on/off.

jimbolo619

Ok Im gonna take your advice TheRamz... And no it does not maintain pressure at 4000rpm it just reaches it for like a second or two and then the car shuts off.
I checked the fuel pressure regulator with vacuum tester and fuel pressure gauge and it was good but it did go back with a lot of pressure through the return fuel line. Is that normal? I also found that my fuel pump and fuel filter were getting clogged up with rust. I cleaned them and replaced the filter and the car no longer had trouble. But after a few minutes It clogged up again and the car went back to its problem...
Think I need to Clean that tank...

Speed

On the early FI Z's, there is a little cone filter in the intake side of the electric fuel pump. It has two little plastic ears, and you can pinch and pull out with a pair of needle nose pliers.

I suggest this because if you have junk in your fuel tank - this is the first place it will be caught before being pulled into the fuel pump.

I have to clean mine about 2 - 3 times a year, as I suspect my gas tank is come apart on the inside.

Speed.

jimbolo619

Thanks for the info Speed. I will check that out. By the way was the best way to clean the tank? I been doing research and I read they add some POR 15 or something like that. Any suggestion is helpful, Thanks.

WanganDevilZ

CHTS? Mine got disconnected and displayed the symptoms you have.

theramz

Don't put that **** in your tank! Take it to a radiator shop and have it boiled out. Last one cost me $100 but it was like brand new. Those cleaner/sealer kits don't get it completely clean and the sealer will come off in time.

jimbolo619

HAHAHA I wasn't planning on it. I was just wondering. I cleaned the tank out today wit some marbles and hot water. Then poured a little kerosene so the inside wouldn't rust overnight. The tank is now CLEAN and Im going to start cleaning every other gas part tomorrow like injectors and fuel rail as well as the gas lines. Any suggestions on how to clean those? Thanks for all the suggestions man.

theramz

There are baffles inside the tank to kep the gas from sloshing all over to one side. I don't think the marbles will reach in all the corners. It depends on how bad it is. I guess you have the tank out so look inside.-Radiator shop.

Speed

Hi!

Regarding tank cleaning - an old hot rod trick - and if your're taking the gas tank completel out of the car! - is to use liquid Tide laundry detergent and water, and slosh it around inside the tank - 2 - 3 sloshings for about 10 - 15 minutes each will clean the inside of the gas tank so well, that you could weld on it without fear of explosions!

The Por -15 is a coating material i think. Best thing to do is when you get the tank clean, shine a light inside the tank. If you have nice shinny metal - I would skip the interior coatings material. However - if you got lots of rusty metal - use an aftermarket tank coating sealer. I think I used the stuff from Eastwood auto restoration on a 63 MGB once.

Oh, if you got rusty scale chunks inside the tank, put in a couple handfuls of marbles and slosh it around with the Tide / Water solution and the marbles will knock the scale off. The marbles roll out easily, and if one gets stuck - no worries - it will never disolve from the gas so it can just stay in there.

Speed