78 280z Fuel issues!!!

[fattyjay22]

I have quite a fuel problem I can't figure out with my 78 280z Black Pearl. It is hesitating very much throughout accelleration, kind of stumbling!! Also when I hit the gas quick, it is backfiring through the AFM. I have replaced MANY parts from my other 280z which was running PERFECT. (I messed up the top end and that is why I am taking the parts off it) I have replaced and adjusted the following parts, AFM, TPS, Brain, Fuel rail, fuel filter, fuel pump,pressure reg, checked for intake leaks with wd-40 and replaced the air filter and carbon canister. I started to plug off misc emissions stuff that should not affect anything, ie air regulator and EGR. I was told that it possibly could be that my return line is plugged. One thing I have not replaced it the Dropping Resinators, which I thought that if they were bad, It may not even run, but I don't know. I am running out of ideas on what it could be. I have also cleaned up ALL of the conections and have been keeping an eye on my fuel pressure. HELP ME, I am about to run into the end of my knowledge rope!! :mad:

[240ZX]

How about some basic stuff like a TUNE UP!!!! Nobody is going to be able to tell you what is wrong with your Z by what you have described. We have no crystal ball to look into.....you gotta start with the basics and then and only then can you start the process of elimination (troubleshooting). Do you have a repair manual? There is no magic when it comes to engines and their various sub systems. Heck, it could be something simple....like bad fuel???? Hope you take this as constructive critizism. Good luck!

[fattyjay22]

Tune up was the first thing I did when I purchased the car, I.E. cap, rotor, wires, plugs, fuel filter, air filter, drained bad old gas and flushed system. I just am curious if there is something I am missing in the system. I just talked to a guy and he even pointed out it may be the ignition. My shop manual has helped, but I just wanted to get some outside info and see what everyone thinks. As always, all sugestions are VERY constructive! :cheeky: !

[Ed]

As always, all sugestions are VERY constructive! :cheeky: !

Well since you put it that way. I'm no expert on F/I there for I give this suggestion. Take your car to a garage where there is someone who knows his way around your particular engine. Pay him for his knowledge, and watch him while he works. Ask question and learn. BTDT. I took my car to a shop when I was running out of ideas and I learned more in 15 minutes than I would have after years of playing and experimenting. Consider it money well spent.

$.02

[TomoHawk]

Have fun finding a shop where they'll lt you watch. Legal junk has owners keeping the customers out of the service area. But there ARE some mechs. that'll tell you about what they're doing, if your friendly & stay out of the way.

:/

[Daniel]

Hopefully simple will be the fix!! I fought that same demon on my '46 chevy truck and that doesn't get much simplier-straight 6, 1barrel. The valves were way out of adjustment. Once adjusted correctly, it ran like a new motor. I'll keep my fingers crossed for ya'.

[fattyjay22]

Thanks For All Of The Input from everyone. I just talked with Doc @ Docs-auto.com ( Affiliated with ZONC.ORG) He has a few suggestions for me. Check boot between AFM and Trottle. Check Thermo sensor, and check valves. We will have to see, he has never failed me yet with my biggest and most difficult problems. I would take my Z to his shop, but he is in N Cali and I am in NW OR. DANM!!!!

THANKS AGAIN EVERYONE!!

If anyone has anyother ideas, please let me know!!!!! :stupid:

[jlc280Z]

Years ago mine was in the shop for the same problem. the mechanic put a resistor (1K) in series with the water temp sensor (two pins) that feeds the EFI computer, not the one pin water temp sensor that feeds the gauge. He said it was running too lean and this made the mixture richer. After looking in the factory manual it makes perfect sense. This sensor controls the "base pulse" for the injectors.

You might want to check the water temp sensor on the thermostat housing. Follow the procedure in the factory manual ie. put it in a pot of water with a thermometer and measure resistance as the water is heated up.

Hope this helps.

JC

Triangle Z Club

Raleigh, NC

[Znut]

fattyjay22,

I have what seems to be a similar issue and was interested to know if you found a solution to your problem. Below is how I'd describe my problem.

Thank you in advance for any assistance.

Znut

____________________________________________________

My 78 Datsun 280Z has been giving me some problems in that it seems it has a bit of a problem in handling its fuel. I have checked the fuel pump pressure and ran fuel injector cleaner through it a number of times with little to no results.

When preparing to start the car I normally need to leave the key in the on position for several minutes before the car will even attempt to start. Once started it will run fine for a few minutes and then it will start to cut-out. When you try to accellerate sometimes it's fine, other times it attempts to die.

The oddest thing of all is that when I have the key in the on position without the car running I can hear a gurggling in the gas tank - I have no idea what that could be, but I'd bet it has something to do with my problem.

[sblake01]

Znut, your problem sounds like it could be a bad check vavle on the fuel pump. A bad one will not allow the system to hold fuel pressure. I don't know if you can just get a check valve but they do come with the fuel pump.

[Grim]

Check for air leaks in the boot. Check in the pleats on the bottem of the boot. They tend to rot.

[adcvideo]

True that make certain timing is correct for an OEM setup, mine was doing that also until I timed it, before I tuned it up and retimed it ...no bueno ..backfiring.