76 Datsun 280z throttle sticking

[76Datsun280z]

Hello, first off I'd like to introduce myself to you all, I'm Austen Wilcox and I'm 17 years old. Three years ago for my 14th birthday, my parents bought me a 1976 Datsun 280z fixer upper you could definitely call it off of Ebay that was about 5 hours away. Ever since, we've been fixing the car up. I couldn't possibly describe everything that we have done to it because it's been pretty extensive and we finally finished it a couple months ago to the point where it's driveable and is all fixed up you could say. There's lots of things that we have encountered along the way with it. For example, the beginning of last summer the engine blew the head gasket, so my dad just decided we pull the entire engine and tranny and have them both rebuilt (the tranny popped out of reverse at the time) because they were in need of it. After taking the engine to a machine shop, we found out that the engine was a l24 engine with the l28 fuel injection system on it!! As I'm sure you guys are aware, the l24 heads weren't designed this way at all. We could never really figure out why it ran so rough, so that day we figured it out. That's just one of the stupid things that the previous owners have done to the car. I can't even begin to describe some of stupid things that they did, my gosh it's unbelieveable. After a few phone calls, we tracked down a l28 engine with nothing on it, we would just swap the fuel injection system and exhaust maniflold on it that we already had. After two weekends, we got the engine in the car. It started up without any adjusments which was kind of surprising to us but ran very rough. After playing with the timming, it runs a whole lot better. Except when it's cold, it runs very very rich and very rough, and that's something that I'm going to ask later on but one thing at a time I guess. Well anyway I won't ramble on and on about as I could write a whole lot more, so I get to the question. A couple weeks ago of driving it, the throttle started getting stuck at around 1800-2000rpm. I'm always noticing this when I come up to a stop light or basically when ever I stop. I just kick it down and I'm on my way, but I'd like to get this taken care of. For some reason when I'm playing with the throttle in the driveway, it won't get stuck! I'ts only when I'm driving it that it gets stuck, I don't know why. I was wondering if you could give me some tips on what to look for and what might need to be replaced. Anyway, sorry for all the rambling, but I'm sure you guys would like some pictures of it, so here she is without paint.

Here it is in the driveway, you can't tell in the picture but it has an air dam on it.

Another thing that is new is the polished/crome valve cover that my dad bought for me off ebay that really spruces up the engine, again my camera on my phone doesn't do it justice.

[76Datsun280z]

These pictures were taken last week on my camera phone so that quality is pretty bad, but that's all I can my photos on for right now.

[Pennyman]

Looking good. I have a '76 as well. Great year for the Z IMO.

[Curtis240Z]

My Z is my first car too. I still have it after purchasing it in '77 and it has slowly transformed into what I like. I bought my daughter her own 240Z which we fixed up and she still owns it too. Good luck with your Z and hope you keep it forever too!

[oldroaddog]

A couple weeks ago of driving it, the throttle started getting stuck at around 1800-2000rpm. I'm always noticing this when I come up to a stop light or basically when ever I stop. I just kick it down and I'm on my way, but I'd like to get this taken care of. For some reason when I'm playing with the throttle in the driveway, it won't get stuck! I'ts only when I'm driving it that it gets stuck, I don't know why. I was wondering if you could give me some tips on what to look for and what might need to be replaced.

I would start at the peddle and work my way towards the engine compartment. Checking lubrication of the linkage, cable, etc. That's going to lead you to the throttle body/air meter which other members can give you more help with.

I love my '75 280Z. Take care of that car and you'll get a lot of enjoyment for many years. Keep it as stock as possible. The value of stock 280's is going up quickly.

[76Datsun280z]

Thanks, guys, I will look today and throttle lingage and see what I come up with. Also, what is that yellowish "bottle" used for? You can see it in the picture that I have of the engine. Mine isn't hooked up to anything and would like to know what it's used for. I can post a better picture of it if you'd like in case you don't know what I'm talking about.

[KDMatt]

Gorgeous looking '76.

Man I wish my dad had priorities like yours! If it'd been up to my father I'd be rollin' a beater Honda like every other college student, haha!

Anyway, the funny thing about the FI-Z's is that there are a lot of big things that can go wrong based on a bunch of tiny little sensors. The first thing I would do, if you haven't done so already, is replace every sensor you can find. Trust me on this one. The electrical on this car is what's probably going to give you the biggest headaches.

Oh, not to mention vacuum leak issues... The fuel-injection is weird about vacuum.

Anyway, there is a 'fast idle' thingamabob on the FI-Z's as far as I know. I wish I could tell you exactly where it is, but a quick look through a Factory Service Manual will find exactly what you need.

If you don't have one, you can download a FSM in .pdf format from http://www.carfiche.com/ ... I also have a copy of this, as well as the Electronic Fuel Injection handbook for the '76.

Welcome to the community, I'm glad to see another youngster like me with a '76... silver nonetheless!

EDIT:

Also, the yellow-bottle (which used to be clear...ish) is a vacuum container as far as I know, and is hooked up to the inside of your car. I think this is what allows you to switch from the vents on your dash to your defrost vents... if this isn't hooked up it could spell fog trouble the next time it rains, .

[76Datsun280z]

Thanks, yeah were going to have it painted silver which was it's original color which my dad thinks will be next summer, maybe sooner, hopefully. When we got it, half the car was primer gray, and the other was the original silver so apparently the owners before us never finished the job. We had a lot of body work done to it too. We had all the rust taken care of which it had a lot of at the time. It still does in one area which the guy missed, so we'll have to get the fixed too.

Also, the yellow-bottle (which used to be clear...ish) is a vacuum container as far as I know, and is hooked up to the inside of your car. I think this is what allows you to switch from the vents on your dash to your defrost vents... if this isn't hooked up it could spell fog trouble the next time it rains, .

Thanks for the help on that one. I've noticed that it gets very foggy in it real quick on those rainy days! The defroster works ok on keeping the windshield defogged but other than that, it all the other windows are all fogged up. Do any of you have any pictures that you could post of these hoses hooked up by chance? Thanks.

[deadflo]

I know when I replaced my stock throttle body on my fuel injected Z, the linkage that connects to the body kept getting "hung up" on the intake manifold. Kind of difficult to describe, but I had to file some of the plastic off one of the ends of the linkage to get it to get past the manifold without sticking. Again I would check the throttle and linkage where it connects to the throttle all the way back to gas pedal. Even check that the pedal isnt getting hung up on the carpet.

[76Datsun280z]

Sorry guys for the long awaited reply/update on this, but I seemed to have fixed the problem by lubricating the throttle lingage every couple of days spraying it with WD40. A couple weeks ago I stopped spraying it and hasn't gottan stuck once so it seemed to fixed the problem.

[racebird1]

If it does it again look at the BCDD on the top of the throttle body this keeps the throttle from droping off when you let off the gas so it doesn't stall and if there is a vaccum problem it will keep it at a high rmp and come down very slowly like it is sticking. Good luck.

[280~Master]

Sounds like you have a great dad. Wish mine had bought me a Z car to fix up. I got an old pick-up instead.

Now on to your issues with your 76. Sensors, Vacuum, corrosion in the wires :devious: , the AFM, your dash pot, BCCD valve, not to keep going but all of these can and will cause problems on your Z someday.

To fix the sticking throttle I would trace it from the pedal to the throttle body cleaning and relubricating every moving part. like stated above. Also check the spring located on the throttle body. If this does not have enough tension to return your throttle valve back to the closed position then you would also get the same problem.

As for your car running rich and rough when cold. I would say it’s a reading problem. What I mean buy that is, the computer is getting an incorrect reading of the temperature so it is feeding to much fuel for the air mixture. This could be caused buy a couple of things. A bad air temp sensor in the AFM, A bad thermo time switch, a bad water temp sensor, your cold start valve could be sticking open, which I doubt; it would run rich all the time then. Or you could be getting a bad connection to one of these items. If your Z is like mine then wires are so old they are corroded all the way back to the computer which gives the wrong resistance/readings to the brain and it causes crazy problems here and there.

Good luck with the Z and keep us posted on your progress.