Perfect idle, bogs on accel forward, but not reverse...

[Dramier]

Long story short, owned a few Z31's, this is my first 280Z.   

 

Car is a '76 280Z L28E 4 speed, all original FI doesn't appear to have been modified at all other than emissions deletions and a muffler.

 

Currently the car idles a little rich, but perfectly revs and holds idle.    In 1st gear it bogs out under throttle, so much so that it is undriveable.  Strangely, it runs nearly perfectly in reverse with none of the same bog.  It is definitely flooding and running stupid rich.   Plugs are fouled black, lots of black smoke from the exhaust.   Is it safe to purge the return lines to the tank on these cars with shop air?   From what I've read, the tanks are prone to rust and debris, so I was thinking the return lines may be plugged causing over pressure.  

 

I've replaced the plugs obviously, replaced the fuel filter, checked each of the fuel injectors by using a stethoscope while the car was idling and listening to each one individually.  All clicking away just fine.   I replaced the FPR as well.   Still no dice, can't accelerate.   Inspected the cap and rotor, looked fine no carbon tracks, no damage, no unusual wear that I could find.   Unplugged the cold start injector as well just to make sure it wasn't somehow being kept on through a fault wiring or other reason.  Didn't check timing yet since the distributor is secure and doesn't look like it's been moved in probably the last fifteen years at least.  

 

I have a new water temperature sensor on hand, but how on earth do you get to the sensor to replace it?   My 3/4" socket won't fit over the sensor end of it, and I can't get a wrench in there, so I'm asking if there's a trick to it or it involves removing a whole bunch of crap to get it out.   From the glance I had over the car this afternoon before I left work, it seems almost like you have to pull the whole distributor out...    Does the thermostat housing unbolt?   

 

I have a fuel pressure gauge and tap coming in the morning and will take that with me to the shop tomorrow and test fuel pressure.   I just went through the FSM and the bible and read 26 pages of hybridz threads, as well as did my mandatory searching and I'm going to try and get some hard numbers on what the fuel pressure is doing and how the sensors look tomorrow.   My questions are the following...

 

Will the water temperature sensor being out of whack be able to pig rich the car so hard it won't even accelerate?    If so, according to what I've read then I should be able to disconnect it and run the car in limp mode and get acceleration, correct?    

 

Apparently these Z's also have a flap in the AFM which I was unaware of, and after finding that out I strongly suspect a binding flap would be making the car way too rich.   If I understood everything correctly, then at idle in neutral it could rev and idle just fine even with a sticking flap, but under load would definitely fall on its face.   I didn't see any threads mentioning people with a binding flap, so I was led to believe maybe that doesn't happen very often.   Is that a common problem or a possibility? 

 

If anybody has any suggestions or additional checks I can do that I might have missed, please let me know so I can do that tomorrow.   I just really feel like there's something I'm missing on this car and didn't find through searching because I don't know these cars yet.   

 

I have my Z currently parked at work since all my tools are there, and I get to work on it about once or twice a week when I'm not completely exhausted after work.   So I've been doing a lot of homework learning about the car, taking notes, etc and then going to work and spending an hour or two with it here and there.   I'm just a little stumped at the moment considering it idles fine and accelerates in reverse.   

[Dramier]

Turned out to be a combination. 

 

Water temperature sensor was way way way out of spec.   Corrosion on the wires as usual.     That's was one part.

 

Second part was return line was clogged.    Got that blown out.

 

Last part was fouled plugs from all the rich running.   Occurred to me last minute that they might need a good cleaning, so pulled all six and cleaned them and she broke the tires loose first time.    

 

The mechanical throttle linkage also stuck and she bounced off the 8k rev about fifty times in the eight seconds it took me to get my hand unstuck from the keychain and finally get the key off.   Cleaned and lubricated the linkage and got that fixed.   

 

So if anybody else searches and finds this, they will know what fixed it.  

[NewZed]

Congratulations on fixing it with no replies.  I almost opened the thread but the title was so weird it looked like a potential quagmire.