Still running rich, perhaps I missed something?

[Mycarispurty]

So I've got this 280Z, rebuilt head, really good compression, etc that runs rich. I was going to pull the engine and just v8 it but I figured I'd just try and fix the rich running problem and drive it now and then until I figure it out. Well here's what I did:

 

Today I took the TPS apart. It was still sealed with some goop but I got it open, the contacts inside look and function as if it were new, but I soaked them with contact cleaner anyway. I put it back on, adjusted it to where with the engine at rest, the contact was pressing against the idle contact, then tightened it down. Fired it up, still runs rich.

 

Then I disconnected the coolant temp sensor and fired it up, still pulsing out smoke and really fires it out when I rev it up real high.

 

After that I disconnected the thermotime sensor AND the cold start valve at the same time, still fires up fine but still does the smoking thing.

 

I'm running out of ideas as to what could be causing it. It did have a really high idle when I first got it, but replaced the AFM with one that a guy had that he tested and it was within spec, and it brought the idle down to normal, but still smokes. I was talking to the previous owner just now, and he said while it's running, if you cut off power to the fuel pump (for some reason there's a switch in the cab that you have to turn on to get juice to the pump) it stops smoking immediately and will run for a little while before it dies, naturally you can't rev it when you do that, but it will idle without smoking. I haven't checked yet to see if it has an aftermarket fuel pump that pumps out more fuel with higher pressure or not, but could a bad FPR or maybe just a pump pushing too much fuel cause that? Excess fuel being dumped into the cylinders that is?

[MJLamberson]

Whats your fuel pressure?

[hughdogz]

Check to see if the vacuum line to the fuel pressure regulator is not cracked or leaking.

 

(good call MJ)

[Mycarispurty]

I have yet to check that. The p/o told me he posted on here asking about it and people suggested to check that, but never did. I guess I can just go to the parts store and get any fuel pressure gauge and hook it inline. Is there any specific place I need to hook it? Also, what pressure range am I looking to be in?

[hughdogz]

Is there any specific place I need to hook it? Also, what pressure range am I looking to be in?

 

Try to get gauge mounted inline just before the fuel rail inlet.

 

You're looking for 43 psi with the vacuum line detached (plug the detached hose). Depending upon how much vacuum you're pulling at idle, it will probably be around 36 psi at idle with the vacuum line attached (assuming 7 psi vacuum manifold gage pressure).

[Mycarispurty]

I'll see what I can find at the local parts store. I'm assuming they're all going to be AN fittings, maybe I can figure out how to route one of those in the line. With the money I'm spending and the work I'm doing, it better be a damn fuel pressure problem

[hughdogz]

You should be able to buy a fitting especially made for this. It will eiher be a tee or just a coupler that is tapped for 1/8" NPT (for the FP gauge). 5/16" brass barbed ends and you're good to go!

 

Something like this (maybe it will be hard to find 5/16" barbed ends): http://store.summitracing.com/partdetail.asp?autofilter=1&part=MRG%2D2975&N=700+115&autoview=sku

[Noddle]

I did mine like this

 

 

 

http://noddle.110mb.com/Fuel%20Pressure%20Gauge/index.html

 

Nigel

[Mycarispurty]

Will you still get accurate readings right there Noodle? Since it's like an auxiliary part of the fuel system? I'll probably still tap in right before it goes into the main metal fuel line, but I will check for the adapters like you used, all I've found are 3/8ths and would rather have 5/16ths like I'm supposed to. I'll check out the company you bought yours from. Also, is teflon tape safe for gasoline?

[Noddle]

It's in between the main rail, and the cold start, since the cold start is closed except at cranking (?) I think it should show full pressure,

when I remove the vacuum from the fuel regulator, the gauge shows it.

 

As for the Teflon tap, I never though about the reaction between it and petrol, but I can say, it has never leaked.