Vacuum problems

[Searsgremlin]

I have a 74 260z and at high speeds (70mph) it cuts out or when you give it full throttle. Ive learned that one of the owners prior to me put a 70, 71, or 72 fuel rail on it and eliminated alot of the emissions parts.

i attached a picture and you can kind of see what im talking about.

it would help alot if i knew where the vacuum lines went originally.

http://s1002.photobucket.com/albums/af141/searsscreamer/?action=view&current=IMAG0936.jpg

[grantf]

I am not an expert on the SU carbs (my car has FI) but I do see two fram g3 fuel filters that look like they need replacing.

[siteunseen]

I'm with Grant. $10 for 2 filters to start with.

[Searsgremlin]

i eliminated the filters and changed all the rubber hoses.

Also i noticed that one of my vacuum lines ran from the charcoal canister to the carb and then t's off to the distributor.

so i was thinking that the pickups in my distributor might be ceased so i checked and they still move. my next thought was that there wasn't enough vacuum strength to move them. so i took a plug out of the fuel rail, got a fitting and ran a line directly from the rail to the distributor vacuum, thinking that it would provide enough vacuum to move the distributor pickups better than the charcoal canister did. so to finish it off i plugged the t where i took off the line that previously went to the distributor vacuum so i didn't have any vacuum leaks.

After this i took it out for a test drive. I was able to get it up to 80 but it still cuts out and it seems to do it mostly when it has a load on it, such a full throttle or traveling up hill.

could it be a poorly adjusted carb? it idles fine and accelerates great(until it has a "load" put on it)

or could it be sucking air somewhere?

Any other ideas?

[Captain Obvious]

Your fuel rail looks correct 74 to me. Your carbs and balance tubes, however, came from 70-72. And, yes... most of your emissions parts have been removed.

The vacuum hose that comes from the front carb and T's to the distributor and the charcoal canister is correct. That's what it's supposed to do.

So what hose it that you want more info on? Can you take a pic?

[30 Ounce]

Your fuel rail is the correct one for a 260. It sounds to me like you need to do a thourogh tune up. There is another fuel filter by the gas tank that may need replacing. Cutting out under load could be a lean condition or poor ignition system. by the looks of those filters though I'd start with the filter in back...

[madkaw]

Not sure what your testing for on the vacuum side of the dizzy, but the vacuum side is probably not your issue. More then likely it would be your mechanical advance is not advancing. Put a timing light on there and check to make sure you are advancing past 30 degrees above 2500.

Check you dizzy cap

Rotor

Wires

Coil- will show up under heavy load

[Wade Nelson]

Sounds like an ignition problem to me. Check spark plug gaps.

[Searsgremlin]

Thanks for the comments,

I ruled out the distributor problem, seems that it was idling around 1100 rpm's while in gear around 20 degrees. so i re adjusted the distributor and its running around 600 rpm while in gear around 8 degrees. and its right around 30 degrees at 2500 rpm. after the adjustments to the timing, i took it for another test drive and it still cuts out. now that i know its not a problem with the vacuum on the distributor or the timing, im going to try the fuel filter at the gas tank next.

ill up date when i change the filter.

[Bonzi Lon]

There should also be a small brass filter in each of the fuel bowl lids, remove the banjo bolt on the lid to get to them.

Bonzi Lon

[Searsgremlin]

just changed the fuel filter, the one in it looked like it was from 74. also changed the oil and oil filter while i was at it. Prior to changing the fuel filter my z wouldnt even stay running, so that must have been a lot of the problem. Also thanks for the advice on the small brass filter in the fuel bowl lids. i checked and one of them was in good condition and on the other side there wasnt one. so i assume someone was "repaired" that carb. luckely i have a parts carb that had the filter, so i cleaned and installed it. Also i tightened down on the screws on the fuel bowl lid and the idle went up. I still have yet to take it for a test drive.

but next i plan on buying the tools to adjust the carbs,

Anyone have any other ideas?

Thanks for all of the help

[Searsgremlin]

just noticed that one of my carbs drips gas out of the air horn while the car is running!

Any ideas on whats causing that, i know that it is a carb problem but what exactly?

Anyone ideas out there?