260z starting problems

[260z210]

well i bought the car with half the motor in the box, after two weeks of figuring out where everything goes. im having trouble getting it to start. i can get it to start for a second, but it turns off really fast, but if i spray starting fluid in the carb it starts very easily but stays on for just a while longer but still shuts off after a few seconds. i hardly know anything about these carbs except the little bit of info Ive read. i also noticed the clear fuel filter i put inline before the carb doesn't fill completely it leaves a big air bubble but when i disconnect a hose i hear air and the filter fills up a little bit more. any ideas also im running a old draw through carb to turbo setup.. and I'm not to sure if i have any vacuum lines hooked up right.

[Captain_Zeros]

if it'll start easily on ether, then it should have spark and compression, leaving it as a fuel issue. Check the fuel filter in the fuel pump by the gas tank too (assuming it's still in the stock configuration back there), if it's clogged up that'll be an obstruction. I'd also consider seeing if it'll run out of a gas can to temporarily rule out crap in the gas tank/lines/etc if the car has been sitting, and it sounds like it has.

That's a pretty interesting intake setup, I'm a little suspicious of it. The flat top carbs are known for being pretty mediocre, and one is designed to feed half an engine naturally aspirated. I have my doubts that one could adequately feed a whole engine with a turbo effectively.

[260z210]

Well the previous owner said it was sitting for a year. So as soon as I got the car I replaced the inline filter and took out the filter in the electric pump, I also drained the tank and blew out all the fuel lines.. When I crank it the fuel squirts out so in assuming the mechanical pump works. I don't know much about the turbo setup but I've seen one setup online that look really similar and supposedly it was running strong before it was dismattled and the carb was rebuilt.

[SteveJ]

You would probably benefit from installing an inline fuel pressure gauge. Get one with a low range. The lowest I saw at first glance go up to 15 PSI. That's still on the high side for your car. You should expect around 3 PSI or so.

Also use a multimeter to see if the electric fuel pump has voltage after the engine catches and the key is in the ON position.

Does the car still have the mechanical fuel pump on the right front of the head?

[260z210]

You would probably benefit from installing an inline fuel pressure gauge. Get one with a low range. The lowest I saw at first glance go up to 15 PSI. That's still on the high side for your car. You should expect around 3 PSI or so.

Also use a multimeter to see if the electric fuel pump has voltage after the engine catches and the key is in the ON position.

Does the car still have the mechanical fuel pump on the right front of the head?

Yeah I was planing on getting one thanks for the info about the pressures.

When I turn on the car I don't hear the pump, but I read on the Haynes book that it sould only kick on after 3000 rpm or something like that. I did hot wire it so I could fill up the lines when I emptied the tank. Should it be running all the time?

& yes it still has the stock mechanical fuel pump.

[SteveJ]

The electric fuel pump should only be running when the key is in the ON position and the alternator is turning.

[EuroDat]

I have never seen a turbo setup like that on a Z. Interesting that it uses the carby manifold. Its hard to beleive the single flat top can provide enough fuel, but that would be a performanc issue and not the problem your having. The ether test points to fuel problem and you are getting fuel "squirting out". If the pressure is oke around 3psi, then I would be looking at the carby. Might be blocked up inside.

Chas

[260z210]

I have never seen a turbo setup like that on a Z. Interesting that it uses the carby manifold. Its hard to beleive the single flat top can provide enough fuel, but that would be a performanc issue and not the problem your having. The ether test points to fuel problem and you are getting fuel "squirting out". If the pressure is oke around 3psi, then I would be looking at the carby. Might be blocked up inside.

Chas

I'm can't wait to see what this setup can do.. I'm pretty sure I found the problem. I took off the fuel inlet tube and it was clogged up with some junk idk where that came from. Well I cleared out what I can see but I still can't blow through the fuel inlet is this normal? Or should I take it to a shop to see if they can clear the jet? Also is there a fuel outlet? I took off what I thought was the water line but it smelled like fuel, I could be wrong and it just dripped around it anyone know?

[EuroDat]

Sounds like your fuel supply in the carby is blocked up with grud. If you have not worked on SU type carbys before, you might want to find someone who knows them. If your up for a challenge, you can download the FSM and study that for a while and go from there. XenonS30

This is what they call a flat top and known also as emmision carbs. The ealier Z use the round tops. I have never worked on flat tops and they are not popular in the Z world. There will be someone on this forum that plays with them for sure. The Datsun 1200 guys play with them more, but that is a differant model flattop (A14T) so Im told.

You have one advantage using one carby, you wont have the problem of getting the two running equal.

It will be interesting to see this setup run. Goodluck.

[soundmasterg]

I've got a similar problem on my '72 240Z. It sat for almost a year, and I finally got a chance to look at it and found my problem with the noisy valves....a lash pad had fallen out on intake 11. So got that sorted and started it up with the chokes advanced and it ran great for a minute or so....then when I went to get out and adjust the timing it died like the fuel was cut off and wouldn't restart. I verified spark and then disconnected the fuel line from the filter and ran it into a gas can and still didn't work so that ruled out the tank. Then I made sure the fuel pump actually pumps, which it does. Then I pulled the airbox and sprayed starting fluid in it and it runs great for a second until that dies out....so I have a block in the fuel lines or inside the carbs...and if I remember right, there is an internal filter in the round top SU's....so there is probably one also in the carb that you have too.

Greg

[Captain Obvious]

Also is there a fuel outlet? I took off what I thought was the water line but it smelled like fuel

There is no fuel outlet on the stock carb.

There is, however, a small screen fuel filter as the last line of defense against dirt as fuel enters the carb. With your sideways mount, it's on the side of the carb over by the distributor. If you had crud in the line, that filter is probably plugged.

There is also a sight glass window into the float bowl that is used to verify the bowl has the correct amount of fuel in it. Now I don't know if you'll be able to get a view of it mounted that way, but it's worth a try.

What an odd setup you've got there... If you're planning to continue to run that system, my advice would be to read, read, and read some more. The number of people who believe in the flat tops are few, and a turbocharged setup using just one of them???? You better learn to work on it yourself!!!

[Captain_Zeros]

Hmm... have you checked the compression on your cylinders? Do you know why the engine came in half of motor in box form?