Idles, But Sputters & Stalls @ Slight Throttle-up

[broken74]

does the problem exist from when you first start the car up to as long as its running? i was talking to a guy at zfest this past saturday and it looked like he had done some work to prevent vapor lock on his fuel fail and bowl and exteneded his heat shield over the header because his msa header was causing too much heat for his fuel system. he said that if he went to mcdonalds and started to pull away it would sputter and jerk and stuff and act like it wanted to die. i doubt that this is your problem, but just throwing something that might be plausible out there so you dont have to have it towed to your friends shop.

brian -broken74-

[72' 240]

Thanks Brian for the thoughts. To answer the question, it starts like I'm flipping a switch; (right up). Then refuses to throttle-up; even after warm-up. I'm bumfuzzelled.

[72' 240]

Don't give-up "guys", I'm still not rollin....

[Zedrally]

I really don't know if this will help, however, I had a similar problem with my 77.

It would start & idle fine but the moment you applied throttle it cut out.

Like yourself, it baffled everyone that looked at it.

The zed sat in the garage for months idleing away occaisionally when I had time to look at another angle.

In my case it was a broken wire on the condensor, which to all appearances appeared ok, but moved and opened circuited when the vaccum advance plate moved.

I should mention that the distributor is an evil hack from an unknown datsun which a PO replaced the original with. This type has the condensor mounted on the vac. advance plate, inside the distributor, not exterior like most zeds.

As I mentioned it may not be the condensor, however, check around the wiring and see if there is a spot where it's going open circuit.

[72' 240]

Mike,

Thanks for the idea. Yes it helps. Perhaps I have not given enough thought to wiring. There is a mysterious situation regarding the heat sensor wire at the front of the engine. There are apparently 3 resistors in parallel that I am not sure of. I'm not even sure that they should be there. There is some mention of resistance noted, I believe, on the schematic. I obviously am confused about this wire. Let me have your thoughts on it man.

[Zedrally]

Depending in what part of the world you live in, it may be part of the EGR system.

EGR was fitted at different times for different export markets.

ie Here in Oz, 73 240's came with the early model SU's and no EGR.

Couldn't see how it could be part of the problem in this case.

HIH

MOM

[Curtis240Z]

Did you check to see if the carb needle/piston aren't sticking? Remove the carb dipstick and lift the piston with your fingers through the inlet of the carb. It should move freely and drop like a rock without the dipstick in place.

[72' 240]

Hey Curtis,

Not lately; I'll check that out later today. Thanks!

72' 240

[72' 240]

There is an EGR. It seems lose enough, and blocks flow in one direction, but they arn't that expensive to slap on, huh? You know those old hoses are rare.

Did you note Mike's ("zedrally") comments on wiring, and his condenser. I am a bit uncomfortible with the proximity of the condenser screw, and the thermostat ear & screw. I have placed a thick riece of rubber between them before to guard aginst arching, but who knows...

Thanks-

72' 240

[Zedrally]

I've had another read of the thread and see no mention of checking that the vacuum advance is working?

mmmmmmm!

MOM

[cremmenga]

I had a question. On my 72 240z, It idles at like 1200 now which i can live with but when you press on the gas it takes like at least a min. to Idle back down. Normaly it stays at around the 3000's. And it gets kinda shaky when you are driving it around and come to a stop real fast, most of the time it ends up dieing. I just don't know why it takes so long to idle down??? HELP!! Could it be a vaccuum leak, possible in the smog pump hoses? because i know they are letting in air, I had a set of plugs made to plug them but haven't gotten home to try them yet. Do you think this is what it is? THanks guys

[beandip]

I really don't know if this will help, however, I had a similar problem with my 77.

It would start & idle fine but the moment you applied throttle it cut out.

Like yourself, it baffled everyone that looked at it.

The zed sat in the garage for months idleing away occaisionally when I had time to look at another angle.

In my case it was a broken wire on the condensor, which to all appearances appeared ok, but moved and opened circuited when the vaccum advance plate moved.

I should mention that the distributor is an evil hack from an unknown datsun which a PO replaced the original with. This type has the condensor mounted on the vac. advance plate, inside the distributor, not exterior like most zeds.

As I mentioned it may not be the condensor, however, check around the wiring and see if there is a spot where it's going open circuit.

THIS IS EXACTLY WHAT I WAS GOING TO RECOMMEND . CHECK THE LEADS INSIDE THE DIST, SENCE YOU ARE STILL RUNNING POINTS. Could be a broken wire that is flexing inside the plastic shield and when the vacume plate rotates to advance the timing it could be lacking contact or shorting out. Gary