Starts right up, then falls on its face.

[SteveJ]

He does not have a hot startup problem.

Pretty much what happens is I will turn the key and it will start right up then if i don't give it gas it will just die after maybe a second. I can keep it running but i have to hit the gas pedal a few times then it will be fine running on it's own. It's like I have to "prime" it while it's running to keep it running. The car is a 1978 280Z all stock it's my daily driver and something I've come used to but when you go to start your car and the ladies are around and it dies it doesn't look to cool anymore. :disappoin It does not happen however after its been ran for awhile it seems to only do it after sitting for maybe an hour or more. Any info is appreciated guys, thanks in advance.

Nathan

That is why I suggested he follow up on what others suggested about the AAR. Unfortunately, Nathan hasn't indicated whether or not he as tried the diagnostics in the FSM.

[z_ya]

SteveJ sorry, it's been kinda busy lately with my day off tomorrow I will run through the FSM again and check. And the problem is not just a hot start problem. I live in the midwest and the temperatures can be pretty stupid in both directions. I know that my AFM is a problem as during the hot summer when i bought the car it ran rich EXTREMELY rich. And now with the cold whether it happens to be spot on. But the car ever since I've owned it has always had this starting issue regardless of temperature outside. I'll buy me a fuel pressure gauge cause it does seem after the first try that things are a bit better. I might go ahead and spend the money for a AFM as well.

[SteveJ]

Diagnose first. Then figure out the parts to buy. It's a lot cheaper that way.

[Zed Head]

Whoever suggested the AFM as the problem might have been thinking of 75-77, which have the fuel pump contact switch. Your 78 should be useing the oil pressure and alternator current to activate the fuel pump circuit. But the fact that your fuel pump has been rewired to be on with the key at On takes the fuel pump safety circuit out of the picture anyway.

Here's one possibility - whoever rewired your fuel pump to come on when the key is at ON, bypassing the safety circuit, might have it wired so that it actually turns off when the key is at Start. Turn key to On, pump turns on, pump turns off when key is turned to Start, engine fires then dies because fuel pressure dropped, fuel pump comes on again when key is released, second try works. Just a wild arse guess and still doesn't really fit what's happening well.

Your symptoms are weird so even the troubleshooting chart will be difficult to use. The first thing you might do is determine if it's spark related or fuel or electrical (loss of power to the EFI system). Get one of those flashing spark testers for a plug wire and watch what happens on the first start, if spark disappears before the engine dies that will tell you something. Or measure fuel pressure while starting. Or use a Noid light (I still don't really know what noid means) or christmas tree light and see if the injectors stop firing before it dies.

Don't buy a new AFM or CSV. The symptoms don't fit.

Edited January 11, 2013 by Zed Head

[Captain Obvious]

Here's one possibility - whoever rewired your fuel pump to come on when the key is at ON, bypassing the safety circuit, might have it wired so that it actually turns off when the key is at Start. Turn key to On, pump turns on, pump turns off when key is turned to Start, engine fires then dies because fuel pressure dropped, fuel pump comes on again when key is released, second try works.

Zed, That's a well thought out interesting idea. I don't know if that's what's going on in this case, but it's a neat thought.

Move the key to ON - Fuel pump runs and builds up pressure in the rail.

Move the key to START - Fuel pump stops - Cold start valve dumps fuel quickly into the intake until the fuel rail pressure is gone.

Quick blast of fuel from the CSV is enough to get the car to start, but with no pressure in the rail, there's nothing to feed the injectors when the key is moved back to ON - Engine stalls.

Maybe on the second start attempt there's just enough pressure in the system to get over the hump? Maybe on the second start attempt, the thermotime switch has opened and the CSV isn't activated which saves fuel for the injectors instead?

Interesting... :bulb:

[SteveJ]

Zed, That's a well thought out interesting idea. I don't know if that's what's going on in this case, but it's a neat thought.

Move the key to ON - Fuel pump runs and builds up pressure in the rail.

Move the key to START - Fuel pump stops - Cold start valve dumps fuel quickly into the intake until the fuel rail pressure is gone.

Quick blast of fuel from the CSV is enough to get the car to start, but with no pressure in the rail, there's nothing to feed the injectors when the key is moved back to ON - Engine stalls.

Maybe on the second start attempt there's just enough pressure in the system to get over the hump? Maybe on the second start attempt, the thermotime switch has opened and the CSV isn't activated which saves fuel for the injectors instead?

Interesting... :bulb:

I think you may be on to something. God, I hate the "improvements" made by idiot previous owners.

[Captain Obvious]

I think you may be on to something.

Haha! Well I'm not ready to claim any progress towards determining what's really going on with z_ya's car. There are still lots and lots and lots of things that could be wrong. I'm just in brainstorm mode trying to come up with hairbrained ideas that fit the problem symptoms well.

I think that a voltmeter and a fuel pressure gauge in the skilled hands of someone who has messed with L-jet in the past could shed a lot of light in a short period of time.

[z_ya]

OKAY haha after checking it out further it seems the fuel filter was to blame so that was an easy fix. However I did go ahead and spend the money for a new AFM cause today it warmed up outside a bit might be about 50 or so and I just quickly revved the engine an black smoke came out. And like I said when it was cold out it ran like a champ not running rich at all so I just went ahead and bought a re manufactured for like 255 that includes the 45 dollar core not taken off.

[Captain Obvious]

Far be it from me to cast aspersions on an easy fix that took care of the problem, but a clogged fuel filter doesn't really fit the symptoms.

However, whatever works, right? If that fixed it, then more power to ya!

So before you replaced the fuel filter... What did it do when you floored it? Did it have good power on the highway when you really put your foot into it?

[z_ya]

I never really took it out on the highway. It has mostly been a town driver for me. But after i replaced the fuel filter i did feel a better response in throttle and it was a bit smoother to. It stalls no more now so thanks guys.

[siteunseen]

I'll quote from my favorite show, Sanford & Son. Fred says "If he keeps on drinking them beers he's going to have to get off that couch", Lamont says "Pop! the simplicity of it. Why didn't I think of that?" Fred says " cause you ain't simple minded like me."

[mjr45]

Have a similar cold start issue, very low idle for 3-4 minutes about 400 during which I have to give it gas then will go up to normal. I know my CSV is bad and everything is hard to start when is -10 like it is up here for the past few days.