Hard start - just tuned and it won't fire!

[The Wingnut]

Hey folks,

Got an L28 in the car with SUs, just had it dialed in yesterday by a Z specialty shop. I'm having severe difficulty in getting the car fired now, one in every 15 tries does the car fire, if that. When it's cold outside, I don't have a problem, but if the weather's warm, or if I just shut it down a little while ago it doesn't want to fire at all. All I get is a little catching, the occasional lighting of a cylinder. A shot of ether doesn't seem to help, either. I've definitely got spark.

Not certain it's vapor lock. Never had a problem with it before.

I'm desperate because I've got to report into to my AF unit Monday morning at 7 AM. The shop where I got the car tuned is closed.

This is infuriating. Prior to the tune I didn't have this problem. I'm going nuts with this, until now, my car's been VERY reliable.

[The Wingnut]

Just let the car sit about 10 minutes after grinding on it like a madman. Caught easily and idles fine after cranking.

I can't have it unreliable like this. It's my daily.

[280~Master]

Sounds like a vapor lock or some part of your carbs are bad. I am not an SU or a weber guy but maybe some one else has ideas. What shop did you go to and what all did they do to tune it?

[The Wingnut]

Just took another jaunt to return a video and pop in at the office. Caught fine and ran fine after a 5 minute stop.

Did not use choke and did not pump the pedal before starting. Am I flooding it, maybe? I usually give the pedal about 3 pumps out of habit before starting.

I've got PLENTY of spark.

I took it to Petaluma Auto Works in Petaluma, CA. Bernard did the tune. Both Bernard and Jason said the carbs were in good shape(and it started fine before the tune)

[The Wingnut]

Just tried to leave the house again. Car started, idled, backed out, then stumbled and dies when I tried to drive away. Won't restart.

PLEASE HELP. I AM GOING OUT OF MY MIND.

[280~Master]

I used to live in that area, San Rafael, Petaluma and Santa Rosa. I have had problems with a shop in that area. Is Bernard hispanic?

I think I have used them years ago. I took a 77 280Z to a Z shop Petaluma for a tune, valves and all, came back with a bad antenna and a couple of other things missing from the car. The mechanic from there told me once he would have to drill and tap the intake to put on heat sheilds. When I heard that I laughed in his face and said I would never use or recommend his shop again.

I know there used to be another shop a little further south that had a great rep for doing great work. Wish I could remember the name. Good luck.

[Arne]

First, pumping the throttle on SUs does absolutely nothing. They don't have accelerator pumps. In fact, you should not use the throttle at all during starting. Just leave it alone until the motor starts and stabilizes.

What all did they do to it? Did they adjust the valves? Perhaps the valves are adjusted too tight?

[The Wingnut]

The shop I went to was Petaluma Auto Works. It's run by two brothers who do look Hispanic.

I suspected there's no accelerator pump. I can't imagine in this weather(balmy spring weather) I'd need the choke to start...should I use it?

The valves were adjusted. Not sure how to check them.

[The Wingnut]

I tired starting the car after it sat for about 10 minutes, nothing. Then gave it half choke, and it fired. Unstuck one of the choke plungers and it evened out. Plungers and choke linkage are now lubed and a non-issue. I can consistently get it to fire if it's not hot.

I can get it to fire if it's cold, looks as if it's a hot start issue...not sure if it's relevant, but I heard ticking coming from the (on-block)fuel pump during cooldown. I just bought a Carter inline pump for back by the tank (it's a 260, so there's an old one back there that got disconnected when it stopped working). Putting that on should at least eliminate any fuel delivery issues.

[beandip]

You shouldn't ever need the choke on a warm engine. She should fire right off. When the engine is cold , this is a totally different matter. Always use the choke to start. When the engine finally does start . Is there smoke coming out the exhaust? like a cloud of black smoke? Did they get into the carbs? Because if they messed with the float levels and set them up too high , this could cause raw gas to run into he intake and flood the engine , making it difficult to start. A cold engine can use he extra gas , but one that is up to temp it is too rich and will flood it. This is just a guess on what is happening. Since you have spark .

[The Wingnut]

Okay, got an update. The weather has cooled down and now the car starts with just a little cranking. I'm thinking I might have had a vapor lock problem. I also found a loose connection on my ignition that might have been causing problems. Since I fixed it, I've been able to get a start every time.

Thanks for the tips on the choke, I did find it odd that it helped a bit while it was hot. I'll see what I can do about checking the float level. if I recall correctly, the floats should be 1/8" from the underside of the float bowl cover.

Tomorrow, I'm going to install the fuel pump at the tank. If I really do have a vapor lock issue, that should help. If it persists, I'll find some insulation for the fuel lines in the engine bay.

[DeesZ]

Just curious.... what brand and number spark plug is in the car? I've had dismal results with anything other than NGK. It may be worth your time to pull them out to see what they look like. Also, I've had coils short out when hot.... just a thought or two.

Please keep us posted with results.