Stall

[tanny]

On my 73 240 I have triple Webers and headers, and no heat shield. I have been having problems with the engine stalling occasionally and not able to be restarted for approximately one hour. The fuel pumps(electric and mechanical) both work well, the fuel filters(including the one in the electric pump are all new and fine. No obstructions in gas line or tank. There is good spark to all plugs(I am certain the problem is not electrical in nature). The cooling system is clean and working well. The last time it stalled, I popped off a fuel line and there was plenty of fuel pressure so I fed a little fuel into the top of two of the Webers and it started up and kept running. There doesn't seem to be any correlation to outside temperature(happens on hot days, cool nights, etc.) What might be the problem? If fuel is getting up to the carbs, could it somehow still be vapor lock? It would seem that if fuel was getting up to the carbs and the floats are working properly(which they apparently are because the car runs fine the rest of the time), vapor lock wouldn't be an issue. Or would it? Any ideas would be appreciated. Thanks, Victor.

[Gav240z]

Not a webbers expert I'm afraid , but do you have the vented style bonnet or non vented?

You mention no heat shield which is most likely your problem if you ask me. Alot of heat sink will occur and disrupt the operation of the carbs if you ask me.

Try some header wrap if you can't get a suitable heat shield that works with the webbers and see if that helps.

All the best,

[Daniel]

With vapor lock the car will idle.It just runs like two spark plugs have no plug wire attached when you try to move.It surges.Are these you symtoms?

[tanny]

No, the engine runs really well up until the moment it dies(it doesn't die immediately as in an electrical fault, but acts like it's running out of gas a couple seconds before it quits.). It sometimes will restart for a few seconds, but then quits for about an hour. I don't believe it's the coil because it did the same thing with two different coils. Thanks, Victor.

[Gav240z]

From the sound of it I really think it's vapour lock. If anything installing the heat shield and header wrap will improve performance anyhow but don't write off any other possiblities.

[tanny]

I've read where the header wraps can be harmful to the headers. Myth or fact? Thanks, Victor.

[Gav240z]

Had a look at your gallery and you have no vents in the bonnet and no heat shield under your extractors, I believe this is a big part of the problem.

Your fuel lines are also not insulated.

[Gav240z]

Fact header wrap will reduce the life of the headers mainly because it's keeping all that heat inside the headers and puts more stress on them. Could cause them to eventually crack and warp I guess but to me this is a minor thing considering how much I believe it will help my 240z perform.

I don't know about you guys but at night when it's real cold my car is a whole different beast.

BTW how long have you been running these carbs on the car? How long has the problem been around? Does it happen in traffic while driving?

Does it cough and splutter backfire at all or just die?

[tanny]

I did insulate a portion of the fuel lines, but not all. Any suggestions on insulating material? I think you're right about it being vapor lock. I'll try insulating all of the engine compartment gas line first, then try the header wrap. Those wraps are pretty expensive, but if it works would be worth it. Victor.

The stall has been around since I got the car running. Cool and hot weather makes no difference. Happens while driving around town and while on highway.

[Gav240z]

I'm open to any other suggestions, but the cheapest and easiest would be to install the heat shield first you could grab one from any wrecker but I was gonna go and get mine made up becaue the stock one is useful but has it's flaws.

This is my inspiration .

[tanny]

Looks like a small amount of effort and money has been put into that engine compartment. Beautiful. Thanks, Victor.

[Gav240z]

One of my favorite Z's around if not the best.

http://www5a.biglobe.ne.jp/~satotats/zhp/

Is the website alot of time any money went into it. More the time I'd say as it was painstakingly and cleverly assembled.