'73 911E Warm Start Problem

[jjlimo]

I am new to this forum and a pretty recent owner of a '73 911E.

The problem is that the engine has trouble starting when it is warm (sitting for about 15-120 minutes). When I first switch the ignitiion, it seems like it might start right away and then it just turns the crank. I often need to crank for over 1 minute before it starts. More recently, it wears down the battery before it starts. It starts okay when it is cold (sitting more than 2 hours) or hot (sitting less than 15 minutes).

My mechanic is looking at it and plans to check the pressure in the fuel line. He thinks it may be fuel vaporization that is leaking somewhere. Does this sound about right? Anybody else have this problem and successfully dealt with it?

It is in great condition and worth the work being put in. Recently I had the ignition box replaced which I had hoped would fix the problem. It has a rebuilt (top and bottom) engine and almost all original parts.

Thanks in advance.

<_<

[wvicary]

The fuel pressure at rest would be the first thing to check. Any mods been done to the car over the years as far as fuel/ignition system is concerned?

[jjlimo]

The fuel pressure at rest would be the first thing to check. Any mods been done to the car over the years as far as fuel/ignition system is concerned?

It has an MFI (perhaps been rebuilt at some point). Other than that, it has a carrera tensioner and an added oil cooler.

Thanks for the quick reply.

[wvicary]

I don't know alot about the MFI systems but can lend some advice learned over the years in regards to the ignition system. You say that the ignition box has been replaced and my advice is to always replace the ignition coil at the same time. The coil is often over looked and the root cause of damage to the control module. Hope you get it sorted soon and please keep us posted.

[jjlimo]

When I got my iginition box replaced (with a rebuilt one), the coil was tested and was fine.

A pressure test was done on the fuel system and revealed that the check valve was faulty. So I am having a new assembly put in. It was either $30 used or $155 new (of which I was told there are only 17 left in the world). I am opting for the new one since it is 1.5 hours of labor either way. Does this sound about right or am I going to be paying for blinker fluid ;) .

Edited March 7, 2007 by jjlimo

[jjlimo]

The fuel check valve was replaced and the warm start problem went away. In fact, the cold start got a little better as well. Plus my blinker is working well :drive: .

I trust my mechanic but it is nice to have this forum to bounce off ideas.

Thanks.

[wvicary]

Glad it was an easy fix and it's always good to hear back if the problem was solved.