1981 Fiat spider fuel pump problem?

Hi all, I have a 1981 Fiat spider pinaforina convertable which usually runs really great. Nothing like it, except that occasionaly there is a problem starting it. Usually when I put the key in the ignition and
turn it slightly you can just hear the whiring of the fuel pump. No problem, it starts great. But occasionaly when you put the key in and turn it there is no whiring sound from the fuel pump and the car won't start. It doesn't happen often, but when it does it's so damn annoying, and now I'm a bit scared to go out and give it a good run in the countryside just in case it won't restart. It's not the pump, foolishly replaced that when I thought it was the pump. But it made no difference. My only thoughts now are either a loose connection (which I can't find), a faulty relay, or, a faulty connection in the ignition switch. Does anyone know what the problem might be, or has anyone had this problem before? I can do most of my own work, but I just don't want to be taking the wrong bits off and replacing them without results. Thanks in anticipation for your help. William.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I usually rig a piece of flex through any convenient grommet, and wire one end across the intermittent device, and the other end has a low wattage panel lamp on the dash. If the supply goes off the light goes out. This can be wired into the system at different points, at the pump, just after the switch, etc. What I do is solder one wire to a pin, then use fine nose pliers to push it through the wire, then bend the ends back and apply insulating tape. Other end has an alligator clip for ground. That way I don't have to cut wires, and the small pin hole is virtually self healing when I pull the pin out. There are also piggy-back push on blades, useful when you wany a temporary tap in. Sure it's not a ground problem?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jul 4, 9:21 am, ato snipped-for-privacy@hotmail.com wrote:

Thanks I'll try that, it's a good idea. As to it maybe being a ground problem, to be honest I don't know. But I will check other functions when next it happens just to see if it's a ground problem at the ignition. Again thanks a lot.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.