What's up with these relays

[DaveMarcotte]

I don't understand relays. My engine fan didn't come on when it should have. Swapped the horn relay in and it worked. Double checked and yes, the fan relay bad. Thought I'd confirm what the other two 30a relays did. I IDs the fuel pump but when I turned the key a second time, no pump sound. swapped with the known working relay and the pump was back. Here's the weird part, when it tried the none working fuel pump relay in the horn spot the horn worked. I'm changing all four tomorrow but I found it curious that a relay worked for one but not the other. Hope I relayed the info correctly

[81SPIDERMATT]

one would hope that a relay when failing would just fail ... sadly relays can go slowly ... working some and not ... it can get frustrating trying to solve a problem ....

and I see what you did there in that last sentence

[spider2081]

I think one of the relay looking devices is a timer that lights the square red warning lights for a few seconds when you turn the key on. It look like the other relays but it internally is not the same. Is there a PN on the relays themselves you can see???
here is a link to wire diagrams and component location for a 1977 Spider.
https://www.mirafiori.com/forum/viewtop ... 49&t=96319

[DaveMarcotte]

I think one of the relay looking devices is a timer that lights the square red warning lights for a few seconds when you turn the key on. It look like the other relays but it internally is not the same. Is there a PN on the relays themselves you can see???
here is a link to wire diagrams and component location for a 1977 Spider.
https://www.mirafiori.com/forum/viewtop ... 49&t=96319

The four relays in question are , horn, fuel pump, fan, ingnition mode, all have the same schematic on the side.

[DaveMarcotte]

I just read that the ingnition mode relay was connect to a heat sensor to switch points when to car was warm enough. Seeing as I no long have two sets of points but rather a distributor less. There's no need for this relay. Have I got that right? I know it's a dumb question but wanna be sure that relay doesn't control something else as well. Thanks

[Yadkin]

I've had the same issues with relays on a 60's resto-mod project, using a power box from a 2003 junker. I'm guessing that internal contacts start to oxidize, and the electromagnet wiring insulation degrades. I thought that I was getting OEM quality relays with the deal, but in reality they were nearly worn out. Luckily ebay sellers have boxes of NOS relays that are exact replacements and sell cheap.

[So Cal Mark]

if you're not using dual points then you can eliminate that relay

[DaveMarcotte]

I think one of the relay looking devices is a timer that lights the square red warning lights for a few seconds when you turn the key on. It look like the other relays but it internally is not the same. Is there a PN on the relays themselves you can see???
here is a link to wire diagrams and component location for a 1977 Spider.
https://www.mirafiori.com/forum/viewtop ... 49&t=96319

So, replaced all the relays. Turned the key to the on position but don't heard the fuel pump as I always did? So swap to the old known to work relay which was the horn relay and heard the pump motor again. Started up and ran for about 18 second then like hitting a switch it stops. Test three times and yes like clock work stops running. Horn relay must be timer right? Plug in the new relay, no fuel pump sound, car starts and runs fine. Went for a 20 minute cruise. Why don't I heard the fuel pump anymore? Or what was I hearing if not the electric pump?

[spider2081]

There were some years where Fiat had a mechanical fuel pump on the driver side of the engine and an electric pump that was active only in the Start position of the ignition switch. Maybe your car is one of them. Take a look and see if you have a mechanical pump forward of the engine mount drivers side of the car. If you do and the cars wiring has not been modified I think an electric factory pump would only operate in the start position of the ignition switch and then the car runs of the mechanical pump

[DaveMarcotte]

There were some years where Fiat had a mechanical fuel pump on the driver side of the engine and an electric pump that was active only in the Start position of the ignition switch. Maybe your car is one of them. Take a look and see if you have a mechanical pump forward of the engine mount drivers side of the car. If you do and the cars wiring has not been modified I think an electric factory pump would only operate in the start position of the ignition switch and then the car runs of the mechanical pump

N mechanical pump. Just rebuild the engine. Definitely an electric pump that used to hear when switch is in the on positive but no longer hear with new relay

[klweimer]

One of the issues I've found with the relays are the sockets they plug into. These sockets are typically a plastic housing with a number of crimped wire terminals that snap into the housing. The terminals can start to lose their spring grip on the relay terminal tab, they can work there way out the back of the connector and generally be a pain. When you have the relay out, look down into the socket housing (I use low magnification) and see if all the terminals floating around in there look OK. None sticking up or sliding out the back. They will float a little in their positions, that's OK. What the heck, might as well spray a little contact cleaner on them while you're there. When you plug the relay back in, check each wire coming out of the socket to make sure they all feel secure. I've had more issues with the smaller terminals than the larger ones.
Kirk

[DaveMarcotte]

One of the issues I've found with the relays are the sockets they plug into. These sockets are typically a plastic housing with a number of crimped wire terminals that snap into the housing. The terminals can start to lose their spring grip on the relay terminal tab, they can work there way out the back of the connector and generally be a pain. When you have the relay out, look down into the socket housing (I use low magnification) and see if all the terminals floating around in there look OK. None sticking up or sliding out the back. They will float a little in their positions, that's OK. What the heck, might as well spray a little contact cleaner on them while you're there. When you plug the relay back in, check each wire coming out of the socket to make sure they all feel secure. I've had more issues with the smaller terminals than the larger ones.
Kirk

Thanks Kirk but the relays are working. The question is prior to the new relays I hear the fuel pump when the key was to the on position and now with new relay I don"t hear the pump but clearly I'm getting the fuel to the carb?

[81SPIDERMATT]

a pump with low voltage may get hotter and make noise and now that it has full voltage it is happy and quiet ... could happen

[spider2081]

I think some of the pumps make a louder noise when they are first turned on while building up pressure. Once the proper pressure is achieved they become quieter Have to noticed it being louder if the car sits for a couple days. I know it that time of the yyear where we are driving them every day.