1988 244 DL
163400 miles

My second fuel relay is failing on me. I saved the 1st one because I was going to - get around to - re-soldering it.

Now seems like a good time.

My only experience with solder has been with steel wire on art projects.
I have a soldering iron that has a worn point. I can file the tip sharp again but ...

Is a soldering iron the tool of choice?
Can anyone give me some tips (Dos and Don'ts) on soldering a circuit board?

For those contemplating soldering their fuel relays or just splicing harness wires.

http://youtu.be/I_NU2ruzyc4

Outstanding.
Thank you.

I think until I can really focus on working on the soldering I need a new back=up relay so i am not getting stranded intermittently.

Do you have any experience with a current after market fuel relay?

I haven't bought a fuel relay in a long time as I always (try to) fix my old one.
Keep practicing the soldering, you'll get there.

The last relay that I bought was a KAE brand, and it worked well.
You should be able to get one for $20-25.

Hope this helps
steve

Well thank you for the help and especially Tony who emailed me some pics of the operation.

Unfortunately it was a bust.

I disassembled my 1st failed fuel relay and with a magnifying glass could see cracks around two of the large posts. I touched solder to these and they look closed ... if ugly ... there is nothing smooth about my soldering. Also I felt the board got very warm around the edges where I held it while I attempted the soldering.

I started the car with the intermittent 2nd relay - Swapped in the #1 relay but not start.
I started the car a second time with #2 and warmed the engine up - Swapped in #1 and the car fired and died - no start.

So I failed in the requirements of fixing the solder connections, broke something or there is something else wrong with the #1 relay.

Is there anyway to check relay function by applying voltage and watching to see if the contacts close?

Another tip...

You need to have the soldering iron hot, apply the heat quickly and stop when the joint fuses.
Test the heat on a piece of solder before heating the relay.
It should melt quickly and flow smoothly.

I get a hunch that you probably held the hot iron in the solder too long.
When you do this, you melt adjacent solder joints that you really want to leave alone and you can introduce oxidizing elements into the molten solder.

I always wipe the solder with a clean rag to remove any film or dirt.
You need a small diameter wire solder, I use something like .020"+- diameter.
I've got a roll of "Aircraft Grade" solder that a friend gave to me.
His uncle used to work for one of the big airplane manufacturers.
I don't know it's composition, but it's solid wire and flows really well at medium temperature.

If the solder doesn't fuse to the copper pin(s), you may have a corrosive film on the copper.
If so, you can heat and remove the old solder then clean the joint, or add some paste flux to the joint before heating.
The flux uses acid to clean the joint and allow the solder to flow (flux) onto the copper pin(s).
Be sure to clean the flux from the new solder joint when finished.

hope this helps
steve

Is there anyway to check relay function by applying voltage and watching to see if the contacts close?

Sure. Trace the coil leads out to the terminal or use this schematic to connect something like a battery charger or other 12V DC power source. Notice the diode will require the correct polarity applied to the fuel pump-side of the relay duo.



This test isn't a verification of the relay's ability to do its job in the car, but just a good indicator the invisible parts of its operation succeed.

Fuel side: + to 85 and - to 86/2
System side: + to 30 and - to 86/1

A couple tips on soldering: First, advice to use a low-wattage iron will set you up for failure. It is an old mantra from the early days of electronic soldering when most of these skills were imported from plumbing and body work, necessary to keep delicate electronics from being barbecued by 250W irons.

Your objective in electronic soldering is to heat the connections to the temperature that melts the solder in 5 seconds or less. To heat something as massive as these relay frames and pins calls for 60W minimum. The tip must be well-tinned so the heat is transferred to the work efficiently without the insulating effect of oxides. Apply the heat to the part with the greatest thermal mass.

If you spend more than 10 seconds heating the work to the temperature solder flows, your heat source is inadequate. It isn't high temperature you want in an iron, it is the power (wattage) to maintain sufficient temperature at the tip.


--
Art Benstein near Baltimore

A closed mouth gathers no foot.

Hi

Make sure your tip is clean and shiny. Apply iron to joint than introduce a little bit of new solder.

If you need a decent soldering iron quickly I am pretty sure you can find a Weller iron (I think about 35 watt) at Sears in the plumbing section for $20-$30.

If you have a decent quality soldering iron the job is always much simpler.

Travis

I would not us any iron over about 35-40 Watts. The solder must be for electronics specifically otherwise the flux may be corrosive to the components and circuit board.

The areas where the solder cracks or breaks is usually around where heavy metal parts are soldered to the thin copper on the board. That is the relay frame and the connector contacts.

You can remove the old solder with a sucker or copper braid and re-solder by heating the heavier part first and then applying new solder. Or you can reflow the old solder again buy heating the heavy parts first and then adding a little new solder to get flux on the joint.

Allow the iron the get fully heated before starting. Apply some solder to the tip and then wipe the solder off. The tip should then be shiny.
Don't put a big blob of solder on, just enough to make a smooth joint between the component and the board. The finished joint should be shiny.

The only thing I would add is the the cheapest irons you see are only 15W (home improvement stores) and that is actually a little too small for the Fuel Pump and OD relays. A nice 25-35W iron seems to be the sweet spot. You will want a conical (pencil point) tip instead of a chisel point.

The heavy lug will take a few seconds to melt and it seems to happen all at once after a lifetime of waiting. Once you have nice melty solder, keep the iron moving and do not bridge adjacent traces. If you do, an exacto type knife can usually cut the bridge.

Mike

magnifying glass helpful