Happy New Year to All. I need to replace a fuel pump with one that does not have harnesses to connect. So, I need to solder the sending unit pos. and neg. wires to the fuel pump wires. My question is does soldered connections and exposed wire residing in a fuel tank full of gasoline pose a risk of fire or explosion? When you look at our sending units there are a lot of metal connectors that sit in gas. How is this safe? Does anyone make a gasoline safe coating to cover the exposed metal. Liquid tape seems to dissolve in gas according to some posts I read. PLEASE HELP

 

Use uninsulated crimp terminals, and raychem heat shrink Do not try to solder and tape connectors in a car, especially not ones that will be covered in gasoline.
And use the right crimping tool for the connectors you use.

 

The raychem heat shrink has a glue on the inside, is gas/oil, heat resistant once it is cured. If you don't have the tools, take the sump out, replace the pump, take in hand to your local garage and ask the service writer or mechanic if they can crimp and seal the wires for you, they do this stuff daily and will have the correct tools and heat shrink to do it safely. Below are pics of what I use.

 

FYI, most of this stuff is available at your local Auto parts store, important thing is use the right crimp ferrule for the size wire, and do not use your grandpas 30 year old generic crimper. The harbor freight crimp tool below is cheap, I use the same one daily for ten years now. The heat shrink is probably 10 bucks for 6-12 inches of it. Make sure you use an actual heat gun, not a bic lighter or fire. You don't burn it, you heat it until it shrinks. This is about as simple and basic as a crimp splice gets, the primary consideration is it's submerged in gasoline, and potentially drawing 10-15 amps. So you want a strong mechanical connection that is sealed well, weak connections will get hit, cause higher load, bad for wiring, fuses, relays. And if bad enough can actually cause a lean condition, weird fueling correction and or enough block learn to actually cause a check engine light. It is good that you are asking. Can't tell you how many times I fixed shoddy fuel pump installs by overzealous diy types. It's easy, quick, and simple to do right. Yet so many do it wrong. Hope this helps you.

 

Soldering to components that will reside in your fuel tank is completely safe. In fact GM did it from the factory on your fuel level sending unit. The only small issue I have personally ran into with this is the type of solder IF you are using E85. Ethanol can cause corrosion with non compatible metals. But for regular pump gas there is no risk of this. Also there is no risk of an electrical spark igniting gas vapor as long as there are no short circuits inside the tank. I would avoid crimp connectors at all costs inside of a fuel tank because of the risk of corrosion and thus increased ohm resistance in the wires going to the pump. Also it's more difficult to get to it to repair if there is a bad connection. This is why when I did the install of my Walbro 455 I used continuous leads that exit the tank through a bulkhead connector and don't connect inside the tank.

Think about it this way. The plastic plug on top of your factory pump wasn't liquid tight. So that means that there was 12VDC passing through to your pump while touching gasoline from the factory. So it's not an issue.

 

I like using the crimp terminals that are parallel connectors. I bought some high quality ones off of eBay that are thick and don't crack. You slide both wires in and crimp the wires into each other. So, you only have one crimp, and it is smaller than the butt type.

 

The trouble is most diy types do not know how to solder, and rarely have the correct tools to do it right, that is why I suggested otherwise. Besides most parts store replacement pumps usually give you two butt connectors, and occasionally heat shrink. It is a safe, effective way to do the repair. However, soldering is fine if you actually know how to solder. Most car guys do not know how. , they think they do. So it's just easier to recommend crimping, and the tools to do it are cheap, useful for other repairs. That's why I suggest crimping.

 

Do you have a jpeg of the connector you speak of?

 

This page has some photos and info:

CRIMPED TERMINATIONS PARALLEL SPLICES (nasa.gov)

This is the type I bought. I wanted thick, seamless, and plated copper. i.e. I didn't want brass:

MVP 25 Uninsulated Parallel Butt Splice Wire Connectors 18-22 AWG Gauge | eBay

I like these a lot better than butt connectors. As you smash both wires into each other, only have one crimp, and it's more compact. The other thing is you can easily connect wires of different gauges. Whereas with butt connectors, you may have to buy a special step down butt connector when connecting wires of different gauges.

 

Those are good, just a bit bulky. But for a fuel pump in the tank wouldn't matter.

I thought you meant the blue cheap ones they give you with trailer wiring kits. They are 100% garbage 🤣

 

Why uninsulated wire connectors vs insulated?

 

I'm guessing the plastic in the insulated connectors may melt in the gasoline?

 

because it does not seal the exposed wires. in air it would not matter, but being submerged in gasoline they do not help. but more importantly the plastic they use on them is not rated for submersion in gasoline, especially not gasoline containing ethanol. you can use them, but the heat shrink tubing needed to cover them is big, and would probably not seal very well to the wires.

 

In wiring inside the tank,from what i have seen, it seems that the more grounds i can get to the sending unit the better off i am. Is this a correct statement?