Please make it make sense

Have you try swap air hose at the pump.

 

You are talking about the windshield washer sprayer? You mean like on a truck when you push a button the spray comes up to the windshield?

Unless there is something that I'm misunderstanding, why would you not use something like this? It's not hard to put a button in the dash and run a few wires if you need to.

Wadoy Universal Windshield Washer Pump Reservoir Kit 99300 Fluid Reservoir Tank Bottle with Pump https://a.co/d/4VyYB62

If you feel that you need something for a truck then buy something like this. If you get it from a reasonably aged truck and you keep track of what year and model it fits if you need a sprayer you will have it either on the shelf or within the next day.

Freightliner windshield washer sprayer and Reservoir - Google Search

*** Older trucks are really cool. Often the problem with them is getting parts.

In my opinion, anytime that you have anything to change on that truck the best thing that you can do for it and for yourself, is to update it to something more modern. It is best to have something that you can buy and get within a day or so, like most trucks that are on the road today.

The way that newer trucks are updated the parts themselves generally are better, too, like electric wipers over air wipers, air ride over spring, that type of thing.

Good luck.

 

oK I an wondering about this because I have a truck in my little collection that had a similar problem.

When you put air through it, what pressure is the air?

Why I ask is the air pressure that normally is use is above 100 psi, the pump for washer fluid is something like 5 psi if that. There may be a problem with the pump itself not producing the pressure to get past a kink or an odd blockage which the gets by.

The truck I have the tube was collapsed causing a kink in it in such a spot you could not see it. The pump would not produce the needed pressure to open the kink, and even with a new electric pump, it would not work.