On my 99 blazer, the fuel pump sender unit has three line connections. I didn't label them when I wrestled the tank out, now I'm not 100% sure which is which. The largest is obviously the output pressure line, but the other two are the same size. One would be the return line from the engine, the other is one of the vent lines.

The output pressure line has an F on it, the one I think is the return has an R on it, and the one in the middle has no lettering.

The one that I think is the vent line is the center one of the three.

Does anyone have a good diagram that has these labelled, or do you know which is which?

My GM shop manuals all show it, but they are not labelled, nor is it clear which goes where.

I will keep looking, but I thought I'd ask all of you experts too.

Thanks a million.

 

The line in the center of the three is indeed the vent. it goes to a three way sort of connection with a line running towards the front and another running towards the rear of the vehicle, the supply (big one) and return (one left of center) just run to the engine.

 

Thanks, I figured out the supply, that was easy. The other two were the source of my confusion.

I really appreciate the info - thanks again.

I had to run all new lines ( I had a separate post on this ) and I'm getting to the home stretch.

Have a nice Holiday weekend, the weather is real nice here today and my BBQ is almost done. Since my family is coming over, I'd rather be working on the car, but the good food is worth the pain.