was in the process of changing out the old spring and putting in the new blue spring
when I noticed a blue dot. Has the mod been done already? What do you think?

 

It's anybody's guess.

It's easy to do the blue spring, especially since Rusty's writeup is top-notch. All I did was the spring, poppet, and cover o-ring.

I bought a remote fuel pressure hose that threads into the test port in the lower left of your picture. If you were to use that or one of those billet caps with a test port in it, you could see what your fuel pressure is now. That would give you a better feel for if it had been done.

I didn't measure my pressure before blue spring, but after it was 60 psig at idle. Didn't have the setup to check it at WOT just yet.

For the promoted benefits of the blue spring versus the effort to install, it's a no-brainer to me. I did find it a lot easier to remove the upper radiator hose to get better access to the cover.

 

Be careful with the input fuel line, tiny o-ring to seal the connectors - make sure you have your hand underneath before fully backing off the connector. The kits usually come with a replacement o-ring (blue).

 

That blue dot was on a lot of covers that didn't have the update done (this has come up before). The spring was never in a production F series truck, unless it was put in by someone after it left the factory.

My '07 had a blue dot and we factory ordered our truck, have no clue what it was for, but it didn't have the longer spring until I put it in there...

 

Call me crazy, but the torx bolts look new, and that cover looks cleaner then the housing itself.....

but wouldn't hurt to check, the kits cheap, and you're looking at 30 min all said and done to switch it out

 

You're crazy - hey, you asked for it!

Made me go look at the pict again, and while the cover looks the same as the body, what you also see is it looks like there has never been a tool in or on anything to do with taking the cover off...

I'm going with it has never been done, and when you have the two springs side-by-side, you'll know it for sure

 

Thanks everyone, will go ahead and replace this weekend. I ran out of time today.

Really appreciate all advice

 

finally got around to replace the spring. Just thought I would let u know that even though the blue markings was on the housing ( see first pic) which I thought was an indication that the mod had already been done. ... Wrong!

 

Thanks for the follow-up final answer to the question -- maybe one of us will remember this thread the next time the "blue dot" question gets asked...

Reps sent your way....