Well I ground my FSS down a few years back when it blew a chunk out of it and it was working fine and shutting the truck down til probably the last 6 months then it started to only start on the 2nd time cranking the motor over instead of the first instant you touch the key like it used to. It only seemed to do this when it was warm so I heard it may be my FSS sticking. So I finally got around to orderin a new FSS on ebay for $15. But my question is should I grind it down and buff it so it doesn't blow a chunk off and not work again or should I just put it in the way it is? Last time it blew I had stock Injectors, and now I have PODs but not sure if they are big enough to keep it from blowing or not especially since they have higher pop pressures than stock injectors. The new rubber plunger on this FSS feels pretty soft so I was thinkin about takin it down to the metal and buffin it but I don't wanna ruin it or have the same probem I have now with, so what do you guys think?

 

If it were me, I'd go ahead and grind it down.

As far as your old one, I had the same issue that you've got, with my last one. It wouldn't pass fuel with the first attempt to start the truck. Had to try two or three times to get it to work.
Digging into it, I found what appeared to be skid-marks on the side of the plunger that led me to believe it was worn on the sides of the plunger and allowing it to bind when at rest.

I got a new solenoid assembly, ground the new plunger, and have been running it now for three or four years now. I don't remember . . . ..

 

Yeah I'd rather have that rubber in the garbage than in my pump (still don't know where the last chunk went??? hopefully not still stuck in my DVs) I know the one I have in now had a pretty good chunk out of it, even after I ground it down but It did the job so thats all that mattered but now I'm wonderin if that is causing it to stick. Thanks for the quick reply David, hopefully this fixes my problem.

So you ground the new plunger you got and the truck still starts on the first crank and shuts down like it should?

 

please post a pic of the plunger tip when you grind it! the ones i've used have a dimple in the end i'm not sure i could replicate that on a grinder. will you shape it into a dome?

 

Don't worry about the dimple just sand it flat till you start to.see the metal. Then round off the sides and throw it in.

 

Yes. Running some 6x0.016" EDMs, flowing enough fuel for 450HP (+/-), and beating the crap out of it regularly, I've not had any issues with the fuel solenoid for over two years now for sure.

I don't believe it's necessary to have an absolute dome shape to it. What we're interested in is the perimeter being able to plug/seal the fuel passage when it goes to shut things down.

 

ok so the shape of a new plunger, with the dimple, is sealing only around the lip? so it sort of spans over the fuel hole? while a domed tip actually sits into the hole a bit and has more meat to support it?

 

My FSS failed shut and stopped my on the highway. I threw my valve away so it'd never happen again. Starts instantly as always before, and I shut it off from the drivers seat with no problem.

 

Be aware though, that some of the after market tips do not look the same without the rubber on them as the stocker does. A guy that I work with bought an after market one, and within a week, it had a chunk ripped out of it. We pulled it out and we were going to grind it down, but there wasn't any metal under it until the very end, where there was a little tiny piece, that the rubber was molded onto. The piece that was left was too small to even make work without the rubber on it.

 

Yes.


@ pigpen . . . .

Yea, we know, gut the FSS, pull a cable, live forever.

If you get tired of your tires going flat, just fill them with concrete and be done with it.

 

Maybe I'll poke it with a needle in the middle or something to see how much rubber there is before it hits metal, it seems pretty solid though.

Can you even buy just the rubber plungers anymore instead of the whole solenoid?

 

Hah Hah, very good! I just don't get leaving an unnecessary component in there that can fail and stop you. Most of us want these trucks to GO with no problems. Well it is as we say 'You're mileage may vary' .

 

Well ground down my new FSS plunger today to the metal, buffed the edges til they were round, put the whole new assembly in and now it won't shut the truck off... It will lower the idle and if you give it throttle it will sputter so its not getting full fuel when the key is off but its still letting enough by to keep it running. The new ground down plunger was about the same length as the old one ground down and it was shutting the truck off... So now I'm thinkin about stretching the spring our that is behind the plunger so that it will push it down further, and maybe I'll buff it up some more to see if it works. Kinda frustrating but I may just put my old plunger in the new solenoid since it was shutting it down before... Someone needs to make some "modified" plungers that are still long enough to cut fuel flow but have a harder rubber or somethin else to not lose chunks from the pressure...

 

What if you put some of that blue machinists metal marking fluid on the tip of the plunged and stuff it in there and twisted a tiny bit. It would show you the high spots and you can adjust the profile to match. I dunno if the tiny amount of blue marker left inside would do anything to the pump considering it already ate a piece of rubber.

 

I ordered a new one from ebay and i cant grind it The rubber tip isnt molded to the plunger, it kinda slips around the end. It seems like harder rubber than the old one though.