Question about the Shimmed FPR...

[clayc_989]

Well, I just shimmed my FPR and it really smoothed out my idle big time. I'm just wondering if the spring in my FPR was getting tired or if the OBS trucks' stock fuel pressure was way below the 70psi or so that it's supposed to be making. (I have yet to check fuel pressure but, nothing bad has happened)

Either way, if the truck, in new condition, made a decent amount of pressure, wouldn't the fact that the shim fixed my idle indicate that my spring was getting weak?

-clay

[fordnut85]

It could be, it is a spring afterall. The only way to tell for sure is to replace the spring and see what happens. I replaced the spring when I did my ship since it was dirt cheap.

[clayc_989]

I would really hope that there shouldn't be some way that the spring is 'calibrated' is there? It would feel pretty dumb going down to the dealer to find a small spring like that...I'm assuming that I could find just about any spring to fit, though the compression factor kicks in here....any thoughts on that?

-clay

[fordnut85]

I would just get a replacement from International, I paid like $11 for it. I wouldn't try and replace it with just any spring, it could end up with catostrophic failure lol.

[Tikal]

Whenever I was doing my FPR shim on my 94 I was wondering the same thing: had the spring collapsed some. I almost think that may be true because my idle was really choppy at around 550-600ish. It probably could've induced carsickness lol. But the idle rpm is supposed to be around 625....or that's what the sticker on my valve cover told me *shrug*

[pipelayerjdh]

I would check the pressure first. You may not need a new spring. Stock pressure is like 50psi, I think. When these trucks were new, they idled rough. At least all the ones I was able to get around at the time.

[clayc_989]

Alright, and thanks....

pipelayer, I actually did this 'cause of your pics...took me five minutes and I'll be getting a gauge pretty soon to test it out. As far as I can tell though, nothing bad has happened. If something were to go wrong, what would? Just so I can look out....

-clay

[alabamafrog]

The spring is actually what controls the pressure, any old spring will not work, it has to be a spring with the right tension on it. I'm not sure about the older trucks but on my truck they made a spring for California trucks that raises the pressure just like the BB, stock pressure is about 58 psi and the California stock pressure is around 80 psi.