65fury

okay so i did the fuel return valve spring deally and got 60psi at idle, so then i drove my truck about 300ft with a few stabs at the throttle, and its back down to 15-25psi at idle (still need to put a needle valve in to control the jumpy gauge) any ways so today i take it on its first run WOO HOO, its good to drive a diesel agian, oh sorry, anyways at about 50-60mph my fuel pressure is reading an average of 40psi, around town at 35-40 its reading 60+psi so whats the deal, have not done a REAL wot run but the few times i rolled into it it only dropped to 25psi. so any thoughts, lp bad?? thanks


jason

65fury

what?? know one has any ideas? this fuel pressure thing is really got me confused, pleas if anyone has an idea let me know thanks


jaosn

TxDiesel007

im no expert on this,

but if you are at 60 psi at idle, u are far to high. i have mine at 40 psi at idle, and at WOT can drop it to 20-25 psi, mostly round the 24 range. Now at normal cruising speed, yeah my fp stays at about the same, and occasionally rises, i had just replaced an LP when i did my mod so id say we have the same setups...

Problem is u stretched ur spring too much, work with it to get it down.. dont get to impatient either, sometimes we dont read these threads right away....

also FYI, the lp provides about 15 psi of fuel at max...

Rick

kawi600

Mine is about 30 at idle and dips down to 15psi at WOT. not good =(
Does this kind of reading sound normal to you guys with 12v's and FP gauges mounted? Maybe I should stretch the spring for 40 at idle? I hate seeing the pressure get so low at WOT.

farmer dave

That pressure isn't that low for a 12v. You don't have to worry as much because the ip isn't being cooled by the fuel like in the 24v. Besides, 15 psi and WOT is more then enough fuel.

TxDiesel007

stetch out the spring..

that should help ya out, id probly have the same numbers if i was at 30 psi at idle... ive had 40 at idle for a while no and havent had problems with it either...

Rick

Farmer Dave

you are right, but without sufficient FP, IE no less than 15 you are damaging the internals of the pump as well and wearin out parts more quickly as well (or so ive understood, do not quote me on it) so why not be a bit more on teh safe side? 18-34 psi is normal for high throttle on these trucks, and 22-24 is normal on idle...

Rick

65fury

sorry to get so impatient i kinda flipped today when i noticed that everywere i went my fp gauge was reading 55-70psi even at 60mph and 35mph around town, so ya im going to go outside to play with the springs to get them down a little bit, thanks for the help.

TxDiesel007

I hate to tell u this...

its not doing you any good if you dont have a needle valve.. GET IT IN THERE, then take readings. Remember to set it to where its barely open and that fuel pressure is merely an average reading, it is affected by temperature, humidity, fuel level in the tank, air coming into the system, additive added, fuel viscosity, and lift pump function and wear...

Ur just screwin up ur gauge without the needle valve, and for all u know ur readings are ok.... Id suggest a new gauge, and a needle valve..

Rick

65fury

yep thats what im going to do today, get that needle valve, but i'd rather not have to get a new gauge, i just bought this one a week ago, if the needle valve doesn't help for some reason then i guess ill try to return it and get another, thanks

65fury

alrighty then, finally got my needle valve in and at idle it reads 25psi, at 40mph it reads 40psi, does that sound right?? haven't done any wot runs yet so i don't know what those psi numbers are yet. thanks for everyones help.


jason

Jambbii

Those are good numbers. Just do a full throttle run now and see what it does.

TxDiesel007

Leave it alone...

id say ur ok for what u currently have....

Rick

65fury

oaky doaky then, i'll just leave it alone......for now thanks again guys


jason