Fuel pressure help

super duty04

super duty04

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Aug 4, 2009
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I am running a stock lift pump on the motor and a 15 psi. helper pump on the frame rail and my fuel pressure is only 15 psi at idle and about 22 psi at wot. Is this right or do I need a new fuel system. Any help would be greatly appreciated.
 
The stock lift pump, in good condition, is capable of over 30 psi. Mine idles at 23 and 30 running with just the stock lift pump. Have you checked the OFV? The spring may be getting a bit weak. I use the Tork Tek adjustable, so far, so good.
 
fuel pressure

I can put vise grips on the return line off the p pump and can get 80 psi at idle. Is it the overflow valve? How do you take the overflow valve out with the pump on the motor? Any help would be greatly appreciated.
 
might have to file the head side for clearance.

A 'quick-fix' alternative is an aftermarket regulator, just make sure you dont use the el-cheapo gauge that comes with it (been there, done that)
 
Your lift pump is good. The fuel is there so you are fine. The OFV is so-so. If it would make you feel better to have more pressure you might try stretching the spring in the OFV to 0.550" or adding a spring from a pen to get a little more pressure.
 
A die grinder with a carbide burr tool will give access pretty easily. Don't get carried away with removing material though.
 
So am I the only one that got lucky and didn't have to clearance the head to get mine off?
CompD Mobile Device
 
Ok, because I couldn't remember any of my buddies doing it either. I was starting to worry I was loosing it!LOL
CompD Mobile Device
 
fuel pressure

Ok thanks a lot guys I will try taking it out in the morning. What kind of pressure is needed to properly run the p pump? What pressure is needed at idle and at WOT? Again, thanks for all the help.
 
Yep, mine needed a little more room to remove. Now I have plenty of room to get it out.
 
I had to grind on my 95' to remove the overflow valve. On my buddy's 96' and other buddy's 97', no grinding required.

By the way, this isn't major grinding, just taking about 1/8th" to 1/4" out.
 
OFV

I got the OFV out but, I dont see any way to take the spring out of it. There is a "ball" on top with the spring in the middle and a ball on the bottom. The "ball" on the top seems to be a press fit. What I did is put the OFV on a piece of wood and used a punch and hammer and knocked that top "ball" down into the OFV which did put more tension on the spring. I do now have 35psi at idle but, is this the correct way of fixing the OFV. If a new OFV is needed where is the best place to get one.
 
Well it sounds like you have found your problem. I just wanted to say that i had i similar problem a while back and it ended up being a slightly blocked fuel supply line. I blew it out with compressed air and problem solved. Just something to keep in mind for future reference.
 
Sounds like you found a way to adjust a non-adjustable overflow valve, good job!


35psi is fine if it maintains 35psi under load, does the fuel pressure drop when you drive down the road pedal -to-the metal?
 
You should get the adjustable OFV mentioned. I stretched my spring (probably too far) and I get ~42 at idle, and it never drops below 35psi at WOT.
 
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