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Discussion Starter · #1 ·
I have a 1997 Ford F350 XLT with a e fuel system. Out of the pump im getting 75 psi and flow is great. However, testing on the return under load it is dropping to 14psi. I have looked at the the fuel lab regulator and it is working fine. I am a little lost on where to test next. I am thinking I am over looking something.

Thanks in advance!

Aaron
 

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Discussion Starter · #2 · (Edited)
  • Fuelab Prodigy Regulator (no leaking out of the brass nipple)
  • I believe hose is 1/2"
  • Pre Regulator is coming in at 75psi with the regulator set at 63-65psi
  • Then when under load it drops significantly to (14-15 psi). My understanding is it is supposed to drop just a few psi
This is the kit that was installed 3 years ago
https://444fab.com/shop/ols/products/obs-premium-kit

I am not a mechanic sorry , may have miss quoted the return.
 

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Just to clarify, are you taking your pressure readings BEFORE or AFTER the pressure regulator?
 

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Discussion Starter · #4 ·
Both, I have tested right out of the pump (has power and Good PSI) Also called Fuel Lab and we determined nothign wrong with regulator. Just stumped at this point.
 

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So you pressure coming INTO the regulator is 14 psi under load?
 

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I would change your pre and post filters and test again.
 

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Hi sounds like your message is mixed ? The high fuel presser you reported is fine ..Now lets regulate it ..Your looking for no more than 60 psi after setting regulator, no need for excess ,, hard on injector seals,, with no benefits for excessive fuel pressure...Not at meet in race mode ! The low pressure sounds ok for returns line .. Just chiming in here to clarify your pressures , lots of good advice ,should your fuel pump not perform up to needs ? look into diesel o rings or riff riff ,, computer took over... Riff Raff.. Unless your in race mode they have what you need ? Filters and Etc have an effect on all aspects of engine performance , thats why you checked in ,, stay in touch ? Lets hear it ? The Gov Holmes
 

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Hope the message is clearing up ? The pressure of importance is what the injectors have to work with ,, Between the fuel pump and your regulator is what the injectors have to work with... Under a engine load at high RPMs pressure will vary .. That is what you must be able to maintain , It is not always easy,, keep peddling and you will get there ,, stay in touch ? The Gov Holmes
 

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Discussion Starter · #11 ·
you need to check the pressure coming into the regulator that is what counts. The pressure on the return side is not that important
Yes have checked pre regulator and pump seems to be fine. I am suspecting that the pump may be on the way out. So i am goign to pick up another bosch pump today and see if that fixes issue.
 

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Yes have checked pre regulator and pump seems to be fine. I am suspecting that the pump may be on the way out. So i am goign to pick up another bosch pump today and see if that fixes issue.
i don’t see an issue unless your experiencing some type of drivability issue
 

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Hear we go again ,,In past posts several members thought they may have installed there fuel pump dry,, and they did...If I was to install an electric fuel pump again I just might give it a dose of lubricate, What comes to mind is the product used in air guns, hammers, torque wrenches ..It is a light lubricant , made for a job like this,, give it a squirt and let it drain into its self , if it still runs let us know.?? The Gov Holmes A shot of air into pump behind the Air Gun lube,, very light would be my method of install ... Any experts out there ?
 

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Ok, to the last post, it is a diaphragm pump lubricating it will do nothing for it. To the original post, the pressure should be checked between the pump and regulator. The engine is between the pump and regulator. You don't need to check or worry about the pressure coming out of the regulator, that is just extra fuel returning back to the tank. In all actuality if you are checking it this pressure should drop when under load significantly as when you put the engine under a load it's using more fuel and returning less to the tank.

So simple answer is, if you are measuring the fuel pressure of the return coming out of the regulator and it drops significantly when under a load. Then everything is working correctly cause the engine is drinking all the extra fuel.
 

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it is a diaphragm pump lubricating
Vick - The OP stated in the opening post that he has upgraded to the efuel system like on the later 7.3 powered trucks. So he has no diaphragm pump anymore.

Cj
 

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Vick - The OP stated in the opening post that he has upgraded to the efuel system like on the later 7.3 powered trucks. So he has no diaphragm pump anymore.

Cj
Yeah I know, the super duty electric pumps are an electric diaphragm pump. The aftermarket pumps like air dog, dad's, etc are gerotor pumps, but the stock Bosch style, walbro, etc are electric diaphragm pumps.
 

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My stock Bosch from Riff Raff is identical to stock pump removed from truck ...They are not diaphragm units ..Not being an expert in this field , one would wonder if you fell off the wagon and bumped your head ?" Have it checked " This is why were hear , having fun right ?? The Gov Holmes
 

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Discussion Starter · #19 · (Edited)
I’m reading a lot of the posts and also a lot of sarcastic posts I am a little disappointed in them. I joined this site to receive support and. Constructive feedback and not treat me like an idiot.

UPDATE:
Replaced the pump and psi returned to normal but truck was still stalling. Come to find out pump is constantly running and does not do the normal 2-5 second prime and turn off. After much testing it seems to be that the EEC has failed and that has been the issue all along. It basically burned out the other pump staring the engine of fuel. I have sent in my PCM to be tested and I’m now waiting for it to arrive.
 

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EI Toro Your friends are the ones pushing fun at you Just think of all us guys out here reporting in at the tavern making goof ups on our coraspondence ..??? Keep the cards and letters coming ,your hanging out on this Post has ben good info , one must jog the thought and memory on these topics ,, this is one of those fun times... The Gov Holmes
 
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