Good news and bad news. Good news is my pump and other riffraff stuff showed up today.

Bad news, swapped the pump in, so far no change, going to do some driving here before work and see if it changes anything, but I'm not hopeful. Also, while pulling the feed line off the old pump I banged up my left elbow pretty bad. When I first hit it, it felt like a funny bone, but within about 10 seconds my ears were ringing. That's stopped now but I have about 25% of my range of motion where my arm has no strength. I don't know what to do with this thing anymore.

Baatzy

 

Were you ever able to hook 12 volts directly? Sorry to hear about the arm

 

did you ever talk to ISSPRO about a new sending unit. Could be just a bad sender all along and not a fuel pressure problem. Just a thought. Do you have a mechanical gauge? Might be worth it to verify it's a real problem.

 

Not while the pump was in the truck. I couldn't find any way to disconnect the wires from the pump without having the pump out of its bracket. I suppose I could hook 12v to it now but I am almost completely sure it would just sit there, pumping fuel like a champion.

Baatzy

 

Like Paul mentioned, and I think I wrote earlier in this thread, I destroyed an ISSPRO FP sending unit in about 120 miles. They told me that the earlier model 7.3 Powerstrokes have a reputation for doing this.

 

I may finally be getting to that 120 mile mark, but I don't think it is the FP sending unit. It seems to keep working, at least it reads like I would more or less expect, and voltages are good.

 

Do you have a mechanical gauge you can tube up to rest on the cowl and compare the mechanical to the ISSPRO while playing around with various driving conditions?

 

Baatzy, PM sent

 

Where do you have your FP sending unit connected? Got a pic?

Edit to add:

Have you serviced your fuel bowl and parker fittings? Pulled the filter bowl and dumped and cleaned it all?

Serviced the fuel bowl drain?

Fuel pressure regulator? Checked the spring? Torn gasket? Gunk built up in it?

You have a FRx installed or other regulated return?

 

No mechanical gauge here, thought I would save myself some money and just get a nice "permanent" gauge for the interior. Well, so much for that idea. Pretty sure my gauge is working correctly though. Although as soon as I say that it will quit working correctly, UNTIL I buy a mechanical gauge, then it will resume to working normally.

My sending unit is mounted on the port just to the rear of the two ports for the lines going to the heads, using a horizontal RiffRaff adapter.

3 or so weeks ago now, I pulled the fuel bowl and did a complete rebuild using the kit from RiffRaff. Replaced the fuel line sleeves with the new ones. Dumped the maybe 3 specks of dirt out of the bottom of the bowl, then cleaned it up the rest of the way.

I have a few ideas of things it could be, shouldn't be, but could be. I am going to take a break from the truck for tomorrow. Hopefully be able to meet up with Rich Wednesday or Thursday. Might take a look at it then. In the meantime I am open to any and all ideas about this thing.

Baatzy

 

Be sure to check that fuel pressure regulator

If it doesn't provide back pressure to the line before the return, no pressure in the fuel rail, it just all runs back into the tank...and may even try to pressurize your tank

I don't know how likely that is to happen, but it would explain why you had Zero psi when not using the tank and pressure when using the tank. Not sure how else that could happen. (Reverse, sure, but not this way)

 

I'm only in the fortunate position of having one available because my oldest son ran his truck with one zip-tied onto his cowl for a year or so after fighting fuel pump issues, and when he sold his truck, he handed the long-hosed mechanical gauge to me, and it sits on the shelf in my garage for any troubleshooting efforts for which I might need it. I guess I should carry it oin the tool bag in my truck for "side of the road" scenarios, but having a brand new pump and freshly inspected and leak-free fuel supply lines, I'm leaving it in the garage for now.

Hope you discover your solution soon. I know how frustrating a dragged out problem can be.

 

Pete, what did your son determine the fuel pressure problem was?

Baatzy,

When you stop by we can swap the sending unit & gauge out of my excursion into your pick-up. should only take 10 minutes.

I have a mechanical gauge and a spare fuel bowl adapter you can use. Might need to by some hose or a fitting or two to make it work. But you can run both until you figure it out.

But for the 5 hour ride home, I would disconnect the wires at the back of the gauge and cut 1/2" off then reinsert them to rule out a crappy connection.

 

Did you get a chance to install the fuel press reg housing & spring I mailed you?

 

Looking back now I wish I had spent the 50 bucks or so for the gauge and all the fittings from work, instead of the route I went.

I forgot to mention that I do have the FRx installed, I didn't clean it when I had the bowl out specifically, but I do remember it looking fine. No obvious goo, gunk, or other "stuff". I looked for fittings so I could remove the FRx and reinstall the stock FPR, but I couldn't find them at work and haven't really been able to look elsewhere, so I haven't gotten that done either.

The worst part about this whole thing is its lack of being a real issue. I can sit here and watch the gauge rise and fall, rise and fall, idle at 65, fall to 40. There seems to be no effect on the trucks performance though. So I can sit and watch my truck not behave right according to the data, but seem to run fine. Some may remember I originally started down this road because of a severe lack of power issue I had driving back to Rapid in late December, and I was hoping that a fuel pressure issue might show itself. Well, it has on the gauge, but other than that I haven't been able to reproduce anything like rough running, lack of power, maintained low pressure, or anything else.

Baatzy