Ip going out?

[frankenwrench]

I have an ip for a 6.9 on my 7.3 idi and have slowly over the course of a few years went up a flat just tweeking some more power, or at least attempting to. Problem is, haven't ever felt a difference till I put some new stage 1 injectors in and it woke up rather nicely. Today I noticed the truck wasn't scooting like it normally does. Fires up great, no wierd noises, and egts are LOW. Took forever to get it up to even 60 and I run 75 almost everywhere with ease. No smoke to be seen out the tailpipe other than wen taking off from a stop. 60 mph yielded 450 degrees on the egt guage, new auto guage that works wonderfully. Almost no power though. I normally start off in second gear no problem, but now I'm almost stalling in first downhill. Compression range from 420- 435 which I think is still acceptable. Cracked an injection line loose while running and got two soft spits far less violent than what I'm used to and truck died on me! Fired it up and every injector line did the same. Ip is up 4 flats, forgot to mention, and no air intrusion anywhere. Filter stays full even after stalling. DidDid ip literally just clap out almost all at once? Air filter is fine and not restricting anything although my boost numbers are significantly lower than usual across the board. Wot is at 7 were it usually hits 12. Ip? Something else I didn't mention that needs checked/addressed?

 

[IDIBRONCO]

Check your lift pump. Less fuel delivery will give you retarded timing and your pump won't be able to push as much fuel to the injectors. Although it shouldn't be noticeable at an idle while cracking an injector line like you did (it is an unscientific test method at best though).

 

[frankenwrench]

Forgot to mention, I removed lift pump long ago and capped that hole. I have a 105 gph 15psi e pump and regulaters is set at 5.5 psi and it holds it there rather well even under a bit of throttle.

 

[Thewespaul]

Check to see if your return is pressurizing, and check to see if the fuel screw backed itself out.

 

[Garbage_Mechan]

Check to see if your return is pressurizing, and check to see if the fuel screw backed itself out.

What is an acceptable amount of back pressure on the return line?

 

[frankenwrench]

.... Both guages are reading almost the same from the regulator to the guage I rigged up on the return. How is this possible? Idle supply at 5.5 and return is 3 psi. Blew the return line out after removing it from tank and got same numbers. Disconnected return line from tank again and blew through the return fitting on sending unit and free flow.

 

[Thewespaul]

Do you have the return line hooked up from the filter head to the return cap? Ideally you want to see no pressure in the return lines, it’s going to limit fueling.

 

[frankenwrench]

Do you have the return line hooked up from the filter head to the return cap? Ideally you want to see no pressure in the return lines, it’s going to limit fueling.

It is but I also have that fitting on the pump head gutted which really has me stumped. No pressure from return t at back of the engine to tank. Just replaced all the return lines between injectors and from ip to filter head wen I got the new injectors just a month or so ago. No pressure then on return lines and trouble free untill yesterday morning

 

[Thewespaul]

Plug that port on the filter head and see if it makes a difference for you, it’s possible the check valve is sticking open and allowing inlet pressure to bypass to the return

 

[frankenwrench]

Plug that port on the filter head and see if it makes a difference for you, it’s possible the check valve is sticking open and allowing inlet pressure to bypass to the return

Well Holly hell! Worked! Now I just need to un stick it and figure out why it stuck in the first place. With the new tank, shower head, lines, sending unit, injectors, and filters I shouldn't be getting junk in there to jam it up. And my tank is still pristine clean so not sure. Maybe it's just old and out of round or something. Maybe it's just what I get for buying an eBay ip three years ago and thinking I was getting somewhere with it. Idk. Either way, thanks to all of you who responded with advice helping me figure this one out! Truely a group of gentleman, ladies, and scholars!

 

[Selahdoor]

Plug that port on the filter head and see if it makes a difference for you, it’s possible the check valve is sticking open and allowing inlet pressure to bypass to the return

Hey Wes, I forget. Which way is that supposed to flow. Into the filter head, or out?

 

[Thewespaul]

It flows from the filter to the return, glad that fixed it up and it was a simple cheap fix!

 

[IDIBRONCO]

Now I just need to un stick it and figure out why it stuck in the first place.

Or you can leave it plugged. It will make it harder to bleed the air out of your filter when you change it, but after that, it's all good.