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power and performance issues

D

DieselDonutz

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Location
Carlisle Pa
Hi Everybody!! it has been a few months since I have been on here. I have been working steady on my truck. last time I was here I was looking for help with my truck ( had just bought it at the time). it had an issue when after it warmed up and not just operating tempature but running for 30min or so, or if I got on it a little, or tried to pull something, it seemed to lose power. it suffered from slow take off, and it had trouble maintaining 65 to 70 on the highway. the engine seemed labored. and also the end of the peddle seemed to cause it to bog. started great, didnt seem to miss at all. didnt stall. It turned out it had a blown head gasket. I since then put brand new heads on it, replaced the injectors, glowplugs, pmd, turbo (hx40ii) added a custom cold air intake, replaced the exhaust with a 4" turbo back, added boost, egt, and fuel pressure gauges, and added a second liftpump. well guess what, I still have the same issue. I am at my wits end. I dont know where else to look. the truck seems to run a little bit better as now it can hold 70 mph unloaded but still bogs at wot and still suffers from slow take off and labored engine at times. sometimes it seems to run well but any time I put it under load it seems to provoke this issue. I get no codes. egt are 300 degrees during normal driving, boost is set to 10 psi (currently) and fuel pressure fluctuates between 10 psi to 5 psi at wot. I have changed out the pmd with 3 different ones with no change. I have in my sig, that I upgraded the ecm with a new heath diesel but it hasnt been installed yet since it is on its way in the mail. I am hoping maybe on a chance that the current ecm may be bad but I am feeling pretty depressed at this point and am thinking that is not the issue. I am really stuck at this point and could really use the help of some seasoned 6.5 diesel owners out there. has anyone got any advice that might shed some light on an area that I havent checked into yet. If so please I am at you mercy!!
 
Try the tune as the factory tune will defuel with high IAT or boost.
 
no, the timing has never been set (atleast not by me) I dont even know how to do that on a diesel. Sigh... I guess that is possible. Does that need to be done with a scanner tool?
 
I second both of you. The stock ecm will de fuel and you need to know what your timing is. You also want to see what your fuel rate is at idle. a weak pump will not deliver enough fuel at WOT
 
Where did you tee into the fuel line for the gauge? best place is just befure the IP inlet.

I don't think the 10 PSI boost is an isue.
Verifying if the timing is correct is a must.
Having said that it might be your IP has an issue.(possibly the steppermotor)
I have the same bog down with my 98 as you have but only with a cold engine and mine will clear up after a mile or so on the road.
Mine has def an IP isue
 
I tied in the fuel gauge directly right before the injector pump. I am getting 10 to 15 psi at idle and 5 psi and wot. I got the new ecu in today and so far it seems to be running great!! I havent really drove it enough to say for sure it isnt going to act up but I should know for sure in a few days. if it doesnt act up I guess I am going to have to assume that it was the stock programming. As far as the stepper motor, I was hearing about that being an issue for some ppl. is that changable if it turns out to be or is just one of those things that you mine as well just change the ip?
 
I am running 2 lift pumps currently which are supplying about 15psi. My fuel pressure gauge is connected about 5 inches of fuel line before the ip inlet. I dont have a clear tube on the return. What would I be able to learn from having the clear tube on the return? I would like to know. if it is important, I will add it. I wanted to mention again that the truck is still running great with the new tune. I am starting to wonder if something was wrong with the old ecm. I did not have them program my stock ecm. I sent them another one that I had on hand. I also wanted to add that if I have strong fuel pressure right before the ip that would exclude a dirty tank sock right? I mean if I have good pressue up to the ip then anything associated with fuel delivery could be ruled out imo. am I wrong on that?
 
so if I have a clear tube on the return and it shows air bubbles then does that just mean that I need to bleed my fuel lines or does that mean there is a greater issue? the only way I know of bleeding the fuel system is by cracking the bleeder on top of the filter. could someone please enlighten me on this.
 
It would point to a pin hole in the supply line, pre LP as long as the LP is working. The IP can suck fuel so if the LP isn't working the leak could be anywhere.

There will be an air bubble that stays at the top of the line so don't worry about that.

The way you describe your truck now, likely all is well.
 
If you are running good I stand by my 1st post - the factory tune did not like the high boost and was cutting fuel. The tune (new flashed ECM) fixed it.
 
DieselDonutz said:
I am running 2 lift pumps currently which are supplying about 15psi. My fuel pressure gauge is connected about 5 inches of fuel line before the ip inlet. I dont have a clear tube on the return. What would I be able to learn from having the clear tube on the return? I would like to know. if it is important, I will add it. I wanted to mention again that the truck is still running great with the new tune. I am starting to wonder if something was wrong with the old ecm. I did not have them program my stock ecm. I sent them another one that I had on hand. I also wanted to add that if I have strong fuel pressure right before the ip that would exclude a dirty tank sock right? I mean if I have good pressue up to the ip then anything associated with fuel delivery could be ruled out imo. am I wrong on that?
Click to expand...

What LP's? why two? I ask because maybe the second was added to raise PSI, compensating for a dirty sock? Also if an aftermarket FSU was installed it will have the wrong sock on it and clog much easier.

I've had two different times when a blocked fuel line presented problems very simular to yours, but I did not have a fuel pressure gauge on either one at the time.
One was a dirty sock and acted just like a bad PMD. Other was a bocked supply line between LP and FFM.
Its cheap and easy to blow them out to confirm that potential problem. If you do blow them out, do it in a clean white bucket so you can see what comes out. Before blowing air back to sock remove fuel cap.
 
Is the clear return line tubing 1/4 ID? or 5/16. Headed to store to get some later.
 
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