MillennialTrucker93

Boost pressure under full load when the computer isn’t kicked is 30-35psi. When the computer kicks it cuts everything in half. Power/ boost everything. Me and the local dealer are leaning towards a phantom EUP issue that’s kicking the computer out under full throttle but not throwing any specific codes. A few hit’s on 2 injector eup’s but I guess you get what you pay for and can’t rely on anything rebuilt now a days. I can’t even buy EUP’s new. 

On 10/20/2021 at 7:05 AM, Vmac3 said:

What is the boost pressure when the engine is under load? I have seen boost pressure sensors cause this issue as well. 

V

On 10/8/2021 at 5:34 PM, Joey Mack said:

pressure should stay steady at around 100... 80 is ok, but 'steady' is key...the pressure drop/change may be the regulator in the pump.  I think it's in the pump because you may not have a fuel return line coming out of the block around #4...  My guess is the fuel lift pump is in the filter assembly inside the right front corner of the engine...  jojo

So did some digging and found the part you were talking about out of the block but my local dealer and anything I could find on this  valve only says 54psi +-7psi relief/check valve. The part number is 691GC228M2 valve. 

On 10/8/2021 at 5:34 PM, Joey Mack said:

Yes it is the secondary filter/ pump assembly mounted to the motor. I do also have a return fuel line coming out of the block at #4 could something be wrong there?

Ok I got some fuel pressure numbers for someone to take a look at

Idle fuel pressure 60psi

at 1600rpm no load 75psi

at highway speeds 1600rpm full load I’m getting a drop down to 60psi and holding. I let off the throttle back up to 75 close to 80psi. 
its stayed consistent throughout the whole day of work 

is that pressure drop normal???

Thank you for the pressure ranges. I’m going to test them this week however my fuel pump is on national back order due to supply shortages. I’ve been tinkering with other things. I’ve also heard that the old fuel lines may close under full throttle prior to the pump. Just changed all the filters this week as well. Nothing in the primary filter before the pump but the secondary filter after when I dumped it out was fairly gross looking. Light grey and dark looked like

On 9/3/2021 at 1:07 PM, Macktech20 said:

I would check fuel pressure off of the fuel pump, I've had a couple of those engines that did the exact same thing you're describing and it was caused by low fuel pressure. Are you having multiple unit pumps code at the same time?

Since I replaced all 6 pumps last year only 1 has come back with a code. Faulty rebuilt pump got a new one under warranty. Now it’s acting like it did with a eup throwing a code but no codes Active or inactive. Seems to do it in the higher rpm ranges more often. It’s like lifting my foot off the pedal half way then back to full throttle does it with the cruise control and without so can’t be the pedal which is new anyways. I got a fuel pump on order but back ordered as usual. It’s not missing and running smooth other than that

Got the computer flashed and changed nothing. No codes present or inactive as well. I’ll replace the pump next. It’s something causing the computer to kick electrical for sure just not any codes. Just can’t find it. 

UPDATE: I went to have the computer checked again and no inactive code now for EUP. But the motor keeps dropping in and out. I read somewhere that this may be a communication issue between the ecu and eup called a BIP? Anyone ever heard of this. Assuming it may need flashed?

On 10/31/2017 at 10:18 AM, Mackpro said:

Yes, if one of the speed/timing sensors go out , you have to crank the engine about 6-8 seconds before it starts. 

Would this cause an engine endspeed code or something like that on an ai400? If a sensor is bad would it or going bad would it cause a limp mode. My code was inactive when we scanned the computer after clearing the computer a few days prior. 

I’ve seen that in brand new 2016 granites. I think your good.

I’m looking for some diagnostic information on my 2005 Cv713 Ai-400. Recently it’s been going in and out of limp mode a lot and it seems to be getting worse. Last year (2020) I replaced all 6 EUP pumps that greatly woke the engine up from the dead after I bought it and about 5 months later I’m starting to get abnormal frequency and pulse codes on specific pumps. 1 at a time I’ve been swapping with newly rebuilt pumps under warranty however Rochester diesel is saying this is rare to have so many fail. I’m looking for ideas that would simulate a bad eup or cause them to prematurely fail in the computer but be something else. After replacing individual eup’s the problem moves to another one. I had all 6 programmed into the computer originally last year and months of 0 problems however with the constant issues I’m having now with this limp mode and pumps I’m hesitant to keep making appointments down Mack to get the next replacement programmed. And when I say constantly in and out of limp I’m saying pulling a hill “while it’s not specific to hills” about a mile it hits roughly 4-5 times for about 3 seconds a piece. I’m getting frustrated because pumps are not cheap even rebuilt so I’m looking for ideas before I’m out of options.