Failing lift pump cause high egt's?

[mcsinfl]

a little background. a few months ago my water pump went bad and I had the dealer replace under warranty. Since then, my egt's seem to be running higher than normal. Usually without a load, didn't matter how hard I mashed the pedal, egt's would only climb 50-100 degrees, hardly ever going over around 650. Now the egt's will climb to 800-900 degrees. well this morning i got code 0628 (lift pump failure). I'm wondering if the lp was going bad these last couple months and the truck has been running lean, causing the high egts?



Another quick question regarding replacing the fuel pump. I kinda made up my mind that I'm going to buy the replacement from geno's rather than have the dealer change to the in-tank pump. thoughts? or should I just have the dealer do it as i'm still under 100,000? new pump/filter around $200. I'm thinking the dealer is going to charge me $100 to diagnose and then $100 deductible

 

[osiris]

If you are willing to spend the money then I would go ahead and get a good pump. Fass, Airdog both have water/air separators and the raptor is an excellent pump. I would think that the failing pump could contribute to your higher temps, are you mounted pre or post turbo? Once I stopped pulling my fuel pressure down to 0 with my raptor I think I lost around 150-200 degrees when I am at WOT

 

[mcsinfl]

osiris, thanks for the input. I'm post turbo. 150-200 degrees seems about what i'm seeing at WOT. I'm hoping that's the problem and not something else



I'm more than willing to spend the money on an upgrade, just don't have the these days... so it's a stock replacement for now. One of the reasons i don't want to go in-tank is for future upgrades to fass/airdog

 

[dan.poitras]

Invest in a transfer pump pressure guage and take the guessing out of the equation.

More fuel = higher exhaust temp

less fuel = lower exhaust temps

 

[PGreenleaf]

If you got a bad lift pump, means the injector pump must gotta pull more ,means less fuel, means LESS heat NOT MORE heat. Only way to check lift pump is measure lift pump pressure at various RPMs.

 

[mcsinfl]

i agree with you guys on the fuel pump gauge. i've been wanting that, a rail pressure gauge, then transmission, smarty, injectors, etc etc... but as of right now I have to make due with what I have as funds are tight. i can only afford to fix the fuel pump.



i know the equation more fuel equals more heat, especially without enough air, and less fuel less heat. but is it possible that, like a gas motor, if they are too lean they aren't getting enough fuel to cool/lubricate and can run hot? Or is that just not the case with diesels? is it always less fuel equals less heat?



if replacing the fuel pump doesn't fix my egt problems, then I've got something else going on that I'll have to diagnose. I guess I'll know in a few days when I get the new pump in.

 

[RShipp]

In response to your lean theory, you can't run a diesel too lean. A diesel engine alway takes in 100% of the air all the time. There is no thottle body to regulate the air intake, hense why diesels don't create vaccum. If you run it too lean it will just quit running.