15 z06 - buyer's tuner says high side pump is bad

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06-12-2020
DomLS3

15 z06 - buyer's tuner says high side pump is bad

Hey everyone. I sold my 15 z06 to someone last week. He took it to a shop in his area and had it retuned. The shop got back with him today and said they are telling him the high side pump is bad. They said pressure drops from 2900 to below 800 psi around 2800rpm WOT. They said low side is fine.

This seems extremely suspect to me because the buyer test drove the car before he bought it and did several WOT pulls and felt nothing wrong (other than some backfire at one point when he did a pull in 4th gear) but he did 3-4 3rd gear WOT pulls and it ran strong with no issues and I've been driving the car almost daily doing several WOT pulls with no issues. I was in the car when he was test driving it.... If the high side pump was bad surely we would have noticed an issue during 3-4 WOT pulls....

I told the buyer to get back with his tuner and see if they backed up the tune I had in it and if they did any logging with that tune prior to making any changes. It wouldn't make any sense for them to get the car and immediately start making changes without doing a baseline first and get some logging from the current tune so we are waiting to find out what they did and if they did any logging prior to making changes. Also waiting on the log where they say the pump is failing.

Am I crazy to feel this smells odd and that the tuner has likely messed something up? I find it hard to believe that the car has been doing WOT pulls with no issue when I own it, including when the buyer test drove the car, and now all of a sudden the pump is failing after a new tuner gets ahold of it. After the buyer test drove the car, it was loaded on a trailer and taken straight to his tuner with no driving in between.

Any insight would be appreciated and I'll try to provide more info as I get it from the buyer.
06-13-2020
ahmedabri97

What is the mods on the car?
It may be you are out fuel only.
06-13-2020
DomLS3

Quote:

Originally Posted by ahmedabri97

What is the mods on the car?
It may be you are out fuel only.

Definitely not out of fuel. Its full bolt on and upper pulley only. Doesn't make enough power to max out the stock fuel system.
06-13-2020
ahmedabri97

Maybe the tuner is commanding excessive fuel which causes the fuel pump to fall pressure or he messed with something.
Another thing that can cause this issues is when the low side fuel pump fuel pressure is starting to fall which causes a fall in the hpfp.

Let them send you a log with both tunes so we can point the problem.
06-13-2020
Ben Charles

Tuner probably clueless
06-21-2020
Camaro6

If low side has pressure and high side is dropping, look for a kinked line or a line that is restricting flow. Tuner might also be hitting a limit or blowing fuel straight out the exhaust if he doesn't know what he is doing with SOI.
06-22-2020
2xLS1

Quote:

Originally Posted by DomLS3

Hey everyone. I sold my 15 z06 to someone last week. He took it to a shop in his area and had it retuned. The shop got back with him today and said they are telling him the high side pump is bad. They said pressure drops from 2900 to below 800 psi around 2800rpm WOT. They said low side is fine.

This seems extremely suspect to me because the buyer test drove the car before he bought it and did several WOT pulls and felt nothing wrong (other than some backfire at one point when he did a pull in 4th gear) but he did 3-4 3rd gear WOT pulls and it ran strong with no issues and I've been driving the car almost daily doing several WOT pulls with no issues. I was in the car when he was test driving it.... If the high side pump was bad surely we would have noticed an issue during 3-4 WOT pulls....

I told the buyer to get back with his tuner and see if they backed up the tune I had in it and if they did any logging with that tune prior to making any changes. It wouldn't make any sense for them to get the car and immediately start making changes without doing a baseline first and get some logging from the current tune so we are waiting to find out what they did and if they did any logging prior to making changes. Also waiting on the log where they say the pump is failing.

Am I crazy to feel this smells odd and that the tuner has likely messed something up? I find it hard to believe that the car has been doing WOT pulls with no issue when I own it, including when the buyer test drove the car, and now all of a sudden the pump is failing after a new tuner gets ahold of it. After the buyer test drove the car, it was loaded on a trailer and taken straight to his tuner with no driving in between.

Any insight would be appreciated and I'll try to provide more info as I get it from the buyer.

So you sold a 5 year old modded car and the new owner took it somewhere to mod it more? Sounds like his problem, not yours.
06-23-2020
sevinn

Have them check the feed line check valve. Probably the issue.
06-25-2020
Alvin

I agree putting the tune back to the way you had it and see if the fuel pressure returns. I've changed some random things that has crashed the high side fuel pressure. Things that really don't make sense but it happened and it woudl reverse if I went back.

I wouldn't be too hard on anyone. Gen 5's are a complicated thing.