HELP! Bogs down on hills in heat

[sassy's tahoe]

Ok.. maybe someone can help me before I take my tahoe out and set it on fire... Tahoe runs fine, except on long trips. After about half a tank of gas, and a long trip, it starts to bog down at acceleration. It acts like its losing fuel. The more I accelerate, the worse it gets. BUT if I stop and kill it for about 15 minutes, then it will act fine. So far, this has happened only during hot weather but Ive never taken a trip in the cold.. I just bought this tahoe used not too long ago. NOW, when this all happens, I can tell you the temp gauge is running temp of about 193 degrees. The battery levels are normal at about 14 amps. My oil guage is somewhat normal of 40-50 readings. (fuel guage never has worked but I use my OD reading to stay on top of it.. its usually around 140 miles after filling up when this all happens (give or take a few miles). For my tahoe thats just under half a tank of gas.
NOW.. weve changed the fuel filter, fuel injectors, replaced all gaskets at manifold (while doing injectors), fairly new battery, supposedly new fuel pump (from previous owner and isnt very old), new plugs/wires, new temp sensor, new thermostat.
Everything Im reading says my fuel pump is the culprit... does anyone else have this issue and know what to fix next?

---------- Post added at 07:17 PM ---------- Previous post was at 07:14 PM ----------

Oh, new radiator and hoses, new oil coolant lines (including tranny coolant lines).

 

[SunlitComet]

it is possible something on the pump body might be broken and sucking in air at a given level but i would strongly suggest you have it pressure tested first. by any chance you have strong odor of gas at the same time?

 

[Misago208]

It may seem like you're asking other for help, but i'm starting to look for a Tahoe or Yukon and this is absolutely key information for checking out prospects.

Thanks for helping me!

It isn't mentioned in the post, did you get the evaporative control system -- and particularly the gas cap -- checked? Maybe gas tank vent is plugged?

+1 on fuel delivery problem. The computer gets inputs from a number of sensors and the way the problem is delayed makes me think the computer thinks something's happening that isn't. Or maybe a physical restriction -- takes a while for vacuum to develop in the fuel tank.

Since you've had the injectors replaced I'm guess your mechanic has a scanner to read the car's Diagnostic Trouble Codes ("DTCs") Do you get a Check Engine Light? And even if you don't there may be Diagnostic Trouble Codes ("DTCs") saved in the computer.

I'm just going off my other Chevy background -- hang in there -- I had a miss and Check Engine Light on my 99 Blazer that only happened on one hill on the way to work at just the right RPM and speed. Sparking Plugs it was. Working fine now.

---------- Post added at 09:00 AM ---------- Previous post was at 08:43 AM ----------

Just another thought.

Some of the posts in the other tech forums suggest that OEM fuel pump is a better choice that aftermarket replacement fuel pumps.

It goes something like, "...replaced aftermarket pump twice, then replaced with GM OEM pump and problem was fixed..."

Since your fuel pump was replaced by the previous owner it's origin and background are kind of up in the air.

I realize you've put a fair amount of money into the problem already and there's no telling if this will fix it or not, but something to keep in mind for "Plan B".

Vincent

 

[KJMac1071]

It may seem like you're asking other for help, but i'm starting to look for a Tahoe or Yukon and this is absolutely key information for checking out prospects.

Thanks for helping me!

It isn't mentioned in the post, did you get the evaporative control system -- and particularly the gas cap -- checked? Maybe gas tank vent is plugged?

+1 on fuel delivery problem. The computer gets inputs from a number of sensors and the way the problem is delayed makes me think the computer thinks something's happening that isn't. Or maybe a physical restriction -- takes a while for vacuum to develop in the fuel tank.

Since you've had the injectors replaced I'm guess your mechanic has a scanner to read the car's Diagnostic Trouble Codes ("DTCs") Do you get a Check Engine Light? And even if you don't there may be Diagnostic Trouble Codes ("DTCs") saved in the computer.

I'm just going off my other Chevy background -- hang in there -- I had a miss and Check Engine Light on my 99 Blazer that only happened on one hill on the way to work at just the right RPM and speed. Sparking Plugs it was. Working fine now.

---------- Post added at 09:00 AM ---------- Previous post was at 08:43 AM ----------

Just another thought.

Some of the posts in the other tech forums suggest that OEM fuel pump is a better choice that aftermarket replacement fuel pumps.

It goes something like, "...replaced aftermarket pump twice, then replaced with GM OEM pump and problem was fixed..."

Since your fuel pump was replaced by the previous owner it's origin and background are kind of up in the air.

I realize you've put a fair amount of money into the problem already and there's no telling if this will fix it or not, but something to keep in mind for "Plan B".

Vincent

I have heard of this with the cheap aftermarket pumps, this exact thing!

Sent from my SM-N920V using Tapatalk

 

[gin_road]

Make sure your catalytic converter is not trying to stop up.