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Fuel issue causes truck to stall, dangerous situation

So far, I have a small fortune into fixing this / related problems. I’ll state what we’ve done and what is currently happening. I’ve taken it to my normal mechanic several times, I’m looking for additional opinions because they basically have no idea. This is on our 2003 Chevy Tahoe, my wife’s daily driver, and what my kids are normally riding in. It only has about 60K actual miles on it and is a flex fuel model, if that matters.

Originally, the truck would have trouble starting. Cranking, but no ignition. Waiting a a few seconds, try to crank again and it would start up. This went on for about a week and then it stopped cranking cranking at all. Had it towed to our mechanic. PCM B fuse was blown. Replaced PCM B Fuse (20A) and it blew again after starting. It died while trying to idle. They did some voltage drop tests, seemed good. I’m not sure they did any current tests at the fuel pump which is on that fuse. Ended up there for 4 days (yes, lots of labor) and leaving with no real clue, but a 25A fuse would work.

A week later,we were still having problems (but my memory is a bit shady). The mechanic did some pressure tests and bleed tests and said that our fuel pump was outside the specified pressure and needed to be replaced. Dropped tank, replaced pump and sending unit with a new AC Delco, replaced fuel filter. Took it home, it seemed great.

Then my wife called me and said her truck was dying at every stop sign. When she got home, I verified, the tank read 1/4 full, truck would die at almost every stop. Truck would die slowing from 45 to 20 mph to make a left turn. This was dangerous, took it back to mechanic. Mechanic couldn’t find an issue, but figured it was the sending unit. Replaced the part under warranty, didn’t charge me any labor. They thought that we were really empty at 1/4 tank and had a bad sending unit, but that doesn’t seem to be the case now.

I know, TLDR, sorry. Here’s the basics of where we are:
Truck runs fine when above 1/4 tank of gas.
Truck suddenly dies when stopping or slowing down when the gas gauge reaches 1/4 tank. Starts right back up with no struggle, otherwise runs fine when tank is low…
Tank never empties. We can get a maximum of 16-17 gallons in it. The tank is 26 gal, and we previously have filled it with as much as 24+ gallons in one filling. The gauge needle barely touches F when full, and basically the car is underivable when it reaches 1/4.

I’m really stumped on what the cause may be. I’ve given up on theories and looking for opinions, theories, research papers, or GPS coordinates of a good cliff. TIA.

This is apparently a known issue:

You’ve already replaced the pump/sending unit, but did you have the strainer kit for the fuel pump inlet replaced as well? That’s part of the recommended fix. If the old strainer is restricting the gas flow, that may be part of the problem.

Below is a quote from a 2004 Tahoe owner from the above link:

“I came here to find out why my wife’s 2004 Suburban would not start. Also, she complained that the fuel reading was inaccurate. Sure enough, I put 5 gallons in the tank and it started. I then renewed my AllData account and bingo. I found it.”

"Bulletin No.: 04-06-04-012C
Date: March 03, 2006
TECHNICAL
Subject:
Vehicle With Flexible Fuel E85 (RPO L59) Will Not Start, Loss of Power, Poor Performance and/or Fuel Gauge Reads Inaccurate/Incorrect (Replace Fuel Pump Strainers AND/OR Redesigned Fuel Level Sensor)

“Do not replace the fuel pump. GM now makes replacement components to fix the problem so that you don’t have to replace the expensive pump. You need to replace the old fuel level sensor in the tank with the newly redesigned one. Also, replace the fuel pump strainer (sock). For all of you without access to a TSB (Technical Service Bulletin), here are the part numbers and info. Good Luck.”

19122083 Strainer Kit - Fuel Pump Inlet
88966958 New Fuel Level Kit - Tahoe and Yukon w/RPO L59**
88966959 New Fuel Level Kit - Suburban and Yukon XL w/RPO L59**
**Note: RPO L59 is the Flexfuel Engine

“So far this has completely fixed our Suburban. Price for 088966959 was $181.54 list. Price for 019122083 was $75.43 list. I was able to get my neighborhood mechanic to drain, drop, and flush the tank and replace the parts for $200. Total repair:$456.97. After he finished, he put just over 10 gallons in the tank and the gauge read 1/3 full, which was perfect. Then I ran the tank down to 1/4 and left it overnight. It started fine the next morning. Then I ran it down to 1/16 of a tank on the gauge. This equates to about 1.5 to 2 gallons of gas in the tank. I then filled the tank with 29.5 gallons. This means that the gauge is reading accurately since the tank hold 31 gallons.”

Thanks, I will ask the dealer to look at that TSB. That is, if my wife doesn’t set it on fire before the dealer has an opening next week.

@mike__b:

Fuel issues, at low fuel quantities, when you brake, accelerate, or turn is a pretty “classic case” of a bad fuel pickup/sock.

The fact that your current mechanic spent so much of your time and $$ “whiffing” on this problem makes me skeptical of his abilities. Sounds to me like he’s more of a “code reader” than mechanic: someone who plugs in the OBDII reader and does whatever it tells him–and is at a loss when a problem comes up, without an associated code, that requires actual deductive reasoning.

I’d go elsewhere…and (if it indeed turns out to be the sock) go to the manager of the shop and make noises about getting some of your money refunded!

Actually, the “pickup” is exactly what I have thought as a possible cause. However, I’m skeptical of it because it’s an instantaneous loss of engine power. If the pickup grabs air, is all pressure from the pump to the fuel rail immediately lost? Is there not a series of check valves that would maintain the pressure in the fuel lines for a momentary pump loss?

I’ve gone to the mechanic for years. It’s a small shop, just a father and son. But at this point, I think this is a sore issue for both of us. They don’t charge me to diagnose, but I do feel like the labor on the PCM B fuse blowing was expensive. I just don’t have time to do all my own repairs any more, and I have no experience with replacing a fuel pump / sending unit.