I Know, I Know... Not another P0300 Question

[Tonyv__]

Hi calsdad. Thanks for the input. I did change the rusted out fuel filler neck as soon as I realized that it was perforated. This was the second time that I changed it, actually. The salt and brine in my region is extremely destructive to vehicles. I’ve had the tank off of this truck a couple of times to replace the fuel pump. The 1st time the pump went, the truck just died on the freeway. The second time I changed the pump was because the fuel level sending unit went bad, but the pump worked great. I’m just trying to use up the gas to get the level low enough to manage The tank removal. But the truck is running so erratic, that I’ll probably end up trying to syphon it out instead. The funny thing about the codes is, that there haven’t been any codes since I cleared the P0300 code weeks ago. Ocassionally I’ll get a flashing CEL that simply goes away, leaving no code. The only pending codes that I get are the 02 sensors, but I believe that’s from the lean condition that occurs when the truck stumbles under acceleration and surges at the 3,000 rpm range, going nowhere.

So on my 96 Silverado I found it much easier to unbolt 6 of the 8 bed to frame bolts. Then loosen the last 2 bolts closest to the tailgate.. unbolt the filler neck. Disconnect any grounds or wiring… Then jack the bed up kind of like a dump truck… i achieved this with like 3 2x4s cut to various lengths. I would position the jack with a 2x4 cut between the jack and the bed of the truck. Jack it up until the jack maxed out. Cut a length of 2x4 from the ground to the bed and wedge it in. Then lower the jack cut another piece of 2x4 from the jack to the lifted bed. Jack again then cut another piece to keep it propped up. When you get to the heigh you want. Cut 2 pieces of 2x4 and make sure they’re wedged good or even screw them into the undercarriage of the bed….

The more I explain it. It sounds crazy but I’ve done the pump on a few trucks this way.

 

[Gustavo47]

I had a similar problem with my 04 Denali for a loooong time. Replace all kinds of part: relays, fuel pump, throttle body, etc. Ended up being the crankshaft position sensor. I got it to throw a code by cranking it for 8 seconds 3 times consecutively without the fuel pump relay in (so that it wont start). Later reverse engineered it in my web search and found a discussion about it. Put in a factory CSPS and it did not happen after. Worth a try.

 

[hushko]

So on my 96 Silverado I found it much easier to unbolt 6 of the 8 bed to frame bolts. Then loosen the last 2 bolts closest to the tailgate.. unbolt the filler neck. Disconnect any grounds or wiring… Then jack the bed up kind of like a dump truck… i achieved this with like 3 2x4s cut to various lengths. I would position the jack with a 2x4 cut between the jack and the bed of the truck. Jack it up until the jack maxed out. Cut a length of 2x4 from the ground to the bed and wedge it in. Then lower the jack cut another piece of 2x4 from the jack to the lifted bed. Jack again then cut another piece to keep it propped up. When you get to the heigh you want. Cut 2 pieces of 2x4 and make sure they’re wedged good or even screw them into the undercarriage of the bed….

The more I explain it. It sounds crazy but I’ve done the pump on a few trucks this way.

Tonyv, Thank you for the advice. While the bed removal procedure would have worked swell for my ‘02 some years ago, it’s actually rusted so badly that I’d be concerned that the bed may not come off in one piece. In fact, it’s so eaten away, that I’ve even considered just cutting a hole through the bed to gain access to the fuel pump My goal is to get this truck through one more NE Ohio winter and possibly into some of the summer months. I’ve got about 355,000 miles on it and had it since new. And today is the 1st day of snow, of course. And the salt trucks have already been out……

 

[hushko]

I had a similar problem with my 04 Denali for a loooong time. Replace all kinds of part: relays, fuel pump, throttle body, etc. Ended up being the crankshaft position sensor. I got it to throw a code by cranking it for 8 seconds 3 times consecutively without the fuel pump relay in (so that it wont start). Later reverse engineered it in my web search and found a discussion about it. Put in a factory CSPS and it did not happen after. Worth a try.

Thanks for your input. I considered the crank sensor, but then again, the truck starts right up every time and idles smooth. It runs perfectly up until 2,000 rpm or so, and then cuts out, surges and pops through the intake when the accelerator is depressed. My understanding is that the crank sensor would cause hard starts and poor idle. Who knows, it may end up being the sensor afterall. However, since discovering the fuel filler neck being rusted off and having driven through a hard rain with rust-perforated wheel wells when all of this began, I’m going to try and rule out water and rust infiltration within the fuel pump 1st. In fact, I’d be pulling the tank today, but I’ve got one of those doggone colds where I don’t even want to get off of the couch :-( Hopefully this week I’ll get the tank opened up and will find out if the fuel pump has been affected/plugged.

 

[Tonyv__]

Tonyv, Thank you for the advice. While the bed removal procedure would have worked swell for my ‘02 some years ago, it’s actually rusted so badly that I’d be concerned that the bed may not come off in one piece. In fact, it’s so eaten away, that I’ve even considered just cutting a hole through the bed to gain access to the fuel pump My goal is to get this truck through one more NE Ohio winter and possibly into some of the summer months. I’ve got about 355,000 miles on it and had it since new. And today is the 1st day of snow, of course. And the salt trucks have already been out……

Ouch that rust is rough. I’m in PA so we see salt too but not this brutal

 

[hushko]

Well, I pulled the tank off of my ‘02 Silverado today. The liklihood of rust scale and water intrusion through the rusted-through fuel filler neck made me think that I should rule out that possibility 1st. The metal flange on the top of the tank is seriously rusted, and after careful de-scaling and removal of the pump, I have iust enough of the four prongs remaining to do one final (very careful) pump install. I ordered the pump and other parts from RockAuto, so I won’t be able to do the install for about a week. I was surprised to find that there were only a few crumbs of rust flakes in the bottom of the tank and no obvious water. I’ll re-post once things are back together to report any changes.

 

[Rocket Man]

Well, I pulled the tank off of my ‘02 Silverado today. The liklihood of rust scale and water intrusion through the rusted-through fuel filler neck made me think that I should rule out that possibility 1st. The metal flange on the top of the tank is seriously rusted, and after careful de-scaling and removal of the pump, I have iust enough of the four prongs remaining to do one final (very careful) pump install. I ordered the pump and other parts from RockAuto, so I won’t be able to do the install for about a week. I was surprised to find that there were only a few crumbs of rust flakes in the bottom of the tank and no obvious water. I’ll re-post once things are back together to report any changes.

I like the little guy on the propane tank looking on and smiling.

 

[hushko]

I like the little guy on the propane tank looking on and smiling.

I was wondering if anyone would notice that. After climbing underneath the truck on a cold wet floor, what seemed like 100 times, clothes inundated with gas from a tank line that decided to pop out of its holding place, and eyes and ears showered with rust flakes, that little fella’s face on the bucket was a comical end to the days work.

 

[hushko]

I took the fuel pump housing apart this morning, only to find a pile of rust and a disturbing looking filter. As crappy as that sounds, heck, this just may in fact be the root cause of the acceleration/fuel pressure drop issue afterall.

 

[Rocket Man]

I took the fuel pump housing apart this morning, only to find a pile of rust and a disturbing looking filter. As crappy as that sounds, heck, this just may in fact be the root cause of the acceleration/fuel pressure drop issue afterall.

View attachment 355614View attachment 355615

That very well could be your problem. Hopefully a new pump assembly takes care of it. Good luck.