Got a 93 K1500 4wd, 5 speed, with a TBI 350. This is a long one so bear with me...
About Mid November Had a fuel pump go out. Truck sat around till Early Jan before I replaced the pump. I sold it to a friend of mine who lives about 45 minutes from me. It ran fine all the way home and he drove it to work for the next week (about 35 miles round trip).
About 2 weeks is when the real probs began. When ever the truck gets warm, it will not rev above 2k-2500 rpm. if you try to it falls on its face like some one just shut the key off but when you release the accell pedal/linkage it will return to idle, most of the time. Sometimes it will surge, almost die, catch itself, and return to idle or it will do this 3 or 4 times and will then die. Then I have to wait 5-10 minutes before it will start again or it will just crank.
I have no codes on the computer. I have replaced all of the ignition components ( Dist, pick up, coil, cap/rotor, plugs and wires), set the timing, and have read out and or replaced the TPS, MAP, CTS, EGR and Sol. Every thing checked good or was replaced.
It has an MSD 6A box but I dont think thats the prob. Its been in the truck for years and I havent had an issue.
HELP, or I will make someone a good deal on it!! Im tired of throwing parts at it. It just "might" spontainiously combust one night!

 

Hi jerm13,

Welcome to the Chevy Forums.

This sounds like one of two things. Either a vacuum leak(which is unrelated to the fuel pump) or a fuel/evaporative emissions issue.

First, go over all parts of your repair and be certain there's no place you could be sucking air into the fuel system. Do you smell gas in the passenger compartment? Could be a flooded evap cannister or a bad evap filter.

Check your EGR valve carefully, that could be gumming up and causing your symptoms.

Test your system with a vacuum gauge. Go over your intake very carefully to be sure you have no deteriorated or broken hoses. Listen carefully under the hood while the engine is running, you may hear the vacuum leak whistling.. One thing the old guys do to test for vacuum leaks on an intake is to put a small amount of oil at the edge of the gasket surfaces and see if the problem stops momentarily. Then you know you need to replace the offending gasket.

 

I am pretty sure its not a vacum leak. I went over the entire engine compartment visualy and use 2 cans of carb clean on every gasket, hose, modual that are on the truck. I checked the evap tank, purge valve, hoses and found nothing.

I was fed up so I started at the begining. Went and got a fuel pressure gauge and hooked it up before the filter (stupid TBI doesnt have a test port!)and read fuel pressure directly from the pump. As follows:

10psi at idle when engine is cold
8 psi at idle when engine is at norm op temp (not too good)
drops between 3-5 psi when at 2500 rpm and 0 psi at 3000 rpm.

Looks to me that I replaced a non working fuel pump with a half-*** working fuel pump. Does anyone agree? I will keep you all informed. Probly be droping the tank later in the week

 

Update.

So we were getting ready to drop the tank today and found something interesting. One of my "assistants" put the wiring harness for the fuel pump and otherstuff between the tank bracket and frame. It was pancaked. So a little hacking and wacking we got that fixed. Thought we were good to go. Fired it up let it idle for 15 minutes and didnt loose fuel pressure....... until we got out on the road. But the wierd thing is when we lost our fuel pressure we lost voltage to the pump and lost spark from the coil/ plug wires. No I'm really comfused. Does the Hot Fuel Management Relay Thingy controll any of this being fuel and spark related. And where is that little SOB. I cant seem to find it. Someone please at least give me an idea. I know its between the bumpers and the tires

 

have you checked your fuel pump relay in your fuse panel?

 

If you set it on fire, take a video.Also, if you get to that point. I'd buy it off you.

 

Yes i have checked and replaced the fuel pump relay, fuse (it wasnt blown), fuel pump oil pressure switch and just about every other sensor on the feakin truck pertaining to the engine/ ems. A little insight to this thing. Its from the Northeast. Very rusty doesnt even come close. We wanted to jusr replace the cap and rotor but when we took them off, basicly the entire distributor crumbled apart.
So after it dies, I hear the fuel pump running for a second but the pres gauge doesnt move. Then I loose my voltage to the pump and it doesnt come back until I cycle the key 3 or 4 times.

 

She lives again

Finally got a brake from the cold and rainy weather about noon today so we finally got to drop the tank. Found out that the wires for the fuel pump and sender were crushed between the tank and a bed rail and the ground wire was all but seperated from the terminal. The vibrations were causing us to loose the power to the pump. But when I was taking it out, I broke one of the hard lines off at the plug that enters into the tank. Thank god vatozone had a replacment. so we got it all back together, fired it up and it ran like a champ and drove it around for an hour. Then it started to miss at crusing and then really bad under accel. Found out we were losing spark from the coil when it got hot

WOW 2 different things going on at the same time. This thing was giving me nightmares something fearce. I learned a lesson though. Take you time and double check your and your buddies work. It will save you a mean headache in the long run. Thanks to everyone for the feedback.

Jerm