81 K10 fuse panel layout

[AuroraGirl]

crank no start while you wait sounds like ignition components or fuel system.
Id open up the distributor cap and see what your module looks like, if its OEM , basically, and id also ohm your coil

Id also ask for a picture of your carb and the fuel line and the fuel pump

 

[RiverRat4]

Hey folks, its been a few since I last posted regarding my issue on crank no start and a seperate issue of parasitic current draw killing my battery if the truck sets for 2 days.

Today I want to focus on the crank no start issue and what headway I have finally honed in on. I/We were immediately focused on electrical issues thinking there was a possible intermittant wire failure or ignition going bad. I went that way because in the beginning of this issue, I began wiggling wires under the dash around the fuse panel with my foot (gently of course) but I did inadvertenty unplug the green blue #10 Ga. wires at a molex connection right by the steering column. I reconnected it and traced it outside through the firewall and I "think" it goes to the transmission? any input on that would be appreciated. However, I began thinking fuel issues and when in a crank no start situation, I would go under the hood and depress the fuel rail schrader valve till it stopped spraying fuel, then the truck will start immediately without issue and run like a champ. So now I am thinking I have a faulty Fuel Pressure sensor, or possibly a breakdown in the fuel vapor reclamation system which I am uncertain is even connected at all since there is no cannister under the hood anywhere. There is a new fuel tank installed and I had to have the tank internal fuel pump re-installed because the original installation messed up the O ring and it had to be reseated. In line with that internal pump, there is a secondary fuel pump along the frame as the line heads to the engine. Any suggestions on where I should start? I am thinking on adding a take off at the scrader valve on the rail and route it to a T valve where one side is the Oil pressure mechanical guage. The oil pressure guage's range in from 0-120 so switching to the fuel side would accurately read fuel pressure which should in in a range around 40-65 psi? At least that will assure me I have good fuel pressure and not low or high fuel pressure since bleeding off the fuel pressure now allows the truck to start without fail.

 

[AuroraGirl]

Hey folks, its been a few since I last posted regarding my issue on crank no start and a seperate issue of parasitic current draw killing my battery if the truck sets for 2 days.

Today I want to focus on the crank no start issue and what headway I have finally honed in on. I/We were immediately focused on electrical issues thinking there was a possible intermittant wire failure or ignition going bad. I went that way because in the beginning of this issue, I began wiggling wires under the dash around the fuse panel with my foot (gently of course) but I did inadvertenty unplug the green blue #10 Ga. wires at a molex connection right by the steering column. I reconnected it and traced it outside through the firewall and I "think" it goes to the transmission? any input on that would be appreciated. However, I began thinking fuel issues and when in a crank no start situation, I would go under the hood and depress the fuel rail schrader valve till it stopped spraying fuel, then the truck will start immediately without issue and run like a champ. So now I am thinking I have a faulty Fuel Pressure sensor, or possibly a breakdown in the fuel vapor reclamation system which I am uncertain is even connected at all since there is no cannister under the hood anywhere. There is a new fuel tank installed and I had to have the tank internal fuel pump re-installed because the original installation messed up the O ring and it had to be reseated. In line with that internal pump, there is a secondary fuel pump along the frame as the line heads to the engine. Any suggestions on where I should start? I am thinking on adding a take off at the scrader valve on the rail and route it to a T valve where one side is the Oil pressure mechanical guage. The oil pressure guage's range in from 0-120 so switching to the fuel side would accurately read fuel pressure which should in in a range around 40-65 psi? At least that will assure me I have good fuel pressure and not low or high fuel pressure since bleeding off the fuel pressure now allows the truck to start without fail.

DO NOT USE OIL PRESSURE GAUGE FOR FUEL PRESSURE.

You need a fuel pressure gauge!

Also, crawl under the truck and look at the pipes coming off the fuel tank, there should be 3 hoses. if you only see 2, then there may be a thing on the tank vent blocking the line, which would be problematic for fuel, undoing the fuel cap would fix this tempoprarily.
Fuel pressure sensor only job is to reduce fuel pressure with vacuum. So unhook and block it to eliminate the possibility, the engine will run rich but it will idle

 

[RiverRat4]

Thank you for your fast and explicit direction. I will examine the truck and report back. It is away for the week but I will get it back next friday. I will pass along the info regarding loosing the fuel cap instead of popping the hood and depressing the schrader valve to relieve pressure. I hope that works as well as the valve, its surely much more convenient.

Thank you again and I will report back

 

[RiverRat4]

ok, got back to the truck and without lengthy explanations, I had to urgently find a "pull a part" junk yard near me to replace the fuel crossover which contains the schrader valve fuel pressure test port. Over use of it to relieve the pressure to allow the truck to start caused someone to bend the insert causing it to stick open thus allowing fuel to spray out anytime the key was on due to the additional fuel pump added to provide the pressure needed. I not only was able to replace the crossover with a functional Schrader valve on it, but believe it or not, I found at the back of the engine on top, going into the manifold was the Fuel Pressure sensor! Not located on the tank as everyone was saying. I nabbed that guy as well and since I was there, I grabbed to Fuel pressure regulator.

In swapping out the crossover, I learned there is only 2 fuel lines not three. one larger (supply) and one smaller (return). With this set up, can it be possible to more accurately identify exactly what year engine this is?

Oh by the way, the hard start is still happening and I still have to bleed off pressure at the schrader to get her to start. I tried the loosening of the gas cap but that didn't change any symptoms.

I did find this tho.... please see the pictures I am attaching. I wonder what this is to?

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[AuroraGirl]

ok, got back to the truck and without lengthy explanations, I had to urgently find a "pull a part" junk yard near me to replace the fuel crossover which contains the schrader valve fuel pressure test port. Over use of it to relieve the pressure to allow the truck to start caused someone to bend the insert causing it to stick open thus allowing fuel to spray out anytime the key was on due to the additional fuel pump added to provide the pressure needed. I not only was able to replace the crossover with a functional Schrader valve on it, but believe it or not, I found at the back of the engine on top, going into the manifold was the Fuel Pressure sensor! Not located on the tank as everyone was saying. I nabbed that guy as well and since I was there, I grabbed to Fuel pressure regulator.

In swapping out the crossover, I learned there is only 2 fuel lines not three. one larger (supply) and one smaller (return). With this set up, can it be possible to more accurately identify exactly what year engine this is?

Oh by the way, the hard start is still happening and I still have to bleed off pressure at the schrader to get her to start. I tried the loosening of the gas cap but that didn't change any symptoms.

I did find this tho.... please see the pictures I am attaching. I wonder what this is to?

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i see a purge valve and what looks like an EGR pipe in that order
Im not sure what the last photo with arrows is

 

[AuroraGirl]

ok, got back to the truck and without lengthy explanations, I had to urgently find a "pull a part" junk yard near me to replace the fuel crossover which contains the schrader valve fuel pressure test port. Over use of it to relieve the pressure to allow the truck to start caused someone to bend the insert causing it to stick open thus allowing fuel to spray out anytime the key was on due to the additional fuel pump added to provide the pressure needed. I not only was able to replace the crossover with a functional Schrader valve on it, but believe it or not, I found at the back of the engine on top, going into the manifold was the Fuel Pressure sensor! Not located on the tank as everyone was saying. I nabbed that guy as well and since I was there, I grabbed to Fuel pressure regulator.

In swapping out the crossover, I learned there is only 2 fuel lines not three. one larger (supply) and one smaller (return). With this set up, can it be possible to more accurately identify exactly what year engine this is?

Oh by the way, the hard start is still happening and I still have to bleed off pressure at the schrader to get her to start. I tried the loosening of the gas cap but that didn't change any symptoms.

I did find this tho.... please see the pictures I am attaching. I wonder what this is to?

You must be registered for see images attach

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there is not a fuel pressure sensor in a late 90s early 2000s Gen 3 LS

If you have throttle cable and EGR, that would be early 2000s iirc

The crossover line doesnt look like the first one, i dont think, but you can date it fairly easy if you just look at the ID stamp/engraving.
Also a send and a return only doesnt make sense, youre probably looking at Send/Vent

The one leads to the canister on the vehicle it came from, the other to the tank. the system would send only the fuel needed, and the pressure regulator was near the tank, which is what returned the fuel in a short loop

 

[RiverRat4]

watching quite a few YouTube vids showing that particular vacuum controlled device and say it is not used for LS swaps. There is a Fuel supply and a fuel return which is modulated by the fuel pressure regulator. I switched out the FPR with another one (used) but same symptoms. I will be testing the return line to make sure there is a patent pathway back to the fuel tank for excess fuel which should prevent the excess pressure preventing the starting unless it is released. I hope I am looking in the right direction.