LS Fuel Pressure Issue High Hot (2 Viewers)

[TexasLandCruiser]

I think at this point you need to drop the tank and ensure the supply/return lines are plumbed correctly. You need to make sure the fuel pump strainer is properly attached, and that the whole fuel pump sending unit is properly oriented in the tank. You need to make sure the return pipe is returning back into the fuel pump "well" inside the tank. You then need to take every breather hose off the tank, make sure each one is clear, and make sure the fuel vapor separator is completely clear, including the top vent line that goes back to the vehicle. Then you need to make sure all of the breather ports on the tank are clear.

I almost wonder if someone connected the fuel return pipe to one of the breather ports. With the FJ62 fuel tank, the fuel pump sits inside a baffled "well" inside the tank. The well has small ports to allow fuel in/out. This prevents sloshing, and keeps a steady supply to the well. The return line returns back into the well, so fuel is constantly circulating inside of it. If the return line was plumbed "outside" this well, it's possible for the well to be pumped empty. Which could cause some of the issues you are seeing.

This is good stuff. Tonight I got started on it. I’ve confirmed the return line is going back to the top of the tank where it’s supposed to. I pulled the separator out and dumped alcohol down each line including the plastic separator itself, sloshed it around them dumped it back into a Tupperware to look for junk. Then blow high pressure looking for debris. I’ve got the tank about halfway out and had to leave. I see one abandoned line on top of the tank but don’t know what it fed. Need to look it up. Here’s some pics, the gas I pulled out was clean, the fuel gauge is way off, at a quarter it has exactly 10gal. Since I had to leave I peeked in the flapper on the fuel pipe neck and it is once of the new tanks from the recall, was spotless inside….however I stuck my finger in and there’s some black stuff, very small amount that’s not fuel, I can see it around the butt joint of the baffles in the crack.

I’ll have more tomorrow. But I need to confirm the lines but they all look correct on vent to vent. The top front passenger side port on the tank on the corner where the 2 lines connected both had fuel pour out yet zero fuel in the separator…

 

[TexasLandCruiser]

I may have missed it, but what fuel pump are you running? I had an issue with two A/C Delco in-tank pump fuel hose. It softened and under a load would collapse and starve the engine of fuel. Replaced with Gates EFI submersible hose and problem solved. This was on an LS swapped square body with dual tanks. Both pumps had the exact same issue within 100 miles and both are in-tank setups.

They installed a granatelli in Los Angeles. I have a edelbrock 255/ 90psi kit coming

 

[TexasLandCruiser]

They installed a granatelli in Los Angeles. I have a edelbrock 255/ 90psi kit coming

Separate note I’m questioning my air intake I put together. I’ve reread the GM engineering instructions on the tubing and it is acceptable but LS1.com guys are saying straighten out the air more and weld my seams, also moving my boss back from the filter some and ditching the 45 in the corner. A lot of moving parts rn

 

[TexasLandCruiser]

Oh crap, I don’t remember the grumpy guys name that mentioned the internal tank seal with Por15 but check out these chunks I was able to take pic. What is that lining? It looks like resin or something and if there’s chunks missing what little I see wonder about the rest. I’ll have more tomorrow

 

[deliverance]

Separate note I’m questioning my air intake I put together. I’ve reread the GM engineering instructions on the tubing and it is acceptable but LS1.com guys are saying straighten out the air more and weld my seams, also moving my boss back from the filter some and ditching the 45 in the corner. A lot of moving parts rn

View attachment 2849723

Your air intake is fine as long as everything is sealed. May see higher IATs at idle if the tube is steel, but driving I bet it cools down.

 

[TexasLandCruiser]

Your air intake is fine as long as everything is sealed. May see higher IATs at idle if the tube is steel, but driving I bet it cools down.

Aluminum but the LS guys said ditch the 45 on the end and move the boss back halfway in the straight. 2 times I’ve pulled the filter off to clean and both times the fuel is slightly different if it’s not just right, so I’ve got a 1 piece coming with boss welded center 10” from throttle and 6” from filter. Per them that’ll give the air time to settle down between upstream and downstream. Everything has been so finicky on this engine. And building a bigger box for filter not a shield, hope to calm any airflow from hood or fan. Oh yeah since this one here is a 3 piece the other day I unclamped it to reach in and feel butt seams to make sure tubes and flush at couplers and found one that was slightly off. That little dip or gap, though rubber sealed it caused the fuel to act weird, as in running rich, after it was lean. If that’s not bad enough back to fuel vacuum stuff, last night I’d blown air in the vent line at the firewall and got some pretty heavy gurgle, the pump sounds different today and the fuel went full rich.

I’m going to finish this and focus on one thing at a time, too many moving parts right now, but…all this is potentially connected with smooth operations

 

[cruisermatt]

Your air filter is fine it doesn’t matter at all and has no effect on your issue
Which i still think has nothing to do with tank pressure

 

[tmxmotorsports]

Oh crap, I don’t remember the grumpy guys name that mentioned the internal tank seal with Por15 but check out these chunks I was able to take pic. What is that lining? It looks like resin or something and if there’s chunks missing what little I see wonder about the rest. I’ll have more tomorrow

View attachment 2849737

View attachment 2849738

 

[TexasLandCruiser]

Your air filter is fine it doesn’t matter at all and has no effect on your issue
Which i still think has nothing to do with tan

Why the check valve? Says hj61 and fj62

 

[Lead Head]

It says Europe and General Market. The U.S. Market FJ62s do not have that check valve.

There should not be any abandoned vent lines on your gas tank. There are 5 ports along the top half of the tank, and each one of those ports has a corresponding port on the vent-tube plate that bolts to the body. The lone bottom port on the vent-tube plate is the port that is supposed to connect to the evap line going to the evap canister/engine.

Your gas tank has been modified, as FJ62 tanks should not have a drain in that location. I think you need to pull the fuel pump sending unit out and see what's going on inside there.

 

[TexasLandCruiser]

It says Europe and General Market. The U.S. Market FJ62s do not have that check valve.

There should not be any abandoned vent lines on your gas tank. There are 5 ports along the top half of the tank, and each one of those ports has a corresponding port on the vent-tube plate that bolts to the body. The lone bottom port on the vent-tube plate is the port that is supposed to connect to the evap line going to the evap canister/engine.

Your gas tank has been modified, as FJ62 tanks should not have a drain in that location. I think you need to pull the fuel pump sending unit out and see what's going on inside there.

Here’s what I found. The sock was caved into the pump inlet, the paper towel is what I strained the last of the fuel with. Also seem counter intuitive to have the lowest spot right where sock picks up. Right at that drain. If you see the black crud that’s what the sock picked up

 

[TexasLandCruiser]

Here’s the rest of what was inside. The lines are ok, put new ones. The tank has some little tar like chunks that were floating around but the tank is galvanized I guess. The one drain you pointed out was directly below the pump intake where the crud was. 2 of the 1/4 vent lines were not originally cut right length and the had a little adapter that made the inside diameter of those 1/8 inch. I don’t know if that means anything. But perhaps my higher demand times, higher and hot when it needed to stay equal maybe those vent line weren’t allowing it to equalize. I’m at the end of my knowledge.

 

[TexasLandCruiser]

It says Europe and General Market. The U.S. Market FJ62s do not have that check valve.

There should not be any abandoned vent lines on your gas tank. There are 5 ports along the top half of the tank, and each one of those ports has a corresponding port on the vent-tube plate that bolts to the body. The lone bottom port on the vent-tube plate is the port that is supposed to connect to the evap line going to the evap canister/engine.

Your gas tank has been modified, as FJ62 tanks should not have a drain in that location. I think you need to pull the fuel pump sending unit out and see what's going on inside there.

This was before removal

 

[Lead Head]

All of those lines should be hooked up. They just get hooked up in the same order on the tank, pretty straight forward. That bottom-most hose goes to the charcoal canister. Someone welded a drain plug directly into the fuel pump well for some reason, probably what some of those burnt chunks are. Just weld residue.

On to the fuel pump bracket: That bolted connection for the positive wire is pretty suspect, as is the bolted ground connection. Second, the big thing is they have cut and modified the fuel pump bracket (crazy, since they're NLA and go for $400+ used). It looks like they welded the bottom of another fuel pump bracket onto the existing one.

With the factory fuel pump, the filter actually sits ABOVE the bottom of the bracket, and it would be impossible for the filter to be crushed into the pump inlet. Here's a picture:

I suspect yours is the type of pump that has the filter that plugs right into the bottom of the pump through the bracket (so it hangs down below the bracket). That, coupled with the bracket likely being a little longer is probably cramming the fuel pump sock hard up against the bottom of the tank. Not sure how you'd fix that besides switching back to an OEM style pump or shortening the bracket.

 

[TexasLandCruiser]

All of those lines should be hooked up. They just get hooked up in the same order on the tank, pretty straight forward. That bottom-most hose goes to the charcoal canister. Someone welded a drain plug directly into the fuel pump well for some reason, probably what some of those burnt chunks are. Just weld residue.

On to the fuel pump bracket: That bolted connection for the positive wire is pretty suspect, as is the bolted ground connection. Second, the big thing is they have cut and modified the fuel pump bracket (crazy, since they're NLA and go for $400+ used). It looks like they welded the bottom of another fuel pump bracket onto the existing one.

With the factory fuel pump, the filter actually sits ABOVE the bottom of the bracket, and it would be impossible for the filter to be crushed into the pump inlet. Here's a picture:
View attachment 2850757

I suspect yours is the type of pump that has the filter that plugs right into the bottom of the pump through the bracket (so it hangs down below the bracket). That, coupled with the bracket likely being a little longer is probably cramming the fuel pump sock hard up against the bottom of the tank. Not sure how you'd fix that besides switching back to an OEM style pump or shortening the bracket.

What’s your thoughts on cutting the weld and raising the pump up about 1/2 inch, I have a few inches to play with at the top? That’d get the sock out of the very bottom.

As for the electrical connections how would you do it different? Just a connector and a nut?

Based on the tank and what I’ve seen looks like It’d be ok to wash it out and reinstall? Noticed the heat from weld and the rivets rusted but the rest looks ok?

Last is I mentioned they put 2 1/4 pieces of hose together to make up 2 of the vent lines with a little plastic hose fitting. My guess is the id of the adapter is about 1/8 id. I blew through bother and barely move air. Is that enough to keep things equal?

 

[Lead Head]

Just replace the hoses with a solid piece of hose. It's like 30 cents/foot at the parts store.

I don't see any reason why you couldn't cut the bracket and move the pump up half an inch.

The original connections were riveted. I would just make sure there are lock washers, the surfaces between the connections are clean (sand them lightly), and make sure they are very right.

 

[TexasLandCruiser]

They shoved that sock right against the bottom. No wonder it struggled for so long.

 

[TexasLandCruiser]

They shoved that sock right against the bottom. No wonder it struggled for so long.

View attachment 2850812

 

[TexasLandCruiser]

Just replace the hoses with a solid piece of hose. It's like 30 cents/foot at the parts store.

I don't see any reason why you couldn't cut the bracket and move the pump up half an inch.

The original connections were riveted. I would just make sure there are lock washers, the surfaces between the connections are clean (sand them lightly), and make sure they are very right.

Thank you!

 

[TexasLandCruiser]

Thank you!

Just replace the hoses with a solid piece of hose. It's like 30 cents/foot at the parts store.

I don't see any reason why you couldn't cut the bracket and move the pump up half an inch.

The original connections were riveted. I would just make sure there are lock washers, the surfaces between the connections are clean (sand them lightly), and make sure they are very right.

I’ve got all new hoses coming, all my yellow zinc clamps are here, new boots for crossmember, edelbrock pump kit Tuesday, having new hoses from pump to rails made with new fittings and if I have time install trap door to pump from Tanks Inc. stripping everything under tank and touch up paint from resto on frame. Exciting times! The fact that this could be it is a bit overwhelming. I have not been able to leave on a trip in a year wondering if I’d make it home because of this mess. I slept in the desert for 2 days broke down last year because of this. Why it didn’t freak out going through engineer pass in September is beyond me other than it was colder.