LS Fuel Pressure Issue High Hot (1 Viewer)

[burnttoastburgos]

That sucks, at least your on the good path now. My RamJet would do great until a few miles of crawl in low/low at high summer temps. Then it would studder to the point of shut down. Stopped, looked around, didnt see anything, obvious anyway....waited about 15 minutes, started up and BAM no issues.......Till we got up in elevation, ambient temps were in the 90's and then it would start in again. Cracked the fuel line at rail to check for fuel pressure and had fuel. Pack up tools started up and BAM, no issues again, drove it home no problem....Thought maybe bad fuel, water or whatever. All the while I had thought it was a wiring issue as I had plenty of fuel at the rail or something in the intake with that motor.....Then fast forward this happening a few more times, until I pull that motor and drop in a BRAND NEW LS3.....took it to Moab, did Moab Rim, got up to the sand, temps were in the high 90's and the same dang thing was happening. Now I figured out this has NOTHING to do with my Motor or wiring, but placement of the fuel pump, which is mounted on the frame. NEVER ever had an issue on the highway, ever....only when locked in low and temps were high......Spoke with a buddy of mine who restores Cruisers, and before I finished my story, he told me I know your issue. "Take out that stinkin frame mounted pump and fit it inside the tank"...He said the first 20 or so restos he did, had the same issues. Went with Aeromotive in tank pumps and has never ever had an issue since. I dropped it off at his shop to do it for me, thats why I stated I will report back when I pick it up. I sure hope this is the same in your case....All the hours of thinking WHAT THE FRIG IS DOIN THIS takes its toll.....but.....this is our passion so we stick it out......Now im just getting started on another build on my 96 cherry LX450 and will keep the oem 6cly until i can take it as it sure is a slug !!.

 

[TexasLandCruiser]

That sucks, at least your on the good path now. My RamJet would do great until a few miles of crawl in low/low at high summer temps. Then it would studder to the point of shut down. Stopped, looked around, didnt see anything, obvious anyway....waited about 15 minutes, started up and BAM no issues.......Till we got up in elevation, ambient temps were in the 90's and then it would start in again. Cracked the fuel line at rail to check for fuel pressure and had fuel. Pack up tools started up and BAM, no issues again, drove it home no problem....Thought maybe bad fuel, water or whatever. All the while I had thought it was a wiring issue as I had plenty of fuel at the rail or something in the intake with that motor.....Then fast forward this happening a few more times, until I pull that motor and drop in a BRAND NEW LS3.....took it to Moab, did Moab Rim, got up to the sand, temps were in the high 90's and the same dang thing was happening. Now I figured out this has NOTHING to do with my Motor or wiring, but placement of the fuel pump, which is mounted on the frame. NEVER ever had an issue on the highway, ever....only when locked in low and temps were high......Spoke with a buddy of mine who restores Cruisers, and before I finished my story, he told me I know your issue. "Take out that stinkin frame mounted pump and fit it inside the tank"...He said the first 20 or so restos he did, had the same issues. Went with Aeromotive in tank pumps and has never ever had an issue since. I dropped it off at his shop to do it for me, thats why I stated I will report back when I pick it up. I sure hope this is the same in your case....All the hours of thinking WHAT THE FRIG IS DOIN THIS takes its toll.....but.....this is our passion so we stick it out......Now im just getting started on another build on my 96 cherry LX450 and will keep the oem 6cly until i can take it as it sure is a slug !!.

What are you doing with fuel evap, using metal line with rubber on both ends? Have you seen the inside of your tank?

 

[TexasLandCruiser]

That sucks, at least your on the good path now. My RamJet would do great until a few miles of crawl in low/low at high summer temps. Then it would studder to the point of shut down. Stopped, looked around, didnt see anything, obvious anyway....waited about 15 minutes, started up and BAM no issues.......Till we got up in elevation, ambient temps were in the 90's and then it would start in again. Cracked the fuel line at rail to check for fuel pressure and had fuel. Pack up tools started up and BAM, no issues again, drove it home no problem....Thought maybe bad fuel, water or whatever. All the while I had thought it was a wiring issue as I had plenty of fuel at the rail or something in the intake with that motor.....Then fast forward this happening a few more times, until I pull that motor and drop in a BRAND NEW LS3.....took it to Moab, did Moab Rim, got up to the sand, temps were in the high 90's and the same dang thing was happening. Now I figured out this has NOTHING to do with my Motor or wiring, but placement of the fuel pump, which is mounted on the frame. NEVER ever had an issue on the highway, ever....only when locked in low and temps were high......Spoke with a buddy of mine who restores Cruisers, and before I finished my story, he told me I know your issue. "Take out that stinkin frame mounted pump and fit it inside the tank"...He said the first 20 or so restos he did, had the same issues. Went with Aeromotive in tank pumps and has never ever had an issue since. I dropped it off at his shop to do it for me, thats why I stated I will report back when I pick it up. I sure hope this is the same in your case....All the hours of thinking WHAT THE FRIG IS DOIN THIS takes its toll.....but.....this is our passion so we stick it out......Now im just getting started on another build on my 96 cherry LX450 and will keep the oem 6cly until i can take I broke down on the way to CO changed filter and was fine for rest of trip. I went to White Sands last week broke again on the way to Altitude! Put a mechanical pressure gauge on rail and witnessed pressure when it was actually doing all that commotion. Need to send you a video of pressure, fuel trims and 02 sensors when it was happening. Everything went normal as soon as I ran 5psi thru vent line on the trail with onboard compressor. I can email you a link also to cloud drop link to video. Pretty enlightening to see exactly what engine was doing being choked out. justanotheremailbox@protonmail.com

That sucks, at least your on the good path now. My RamJet would do great until a few miles of crawl in low/low at high summer temps. Then it would studder to the point of shut down. Stopped, looked around, didnt see anything, obvious anyway....waited about 15 minutes, started up and BAM no issues.......Till we got up in elevation, ambient temps were in the 90's and then it would start in again. Cracked the fuel line at rail to check for fuel pressure and had fuel. Pack up tools started up and BAM, no issues again, drove it home no problem....Thought maybe bad fuel, water or whatever. All the while I had thought it was a wiring issue as I had plenty of fuel at the rail or something in the intake with that motor.....Then fast forward this happening a few more times, until I pull that motor and drop in a BRAND NEW LS3.....took it to Moab, did Moab Rim, got up to the sand, temps were in the high 90's and the same dang thing was happening. Now I figured out this has NOTHING to do with my Motor or wiring, but placement of the fuel pump, which is mounted on the frame. NEVER ever had an issue on the highway, ever....only when locked in low and temps were high......Spoke with a buddy of mine who restores Cruisers, and before I finished my story, he told me I know your issue. "Take out that stinkin frame mounted pump and fit it inside the tank"...He said the first 20 or so restos he did, had the same issues. Went with Aeromotive in tank pumps and has never ever had an issue since. I dropped it off at his shop to do it for me, thats why I stated I will report back when I pick it up. I sure hope this is the same in your case....All the hours of thinking WHAT THE FRIG IS DOIN THIS takes its toll.....but.....this is our passion so we stick it out......Now im just getting started on another build on my 96 cherry LX450 and will keep the oem 6cly until i can take it as it sure is a slug !!.

Hey I was just in your neck did South Alpine out of Silverton, Need to send you a video of pressure, fuel trims and 02 sensors when it was happening. Everything went normal as soon as I ran 5psi thru vent line on the trail with onboard compressor. I can email you a link also to cloud drop link to video. Pretty enlightening to see exactly what engine was doing being choked out. justanotheremailbox@protonmail.com

 

[Bullzi]

This is the best one i have seen @Bullzi

Builds - Bean! The Adventure Continues (1987 FJ60)

I'm particularly proud of the seams around the hinges and door checks...they came out really good. The corner areas inside the engine bay also look much nicer now. This was a ton of work and I'm hoping it pays off in the form of dry carpet! It's obviously not necessary to base and clear the area...

forum.ih8mud.com

Thanks @cruisermatt, that is kind of you to say.

@wester11 - I have the same EROD engine in mine. It was put in for the PO by Torfab. It’s an LC9 that was installed in 2014 but was the engine they put in 2011 Silverados. The PO drove it like crazy and it now has over 150k miles. I have owned it since 2019.

Interestingly enough, I have/had a similar issue as you. Going up in elevation or when the drivetrain is “heat-soaked” as you put it, I occasionally get what feels like fuel starvation. It’s like the fuel pressure is pulsing. If I let it sit, it will go away. I don’t usually have any pressure or vacuum in the tank and my tank is pretty clean (it is an aftermarket 38gal LRT).

Anyways, I went through a bunch of theories but it happens so infrequently that it’s hard to pin down. My fuel trims are always a little lean, but they do lean out more before it happens. Sometimes it will throw a lean code while it’s happening. Usually it doesn’t stall the engine. I’m still getting my truck back together after the re-paint, but I’m hoping the new fuel pump hanger I built will help…or at least I can rule that out as a possible issue. The old one had some issues. Also the old fuel hose that connected the pump to the hard line was not meant for submersible applications and was super soft, so maybe it was collapsing under certain conditions? Seems unlikely seeing as it would be pressurized, but it was soft. Replaced it with Gates submersible hose.
I also think my charcoal canister was clogged. On my truck it lives up under the cargo area in front of the fuel tank and the dust from dirt roads can clog them. I just put in a new one.
I also replaced all my vent lines. They were in good condition and clear, but I figured since I had it all apart and easy access, it was the right move.
Lastly, my in tank pump is a wolbro and I am using a Corvette filter/regulator…I had always heard these pumps are the bees knees, but I’m kind of forming my own opinion on them now. When I bought the truck, the PO had told me he ran it out of fuel and the pump got loud. He suggested I replace it (it was a wolbro). I bought a new one and it was bad - it wouldn’t pressurize the line. Sent it back to summit and they confirmed it was a dud and sent me a new one. This one seems to run fine, but is pretty loud. If I continue to have issues, I’m going to do what @cruisermatt suggested and get a Denso from a 4th gen 4Runner.

Sorry for the book, if you have any questions about my experience, let me know. Hope your issue is fixed!

 

[TexasLandCruiser]

Thanks @cruisermatt, that is kind of you to say.

@wester11 - I have the same EROD engine in mine. It was put in for the PO by Torfab. It’s an LC9 that was installed in 2014 but was the engine they put in 2011 Silverados. The PO drove it like crazy and it now has over 150k miles. I have owned it since 2019.

Interestingly enough, I have/had a similar issue as you. Going up in elevation or when the drivetrain is “heat-soaked” as you put it, I occasionally get what feels like fuel starvation. It’s like the fuel pressure is pulsing. If I let it sit, it will go away. I don’t usually have any pressure or vacuum in the tank and my tank is pretty clean (it is an aftermarket 38gal LRT).

Anyways, I went through a bunch of theories but it happens so infrequently that it’s hard to pin down. My fuel trims are always a little lean, but they do lean out more before it happens. Sometimes it will throw a lean code while it’s happening. Usually it doesn’t stall the engine. I’m still getting my truck back together after the re-paint, but I’m hoping the new fuel pump hanger I built will help…or at least I can rule that out as a possible issue. The old one had some issues. Also the old fuel hose that connected the pump to the hard line was not meant for submersible applications and was super soft, so maybe it was collapsing under certain conditions? Seems unlikely seeing as it would be pressurized, but it was soft. Replaced it with Gates submersible hose.
I also think my charcoal canister was clogged. On my truck it lives up under the cargo area in front of the fuel tank and the dust from dirt roads can clog them. I just put in a new one.
I also replaced all my vent lines. They were in good condition and clear, but I figured since I had it all apart and easy access, it was the right move.
Lastly, my in tank pump is a wolbro and I am using a Corvette filter/regulator…I had always heard these pumps are the bees knees, but I’m kind of forming my own opinion on them now. When I bought the truck, the PO had told me he ran it out of fuel and the pump got loud. He suggested I replace it (it was a wolbro). I bought a new one and it was bad - it wouldn’t pressurize the line. Sent it back to summit and they confirmed it was a dud and sent me a new one. This one seems to run fine, but is pretty loud. If I continue to have issues, I’m going to do what @cruisermatt suggested and get a Denso from a 4th gen 4Runner.

Sorry for the book, if you have any questions about my experience, let me know. Hope your issue is fixed!

View attachment 2855336

View attachment 2855337

Thank you for walking me through your deal. Appreciate the explanation. Same deal 2011 Silverado engine. I’m in a tough spot with availability of room for the pump hanger, only giving me 7”. For now it’ll have to do. I sure hope all the new plumbing help, with the little melted rubber chunks I flushed out. I don’t know if I should leave the extra hard line in that lengthens the vent to the canister, I’d read having multiple low spots can clog/ rust etc and close off. See my pics here. My tuner had me running slightly rich and it leaned and died last trip, a week ago in the garage I blew pressure through the lines from the canister side tube engine bay firewall. Cap was on for about 1-2 psi them pulled it, trims fine, I put cap on and off letting it build a little pressure but not too much. After a few times I just let it continue to run with 5-10 psi passing thru vent thru cap. About 10 minutes in I shut everything down put back together and started and drove. Within 5 minutes the fuel trim both went 15+ finally going super rich. So drove it stop and go. Under power and load trimmed out 0, stop light richen up to peg out. Drive it clears up.

At that time I knew it was all coming out and don’t know enough about this to say that cycling air thru the system for awhile cause the trims to freak out.

I’ve got enough moving parts I’m just getting back together and see how it acts. Is there any way I can send you 2 videos? I’ve got a gauge on the fuel rails and scanner video showing when the cycle starts. It’s nuts cause I’m watching the mechanical gauge stabilize, drop to 10 psi and watching scanner trims follow it to a T.

I did pull the cap at higher elevations and every time it was acting up I’d run back and pop the cap and it’d vent pretty good and settle down.

(@cruisermatt has been patiently watching my chaos)

FYI I don’t like my rebuilt pump setup. I built it back from scratch. Idk I think with so much falling apart I doubt myself, maybe it’ll work fine. I put the Walbro in and wanted to do the Denso but PO butchered the hanger so making do. I’m close to buying the Tanks Inc setup but my tank bolt pattern is 7 bolt and their is 6 bolts.

 

[Bullzi]

You could probably still use the Denso pump on your rebuilt pump hanger, but you might have to chop off that bottom bit and use hose clamps to secure the pump. But I would stick with the Walbro unless you still have issues.
@cruisermatt, any chance you could link or give a part number for the Denso pump you run? I know you said 4th gen 4Runners, so would that be the pump off a 2009 V8 4Runner? I don't know those vehicles very well...When I was looking, I couldn't find anything that wasn't mad in China.

I don’t know if I should leave the extra hard line in that lengthens the vent to the canister, I’d read having multiple low spots can clog/ rust etc and close off.

I still have this hardline on my truck before the evap canister. I think it gives some (limited) rollover protection and also gives some (limited) protection against liquid entering and killing the evap canister. I am curious how your evap was plumbed before you took it out? I'll sketch out a diagram of how mine is for reference.

 

[TexasLandCruiser]

You could probably still use the Denso pump on your rebuilt pump hanger, but you might have to chop off that bottom bit and use hose clamps to secure the pump. But I would stick with the Walbro unless you still have issues.
@cruisermatt, any chance you could link or give a part number for the Denso pump you run? I know you said 4th gen 4Runners, so would that be the pump off a 2009 V8 4Runner? I don't know those vehicles very well...When I was looking, I couldn't find anything that wasn't mad in China.


I still have this hardline on my truck before the evap canister. I think it gives some (limited) rollover protection and also gives some (limited) protection against liquid entering and killing the evap canister. I am curious how your evap was plumbed before you took it out? I'll sketch out a diagram of how mine is for reference.

My evap system went down the factory setup to the firewall. Firewall to front left at apron next to coolant. Purge loop up parallel with vent line and terminates there. I’m curious about tank pressure switch. Where’s that getting its info from? When I put all the evap back on from the last trip issue I hooked up purge cold engine and it wasn’t pulling, after a few minutes it kicked on. I plugged it for test and it is pulling correct. I double checked the lines from PO and everything was plumbed correct, or at least from the Erod manual. The vent lines appeared to be correct, if I recall they go in sequence front to rear on tank front to rear on the vent connector, with half inch in center from tank to connector. I pulled the separator out and flushed it with alcohol for a few minutes and dumped it in a tub to see if there was anything. Super clean. I did notice last time I ran shop air from front vent tube to rear it gurgled a lot. Only thing not accounted for is the plug that was attached to the sending unit 2 prong, pic below.

I’m falling out of love with the hanger I have and ready to chop it. But finished putting everything back together tonight and the clearance from the plate to the pump is about 3/4 of an inch. That’s with the pump pick up at 1/2 inch off the bottom

 

[Bullzi]

Here is a diagram of my vent system...keep in mind that my tank is different and the vents are at the corners:

As for the tank pressure switch, I do not have one. I think the programming on the Erod engines just opens the purge valve every so often to purge the canister...I could be totally wrong on that though...It is something I have wondered about.
So do you not have a working fuel sending unit?

Where is your evap canister? Front of truck or back of truck? It seems strange that your vent line to the front of the truck is filling with fuel. My vent line to the front of the truck was repurposed as my purge line.

 

[TexasLandCruiser]

Here is a diagram of my vent system...keep in mind that my tank is different and the vents are at the corners:
View attachment 2856762

As for the tank pressure switch, I do not have one. I think the programming on the Erod engines just opens the purge valve every so often to purge the canister...I could be totally wrong on that though...It is something I have wondered about.
So do you not have a working fuel sending unit?

Where is your evap canister? Front of truck or back of truck? It seems strange that your vent line to the front of the truck is filling with fuel. My vent line to the front of the truck was repurposed as my purge line.

My evap system went down the factory setup to the firewall. Firewall to front left at apron next to coolant.

The sending unit is good, off constantly by 5 gals but I usually run fuel on time at cruise based on fuel burn. 25 years aviation tend to time stuff.

The purge has no method to it I can tell and nothing on my tank. When I had the purge vacuum blocked off freaked me out because I had it hooked to harness and shot some shop air into the tank and it kicked on immediately and can’t figure out how it got the message. Could have been a coincidence.

 

[TexasLandCruiser]

Test run on pump before install yesterday and worked fine. Bought spare fpr and building a trip kit. If I get it up tomorrow probably leave Friday. Closest 10k feet it 10 hours away. Go see if replacing all the tank lines, supply line, pump, regulator, flush tank, rewire everything, rebuilt everything on the pump house, pulled all the metal lines and rootered them with .22 scrubber head, boroscope inspected everything after done, pulled the fuel separator- flushed, and cleaned up the wire wrap on the sender (unrelated).

 

[burnttoastburgos]

did it work out?

 

[TexasLandCruiser]

did it work out?

Hey there, I’m still at the shop but put a return regulator on the tank from filter and stabilized the fuel, the pump hangar and bracket with replaced with Tanks Inc hardware and @tmxmotorsports helped me with the adapter for the 62 to 60 lid. I test drove it and the fuel pressure was really stable. Not sure I like this but the 5/16 lines going to the collector were small and the shop T'ed it all into large hoses and instead of 5 lines to and from separator there is 3.

 

[TexasLandCruiser]

I need to update this thread with the latest or closing. After being patient with the shop picked up the Cruiser last week. Installed Tanks Inc fuel pump hangar and pump supplied. Walbro 255lph and Aeromotive return regulator. I had a lot going on since all my nuttiness.

Shop found ignition was dropping signal but In an odd way (according to them) ground circuit had a square wave signal on the scan that looked like it was getting a short. Check all the rest of the harness and it was fine, dedicated a ground to the ignition and fixed that.

Now I’ve got tank issues with plumbing, shop was too busy to finish the job so taking back to original Toyota shop. I got caught between shops willing to work on LC or LS but couldn’t find both.

I did replace the horn button thing now have nice loud horns