Fuel Issue - Leakdown fail (1 Viewer)

[nachocruiser]

Howdy ya'll,

I've got a 2004 LC with a recent power issue when coming home from a ~2k mile long trip loaded up with the family and towing +4k pound pop-up. I noticed climbing up the Colorado Rockies a subtle loss of power and then it would sort of kick in slightly but not really recover. It would still climb but felt more like one of my 3rd gen 4runners pulling that load than a V8.

I kept getting a P0171 and P0174 so running lean. That seems to make sense as it felt like it was struggling for fuel, I would clear the codes and they came back pretty quick. I was suspecting at that time fuel pump or ignition packs. Once home I've started noticing excessive cranking before starting. Not too bad but noticeable from the quick fire up of usual.

I started digging through MUD(amazing resource!) and tested fuel pressure with a banjo fitting setup. I'm getting about 36psi which seems a teeny bit on the low side but the real fail was an immediate loss of pressure to pretty much zero when I shut her off. I was hoping fuel pump but now I'm thinking leaky fuel injectors or fuel pressure regulator. I have the FSM so I'll check for a test on it.

The rig has about 224k. I got her about 3 years ago with 200k on the clock.
She's probably ready for new spark plugs which will go in with this service call (I did check and torque them when I got her, thanks to advice I found here),
probably has original ignition coils(don't suspect them, but already have new ones for when they go),
probably original fuel pump/filter(I have a new filter that will go in with this service call as well), and
I cleaned the MAF right before this 2K mile family trip.
That's about all the relevant info I can think to relate.

I'm planning to pick up a TYC 152059A fuel pump just to have on the ready, I'm all about OEM or Dense but I'm tight on funds at the moment and $15(Rock Auto) vs even the $130 Denso seems like a worthwhile risk unless someone really has bad things to say about it? I've been digging through MUD and found maybe one person who put it in but no feedback since.

Any feedback on the diagnosis here would be much appreciated. What say ye? The injectors or fuel pressure regulator or....?

 

[Eyedaho]

My first thought is to look at the recent history. It was running great, you cleaned the MAF sensor, and now it's getting codes for running lean. I would start there.

 

[nachocruiser]

Thank you for the reply. I don't see the MAF affecting/causing the immediate pressure drop on the leakdown test though. Am I mistaken here?

Maybe the MAF is adding to my fuel issue but it seems this leakdown test fail would be my first order of business no?

There is no test for the fuel pressure regulator mentioned in the FSM. Any suggestions there? Could a faulty fuel pump cause the leakdown test fail?

BTW, it ran great for most of the 2k miles after cleaning the MAF which was shortly before heading out on this trip...

 

[J1000]

The fuel damper acts as a check valve for the fuel rail so possibly it's gone bad. Problems with the fuel damper can also lead to long cranks or trouble with hot-restarts.

 

[Mike NXP]

Thank you for the reply. I don't see the MAF affecting/causing the immediate pressure drop on the leakdown test though. Am I mistaken here?

Maybe the MAF is adding to my fuel issue but it seems this leakdown test fail would be my first order of business no?

There is no test for the fuel pressure regulator mentioned in the FSM. Any suggestions there? Could a faulty fuel pump cause the leakdown test fail?

BTW, it ran great for most of the 2k miles after cleaning the MAF which was shortly before heading out on this trip...

I'm not expert but the test you described isn't a leakdown test. A leakdown test is when you introduce air into the cyclinder and close it off to see if it hold or leaks, indicating a compression issue.

Sounds like you were testing fuel pressure and when you turn the key off the pressure drops to 0, isn't that normal? Is it normal to see fuel pressure on the fuel rail without the vehicle running?


I'm not convinced what you described is even a problem, our heavy trucks pulling 4k lbs going up a mountain pass, I'm not surprised it felt like a total pig. The kick down you may have felt was it going in and out of OD?

Just guessing

Most people with similar issues find it's a fuel pump on it's way out. Bunch of forums on here around people loosing power up hill and having it kick back to life. No engine codes. Most likely fuel related. Again all just guesses without any real testing

 

[nachocruiser]

I'm not expert but the test you described isn't a leakdown test. A leakdown test is when you introduce air into the cyclinder and close it off to see if it hold or leaks, indicating a compression issue.

Sounds like you were testing fuel pressure and when you turn the key off the pressure drops to 0, isn't that normal? Is it normal to see fuel pressure on the fuel rail without the vehicle running?


I'm not convinced what you described is even a problem, our heavy trucks pulling 4k lbs going up a mountain pass, I'm not surprised it felt like a total pig. The kick down you may have felt was it going in and out of OD?

Just guessing

Most people with similar issues find it's a fuel pump on it's way out. Bunch of forums on here around people loosing power up hill and having it kick back to life. No engine codes. Most likely fuel related. Again all just guesses without any real testing

Hello Mike NXP,

Thank you for the reply. You are right about the cylinder compression leakdown test. What I'm referring to is in the FSM as a fuel pressure test. It should hold pressure for at least 5 minutes at 21psi or more. Perhaps it's not called a leakdown test but it sort of is, no?

I hear you on the pig comment, and am familiar with how it 'normally' feels. I've had it while living here in Colorado at 9K feet the whole time (3 yrs, 20k miles) and have towed with it plenty. I keep it in 4th when towing and even usually when getting around the mountains here while not towing. There is definitely something wrong, just not sure what. Hoping it is the fuel pump as much easier and cheaper to deal with. Going to ohm out the pump here shortly...

The fuel damper acts as a check valve for the fuel rail so possibly it's gone bad. Problems with the fuel damper can also lead to long cranks or trouble with hot-restarts.

Thank you J1000 for your input. Real good possibility here too. I'll likely order a fuel pressure regulator and damper as even if not needed now, probably in the future. $100 for both from Amayama.

 

[Mike NXP]

Hello Mike NXP,

Thank you for the reply. You are right about the cylinder compression leakdown test. What I'm referring to is in the FSM as a fuel pressure test. It should hold pressure for at least 5 minutes at 21psi or more. Perhaps it's not called a leakdown test but it sort of is, no?

I hear you on the pig comment, and am familiar with how it 'normally' feels. I've had it while living here in Colorado at 9K feet the whole time (3 yrs, 20k miles) and have towed with it plenty. I keep it in 4th when towing and even usually when getting around the mountains here while not towing. There is definitely something wrong, just not sure what. Hoping it is the fuel pump as much easier and cheaper to deal with. Going to ohm out the pump here shortly...




Thank you J1000 for your input. Real good possibility here too. I'll likely order a fuel pressure regulator and damper as even if not needed now, probably in the future. $100 for both from Amayama.

Totally, thanks for the reply. I wasn't aware the pressure was supposed to hold.

Hmm so maybe the previous comment above about the damper which is supposed to hold pressure could be failing. Or maybe just the pump? Always nice to see the cruiser just keeps chugging though and didn't leave you stranded

 

[nachocruiser]

Sure thing @Mike NXP , we're all in this together via this forum and definitely nice to see the cruiser kept chugging vs leaving us stranded(multiple children and it was approaching 2am in the mountains still an hour away from home...) Praise Yah!

Anyhow, been busy today but fiinally able to report back. Resistance test on pins 4 & 5 are a dead short. I have a wiring diagram and will be checking it out, but what does that tell me about the pump (besides that it obviously fails the test and apparently means replacement)? They are a black and a white wire, the biggest wires going in suggesting pwr and gnd but a dead short and it still manages to run?! I don't know motors very well but that strikes me as odd. I would expect an out of spec reading but a short?

Further pressure readings are coming in at a low of 34psi(min is 38psi according to FSM) and still dropping to about 5psi immediately at shut off. Apparently too then, the pump plays a part in holding pressure after shut off? A little surprised by that as well but what do I know...

Looks like a fuel pump will be my first part swap and we'll see about the regulator and dampener later(though I'm ordering tonight, I like having an inventory. I'm going with the TYC 152059A pump. Still hoping to see if anyone has experience with it??? At $15 I'm getting a spare just in case!

I'll follow up once the pump and other parts come in.

 

[Mike NXP]

Sure thing @Mike NXP , we're all in this together via this forum and definitely nice to see the cruiser kept chugging vs leaving us stranded(multiple children and it was approaching 2am in the mountains still an hour away from home...) Praise Yah!

Anyhow, been busy today but fiinally able to report back. Resistance test on pins 4 & 5 are a dead short. I have a wiring diagram and will be checking it out, but what does that tell me about the pump (besides that it obviously fails the test and apparently means replacement)? They are a black and a white wire, the biggest wires going in suggesting pwr and gnd but a dead short and it still manages to run?! I don't know motors very well but that strikes me as odd. I would expect an out of spec reading but a short?

Further pressure readings are coming in at a low of 34psi(min is 38psi according to FSM) and still dropping to about 5psi immediately at shut off. Apparently too then, the pump plays a part in holding pressure after shut off? A little surprised by that as well but what do I know...

Looks like a fuel pump will be my first part swap and we'll see about the regulator and dampener later(though I'm ordering tonight, I like having an inventory. I'm going with the TYC 152059A pump. Still hoping to see if anyone has experience with it??? At $15 I'm getting a spare just in case!

I'll follow up once the pump and other parts come in.

Remember, everytime you install an aftermarket part , a little piece of your cruiser dies on the inside =]

 

[Eyedaho]

Thank you for the reply. I don't see the MAF affecting/causing the immediate pressure drop on the leakdown test though. Am I mistaken here?

Maybe the MAF is adding to my fuel issue but it seems this leakdown test fail would be my first order of business no?

There is no test for the fuel pressure regulator mentioned in the FSM. Any suggestions there? Could a faulty fuel pump cause the leakdown test fail?

BTW, it ran great for most of the 2k miles after cleaning the MAF which was shortly before heading out on this trip...

Apologies, it was early and I read it as a 2000 mile road trip. I thought you had just cleaned the MAF before the trip, and a flaky MAF could cause a lean condition.

 

[Rebus Knebus]

Resistance test on pins 4 & 5 are a dead short. I have a wiring diagram and will be checking it out, but what does that tell me about the pump (besides that it obviously fails the test and apparently means replacement)? They are a black and a white wire, the biggest wires going in suggesting pwr and gnd but a dead short and it still manages to run?! I don't know motors very well but that strikes me as odd. I would expect an out of spec reading but a short?

The low end of the resistance spec is something like 0.2 ohms, which is going to be indistinguishable from a dead short on your basic cheap multimeter. I don’t think it’s failing the test.

 

[nachocruiser]

Apologies, it was early and I read it as a 2000 mile road trip. I thought you had just cleaned the MAF before the trip, and a flaky MAF could cause a lean condition.

No worries @Eyedaho I appreciate any good faith suggestions

The low end of the resistance spec is something like 0.2 ohms, which is going to be indistinguishable from a dead short on your basic cheap multimeter. I don’t think it’s failing the test.

You are correct sir. I did not even notice how low the spec was as once I saw a short, I just chalked it up as a fail. Armed with this new insight, I busted out the Fluke 87V and got readings of .9 and 1 ohm at about 50 degress F. I say that puts the pump in spec(.2-3ohm @ 68 degress F) for that test.

I still don't like the low fuel pressure reading of 34psi when running and I don't see how the pump plays a part in keeping the pressure from 'leaking' down on shut off.

I ordered 2 TYC pumps (one spare) from Rock auto as well as oem fuel pressure regulator Toyota 23280-50050 and damper Toyota 23270-50012 from Amayama. Based on @J1000 's input, I'm thinking to start by replacing the damper to see if I pass the 'leakdown' test first and go from there.

 

[Eyedaho]

No worries @Eyedaho I appreciate any good faith suggestions




You are correct sir. I did not even notice how low the spec was as once I saw a short, I just chalked it up as a fail. Armed with this new insight, I busted out the Fluke 87V and got readings of .9 and 1 ohm at about 50 degress F. I say that puts the pump in spec(.2-3ohm @ 68 degress F) for that test.

I still don't like the low fuel pressure reading of 34psi when running and I don't see how the pump plays a part in keeping the pressure from 'leaking' down on shut off.

I ordered 2 TYC pumps (one spare) from Rock auto as well as oem fuel pressure regulator Toyota 23280-50050 and damper Toyota 23270-50012 from Amayama. Based on @J1000 's input, I'm thinking to start by replacing the damper to see if I pass the 'leakdown' test first and go from there.

I think there's a check valve in the fuel pump, so the residual fuel line pressure remains trapped between that check valve and the fuel pressure regulator, which acts as a check valve at/below the set pressure. At least that's my limited understanding.

 

[2001LC]

As @J1000 mentioned and is FSM first test, damping screw popping up. Good, move to:
Next, static fuel pressure spec 38-44. At 36PSI, you've a failure. Resolve, then:
Next leak down. Hold minimum of 21PSI for 5 min. You failed.

This could be just FRP, with bad needle.

But I'd take a look in fuel tank also. It would be a waste once in tank. To not install a new Denso Fuel pump and OEM tank seal. Using aftermarket, may take you down a rabbit hole.

I've found lean fuel trims that corrected, with fuel pump & fuel filter R&R.
I had to vacuum out the sediment from gas tank. Also, Sock & Filter was worst I'd ever seen.

 

[excessive]

wow, i wonder how that sediment got in there?

 

[2001LC]

Old fuel storage tanks at gas stations, made of metal. They rusted and ground water enters.

I'm carful where I get gas. Locally I've either seen new fiber-tanks installed, or looked up at states inspection web page.

I avoid the older stations, with supper cheap gas.

On the open road, I look for newer mega gas station.

Interesting on this clean very well turned and ran 44K in gas tank. 2006LC 250K miles. We couldn't get Long Term Fuel Trim into range we'd like of ~3% (below 5%). Kept seeing LTFT~7% (engine running lean). Until we changed Fuel pump & fuel filter. Now we get LTFT of~3%

 

[nachocruiser]

Sorry for my delay in responding. I had guests in town and was waiting for parts. Still waiting on the fuel pressure regulator and damper though I don't think I will be needing them right away.

Interesting posts @2001LC, thank you for sharing. You're one of the many with super helpful posts on this forum.

I got the TYC 152059-A pump installed today (FYI, it incuded a new strainer and box says made in China; I didn't do any tank seals etc. they looked good). The pump seems to have fixed the main issues, so yay for that . Running steady at about 48-50 psi. I did the ohm test on it and it read 1.4 ohms. Holding at over 40psi when shut off for well over 30 minutes before I called it good. I should go back and do the damper test as @J1000 and @2001LC suggested but this confirms what @Eyedaho posted about the check valve in the pump holding the pressure. That is a good detail to know for anyone having these symptoms. My STFTs are ~-3% and LTFT ~+5%. I intend to do the fuel filter here soon and see if that helps there.

Interesting additional info/thoughts. The fuel pump must have been changed before as one of the two screws to the dust cap was missing and the pump I pulled out was a Delphi FE0402. I bought the rig with ~202k on the clock and got pretty decent records but no indication that the fuel pump was ever changed (though it must have been). I'm going to ballpark the factory pump at 160-190k which means that Delphi did not last very long(I'm at 222k) and doesn't bode well for this TYC but we will see. I intend to update this post with any issues I have with the pump.

Here are some pics of the two pumps:

 

[Les Summer]

Sorry for my delay in responding. I had guests in town and was waiting for parts. Still waiting on the fuel pressure regulator and damper though I don't think I will be needing them right away.

Interesting posts @2001LC, thank you for sharing. You're one of the many with super helpful posts on this forum.

I got the TYC 152059-A pump installed today (FYI, it incuded a new strainer and box says made in China; I didn't do any tank seals etc. they looked good). The pump seems to have fixed the main issues, so yay for that . Running steady at about 48-50 psi. I did the ohm test on it and it read 1.4 ohms. Holding at over 40psi when shut off for well over 30 minutes before I called it good. I should go back and do the damper test as @J1000 and @2001LC suggested but this confirms what @Eyedaho posted about the check valve in the pump holding the pressure. That is a good detail to know for anyone having these symptoms. My STFTs are ~-3% and LTFT ~+5%. I intend to do the fuel filter here soon and see if that helps there.

Interesting additional info/thoughts. The fuel pump must have been changed before as one of the two screws to the dust cap was missing and the pump I pulled out was a Delphi FE0402. I bought the rig with ~202k on the clock and got pretty decent records but no indication that the fuel pump was ever changed (though it must have been). I'm going to ballpark the factory pump at 160-190k which means that Delphi did not last very long(I'm at 222k) and doesn't bode well for this TYC but we will see. I intend to update this post with any issues I have with the pump.

Here are some pics of the two pumps:View attachment 3472510View attachment 3472511View attachment 3472512

If anyone comes along and sees this, does anyone know when or why I can't get a Denso Fuel Pump for my 2000 Land Cruiser anywhere? I've seen it as a kit with part number 151-22407. Any recommendations outside of getting one from the dealer and not spending a fortune? I would not be interested in either this Delph or the TYC. I want to have a good pump on hand, so I'm taking my time looking for the best deal. A recommendations, of a pump I can actually buy now, would be greatly appreciated.

 

[nachocruiser]

@Iverano, I'll share what I found for the record. I couldn't find this info documented in one post so I'll post it here in hope it helps someone in 2023 and beyond:

The quick of it seems to be that the 3 below Denso part numbers I found are difficult to source, at least right now and even the last 2 years or so (according to other Mud posts). The reason seems to be, according to one relatively recent Mud post I found, that Denso was getting out of the business, even sold off that part of their business in pursuit of electric cars (which if true, further evidence's WEF type stuff is materializing). And/Or is being manufactured in china now (by the new owners of the product line?). Either way, mostly just not available on the websites and people even getting orders cancelled.

I'd be curious to hear what you experience.

Denso 950-0210 was ONLY? for the last 2005-2007 100 series. ~$130 (where listed) Don't know about strainer or fittings. (I have a 2004)
Denso 950-0107 Includes extra fittings AND the strainer ~$200 (where listed)
Denso 951-0003 Includes extra fittings no strainer ~$130 (where listed)

Toyota OEM 23221-66040 (an updated/new part number according to Amayama) ~$300 delivered to US and available don't know about strainer etc.

Both TYC's I ordered came in about a week for ~$40 shipped from Rock auto. I saw the Delphi for well over $150. Other lesser known likely made in china/questionable quality like the Delphi I pulled, everywhere in between but apparently available at least.

I did not come across the part number you mentioned. Please let us know what you find.

 

[2001LC]

Looks like production date 1998-May 2005 (non VVT 100 series). OEM only or non Denso.

The Denso 950-0210, is for production date May 2005-2007, which is the 2006-2007 VVT.