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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => Project Classic Motobricks => Topic started by: Cinderedblock on April 09, 2025, 07:41:53 AM
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I have been working on replacing my clutch and the inside of the bell housing didn't show any signs of oil. After removing the clutch housing oil started to slowly seep out.
Im assuming my seal has failed, I wanted to see it wouldn't leak with the housing back in but I don't have a good way to test it.
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Welcome to the site!
How long have you owned the K75 that's getting the clutch replaced; how many miles are on the odometer and how many of those miles have you ridden it? What was the purpose of removing the clutch housing? An oil-free intermediate flange indicated the seal and o-ring were okay. For a clutch replacement, the clutch housing usually stays put. Removal of the housing may have compromised the seal or o-ring. What was the oil level in the crankcase before this adventure began?
Running the engine while riding the Brick is the leakage test most of us use; we discover leakages usually after an enjoyable ride. :laughing4-giggles: Leakage generally happens before repair or replacement of parts is undertaken, unless a complete rebuild is being done; then leakage happens after reassembly, usually during another enjoyable ride. Drops, streams or pools of oil on the engine case or pavement afterwards is the way most of us learn about leakage from engine component seals and o-rings.
I recommend replacing the shaft o-ring and the seal right now. They will be effective for tens of thousands of miles if they are installed carefully in conformance with established procedures.
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The odometer stopped working 2 owners ago set at 18k. The owner I bought it from had it serviced by a mechanic and rarely rode it. I probably have only ridden it 400 miles bringing it home and riding around. On my return trip the bike started bucking and it wasn't the engine. I had to do a clutch adjustment on the road to get it going again. I had maxed the adjustment bolt out and it only bought me the next 200 miles. Before my trip I had to adjust the cable tension, the engine wasn't disengaging making it hard to shift. That's why he never noticed, the clutch was so far adjusted in it didn't slip but it was shot.
No Freeplay in the lever, the bucking was the bike disengaging and engaging the engine. Disengaging the clutch and the engine would rev normally and it would buck in any gear.
I was just following the clymer manual, without knowing the state of the bike and that the clutch must have went through its lifetime I figured I should lubricate the housing splines as the manual explained and get an idea of what I'm working with.
They were bone dry but not worn thankfully everything looks great in here. It was a bit hard to get out on account of the absence of grease. I'm referring to page 196 (figure 22 and 23). Im not just doing the friction plate, Im installing a full kit.
This is my first clutch replacement so I thought I should do a full service. I've been praying that by taking out the housing the seal has nothing to seal against but I guess the only way to test is to put more oil in and reattach the starter and see if it leaks before fouling my new clutch kit. I drained the old oil to stop the leak because the oil change was next anyway.
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I've been praying that by taking out the housing the seal has nothing to seal against but I guess the only way to test is to put more oil in and reattach the starter and see if it leaks before fouling my new clutch kit.
You've lost me. It seems like you're over-thinking this.
A functioning rear main seal assembly shouldn't be leaking regardless of whether the crankcase is full or half-full before you install the clutch housing, and it shouldn't leak after the housing and its o-ring are installed and torqued. Starting the engine after assembling the clutch wouldn't prove much to me if the transmission and rear drive weren't putting a full load on the assembly by taking me the twenty mile to Morse Farm for a maple creemee. I've not observed anybody testing like you propose after rear main seal, o-ring and clutch housing and clutch pack installation. Maybe it's a well-kept secret part of the procedure. or I'm speed-reading too fast. Regardless, please update Motobrick with your progress.
Good luck with your Brick. 112350
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I'm overthinking it, the seal should never have leaked. I probably broke it trying to work the housing out. I'm just incredibly reluctant to order the seal. I've went ahead and put it on rush order.
I just hope that was the only issue. Since this is my first time in a K75 clutch I was just rethinking some of the things I observed. I never pinpointed exactly where the oil was coming from, I just assumed it was the seal.
When I replace the seal I assume I should test it first before putting anything back in, wouldn't that require the oil pump coming on to get oil to that part of the engine?
Picture is before I took the clutch housing out.
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One of my workshops looks just like that but it's covered with snow right now. More or less dry ground is possible relatively soon, July maybe!
I'll try again: I wouldn't waste my precious time by trying to test that assembly unless the test was happening in a my speeding Brick taking me somewhere else other than to a pile of shop rags and tools.
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I really can't confirm one way or the other with the k75's as I've not owned one, however.... with the 1100's if the oil level is ABOVE the center dot/middle of the sight glass, the oil will leak out if you pull the clutch basket.
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That's what I was wondering. I can't really risk having to disassemble this again. All the clutch fasteners are single use so Im going to try replacing it before closing up and see what happens. It's worth the $100 rather than later I have reasoned. I'll just have to be very delicate with my installation. I don't want to make this worse.
Id like to run a test but as it's been pointed out thats mostly useless until tested under load.
If anyone else has any other instances of oil seeping out during basket remove please let me know.
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I'm 99 percent sure you did not damage the seal when you removed the clutch basket. I believe Scott's point applies to the K100 too, as well as the K75. It didn't leak before you removed the clutch basket so it wasn't leaking. I'm pretty sure it leaked from above the top of the lowest part of the seal, which it will if the oil level is above it when the basket is removed.
There is a photo which shows what I'm trying to explain, in a recent thread by Filmcamera.
Sometimes the problem is just that the clutch cable is stretched.
I think they're being over cautious in describing the clutch fasteners as single use. One of the reasons being that thread locker was probably used, so if heating them up before removing, and then cleaning the threads, it's not an issue to worry about. I think it's safe to reuse them, regardless. Next time you lube the splines, you can check to see if any are loose.
Since the clutch basket is removed anyway, you might as well replace the seal and O-ring, and you probably won't have to go back in there for many years.
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The worrying thing is that should be common knowledge. I'm at the crossroads where I have installed and torqued the basket and waiting on my alignment tool. I can either finish installing the clutch then find out the hard way or dig back in and replace the seal when the seal arrives and I'm hesitant to do either. I already ordered a new round of clutch bolts and nut, I just have to decide.
It sounds like I'm either I'm wasting my time worrying about the seal or about to make a major mistake and have to go through all this again.
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After closing up and replacing all the fluids I took it for a ride. So far no signs of leaking or slipping. Brought it up to 110mph for a bit and so far it's alright. It has a vibration issue from the transmission back I need to address.
The drive shaft splines are worn but the final drive looks new so I'm going to order a replacement shaft ASAP before the final drive gets damaged. Hopefully that should be the source of the issue. If not it may be the final drive.
On the stand when I engage the wheel and it starts spinning it makes some noise and has a low frequency vibration. At first I thought it was an unbalanced tire but I'm really not sure. I should test the brake disk. I'll do some troubleshooting before posting about that.
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I doubt those slightly worn driveshaft socket teeth are creating vibration.
Be sure the wheel bolts are tight and there is the correct amount of the correct weight oil in the transmission and rear drive. You can always pull the driveshaft from the swing arm to check the u-joint to be certain that it was snapped into place before you assembled the rear drive to the swing arm and inspect the u-joint for smoothness of movement.
If the wheel doesn't feel loose when you grab it on each side trying move it any direction except in rotation, the crown bearing within it is likely okay.
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I'm of the school if thought that say's, "If you’re deep in an engine, always renew maintenence parts in reach".
The rear main seal is one to preemptively replace if you have the clutch out. It's a cheap & easy job "today" when you have a hand on it.
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I'm of the school that believes taking calculated risks by using something that seems to be working okay is exciting because I know I'll never be climbing K2 or flying by wingsuit. I'll accept the consequences, which will be considerably less than falling into a crevasse high in the Karakoram Range or embedding myself into the Precambrian gneiss of a mountain in Norway. It's probably a much cheaper thrill, too! 112350
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...much cheaper...! 112350
We are talking about the same 10 minute, $30 rear main seal renewal, yes? :)
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We are talking about the same 10 minute, $30 rear main seal renewal, yes? :)
I wouldn't know about the 10 minute qualification because I haven't replaced mine in 90K miles, but I believe that seal is the subject. That's what makes it even more exciting!
You're discussing a cheap seal; I'm advocating a cheap, and almost daily, adventure.
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After replacing the clutch and doing some tests I thought I was done.
However
After riding in town in 2nd and keeping it reved (5-6K) up it started bucking again. With the bike in gear it pulls normally then the power gives out, then it will pick up again randomly.
I have no idea what is causing a loss of power to the rear wheel. It's not the engine, I can disengage the clutch and it revs fine. It does it in any gear. And if I stop and wait 10 minutes it will stop slipping for a very short time. Enough to get up to 85mph without issue until it begins again.
I can ride the friction zone and it will continue crawling forward without the sensation of a clutch slip. It just feels like the power it's being pushed with drops.
I am at my wits end with this problem.
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Are you absolutely positive beyond the shadow of a doubt that your problem isn't in the engine and fuel delivery?
It takes almost no power to rev the engine with the clutch pulled in. That, to me, doesn't prove a thing.
Have you checked the mundane stuff like the fuel filter in the tank and the fuel line hoses? How is your fuel pressure regulator? Is the fuel tank not venting properly? Any air leaks?
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Very confident. The RPM doesn't drop but the power delivered to the wheel does.
It drove without issue for 2 days under heavy load.
I'm currently praying that grease sling onto the new plates so I'm opening it up again to clean them.
It started after I was riding in town in second and keeping the engine at 7k rpm so I have a feeling that would definitely sling grease.
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So when you open the throttle in 4th or 5th gear, the RPM increases but the speed doesn't.
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Very confident. The RPM doesn't drop but the power delivered to the wheel does.
That could be the description of a slipping clutch. Sometimes a worn or oil-compromised clutch won't slip until higher revs are reached.
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Now I read that you've already installed a either a new clutch or new clutch pack.
Readjust it by the book.
(https://www.motobrick.com/gallery/3/1601-060621181558.png)
(https://www.motobrick.com/gallery/3/1601-060621181503.png)
(https://www.motobrick.com/gallery/3/1601-060621181421.png)
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...there's also the possibility that a slipping clutch could be caused by contamination of the new clutch itself. if too much spline grease was used and then slung on the clutch after startup that could be the issue, as could a leak of the main seal.
just variables and food for thought while working through the issue. First thing is to rule in or rule out clutch slippage after proper adjustment.
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I've followed the clymer manual and Chris harrels videos on adjustment using wire for a 3in measurement for the cable and proper play at the lever.
I'll document what I find inside once I get it open again. Haven't had much time lately to continue.
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Now that you have asserted that the clutch linkage has been inspected and adjusted by the book, my Step 1 would be to pull out the driveshaft and check its u-joint for looseness or rough rotation before it breaks and the driveshaft possibly fractures the swing arm.
Rule out that the main engine ground terminal beneath the frame backbone is clean and also the wire terminals attached to it are also clean. Verify that the LE Jetronic's plug and its connections are clean and that it is tightly plugged in so that it cannot be loosened by pulling its plug in an outward arc to the left from where is cable is attached. Check the ignition control plug and contacts are clean and tight. Like Mighty Gryphon this could possibly be an electrical problem despite your description.
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I'll start checking electrical and the engine.
I have a new driveshaft on order due to worn FD splines.
Original had no play, just starting to round, never lubed by previous owner.
I still feel like it felt like slipping and not engine related but I can't rule it out without troubleshooting.
Here is what my clutch plates looked like
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I've found the spring for the pushrod bearing is incredibly strong even with the lever in the most relaxed position. It seems it could cause a clutch slip if it presses on the pressure plate too hard.
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I've found the spring for the pushrod bearing is incredibly strong even with the lever in the most relaxed position. It seems it could cause a clutch slip if it presses on the pressure plate too hard.
In your photo of the circular diaphragm spring, was that side facing toward the front of your Brick, or toward the rear? Post a photos of the "pushrod bearing spring," its cup and its bearing.
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I've found the spring for the pushrod bearing is incredibly strong even with the lever in the most relaxed position. It seems it could cause a clutch slip if it presses on the pressure plate too hard.
This is something I vaguely remember happening to me after I made an error. I had to, as you are doing, re-split the engine/trans... but I can't recall the exact error yet. I do know it was something done contrary to instructions and easily redone and caused no damage.
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The issue is this persisted since I bought the bike. It slipped on my ride home, it cooled down and I got home. It slipped at home. I swapped the clutch plates because I thought it was shot and it's slipping after. I put everything back the way I found it so it's possible.
I've been comparing stuff with videos and the manual to make sure I'm doing it right and I think it's working.
I'm winding about the clutch release bearing. The other post about "clutch release stuck when hot" made me wonder now I see the pushrod may not be behaving correctly
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I need direct answers to my questions and I need photos for my own understanding, not to hassle you. The minimum thickness of the clutch disc is 4.5mm. Put a straight-edge across the pressure plate in several places and check for warpage.
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Keep in mind both are fresh from the factory. It seems statistically unlikely the original set and new set are the problem.
I would hope my brand new clutch is right.
That's why I replaced the pressure plate already
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I haven't pulled out the spring and bearing since I just changed the transmission oil. I may try removing them this afternoon for inspection if I can collect it or tip it
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Keep in mind both are fresh from the factory. It seems statistically unlikely the original set and new set are the problem.I haven't pulled out the spring and bearing since I just changed the transmission oil.
The specific clutch problem you've been describing is likely statistically improbable.
The clutch release bearing, spring, and cup should pull right out of their position at the rear of the transmission and drop into your hand so if they aren't releasing from their position easily, that's a problem and perhaps a statistically improbable one, too. :laughing4-giggles:
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I mean during the first disassembly, yes I took them out. Didn't notice anything unusual. That was 2 weeks ago. I have since changed the oil.
The transmission oil was nasty, the others were not. Never noticed oil come out from the bottom despite the transmission not being drained during this time.
Now I have the transmission out again and I didn't want to drain the oil. If I remove the boot it's going to come out. Unless there isn't supposed to be oil behind the rubber boot. Because there is.
I'm going to tip the transmission forward tonight and pray it's not going to leak out the plug on top and I'll send more pictures.
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I have a K75. I've removed the transmission three times—for spline lube and clutch work. There's no need to tip it to remove either the one-piece clutch piston or the multi-piece piston assembly. If you haven't filled the transmission beyond the fill line on the shock adjusting tool, or if you measured it correctly according to the manual, only a small amount of oil will dribble from the clutch boot. Put a clean pan under the boot to catch it and you can put it back in the transmission later. That's all there is to it. If the piston assembly cannot be removed easily, that might indicate the source of your problem.
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Is your clutch using the pushrod with the flare near one end?
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I'll get more pictures soon [ Invalid Attachment ]
This is the only end flared out.
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It looks like you've got the correct rod, anyway. icon_cheers
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Here are some more
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Heres the pushrod [ Invalid Attachment ]
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Am I see a ball bearing down it that hole? If I am, it shouldn't be there.
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Yeah looks like it's on top of that snap ring. It's not falling out
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[ Invalid Attachment ] [ Invalid Attachment ]
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Yeah looks like it's on top of that snap ring. It's not falling out
Do you mean the snap ring is on top of it?
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No, the snap ring is behind it. This would stop the cluck release bearing from going all the way back to the snap ring back there.
It may be wedged into the snap ring or its part of whatever is back there. It turns with it
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Your last photo of the bearing assembly was much clearer and helpful. Measure the depth of the release bearing and the distance to the circlip of the internal bearing assembly from the edge of the opening the post them.
I suggest you assemble the push rod and release bearing bearing into the transmission then show us how far it protrudes from the transmission.
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For anyone curious about my rear main seal. I never replaced it and it's not leaking at all. After stress tests and pulling the transmission a week later plus still overfilling my oil. It has not leaked at all. Removing the basket with overfilled oil does infact cause a small amount to come out. Seems perfectly fine to me.
On a second note, through careful consideration I have concluded I'm approaching this problem incorrectly.
The entire assembly works until it doesn't and all points of failure have already been replaced. (New spring plate, etc) without impact.
I have not troubleshooted the actual condition of failure leading me to believe I have brain damage.
The fan has never turned on since I've had the bike.
The over temp light has never come on either.
The clutch stops being a problem when it stops being hot.
I know what I have to do, I'll post my findings when I fix it.
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I have not troubleshooted the actual condition of failure leading me to believe I have brain damage. . . . I know what I have to do, I'll post my findings when I fix it.
If you believe you have brain damage, maybe it would be wise to present your plan to the group before you have mechanical damage to accompany it.
:laughing4-giggles:
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I'm going to jump the relay for the fan and the light to ensure both work then begin checking the thermostat. I haven't even inspected the plug for the temperature sensor yet.
I've been told A3 to 15 on the fan relay and A2 to 31 for the light.
I'm still going to review the electric diagram in the manuals and carefully inspect the relay box first. There are modifications already so I need to map them out to know what I'm working with (an external starter relay has been installed drilled into the rear fender behind the battery).
If all looks good, I'm going to flush the coolant because I don't know when it was last done.
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Posts #10 and #11 in this 2015 thread (https://www.motobrick.com/index.php?topic=6702.msg45770#msg45770) are relevant to your plans. I'm supplying the link in case you, or anyone else, hasn't read them. Pin #45 in the text actually refers to pin #15 on the relay and is likely a typo in the diagram.
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I haven't started jumping things but I encountered a mystery switch behind the temperature sensor with two wires and 3 positions. It doesn't force the fan on so I'm about to chase it.
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Mystery solved, that is an ignition switch bypass. It jumps out the key
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Good catch! That could be contributing to engine's bucking problem.
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I probably should have listened to considering the engine, I found no issues in the cooling loop.
I'm going to replace the hall effect sensor. I understand they fail under heat and the forum post discussing it matches my description "Bucking Bronco". I also don't think anything I've tried so far would explain such a persisting intermittent issue.
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Please link any helpful resources for installation. All I know is to mark it and make sure I install it identically.
On another note I have found more things
The seal on my gas cap is gone, new on order.
Tank was 1/8 water, this probably happened due to me hosing the tank off several times these past few days. The fuel pump is "functional" but missing a mounting clip and I don't think it's OEM, the terminals for the power wires look different. There is a hose clamp involved too. Interesting [ Invalid Attachment ] [ Invalid Attachment ] [ Invalid Attachment ] [ Invalid Attachment ]
The power saver relay was super glued in it's socket. I cleaned the glue so it's a little loose but I'll put a ziptied on that like a professional.
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There may be more electrical tomfoolery
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The fuel pump is "functional" but missing a mounting clip and I don't think it's OEM, the terminals for the power wires look different. There is a hose clamp involved too.
That pump is a mess and could be part of the bucking problem because the fuel sock is partially clogged. Also, it probably doesn't have a low enough protrusion into fuel from its position in the holder. You can do better than that one without paying OEM price. The glue-spattered connector should be replaced if you can find one on ebay or in salvage.
I'm not convinced the Hall sensor is the problem because I'm uncertain this relic has been ridden long enough to get hot. :laughing4-giggles: Have you done the static LED test on the sensor to determine if it's working at all?
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The fuel pumps access to gas would be easy to troubleshoot. But now that you mention it I can't say I've tested. If that's all it was Ill loose my mind. I never had problems when the tank got low enough for the fuel light to come on several occasions.
Can you help me identify the orange relay, I've got conflicting information, I seen it labeled fuel pump relay and power saver relay.
I pulled the fuel filter and the sock. The sock didn't have anything in it, just discolored in the picture. The fuel filter didn't have much problem forcing gas through it so I put it back for now. I didn't have a replacement on hand. I should probably check the pressure, haven't inspected the regulator.
I have not tested the hall sensor and I dont dare try. I'm not convinced either but my symptoms feel similar. I looked at my ground connection at the transmission and it was incredibly corroded at the bolt so I cleaned it up.
I'm just waiting to take it for a ride and gather more information when it fails next.