asked Feb 14, 2010 at 4:49pm
Hp HP LaserJet 4L

Paper feed problem HP Laserjet 4L

My old reliable LJ 4L started acting up after I replaced the cartridge. Paper started jamming more and more frequently at the entry to the toner cartridge. HP said take out the cartridge and replace it. I did, and it worked a few cycles then began jamming nearly every time.

Manual feed does not work. Same symptom. Paper stops at entry, paper jam light comes on.

Cleaned the rollers. Again, it worked a few times. Bought a second (low price) cartridge. Cleaned up the toner spill and got 8 good pages before the same thing happened again.

The symptoms are very similar to the ones described in the paper sensor arm replacement kit, EXCEPT the paper sensor arm is NOT broken off. The paper comes to rest on the arm.

I can get it to feed by pushing the reset button, but it doesn't print under those conditions--just flushes the paper out, reloads a new sheet, and jams again.

I am suspecting a sensor, and I haven't the foggiest idea how to get at it, even if I had the right test equipment (the manual suggests an oscilloscope would be needed to check the timing sequence).

Anyone have any ideas?


The low price cartridge part should be a clue. I've seen cartridges, particularly Staples brand, cause jams. I'm going to blame the toner cartridge based on the fact that the paper starts feeding ok temporarily when you change them. Those cartridges can damage the motor drive gear as well, causing it to split from the strain of driving the badly rebuilt piece of crap. You get what you pay for, the old adage goes.
by moe on Feb 14, 2010 at 6:54pm Add comment
Sorry. I did not explain the problem carefully. The problem began when I put in a new HP cartridge (though they do not make them any longer). As I had already sent back the old cartridge to recycle, I needed a second one to confirm it was NOT the cartridge. That's when the low cost cartridge came in. It was only in the printer for about 15 minutes total, and did print a few pages. The HP cartridge actually did about the same.

In addition, the feed problem is the same with the cartridge out. I have defeated the top and back switches with tape, and I can watch the paper feed. It goes as far as the sensor arm and stops. The paper jam light goes on. Manual feed: same thing. It grabs the paper, advances it to the sensor arm, stops. Turns on the paper jam light.

Pushing the reset button flushes the paper out of the printer cleanly.

Perhaps that's a better explanation?


cps - cschade
Same happening to me since last week. The paper stops either righ at the roll or gets past the roll a bit and stops before it reaches the cartridge. The cartrige is the authentic HP, so no problem there. I am thinking about getting the replacement kit from here: but the sensor arm doen't look broken either. The arm is also sold for $10 online.
Any luck with your fixes?
by Anonymous on Feb 22, 2010 at 6:59pm Add comment
The paper wouldn't get that far if the arm was broken. If it doesn't look broken, why change it. Once it gets past the arm, the arm is no longer a possibility.
by moe on Feb 22, 2010 at 8:24pm Add comment
That's basically what mine is doing. The paper stops resting against the sensor arm.

Am I right to suspect a sensor or an electronics problem? It's odd, because I expect sensors to be all or nothing, and this problem has built up over the months starting when I replaced the cartridge the first time.

If it is a sensor, I haven't the foggiest idea how to test it.



by cschade on Feb 23, 2010 at 6:05pm Add comment
Optical sensors never go bad. I've fixed a few by directing a blast of air from one of those air dusters with the long tube on them. You blow it down around the arm and in theory it will blow the dust blocking the optical sensor from seeing the arm.
by moe on Feb 23, 2010 at 7:25pm Add comment
That was my theory, and I already tried a few puffs of air from a camera cleaning bulb. I'll get a can of compressed air and really zap it. Can't hurt, and the worsening symptoms over time are consistent with something gradually building up. Do spiders ever nest in printers?


cps - cschade
Oh yeah. My favorite was some years ago when one electrocuted itself on the charge corona wire of a LaserJet III. The result was blank pages, since the HV was shorted out. Plucked the sucker off and it fixed it.
by moe on Feb 24, 2010 at 10:29pm Add comment
I can get the feed mechanism to work when I feed manually (with the cover off). After a sheet of paper gets to the roller I manually turn the roll a bit. It grabs the paper and pulls it all the way. I will try blowing the dust off too. Will let you know tomorrow if it helped.
by Anonymous on Feb 26, 2010 at 4:19pm Add comment
Well, I don't know about you, but I think I have a poltergeist. The air worked--or seemed to. For the first time in weeks, paper would feed past the sensor and through the rollers into the output. I put in the cartridge and successfully printed several test sheets.

I overlooked recent history.

All previous "fixes" (removing and replacing the cartridge, cleaning the rollers, using a different cartridge) have all "worked" but after a while the problem recurred. In this case, "after a while" was as soon as I hooked it up to my computer.

I hope you have greater success, but I am completely stumped. I would have given up on this months ago and thrown the printer away if it wasn't such a *good* printer. If anyone has any ideas, or knows a competent exorcist, I'm all ears.
by cschade on Feb 26, 2010 at 5:34pm Add comment
I had the same problem. I printed twice since I "fixed" the problem. I noticed a lot of fine white dust when I removed the cartridge on the left top inside of the printer. I used a pencil
eraser top and rubbed it of and blew it off as well. Seemed to correct the problem
I have owned this printer forever. I have been using remanufactured cartridges for years without any problems. About
40 bucks including shipping. Good luck. - Anonymous
I just ordered a replacement cartridge. Next I removed the existing cartridge to shake it a bit. That's what I do to get a little more use out of the remaining toner.

Next, I put the cartridge back and to my great annoyance I have the same problem with the paper jaming in the front. What a great printer! Perhaps we should put it on Facebook. I might bury in the backyard along with the refurbished cartridge I just ordered!

I'm not giving up.Tomorrow off to Staples to buy some air.

by unknown on Mar 12, 2010 at 8:16pm Add comment
I just ordered a replacement cartridge. Next I removed the existing cartridge to shake it a bit. That what I do to get a little more use out of the remaining toner.

Next, I put the cartridge back and to my great annoyance I have the same problem with the paper jaming in the front. What a great printer! Perhaps we should put it on Facebook. I might bury in the backyard along with the refurbished cartridge I just ordered!

I'm not giving up.Tomorrow off to Staples to buy some air.

by unknown on Mar 12, 2010 at 8:24pm Add comment
Well the white powder idea was interesting, but that's not it. At least I don't have to worry about my printer getting anthrax. I am starting to suspect either (1) spider webs so dense that air won't blow them away (I just dug a bunch out of a bicycle pump, so I think this is a remote possibility) or (2) a failed light source for the sensor. I was told the sensors don't fail, but they must have a light source, which might. Does anyone know if the light source is infrared or visible light? If visible light, I might be able to test the printer in darkness, and see if I can see any light near the sensor arm. Or am I just stabbing in the dark?


by cschade on Mar 17, 2010 at 6:25pm Add comment
Just as a follow-up. Since blowing air blindly at the sensor through the port for the paper detector arm did not work, I screwed my courage to the sticking place and used the service manual to disassemble the printer down to the DC board. The sensor appeared clean, when I found it, and it was not loose on the board. I can't rule out a cracked circuit board, which caused a similar intermittent problem in a radio I had years ago.

With no better idea, I blasted the sensor directly with compressed air, then reassembled the printer. To my surprise, I had no extra parts and only lost one screw (some readers will think that my perseverence is evidence I lost a lot more than one screw!).

To my utter amazement, it began to feed paper correctly. It worked the next day. And the next.

I don't know if it's actually fixed. I'm very suspicious of a loose component or microcrack in the board, which I will *never* find. Such things cause exactly the symptoms I have observed. Mess with something and it works for a little while. I may just be having a slightly longer mean time between failures. On the other hand, if it keeps working, the advice will be to blow air directly on the sensor assembly.

Stay tuned. - cschade
A couple of people have fixed those boards with the infamous board baking technique popularized by this board. You need to remove the board from the plastic housing and remove the plastic cover over the HV power section. It wouldn't hurt to take the solenoid off the board either. 350-400 degrees for 8 minutes. That reflows all the solder. I'd wait until it broke again.
by moe on Apr 29, 2010 at 2:29pm Add comment
Very clever. Appreciate the tip. And yes, I will wait until it breaks again. Taking anything that complicated apart makes me nervous, but I really like the workmanship that I see when I peel all those layers.

by cschade on Apr 29, 2010 at 5:24pm Add comment
Paper coming from the paper tray hangs on the upper left corner of the paper before entering theprinting process.
by wjmciver on Feb 22, 2011 at 5:38am Add comment
Remove the paper tray. In the upper left corner is a black plastic assembly held in by one screw. Remove it and clean it. - moe
I looked hard with a bright light and found a scrap of paper stuck in the feed just past the rollers - got it easy from the top with the cartridge out. Now I have a new printer and a spare!
by unknown on Aug 18, 2011 at 6:03pm Add comment

We have an excellent HP Laserjet 4L and it has started getting paper feed errors.

Much the same as mentioned on this thread.

It reports a paper problem and when opened I find the paper taken up for an inch or so and then it's all stopped.

And the important thing about it: It is intermittent. 90\% of the time it is there. But just sometimes it prints a sheet without a problem.

I kept changing the paper thinking we had batch of thick hard rubbishy paper and it worked for two sheets after that.. and then stopped again.

That must be a big clue, right? Shows all the mechanism is okay. Shows the paper path is not obstructed. Shows it can pick up. But for some reason not feeding the full way...

Anyone still watching this thread? Got any ideas for me?

by abrogard on Aug 29, 2014 at 4:13am Add comment
This is a very old printer. Pickup roller is probably worn by now it does not work all the time.
by dmzcompute on Aug 29, 2014 at 5:25am Add comment

Well it was a sudden onset thing. Does that fit the diagnosis?

One day working fine. The next day not working at all. Repeated attempts to fix give rise to, like I said, the occasional page printing out okay.

Could the roller have gotten slippery? Can it be treated (sprayed?) with something that'll give it more stickiness or something?
by abrogard on Aug 29, 2014 at 5:32am Add comment