Craftsman oilless wont start with pressurized tank

twiggles · Apr 15, 2013

Hello Gentleman (and Ladies),

I have a question. I have been scratching my head over this for a couple of days. I have a Craftsman 919.16500 oilless air compressor.

I got this unit for free, so I am trying to get it up and running. Initially I was having problems with it not starting at all, just blowing the breaker. I replaced the start capacitor, and now it starts and pumps quickly to 125 PSI.

My problem, is now the compressor wont kick on when there is pressure in the tank. It acts like it wants to start, but wont...I figured this was a check valve issue, so I replaced that. Nothing...The unloader valve is working (I can hear and feel it unload when the compressor motor stops.

SUMMARY:
Wont start with pressurized tank. Motor hums like it wants to start, but wont kick on.
New Check Valve, start capacitor
Functioning unloader valve
Motor runs great, has had an easy life before I received it

Any suggestions? Thanks in advance!

Flexia · Apr 15, 2013

Maybe the new check valve is faulty or maybe insalled backward

Sent from my SCH-I605 using Tapatalk 2

Chaznsc · Apr 15, 2013

Disengage the air line from the PUMP to the TANK. See if it starts. If it does, your problem is the check valve.

Hundojoe · Apr 15, 2013

What size breaker is it plugged into? Does it trip the breaker? Are you plugged into n extension cord? The compressor prolly needs at least a 20amp circuit to start when the tank is full or empty enough to need to start, and definitely never use an extension cord.

Jvvmusme · Apr 15, 2013

I had the same problem. Mine did not start with the tank pressurized when the electric motor was cold . I had to drain completely the tank and with no pressure on the tank it would start fine and after the first cycle (or first refill) everything was OK. I changed the capacitators and improved significantly, but it also had to do with the electric supply.
Due to the fact that I only work on weekends I would drain the tank every saturday and then it would would work OK. Not bad, because it makes you drain the tank every weekend....
Try higher capacitatros first. Then the electric supply...
My motor is china made....

twiggles · Apr 15, 2013

Chaznsc said:
Disengage the air line from the PUMP to the TANK. See if it starts. If it does, your problem is the check valve.

Good Suggestion, I'll try that this evening.

Hundojoe said:
What size breaker is it plugged into? Does it trip the breaker? Are you plugged into n extension cord? The compressor prolly needs at least a 20amp circuit to start when the tank is full or empty enough to need to start, and definitely never use an extension cord.

Its in a 15A breaker, but it starts fine without pressure, so I dont think this is an issue. It does not trip the breaker, just wont start. I an runnning straight to the outlet with no extension cord.

Fleixa said:
Maybe the new check valve is faulty or maybe insalled backward

I'm going to do the above test to see how it works. With this model, there is no way to install the check valve backwards.

PT Doc · Apr 15, 2013

How much pressure in the tank?

Train · Apr 15, 2013

I know on my Craftsman oil less, it I'm using a long undersized extension cord, it does the same thing. If I change it to a heavier cord the problem disappears. You're not using a cord so I'm wondering what else might be on that circuit.

Hundojoe · Apr 15, 2013

The 15amp circuit can not support the amount of current to get the motor started, the motor prolly pulls like 3 time the amount of power to start as it does when it's up and running. And with pressure pushing back on the pump is where your problem is. Try plugging it into a 20amp outlet and see what happens, my money says it will start up every time. Just my 2 cents. Good luck

NY_treeguy · Apr 15, 2013

As others have said, check the cord and the check valve. "Inherited" a CH that would't run right. Put a heaver cord on and replaced the check valve and it ran like a champ.

RECox286 · Apr 15, 2013

Is there an unloader on the compressor ? Do you, or did you ever

hear an excape of air when the compressor shut down at full pressure ?

If you did at one time, but don't now, then the machine is trying to

start under full pressure, rather than ambient pressure. Check the

outside of the pressure switch for a small diameter length of tubing

connected to a schrader valve operated by a lever. If there is one,

and it is not working, find out why. Worst case: you will need a new

pressure shut off switch.

Uncle Bob

twiggles · Apr 15, 2013

PT Doc said:
How much pressure in the tank?

Cut in switch starts around 80 PSI I believe...

Hundojoe said:
The 15amp circuit can not support the amount of current to get the motor started, the motor prolly pulls like 3 time the amount of power to start as it does when it's up and running. And with pressure pushing back on the pump is where your problem is. Try plugging it into a 20amp outlet and see what happens, my money says it will start up every time. Just my 2 cents. Good luck

I'll try a 20A outlet soon...

NY_treeguy said:
As others have said, check the cord and the check valve. "Inherited" a CH that would't run right. Put a heaver cord on and replaced the check valve and it ran like a champ.

New Check Valve, Im thinking it must be something to do with the 15 circuit...

RECox286 said:
Is there an unloader on the compressor ? Do you, or did you ever

hear an excape of air when the compressor shut down at full pressure ?

If you did at one time, but don't now, then the machine is trying to

start under full pressure, rather than ambient pressure. Check the

outside of the pressure switch for a small diameter length of tubing

connected to a schrader valve operated by a lever. If there is one,

and it is not working, find out why. Worst case: you will need a new

pressure shut off switch.

Uncle Bob

The unloader valve is working correctly.

nit2wn · Apr 15, 2013

Need a 20 amp circuit. Mine would do that even new. Needed a heavier circuit. I used to run it off my generator since it was closer and needed to be ran anyway.

ezover · Apr 16, 2013

when i got my CM oil less compressor about 10 years ago the instructions
stated to let it run for 30 min with the check valve open. well being the impatient type i did not do that and had the same problem you have.

kept popping breaker, capacitor burnt out. replaced capacitor, ran pump with open valve for an hour, and have it plug in to a 20 amp breaker using the 3 foot lead the came with the compressor. and that solved my problem.

The Cobbler · Oct 24, 2013

I had the same problem with a craftsman oil-less. I'm not sure of the model number, but I will get it & post it here.
It would start no problem with no tank pressure, but it would blow a breaker when the tank was full. 20 amp breaker didnt help the situation .It was brand new , but I got it at a misguided freight sale and obviously no warranty. What I ended up doing was adding a cold start unloader valve, another name is unloader assist valve available on ebay & other places.
Tie it into the pump discharge line( before the tank check valve) what it does is bleed off some of the air until the pressure reaches about 10 PSI, then the valve closes . that gives the motor lots of time to get up to full run before it has to deal with pressure on the pump. Cost was about $4 and a brass tee was $2 .

see the part here http://www.aircompressorservicekits.com/Cold-Start-Unloader-Valve-25.html

If I get ambitious I will take a few pic of my set up & post here if I can..

any questions I would be glad to answer.

JBourquin · Oct 25, 2013

Damn, I've had a 33gal 150psi Craftsman compressor that's been kicking breakers for as long as I've owned it. (bout 7yrs) Just delt with it as I never really used it much. Now I know how to fix it. Thanks guys..

madjack · Oct 25, 2013

Common problem. Have 2 CMan compressors that did this along with a Porter Cable. Changed from the chinese capasitors to mexican made. and use 12 gauge cords. No more problems

GoodEnough · Dec 26, 2013

The Cobbler said:
I had the same problem with a craftsman oil-less. I'm not sure of the model number, but I will get it & post it here.
It would start no problem with no tank pressure, but it would blow a breaker when the tank was full. 20 amp breaker didnt help the situation .It was brand new , but I got it at a misguided freight sale and obviously no warranty. What I ended up doing was adding a cold start unloader valve, another name is unloader assist valve available on ebay & other places.
Tie it into the pump discharge line( before the tank check valve) what it does is bleed off some of the air until the pressure reaches about 10 PSI, then the valve closes . that gives the motor lots of time to get up to full run before it has to deal with pressure on the pump. Cost was about $4 and a brass tee was $2 .

see the part here http://www.aircompressorservicekits.com/Cold-Start-Unloader-Valve-25.html

If I get ambitious I will take a few pic of my set up & post here if I can..

any questions I would be glad to answer.

Cobbler, I'd like to do this to my CAT compressor. Can you take some photos as a guide for the totally clueless? I basically know how to hook my hose up to the compressor, and little more.

Also, does HF sell the brass T I'd need? Or another website?

theoldwizard1 · Dec 26, 2013

GoodEnough said:
Cobbler, I'd like to do this to my CAT compressor. Can you take some photos as a guide for the totally clueless? I basically know how to hook my hose up to the compressor, and little more.

See attachment. Typically, all of these fittings would be 1/4" NPT (national pipe thread).

Remove hose. Remove brass elbow. Install "street tee". Install male-to-male coupling. Re-install hose. Install unloader assist valve. All threads require teflon pipe tape at least 3 full wraps.

Also, does HF sell the brass T I'd need? Or another website?

eBay !

GoodEnough · Dec 26, 2013

Thanks!
Theoldwizard1 is one hell of a good fella with all his help.

I will order this unloader valve for $4

Street T costs $7

Male to Male 1/4 for $3

Total cost $14/delivered.

theoldwizard1 · Dec 26, 2013

GoodEnough said:
Thanks!
Theoldwizard1 is one hell of a good fella with all his help.

Shhhh !!!

Don't tell anyone ! It will ruin my reputation as a grumpy old fart !

The Cobbler · Dec 26, 2013

oldwizard beat me to it, he has everything covered I think.... let me know if you still need a picture or 2.

Craftsman oilless wont start with pressurized tank

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