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Onan Gen 4kw BF 3CR / 16004B Repair - Gen Turns - No Engine Start


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  #1  
Old 01-03-2018, 10:41:25 PM
andreaskc andreaskc is offline
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Default Onan Gen 4kw BF 3CR / 16004B Repair - Gen Turns - No Engine Start

I have the referenced (subject line and attached pic) generator that I picked up and bringing back to life. I'm new to these models. Gen. head turns w start button but engine doesn't fire up.

Measuring volt drop to 8.5v at solenoid, coil, and points. Removed wire from oil pressure switch. This v drop normal from 12-13v?

Consistent clicking sound on start button seems to be coming from fuel pump? Not getting fuel up out of tank (Have a clear fuel hose and not seeing anything and no restriction in fuel hose/tank). Interesting reversing polarity on battery causes clicking sound wo start button and nothing else happening.

Coil tests out at 12.4 ohms and is slightly under spec of 12.6.

Tonight, I put on a spark plug tester light and can see a slight spark once when I press the start button and also once when I let off the start button.

Previous owner claimed it ran, but I'm skeptical... the fuse holders were trashed. The only thing I've changed so far is replacing the fuse holders and soldering in the connection. Wiring diagram on it looks to match well with existing wiring.

Also have switched up batteries from garden tractor battery to monster 1000ca 12v. No real difference.

Thinking about starting with fuel pump replacement. Any other thoughts on my observations? Would fuel pump cause the voltage drop and make one-time sparking only present on switch on/off?
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Old 01-03-2018, 10:48:52 PM
oregonfarmboy oregonfarmboy is offline
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

I would check the fuel pump before i replaced it. Those are pretty tough little units. I would pull the filter and clean it. One of my ccks had sat for quite a while and the pump filter was filled with grit and other stuff. cleaned it and everything was fine. You could then simply connect power directly to it to insure that it is indeed pumping fuel. May want to also check and clean the remainder of the fuel system while you are at it. A lawn mower battery will not start a cck. Good move to go with the heavier battery. In certain situations I have connected two together to give me more cranking amps.
Good luck and keep us informed.
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Old 01-03-2018, 11:27:30 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

clean your points. start there.
may need to hook that low oil back up, depends on if itís no or nc
could also be a bad relay
after you clean points, try running 12v+ directly to + on points tower
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  #4  
Old 01-03-2018, 11:35:06 PM
andreaskc andreaskc is offline
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Ah great feedback, thanks!. I did clean up the points already. Will clean up fuel filter tomorrow and try connecting directly to coil.
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Old 01-04-2018, 10:48:00 PM
dracer dracer is offline
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Quote:
Originally Posted by andreaskc View Post
I have the referenced (subject line and attached pic) generator that I picked up and bringing back to life. I'm new to these models. Gen. head turns w start button but engine doesn't fire up.

Measuring volt drop to 8.5v at solenoid, coil, and points. Removed wire from oil pressure switch. This v drop normal from 12-13v?

Consistent clicking sound on start button seems to be coming from fuel pump? Not getting fuel up out of tank (Have a clear fuel hose and not seeing anything and no restriction in fuel hose/tank). Interesting reversing polarity on battery causes clicking sound wo start button and nothing else happening.

Coil tests out at 12.4 ohms and is slightly under spec of 12.6.

Tonight, I put on a spark plug tester light and can see a slight spark once when I press the start button and also once when I let off the start button.

Previous owner claimed it ran, but I'm skeptical... the fuse holders were trashed. The only thing I've changed so far is replacing the fuse holders and soldering in the connection. Wiring diagram on it looks to match well with existing wiring.

Also have switched up batteries from garden tractor battery to monster 1000ca 12v. No real difference.

Thinking about starting with fuel pump replacement. Any other thoughts on my observations? Would fuel pump cause the voltage drop and make one-time sparking only present on switch on/off?
when you get a spark when you first press the start and again when you let off , is usually as sign of a bad ig modual , I do not know if that model has one on the board or not , if you have a condenser hooked to the points not the coil it does not have one , check the points and clean them , and then check with a test light to make sure thy are making contact
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Old 01-04-2018, 11:20:56 PM
andreaskc andreaskc is offline
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Took off the fuel pump. See attached pic. Inside is missing stuff. Just twisted off the cap. No filter. Not sure how the middle plunger comes out. Service manual says to take off with pliers? It doesnít budge. Smells like serious varnish. There was a plug of gelled solid gas in intake tube. Clicking of pump was definitely what could be heard when trying to start it.

Hooking up pump off the frame just makes it click away... could be salvaged other than its missing half a dozen filterish parts?

Pressing start w pump off will turn the gen head. Still no spark in tester other than once on on/off.

Hooked positive to coil... but donít see anything in the tester light?
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Old 01-04-2018, 11:29:10 PM
andreaskc andreaskc is offline
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Quote:
Originally Posted by dracer View Post
when you get a spark when you first press the start and again when you let off , is usually as sign of a bad ig modual , I do not know if that model has one on the board or not , if you have a condenser hooked to the points not the coil it does not have one , check the points and clean them , and then check with a test light to make sure thy are making contact
There is a condenser on coil and points. I believe the ignition module is a small plastic 4 wire block thatís inside the box next to the start button?

Points are cleaned up, but havenít really checked gap much and I just pulled a little emery to wipe the crud off
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Old 01-04-2018, 11:33:17 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

i would soak that pump in carb cleaner then try to push that ball up
you. might be able to salvage it, if not electric replacements are pretty cheap

as far as your spark issue, sounds like something is grounding it.

what wires come off the negative side of coil and trace whereís they go.
and let us know
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Old 01-05-2018, 12:04:21 AM
Chas183 Chas183 is online now
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

I would clean and adjust the points again.
The gap should be .020.
Also check using a test light that the point open and close as dracer suggested.


chas183
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Old 01-05-2018, 12:10:47 AM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Yes, one end of test light connected to coil (-) and other end to good ground, crank the engine, the test light should blink on and off as the points open and close if they are working correctly.

Also do NOT believe there is an ignition module in a BF, just points. I believe what you are calling a module in the box is actually a power relay to energize the fuel pump and coil.
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Old 01-05-2018, 12:51:50 AM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

That model has an ignition relay,run relay,points,condenser. No module.
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Old 01-05-2018, 12:58:24 PM
zuhnc zuhnc is offline
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

There should be a little wire loop holding that check valve and seat into the center of the pump. The tube does not pull off. Once that check valve and seat is out, there is the pump plunger with another check valve in it, as well as a little rubber bumper at the top of the plunger. Soaking that assembly, as others have advised, will allow you to more easily remove that first valve and seat. The little wire loop has the ends bent to go through the small holes in the side of that tube, to hold the plunger, and check valve and seat in place. You may be able to search the net for just the filter that goes into the pump body. Good pumps, but subject to "stickage" with no use. If you have to replace it, get one with NO MORE than 4psi output pressure. zuhnc
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Old 01-13-2018, 02:30:49 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Ok, still not getting fire to plugs. I get one spark when pressing start and one last spark when letting go of the button but nothing while holding the start button down.

I can put a Test light to the + coil and ground and get a bright light. Test light on - coil and ground results in nothing.

I did replace the coil, points, New plugs and points condenser. Adjusted gap to 20 on points. New Plugs were right on. I also picked up a new fuel pump and fuel filter.

Now getting fuel and can now see spark on points. Spark plug test light now bright. Again only once on pressing start and once when letting go.

There is a small plastic block in the wiring box that the wiring/schematic labels crank ignition relay. Could this relay cause this problem? Only other item not replaced is the start solenoid.

Pic of setup attached...
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Old 01-13-2018, 02:38:42 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Also there is a condenser on the coil hooked up to the + side that has not been replaced.
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Old 01-13-2018, 03:05:27 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Woohooo! Figured it out, w cover to points box screwed in it was grounding out. Got it started, auto-choke not working, but after manually choking it, it started pretty soon after.
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Old 01-13-2018, 04:44:22 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Have most of it put back together, other than the points box cover. Made a little wheeled cart for gen, battery and tank. Considering a box cover to put over the top in case I want to run it in inclement weather
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Old 01-13-2018, 07:15:02 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

Main carb adjustment screw drips a bit after running. I assume just from minor pressure left over in fuel line? Iíve seen some posts on some onanís that close off fuel on shutdown? Am I missing something in my setup that would prevent it from leaking out the carb?

Any easy solutions or suggestions?
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Old 01-13-2018, 10:08:23 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

glad u got it running, told u something was grounding the points
as for that leak, i think there is a rubber donut thatís prob dried out.
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Old 01-14-2018, 06:16:32 AM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

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Originally Posted by andreaskc View Post
Main carb adjustment screw drips a bit after running. I assume just from minor pressure left over in fuel line? Iíve seen some posts on some onanís that close off fuel on shutdown? Am I missing something in my setup that would prevent it from leaking out the carb?

Any easy solutions or suggestions?
There is no fuel pressure at the main jet.
The leak can be stopped by tightening the main jet packing nut. (It's the smaller hex) .

Also, unless you've removed it, it appears that one of the cylinder head tin "covers" is missing.
It's important. It directs the air flow over the head and cylinder.
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Old 01-14-2018, 01:24:28 PM
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Default Re: Onan Gen 4kw BF 3cr / 16004b Repair - Gen Turns - No engine start

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Originally Posted by lokay5 View Post
There is no fuel pressure at the main jet.
The leak can be stopped by tightening the main jet packing nut. (It's the smaller hex) .

Also, unless you've removed it, it appears that one of the cylinder head tin "covers" is missing.
It's important. It directs the air flow over the head and cylinder.
Ah cool thanks, will check out tightening the nut wo messing with adjustment hopefully.

Some of the earlier pics I had taken off the cover to check the oil pressure switch in the event it was causing my spark problems. Iíve since put it back on.
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