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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
scoops scoops is offline
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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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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
scoops scoops is offline
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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 offline
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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
nothingbutdarts nothingbutdarts is offline
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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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