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Re: [GMCnet] I give up. (Onan) [message #190506 is a reply to message #190449] Fri, 16 November 2012 20:16 Go to previous messageGo to previous message
Robin Hood is currently offline  Robin Hood   United States
Messages: 1078
Registered: April 2011
Karma:
Senior Member
Update. I have replaced the fuse. Fuel pump (the new one from NAPA that was
working fine) still dead as a murph.

With fuse replaced I have 12v to the coil and 12v to the fuel pump. I used
jumper wires to bring straight 12v direct from the battery to the fuel
pump, verified with the meter, still nothing.

Hypothesis: bad fuel pump.

Problem: it's brand new and I don't see how a backfire could cause a fuel
pump to go bad...

Hypothesis: the backfire, while full of sound and fury, may in truth
signify nothing. The blown fuse on the other hand may be a clue to a more
sinister and hidden story. The pump may have been fine until my tipsy
novice self started poking around with the meter. Perhaps my probes touched
something(s) at the same time that they ought not've. Perhaps whatever
happened took out the pump's internals and was going to zap the board until
the fuse gave its last full measure in support of the mission.

And so I find myself more or less where I started: with a generator with a
bad pump. :) albeit with a known good ignition and carb now at least.

I'm going to Try percussive maintenance in the morning.

Suggestions and thoughts are welcome as always.

On Friday, November 16, 2012, Ken Burton wrote:

>
>
> Robin Hood wrote on Thu, 15 November 2012 21:16
> > On Thu, Nov 15, 2012 at 7:19 PM, Robin Hood <loxley@gmail.com<javascript:;>>
> wrote:
> > > Is there a failure mode that includes backfires and the 5 amp fuse
> blowing?
> > >
> >
> >
> > http://youtu.be/Oz_ZPHdO3FE
> >
> > Summary:
> >
> > 1. Ok, no more drinking.
> > 2. I started the generator, removed the jumpers, and just as I was
> > about to put the meter on pins 8 and 11, the generator started to die,
> > and then died with a spectacular backfire. You can see the glow of the
> > fireball coming out the exhaust pipe.
> > 3. Soon after this, likely due to either the backfire or due to me
> > poking around with my meter trying to make sure I got onto pins 8 and
> > 11, I noticed the 5 amp fuse was blown.
> > 4. I found 1 wire on the VR that had continuity with wire number 8,
> > another wire on the VR with continuity going to the now-empty fuse
> > holder ("B-pos), and one wire on the VR that I don't know where
> > terminates. There is not continuity between any wire and the wire
> > currently connected to pin 8 on the board.
> > 5. Jumpering the board no longer even causes the fuel pump to run.
> >
> > I believe the same thing would have happened had I just been drinking
> > a coke, but, yeah, lesson learned.
> >
> > Robin Hood
>
> Put another fuse in it and try again.
>
> OK you have identified the wire that goes to the B+ terminal. The
> remaining two wires get hooked together and attached L2. That is the pair
> that you want remove and keep taped together when you want to remove the VR
> from the circuit.
>
> Do not worry about the blown fuse. I have blown hundreds of them trouble
> shooting things over the years. That is why the fuses are there and why
> they are easily replaceable. We probably have 300 - 500 replacement glass
> fuses around here for that very reason. Laurie and I have also had over 50
> years to collect them. I've probably got another 200 of the Blade fuse
> types.
>
> Do not go over size on the replacement. Use only 5 amp fuse.
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>


--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
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