Home » Public Forums » GMCnet » [GMCnet] I give up. (Onan)
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| Re: [GMCnet] I give up. (Onan) [message #188241 is a reply to message #188208] |
Thu, 25 October 2012 17:26   |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Robin Hood wrote on Thu, 25 October 2012 12:23 |
Excellent tests, I'll try them when I get home. It will certainly be embarassing if my problem was that end of the fuel line in the gas tank isn't submerged. The lack of change in pitch or tempo of the new pump is worrisome; on my Pontiac I can hear the difference when the fuel hits the little electric pump I installed when the mechanical gave up the ghost. In Duane's video, the same thing happens when the fuel hits the Onan pump.
--
Robin Hood
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Robin,
I finally had time to get to your video, and you had a question about the two wires that connect to the voltage regulator.
First, if you are running from a battery that is not part of a coach, you want that to work, you need it to keep the battery up so the ignition and fuel pump stay working while you are trying to run the generator.
The connections are simple as only one goes to the battery. That is the terminal labeled B+. It actually goes to terminal 5 on the control board. The other wire maybe found to go to a dual connector on terminal 8 on the control board.
When the unit is in a 26 and is run from the house bank, you don't need this regulator and it is best disconnected if you have a modern converter as they will fight each other.
And, yes, it sure sounds like the pump isn't pumping fuel.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] I give up. (Onan) [message #188255 is a reply to message #188241] |
Thu, 25 October 2012 18:54 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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OK, I got home and tried the various tests.
http://youtu.be/InZn4C-ZHj4
Summary: Pump is pumping, wife is aggravated about me getting gasoline
everywhere. I managed not to catch myself on fire. Blowing into the
fuel inlet with the bowl on won't work, but with the bowl off, I could
force air (and gasoline!) through. More spillage. With the bowl on,
not much gas goes into the bowl. I want to mail this thing (the carb)
to somebody who knows how these things are supposed to be set up and
what's proper vs seriously out of whack.
On Thu, Oct 25, 2012 at 5:26 PM, Matt Colie <matt7323tze@gmail.com> wrote:
>
>
> Robin Hood wrote on Thu, 25 October 2012 12:23
>> Excellent tests, I'll try them when I get home. It will certainly be embarassing if my problem was that end of the fuel line in the gas tank isn't submerged. The lack of change in pitch or tempo of the new pump is worrisome; on my Pontiac I can hear the difference when the fuel hits the little electric pump I installed when the mechanical gave up the ghost. In Duane's video, the same thing happens when the fuel hits the Onan pump.
>> --
>> Robin Hood
>
> Robin,
>
> I finally had time to get to your video, and you had a question about the two wires that connect to the voltage regulator.
> First, if you are running from a battery that is not part of a coach, you want that to work, you need it to keep the battery up so the ignition and fuel pump stay working while you are trying to run the generator.
> The connections are simple as only one goes to the battery. That is the terminal labeled B+. It actually goes to terminal 5 on the control board. The other wire maybe found to go to a dual connector on terminal 8 on the control board.
>
> When the unit is in a 26 and is run from the house bank, you don't need this regulator and it is best disconnected if you have a modern converter as they will fight each other.
>
> And, yes, it sure sounds like the pump isn't pumping fuel.
>
> Matt
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumière (say show-me-air) Just about as stock as you will find
> SE Michigan - Twixt A2 and Detroit
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--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
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| Re: [GMCnet] I give up. (Onan) [message #188259 is a reply to message #188258] |
Thu, 25 October 2012 19:31 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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I other words, find a way to bend the tab on the float that allows the
float to ride higher in the bowl yet the needle is wide open unto the float
goes higher.
I did give that a try but it kept on closing the inlet with the needle.
Couldn't Find a sweet spot between the float and the needle.
On Thursday, October 25, 2012, A. wrote:
>
>
> Robin Hood wrote on Thu, 25 October 2012 18:54
> > OK, I got home and tried the various tests.
> >
> > http://youtu.be/InZn4C-ZHj4
> >
> > Summary: Pump is pumping, wife is aggravated about me getting gasoline
> everywhere. I managed not to catch myself on fire. Blowing into the fuel
> inlet with the bowl on won't work, but with the bowl off, I could force air
> (and gasoline!) through. More spillage. With the bowl on, not much gas goes
> into the bowl. I want to mail this thing (the carb) to somebody who knows
> how these things are supposed to be set up and what's proper vs seriously
> out of whack.
> Nothing seriously out of whack. The float is either not attached
> correctly to the needle valve, or the float bracket that attaches the float
> to the needle valve needs to be bent a little so that the float is not
> sitting on the bottom of the bowl while the needle is fully closed.
> It is as frustrating to us as it is to you because it is such a simple
> fix/adjustment, I just can't figure out how to walk you through it using
> text only.
> --
> '73 23' Sequoia
> UA (Upper Alabama)
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--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
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| Re: [GMCnet] I give up. (Onan) [message #188270 is a reply to message #188262] |
Thu, 25 October 2012 20:32 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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Still doesn't start on ether. It realy ought to. WIth the carb off,
I've sprayed ether or starting fluid into the intake and cranked, to
no avail.
I'm charging my battery as it's run down some. I think I'll try and
ignore the whole carb thing for the moment. Wiith the board bypassed
and power to the coil and spark at the plugs, it really should be
firing.
On Thu, Oct 25, 2012 at 7:35 PM, Dan Gregg <gregg_dan@hotmail.com> wrote:
>
>
> Robin, you should feel pretty good by now. You have determined what the problem is. I am assuming it runs when you shoot either into the carb. Now, just figure out why the float is not working. Almost sounds like what Carl mentioned, the float is bumping the bowl when you put it back together. If not, Id still say it might be the needle is bent and will not drop the float when empty. At this point, I vote Carl's theory.
> Dan
> --
> Dan & Teri Gregg
>
>
> http://danandteri.blogspot.com/
>
>
>
>
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--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
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| Re: [GMCnet] I give up. (Onan) [message #188308 is a reply to message #188270] |
Fri, 26 October 2012 06:37 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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When you check sparks, are they weak or strong? I'm beginning to wonder whether there's a weak spot in the coil which breaks down under the increased resistance of compression on one cyklinder when it's called upon to fire. Also, have you spun the engine with your hand over the carb intake and proved suction, thereby eliminating a sticky or non seating intake valve? I like a challenge, and I'm intensely interested in what's keeping this thing from running.
From: Robin Hood <loxley@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Thursday, October 25, 2012 9:32 PM
Subject: Re: [GMCnet] I give up. (Onan)
Still doesn't start on ether. It realy ought to. WIth the carb off,
I've sprayed ether or starting fluid into the intake and cranked, to
no avail.
I'm charging my battery as it's run down some. I think I'll try and
ignore the whole carb thing for the moment. Wiith the board bypassed
and power to the coil and spark at the plugs, it really should be
firing.
On Thu, Oct 25, 2012 at 7:35 PM, Dan Gregg <gregg_dan@hotmail.com> wrote:
>
>
> Robin, you should feel pretty good by now. You have determined what the problem is. I am assuming it runs when you shoot either into the carb. Now, just figure out why the float is not working. Almost sounds like what Carl mentioned, the float is bumping the bowl when you put it back together. If not, Id still say it might be the needle is bent and will not drop the float when empty. At this point, I vote Carl's theory.
> Dan
> --
> Dan & Teri Gregg
>
>
> http://danandteri.blogspot.com/
>
>
>
>
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--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] I give up. (Onan) [message #188310 is a reply to message #188308] |
Fri, 26 October 2012 06:55 |
Robin Hood
Messages: 1078
Registered: April 2011
Karma: 3
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Well, truth be told, I didn't personally observe the sparks. Tom is
the one who did that. He said that both plugs had spark after taking
them out and laying them a certain way on the generator whilst
connected to their wires. he described the spark as "weak". I will
see if I can duplicate what he did and get it on video. I'm in no
particular hurry, at least we're making progress, I think.
I will also try sticking my hand over the intake with the carb off,
and see if there is suction.
Yes, I am aware that I need a fire extinguisher, if not for the Onan
than just for general household usage. I've got waaaaay too many
classic vehicles and a home to worry about to not have better fire
protection.
Question: How full should the bowl be of fuel?
Question: How does fuel get from the bottom of the bowl back to the
top? There are two screws (one of which also holds the bowl onto the
carb) that are part of the bowl that have small holes in them. It
would seem to me that if they weren't turned just right that fuel
couldn't flow through the hole in the bottom of the bowl, through the
horizontal screw, through the hole in the side of the screw that holds
the bowl on, and then up the hollow center of that screw to what i
presume to be some sort of venturi or something. I mean, i don't
think the bowl is going to be pressurised by the fuel pump due to the
float controlling the inlet needle... so, what, does the air passing
through the throat of the carb somehow get sufficient quantities of
fuel vapor by blowing across the top end of what may as well be a tiny
straw with the bottom end stuck into a fuel bowl?
Question: Assuming that spark and timing are both adequate and the
control board is bypassed, shouldn't cranking the Onan whilst spraying
engine starting fluid into the intake (with the carb off) get
something to fire? I've heard that starting fluid isn't really fuel,
but is just oxidizer, but that sort of defeats the purpose. I mean,
oxidizer is great and all, I'm a big fan of oxygen. But shouldn't it
also be "fuel"?
On 10/26/12, Johnny Bridges <jhbridges@ymail.com> wrote:
> When you check sparks, are they weak or strong? I'm beginning to wonder
> whether there's a weak spot in the coil which breaks down under the
> increased resistance of compression on one cyklinder when it's called upon
> to fire. Also, have you spun the engine with your hand over the carb intake
> and proved suction, thereby eliminating a sticky or non seating intake
> valve? I like a challenge, and I'm intensely interested in what's keeping
> this thing from running.
>
>
> From: Robin Hood <loxley@gmail.com>
> To: gmclist@temp.gmcnet.org
> Sent: Thursday, October 25, 2012 9:32 PM
> Subject: Re: [GMCnet] I give up. (Onan)
>
> Still doesn't start on ether. It realy ought to. WIth the carb off,
> I've sprayed ether or starting fluid into the intake and cranked, to
> no avail.
>
> I'm charging my battery as it's run down some. I think I'll try and
> ignore the whole carb thing for the moment. Wiith the board bypassed
> and power to the coil and spark at the plugs, it really should be
> firing.
>
> On Thu, Oct 25, 2012 at 7:35 PM, Dan Gregg <gregg_dan@hotmail.com> wrote:
>>
>>
>> Robin, you should feel pretty good by now. You have determined what the
>> problem is. I am assuming it runs when you shoot either into the carb.
>> Now, just figure out why the float is not working. Almost sounds like what
>> Carl mentioned, the float is bumping the bowl when you put it back
>> together. If not, Id still say it might be the needle is bent and will not
>> drop the float when empty. At this point, I vote Carl's theory.
>> Dan
>> --
>> Dan & Teri Gregg
>>
>>
>> http://danandteri.blogspot.com/
>>
>>
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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>
>
> --
> Robin Hood
> Jackson, MS
> 2003 Buick Lesabre
> 1968 Pontiac Catalina
> 1978 GMC Royale motorhome
> 1977 GMC Palm Beach motorhome
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--
Robin Hood
Jackson, MS
2003 Buick Lesabre
1968 Pontiac Catalina
1978 GMC Royale motorhome
1977 GMC Palm Beach motorhome
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| Re: [GMCnet] I give up. (Onan) [message #188314 is a reply to message #188310] |
Fri, 26 October 2012 07:25 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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If there are sparks and suction, you ought to get a rise out of it when 'ethering' it. Both my questions are kind of clutching at straws, but you've already eliminated the obvious stuff, leading us to RF&RA (Rage, Frustration, and Random Action). I worry about spark because the ignition system in these things is adequate, but barely so. And, the spark will jump the lowest resistance path. Hopefully, this is across the two spark plug gaps. Howeve, resistance does rise across the gap when the air pressure it's in increases. My Junkerac will sometimes put a very bright spark from the plug cap edge to the cooling shroud when cranking. This I surmise because the throttle is wide open, thus the cylinder pressure is quite high and there is less resistance to the shroud than across the plug gap. I expert Tom placed the spark plugs in such a way that they touched the engine, and that he could see the gap in each. It is an 'all or nothning'
system, both plugs must fire together to indicate proper operation.
I'm headed to Starkbug in January, run the coach up there and we'll beat on it if it isn't resolved by then.
--johnny
'76 23' transmode norris
'76 palm beach
From: Robin Hood <loxley@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Friday, October 26, 2012 7:55 AM
Subject: Re: [GMCnet] I give up. (Onan)
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] I give up. (Onan) [message #188382 is a reply to message #188343] |
Fri, 26 October 2012 17:51 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Guys,
He found a fuel delivery problem. Let him fix that BEFORE looking at other things. The ignition system is delivering spark so leave it at that.
This ignition design is a "wasted spark" design. Both plugs fire at the same time and are wired in series to each other. The result of this design is the spark jumps two gaps if .016" in series. You will never get an extremely strong spark across the plugs. That is why they use the relatively small gap on the plugs and available battery voltage during cranking is important.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] I give up. (Onan) [message #188451 is a reply to message #188208] |
Sat, 27 October 2012 16:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Robin,
I was too busy while I was in the USA getting Double Trouble ready to store for next year to comment on this thread up until now.
I'm back in Sydney and figured I take a minute to chew you out!
With all due respect back on August 29th I spent a LOT of time putting the steps below together for you; you even said "wow!"
I've read all the subsequent messages and watched the videos from what I've read and as far as I can tell you haven't followed them.
If you would have followed them I'll bet the Onan would be running by now!
In one of your video's I noticed that you have the Onan on blocks which you pointed out are screwed down, excellent. From what I can
tell from the photos / video one set of blocks is located under the lower left front mount, the second set is located under the
lower left rear mount and third set is located under the fan shroud on the right. I would like to point out that the fan shroud is
not designed to hold up half the weight of the Onan. It may be OK when the Onan is static; however, once it fires up (and it will)
you're going to be at risk of it falling off those blocks. Yes I see that you've got the hoist hooked on and that's good, however, I
would suggest you get some ratcheting straps to hold it down on the blocks. It might be a good idea to build up the height of the
blocks on the right side until they are under the upper mount on that side too.
BTW everything you have noted to date points to a fuel system clogged up by varnish which stands to reason since IIRC the GMC this
Onan came out of had been sitting around for years.
Regards,
Rob
Robin,
When I watched the video the first thing I noticed was how clean the Onan appeared to be. This suggests that has very few hours.
That could be verified by checking what the hour meter reads.
I am of the opinion that by trying to jury rig this unit and get it going ASAP could cause damage that is unnecessary. ToddS has
given you some VERY GOOD advice. I am going to continue along his lines below.
The device you called the fuel filter in the video is actually a solenoid. When energized it allows fuel to enter the bottom of the
fuel pump.
If you look carefully at the fuel pump you will see that there are three tits equally spaced around the bottom and there's a nut on
the bottom.
I suggest you:
1) remove the fuel pump and solenoid from the Onan (Ref: Parts Book 78Z page 28-51)
2) put the mounting tab of the fuel pump in a vise with the bottom facing upwards
3) remove the solenoid from the bottom fitting of the fuel pump
4) screw the fitting that is in the inlet to the solenoid into the inlet of the fuel pump
5) remove the Cover (Key 1) of the fuel pump using a wrench
6) remove the Filter (Key 4)
7) inspect filter and housing for varnish left by evaporated gasoline
8) clean the filter by spraying carb cleaner from the ID towards the OD
9) remove the Retainer (Key 5) and remove Keys 6-10
10) clean all those items with carb cleaner
11) in the center of the pump housing there is a plastic check valve; clean it with carb cleaner and make sure it moves easily
12) slide the Plunger (Key 10) back into the fuel pump and make sure is slides back and forth easily
13) reassemble the fuel pump
Move on to the carb now Ref: Parts Book 78Z page 28-74/75
1) remove the wing nut (Key 27) and remove the air cleaner
2) hold the air cleaner up to the light and look up the inside - if it is dirty blow it out with your compressor from the ID
3) remove the fuel line from the carb
4) remove the choke and throttle connections to the carb (take a photograph so you can put them back where they were)
5) remove the screw clamp (Key 23) that holds the hose (Key 26) to the carb and remove the hose
6) remove the two nuts & washers (Key 3 / 4)
7) GENTLY move the carb up and down to break the carb to manifold seal trying not to damage the gasket
Ref: Onan Operators Manual and Parts Catalog 6A73 Page 13 - Carburetor Parts Group
http://www.bdub.net/manuals/Onan/Onan6kwNH_Operator-Parts.pdf
8) gently screw in the Idle needle (Ref No. 16) on the side of the carb and count the turns carefully - write the number of turns
down. Do not screw the needle in HARD, you WILL damage the needle / seat if you do
9) remove the Idle needle and spring
10) gently screw in the Power needle (Ref No. 15) on the bottom of the carb and count the turns carefully - write the number of
turns down. Do not screw the screw in HARD, you WILL damage the needle / seat if you do.
11) remove the Power needle
12) invert the carb and remove the Bowl Retainer (Ref No. 17
13) remove the Bowl assembly
14) push the Shaft (Ref No. 8) out and remove the float and needle
15) remove the Needle Seat (Ref 19)
16) remove Nozzle (Ref 9)
You now have the carb disassembled far enough to clean everything properly. If you look at the Nozzle (Ref 9) you will see that the
hole in this part are EXTREMELY small, you may have to soak it in carb cleaner to get the varnish out.
Once you have cleaned all the parts and there is no varnish anywhere re-assemble the carb and set the Idle and Power needles to the
recorded settings. Check the float setting as per page 13 too.
Reinstall the carb and fuel pump.
Lets move on to the ignition system:
Since your Palm Beach is a 1977 I am going to assume it has the later version of the points; ref: Onan Operators Manual and Parts
Catalog 6A73 Page 12 Figure 2. Carefully open the points and inspect them. They should be clean and shiny with no pits or tits
If they are not:
1) turn the adjusting screw until the points are fully closed
2) cut some 400 grit wet or dry paper into long strips
3) open the points manually and insert one end of the strip in the points
4) slowly pull the strip through the points
5) repeat this on both sides of the points until they are clean and shiny
6) clean the points with a bit of carb or brake cleaner being careful not to spray the shaft that goes down into the engine
7) lubricate the shaft that goes down into the engine with a bit of engine oil
8) adjust the points as per page 13.
You now KNOW that the fuel pump and carb are clean and free of varnish and the points are clean and set properly. This means you
should get gas and spark!
You are correct if you jumper #5 to #9 one the board the fuel pump will run. You could leave the connection to the carb loose and
verify that before you tried to start the Onan.
Regards,
Rob M.
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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