New Onan not working right

> Thanks Jim. I'll give that a try. What do you think about the remote mounting of the fuel pump idea? I guess I'll have to see if the gas can idea
> makes any difference first. The funny thing is that the old generator ran for hours on end, while driving under the same conditions. The only issue
> I ever had with it was fuel pump related, and it acted very similar to what this one is doing. A new fuel pump completely cured that problem. I
> suppose the brand new Mr Gasket 42S pump was bad right from the get go.

My approach would be to positively confirm that it is indeed a fuel delivery problem and then go from there. By the process of elimination I would sequentially rule out the fuel lines to the main tanks, then the fuel solenoid/filter/pump, and then the carb. It may take remote mounting of the pump to solve your problem, I do not know - but I do know that I’d only do it if absolutely necessary.

Is it indeed the case that when the engine stops after running 20-40 minutes that the carb bowl is dry each and every time? When this happens is the float observed to be at the lowest point of its travel when the bowl is removed? I worked on an Onan at our rally that would run for a while and then die; the owner had worked on it was very frustrated. Each time it died I carefully pulled off the bowl and each time I found that the float was up - held there by the needle being stuck in the seat. The solution was to rebuild the carb with one of the K1-LMB kits which contains a new needle, seat and bronze seat cup. Note that not all K1-LMB kits are the same, some have the bronze cup and some don’t - the former are much easier to install. After the rebuild it is imperative to follow the procedure in the Onan manual to check and - if necessary - set the float travel.

Re the 42S pump - I bought one of those to use at our GMC rallies and the thing stopped pumping after only a couple hours of operation - it was still clicking - just no pumping action. I do realize that some have had very good luck with them; mine was probably just a random dud.

Re electric pumps in general: IMO absolutely nothing beats the original Bendix pump for reliability and serviceability; there’s a reason that pump design was used by the millions on military engines. I have a turbine-powered APU in its original military configuration and it has a 24V Bendix pump on it which delivers about 30 GPH of Jet-A into a very thirsty machine. The Bendix is very easy to maintain - you can pull out the pump internals and clean/check every part of it.

—Jim


Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
 
I don't recall if this was already tried or mentioned.
A fuel delivery problem is easy to verify. Just squirt some fuel down the carb(An unlit propane torch stuck down the carb will do the same thing) when the engine won't start. If it fires up momentarily, your problem is elsewhere.

Another far fetched thought. How is hot engine compression when it won't start? Is it possible that valves are too tight, dropping compression when hot?

Les Burt
Montreal
'75 Eleganza 26'

>

>>
>> Thanks Jim. I'll give that a try. What do you think about the remote mounting of the fuel pump idea? I guess I'll have to see if the gas can idea
>> makes any difference first. The funny thing is that the old generator ran for hours on end, while driving under the same conditions. The only issue
>> I ever had with it was fuel pump related, and it acted very similar to what this one is doing. A new fuel pump completely cured that problem. I
>> suppose the brand new Mr Gasket 42S pump was bad right from the get go.
>
> My approach would be to positively confirm that it is indeed a fuel delivery problem and then go from there. By the process of elimination I would sequentially rule out the fuel lines to the main tanks, then the fuel solenoid/filter/pump, and then the carb. It may take remote mounting of the pump to solve your problem, I do not know - but I do know that I’d only do it if absolutely necessary.
>
> Is it indeed the case that when the engine stops after running 20-40 minutes that the carb bowl is dry each and every time? When this happens is the float observed to be at the lowest point of its travel when the bowl is removed? I worked on an Onan at our rally that would run for a while and then die; the owner had worked on it was very frustrated. Each time it died I carefully pulled off the bowl and each time I found that the float was up - held there by the needle being stuck in the seat. The solution was to rebuild the carb with one of the K1-LMB kits which contains a new needle, seat and bronze seat cup. Note that not all K1-LMB kits are the same, some have the bronze cup and some don’t - the former are much easier to install. After the rebuild it is imperative to follow the procedure in the Onan manual to check and - if necessary - set the float travel.
>
> Re the 42S pump - I bought one of those to use at our GMC rallies and the thing stopped pumping after only a couple hours of operation - it was still clicking - just no pumping action. I do realize that some have had very good luck with them; mine was probably just a random dud.
>
> Re electric pumps in general: IMO absolutely nothing beats the original Bendix pump for reliability and serviceability; there’s a reason that pump design was used by the millions on military engines. I have a turbine-powered APU in its original military configuration and it has a 24V Bendix pump on it which delivers about 30 GPH of Jet-A into a very thirsty machine. The Bendix is very easy to maintain - you can pull out the pump internals and clean/check every part of it.
>
> —Jim
>
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
>
> I don't recall if this was already tried or mentioned. A fuel delivery problem is easy to verify. Just squirt some fuel down the carb(An unlit propane torch stuck down the carb will do the same thing) when the engine won't start. If it fires up momentarily, your problem is elsewhere.

He’s found the carb bowl dry at the time the engine quits. A “too much air in the bowl” type of failure. :)

—Jim

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
 
Ok. Although I agree with you that the fuel delivery is highly suspect, the question I still have is this.
Did the float bowl run dry, stopping the engine, or did the heat boil it dry after the engine stopped. It wasn't mentioned how quickly the float bowl was removed after it stopped. Providing the supplemental fuel just helps confirm the diagnosis, since you can do it within seconds of the engine stopping.

Problems like this can be frustrating. Incomplete diagnosis makes the chase even more frustrating. Sometimes we get lucky, sometimes we don't.

Les Burt
Montreal
'75 Eleganza 26'

>

>>
>> I don't recall if this was already tried or mentioned. A fuel delivery problem is easy to verify. Just squirt some fuel down the carb(An unlit propane torch stuck down the carb will do the same thing) when the engine won't start. If it fires up momentarily, your problem is elsewhere.
>
> He’s found the carb bowl dry at the time the engine quits. A “too much air in the bowl” type of failure. :)
>
> —Jim
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Les Burt[1

> A fuel delivery problem is easy to verify. Just squirt some fuel down the carb(An unlit propane torch stuck down the carb will do the same thing)
> when the engine won't start. If it fires up momentarily, your problem is elsewhere.
>
> Another far fetched thought. How is hot engine compression when it won't start? Is it possible that valves are too tight, dropping compression
> when hot?
>
>
>
> Les Burt
> Montreal
> '75 Eleganza 26'

Compression was great when hot.

--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
The continuing saga of the reconditioned Onan:

My son exchanged the Mr Gasket pump for a new one, and I installed it this morning. The generator reluctantly fired up, after priming it, ran long
enough for me to adjust the timing slightly, and adjust the carburetor. As I was doing all this it quit and wouldn't restart.

I loosened the float bowl on the carb and it was dry. I then took the carburetor off and went through it, really finding nothing wrong with it. Put
it back on and it would start with starting fluid, but not continue to run. I then took the fuel line off the carb, jumpered the +coil to + battery.
The brand new Mr Gasket 42S pump was making noise, but no fuel was coming out, with the intake submersed in a can.

I then took the Mr Gasket pump off the old Onan, hooked it up, primed it, and the generator started right up and is running the roof air in my
driveway as I type this.

It appears Mr Gasket electric fuel pumps are not specifically too good. I will order the direct fit from Jim K and put it on and see what kind of
luck I have with that.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
Or propane

> The continuing saga of the reconditioned Onan:
>
> My son exchanged the Mr Gasket pump for a new one, and I installed it this
> morning. The generator reluctantly fired up, after priming it, ran long
> enough for me to adjust the timing slightly, and adjust the carburetor.
> As I was doing all this it quit and wouldn't restart.
>
> I loosened the float bowl on the carb and it was dry. I then took the
> carburetor off and went through it, really finding nothing wrong with it.
> Put
> it back on and it would start with starting fluid, but not continue to
> run. I then took the fuel line off the carb, jumpered the +coil to +
> battery.
> The brand new Mr Gasket 42S pump was making noise, but no fuel was coming
> out, with the intake submersed in a can.
>
> I then took the Mr Gasket pump off the old Onan, hooked it up, primed it,
> and the generator started right up and is running the roof air in my
> driveway as I type this.
>
> It appears Mr Gasket electric fuel pumps are not specifically too good. I
> will order the direct fit from Jim K and put it on and see what kind of
> luck I have with that.
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html
 
> Or propane

No, propane wouldn't work for me. I only have a 7.5 gallon tank (PO installed). Besides, I sometimes need to run both AC units at once and a 20%
reduction in power would prevent me from doing that.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
Next step was to hook the fuel line from the tank back up to the pump, fire it back up, put it back in it's hole, and see how long it would run that
way. It ran for over an hour without issue before decided to shut it off so as not to annoy the neighbors further.

I think I'm getting to the bottom of this...finally.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
I've had good luck with the Mr Gasket pumps, but they are as I understand it Chinese which means quality probably varies considerably. They
might get hot and quit, and if the rear of the filter isn't supported, even the Wix will eventually vibrate enough to create an air leak. Keep after
it.

--johnny

--
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" - ol Andy, paraphrased
 
Last edited by a moderator:
> I've had good luck with the Mr Gasket pumps, but they are as I understand it Chinese which means quality probably varies considerably.
> They might get hot and quit, and if the rear of the filter isn't supported, even the Wix will eventually vibrate enough to create an air leak. Keep
> after it.
>
> --johnny

I guess I shouldn't speak badly of Mr Gasket. The first one I put on the Onan lasted a couple of years before it started to work intermittently and
the second one has been going strong for about three years now. It seems curious that two brand new ones, right out of the package, failed within an
hour. I'm just going to give up on them and will hope for the best with another, hopefully better option:

http://appliedgmc.com/prod.itml/icOid/1492
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
Last edited by a moderator:
> Or propane

No, propane wouldn't work for me. I only have a 7.5 gallon tank (PO installed). Besides, I sometimes need to run both AC units at once and a 20%
reduction in power would prevent me from doing that.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
 
I ran two of my gensets on natural gas with propane backup before I retired. In that service, they derated about 15% on propane and just at 20% on
local natural gas. In my circumstance, the cost of a slightly larger genset paid out very quickly in pretty much zero maintenance, double time
between oil changes, and 'spark plugs as necessary'... which necessity never appeared. These were 300CID Ford industrial engines from Onan.

--johnny
--
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" - ol Andy, paraphrased
 
Jerry,

Do you think the Onan could handle the start up current of the two Onans if the water heater and/or other items were on?

Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Gerald Work
Sent: Monday, July 3, 2017 12:41 AM
To: gmclist
Subject: [GMCnet] New Onan not working right

Hi Carl,

I know the 20% reduction in power number is often quoted but does not hold up in my testing. Propane does have less heat content
than unadulterated gasoline, but it also burns more completely partially offsetting that and who knows the power hit when running on
today's gasoline. My testing in the Clasco showed that Onan could easily keep up with all the load I could throw at it - AC,
electric heater and microwave all at the same time (don't know if the battery charger and water heater were also on or not) so would
likely handle two AC units as well.

I don't have a dog in this fight so not trying to push propane but it sure seems to cure a lot of Onan ills for an investment of
under $300. And you wind up with an Onan that starts easily, runs smoothly at all loads and will likely out live all of us and the
next generation of owners to boot.

Jerry
 
> Jerry,
>
> Do you think the Onan could handle the start up current of the two Onans if the water heater and/or other items were on?
>
> Regards,
> Rob M.
> Sydney, Australia

Rob,

Is this a typo?
The answer I would give is "Probably".

This would be my carefully considered opinion as a lifelong "engine guy".
The NH engine is nearly 60cuin. running at 3600 it should be good for 24+ HP (~18kW) At half the speed, it will still produce near the same torque so,
let's guess 9kW. Take a 20% hit on that and we are still at 7.2kW.
So, yes, I think he is OK - Unless he conscripts 4 friends so that they can turn on both A/C units, the microwave, the water heater and the PD9260 all
at the exact same moment. ;)

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Matt,

Yes, I meant A/C units.

I disagree with this statement:

Unless he conscripts 4 friends so that they can turn on both A/C units, the microwave, the water heater and the PD9260 all at the
exact same moment. ;)

Here's why:

1) Once you turn the A/C units on the compressors will cycle on their own to meet the temperature set.
2) Power to the element in the water is controlled by a thermal switch.
3) The amperage draw on PD 9260 is affected by the level of charge of the batteries and the DC items on.

I have two Brisk Air (supposedly low amperage draw) units on Double Trouble and when I'm running them both I can hear the Onan
strain under the load when both compressors come on.

I guess someone that has an Onan that runs on LPG to run a test.

Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Matt Colie
Sent: Monday, July 3, 2017 10:14 AM
To: gmclist
Subject: Re: [GMCnet] New Onan not working right

Rob,

Is this a typo?
The answer I would give is "Probably".

This would be my carefully considered opinion as a lifelong "engine guy".
The NH engine is nearly 60cuin. running at 3600 it should be good for 24+ HP (~18kW) At half the speed, it will still produce near
the same torque so, let's guess 9kW. Take a 20% hit on that and we are still at 7.2kW.
So, yes, I think he is OK - Unless he conscripts 4 friends so that they can turn on both A/C units, the microwave, the water heater
and the PD9260 all at the exact same moment. ;)

Matt
 
I realize the genset would run cleaner, but I don't use it enough to justify the PIA of converting it... and I don't carry that much propane anyway.
Which propane is used for cooking and if it's cold heating. The summer show I used to dry camp runs four days, full tanks of gas keep the Onan going.
I doubt the propane tank would. However, I got tired of roasting on the asphalt (Greenville, SC) and this year I'm booked into the local state park
campground.If you have a big propane tank and use the genset a lot, it might be worth your whileto convert it.

--johnny
--
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" - ol Andy, paraphrased
 
Johnny,

Quite often the statement "Because I can" is noted as justification to modifying something on a GMC, on one of the car shows I watch
here heard a great comeback; "that doesn't mean you should." ;-)

Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Johnny Bridges via Gmclist
Sent: Monday, July 3, 2017 10:41 PM
To: gmclist
Cc: Johnny Bridges
Subject: Re: [GMCnet] New Onan not working right

I realize the genset would run cleaner, but I don't use it enough to justify the PIA of converting it... and I don't carry that much
propane anyway.
Which propane is used for cooking and if it's cold heating. The summer show I used to dry camp runs four days, full tanks of gas
keep the Onan going.
I doubt the propane tank would. However, I got tired of roasting on the asphalt (Greenville, SC) and this year I'm booked into the
local state park campground. If you have a big propane tank and use the genset a lot, it might be worth your while to convert it.

--johnny
 
I realize the genset would run cleaner, but I don't use it enough to justify the PIA of converting it... and I don't carry that much propane anyway.
Which propane is used for cooking and if it's cold heating. The summer show I used to dry camp runs four days, full tanks of gas keep the Onan going.
I doubt the propane tank would. However, I got tired of roasting on the asphalt (Greenville, SC) and this year I'm booked into the local state park
campground.If you have a big propane tank and use the genset a lot, it might be worth your whileto convert it.

--johnny
--
 
Jerry, if I have t pull it out on the slides, it's a pain by definition :) For my uses, there just isn't any upside.

--johnny
--
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" - ol Andy, paraphrased
 
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