friend has a 98 model 7000 watt gas onan,fuel pump is on toglle been this way for a while and now wont stay running.it will crank up and run untill about the time ac should kick in then dies.he has verified fuel is flowing.any ideas,hello rich lol

Without more info about the machine it's not possible for me to make any suggestions...

A '98 is probably the old design, flathead twin cylinder engine....

Numerous things possible with them as well as the newer style OHV twin engine design produced after about 2000

mod.7nhmfa26105g
6.8 kw

Now we're talkin...

Old Black cover flathead with an electronic governor

I have had at least 3 of those that had a bad electronic governor control box. Would run fine for a while and randomly quit and maybe start right back up.

The oil pressure switch is another possbilty....and even the front control board behind the start stop rocker switch....

When I get one like that I basically test or replace the possible offenders untill the issue is gone.

I had one last summer that had damaged sockets on the control board where a connector plugs in.....Would work sometimes and not others....a b-i-t-c-h to find but I found it...


If it's the electronic governor control it's a small metal box mounted under the gen. end and has 2 plug in connectors......It's an obsolete part now and not available from Onan but there is an aftermarket replacement......

Without having "known good parts" you cannot fix these things.....I have an expensive G-Man tester for the old models but it does nothing for the electronic governor models....

I would have to look up the gov control and get a part number and than I can find the aftermarket replacement....

The O.P.S> is the first thing to try and test.

It maybe a 1 wire or a 2.....Its' mounted on a manifold that also has the oil filter on it..

Gotta remove sheet metal to get to it...

If it's 2 wire it has to show continuity solid when the machine is running.

1 wire and whatever it reads to ground stopped, it should go the other way running and be steady.....

It's probably closed to ground off and open running...and usually a pretty low pressure switch.....

I don't work on the old ones much anymore so when I do I get a refresher course.....

I'll go look up that governor control and be back with some info about where to buy one...

Rusty the first thing is to determine if it's just the generators engine can't handle the load from the AC unit.....and to make sure the AC unit is not at fault...sometimes the compressor tries to start and kills the generator....or pops the breaker after the generators engine bogs down....

Basically you have to confirm that the engine can carry the AC amp load it is supposed to....That machine is good for 50 amps when new. Could run 2 rooftop AC's...


Once you are sure it's not an engine issue than you move on to the other items....

Here's a link to that gov control


https://www.flightsystems.com/p-56-0752-00.html

Oil Pressure switch is a 309-0615
Control board is 300-5276-01

thanks rich ,i think its goig to get back the board in the end

Rich, he has already replaced the oil pressure switch.

SCDIV1 (aka Rich), that's a ton of good information. You're a good egg for sharing your knowledge.

About 2 weeks ago a racer friend called me about his 10KW diesel Onan....

It was doing the random shutdown routine they often do after running for a while. Typical Code 36 shutdowns.

He had it at a Cummins-Onan dealer and they had no idea what was wrong which I find hard to imagine...

I told him what it likely was and exactly how they could test the machine to prove what I said was correct. They did exactly what I told him to tell them and it proved the control board was the issue. They would order one for the next day....

They tried to charge him an $800 diagnostic charge along with $200-$300 labor to replace the board...

I wanted to know where I should send my consultation fee bill. They did knock $650 off the bill since I offered to sell him the board for less and told him how to change it....

A common failure and I've advised many racers all over the USA and if they wanted I could sell them the parts direct from Cummins-Onan..

I have a brand new just out of the box Cummins Portable Inverter 4500 on a bench trying to figure out what's wrong with it.

Engine not being controlled properly and runs erratic....Hours of taking things apart. No service manual for it and just an operators manual with an electrical diagram/print and a parts breakdown...

Numerous items it could be but none available and ZERO help from Cummins. They have really no one to consult on any machine so your on your own basically and it's brand new !

We bought some of their newer portables to sell including 2 of these.....

I try to pass on what I know and have learned because no one else is!

This Inverter type portable is marketed by others under different brand names. A nice looking machine and not cheaply built but this one is a loser !! LOL

Can we say 4500 ..... ????

thanks again rich people like you and others on this board are greatly appreciated.i passed on the info and will see how it goes thanks again

quote:

Originally posted by SCDIV1:

I have a brand new just out of the box Cummins Portable Inverter 4500 on a bench trying to figure out what's wrong with it.

Engine not being controlled properly and runs erratic....Hours of taking things apart. No service manual for it and just an operators manual with an electrical diagram/print and a parts breakdown...

Numerous items it could be but none available and ZERO help from Cummins. They have really no one to consult on any machine so your on your own basically and it's brand new !

We bought some of their newer portables to sell including 2 of these.....

I try to pass on what I know and have learned because no one else is!

This Inverter type portable is marketed by others under different brand names. A nice looking machine and not cheaply built but this one is a loser !! LOL

I have one of these 4500 inverter generators. It has always surged with no load on it, the idle is electronically controlled and no adjustments. Also more than once the float has stuck in the carb causing a massive fuel leak, anyone who owns one make sure you turn off the fuel when not in use!! Nice little generator for the money but definitely a throw away IMO when it breaks.

Steve the engine speed on those is controlled by a very small stepper motor and it also has a stepper motor to operate the choke.

The speed control stepper motor gets its power from the inverter module directly....

It is very common on portables for the carbs needle and seat to leak if the tank is full and since it's above the carb the weight of the fuel can cause the leak.

I've seen that issue many times on portables...


The 4500 is a very nicely built unit compared to the usual import stuff.....but without any replacement parts to plug in on a problem like I have it's very difficult to fix.

Your surging idle could be just a little dirt in one place that's very easy to look at. A little black plastic part that pops right out after removing the idle stop screw.

Maybe that's not it but its easy to check...

Thanks Rich, the surge has been there from the day I took it out of the box but I will check it out. You can see the throttle pulsing while it surges so maybe an issue with the stepper motor/board. Once something is plugged in its fine.
The first time I found out about the sticking float was when we got back from a race and the inside of the trailer had about 2 gallons of gas on the floor, could of lost everything that day!! The last time it did it was while it was running, we were parked in the grass and it was using a huge amount of gas, took the side cover off and gas was just pouring out from the carb. Took the bowl off and jiggled the float and it was fine the rest of the weekend.

I have a Honda 3000 but it wont run my 15K btu A/C for more than an hour without tripping. I can run it with this one and a tank of gas last all day. Plan is to get w Honda EU7000 in the off season and build a cabinet with slide out on tongue of the trailer

Steve this modern equipment is great when it works right but a total disaster to someone like me who works on the stuff.

From welding machines to generators, the same story....Modern electronics....PC boards and high tech electronics.....They fail or don't work right and it's trouble for anyone involved...

The carb flooding was a real danger !!! You could have easily had a bad fire.....you were lucky...

quote:

Originally posted by Canted Valve:
SCDIV1 (aka Rich), that's a ton of good information. You're a good egg for sharing your knowledge.

he helped me diagnose and fix my 12.5k deisel, also helped with parts. Huge help on this board for anything onan for sure.

as an update ,improper troublshooting was some of the issue.a return visit to the oil shutdown switch fixed the issue,thanks again

Great...

That's a cheap easy fix...and they do go bad...