Onan 2800 Microlite Runs great then randomly surges then dies...

[VER_1]

My solution to 2.8 Onan Generator is Chevron gas with techron and when I cant get it I install a can of the stuff. It works.

[cruising7388]

Originally Posted by jbucking

Thank you for everyone's input. I have learned a great deal. Today I started the generator and let it run for a while. It ran fine, then I turned on the A/C and put in under a load. Within 10 minutes the motor started to surge, get progressively worse, and then stop. I crawled back under the RV and pulled off the fuel line to the carb and put it into a clear glass bottle. I hit the remote starter button under the RV repeatedly and NO FUEL CAME OUT. Then after about 5 minutes of cooling down it was pumping fuel again. I don't think there is any doubt that I have a fuel pump problem. Thanks again for everyone's help.

This sounds more like a vapor lock problem in which case replacing the fuel pump module won't resolve this.

[SteveJ]

When I replaced the fuel pump I bought a low pressure universal electric. I mounted that out side of the genny case for easy replacement at a later date. It worked well. The one I replaced was the third one in 168 hours of run time, previous two were from the previous owner, mounted in the factory position utilizing genuine Onan parts.

Not impressive, to say the least.

Onan has now been replaced by a remote key fob start/stop Champion after other issues came up. Much gooder.

[jbucking]

Is vapor lock with Onan generators a common problem ? From what I understand, Onan fuel pumps stopping when hot is a sign of failure of the pump. This stopping problem is a recent development. One would think it would have vapor locked since new if it was a design flaw. I wish I could reach the pump. I would ice down the lines to cool them and see what happens. I hate to replace the pump and have the problem continue.

[jbucking]

Originally Posted by REV

My solution to 2.8 Onan Generator is Chevron gas with techron and when I cant get it I install a can of the stuff. It works.

Did the Chevron gas stop a vapor lock problem ?

[booster]

I would agree that vapor lock would not normally start after not being there for a long time. It sounds like a weak pump is just losing capacity as it gets hot, and we have heard of that in the past. Usually solved with a new pump from all I recall.

[BBQ]

Originally Posted by SteveJ

When I replaced the fuel pump I bought a low pressure universal electric. I mounted that out side of the genny case for easy replacement at a later date. It worked well. The one I replaced was the third one in 168 hours of run time, previous two were from the previous owner, mounted in the factory position utilizing genuine Onan parts.

Not impressive, to say the least.

Onan has now been replaced by a remote key fob start/stop Champion after other issues came up. Much gooder.

Mounting the pump outside would cure the heat absorption problem some people experienced. Maybe a new pump is not needed; all it needs is to mount it outside.

[Bud]

Originally Posted by BBQ

Mounting the pump outside would cure the heat absorption problem some people experienced. Maybe a new pump is not needed; all it needs is to mount it outside.

I have not heard about a vapor lock problem with a 2800 onan. If there is one, it should show up Especially at high altitudes. Anyone know if this is the case.

Bud

[jbucking]

I personally operated this generator at 5000 feet (while adjusting the altitude adjustment on the carb) without issues in the past.

[hbn7hj]

Booster is correct. Replace the fuel pump with a non Cummins Onan fuel pump. If it is "vapor lock" it is caused by the fuel pump over heating, the only source of heat to the fuel line. You are gonna have to get to work or hire someone to do it.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[VER_1]

NO chevron gas will not help with a vapor lock as vapor locks are very rare and when they happen it is typically when it is hot outside and or your engine is overheating and or a mechanical problem somewhere in your fuel delivery system.

If you research the main ingredient in Chevron Techron additive it is the best since they own the patent and in some cases allow other manufacturers to lease the patent to the ingredient I assume but don't know for sure as maybe the patent is expired.

In any case if you keep the onan generator with chevron gas you will have less crud built up inside the carb. As when I was a kid the chevron truck driver would pour some additives down the hole at my grandpas station. My Grandpa swore by it as most cars were carburetors back then.

Now in the past most manufactures said additives not needed or required but that has and always will be false with a gas compression engine. Now some auto manufactures see the ligh and are now requiring additives if the customers use non top tier gasoline.

I never had a injector or carb issue with my cars as I run chevron and if I don't I use their additive you can buy at any auto parts store.

However alittle more inside information from a Mad Scientist I have read about online is that you should not use the same gas all the time as it leaves a buildup of its own. So I do occasionally use another top tier to remove the chevron buildup and then go back to chevron. Yes, Chevron is more expensive but if you look at the solvents the competitors use for their additives it is alot cheaper. As why chevron costs more plus alittle corporate greed I am sure.

Hope this helps.

[Bud]

"Now in the past most manufactures said additives not needed or required but that has and always will be false with a gas compression engine."

I suppose that this may just be 'ymmv'. I have used the cheapest gas all my life. One of the few times I purchased 'expensive' (shell oil) gas, it cost shell oil $1200+. My present B is happy with 99,000+ miles with cheap gas with original stuff....... The last vehicle I used for travel was a GM minivan with 200,000+ miles and virtually all original parts, all original parts except radiator thermostat basically - all with cheap gas.

"Now some auto manufactures see the ligh and are now requiring additives if the customers use non top tier gasoline."

Please provide a link.

Thanks.

Bud

[booster]

As with a lot of things in our world, I think the Top Tier thing will be "discussed" forever without anyone getting convinced to change their opinion of whether it is great or bogus.

Add to that the fact that different engines appear to be have a very sensitivity to collecting deposits in different areas, and it gets even more complicated. In general, none of us will ever live long enough to have enough "sample" size to adequately be able to determine if our opinion is correct or not.

As I understand it, there are some things that appear to be relatively indisputable. They would include the fact that the Top Tier requirement for detergent amount is substantially higher than the government requirement. This doesn't mean non Top Tier gas doesn't have as much detergent, it only means they don't have to have that much. The few, small, sample tests I have seen would indicate the low cost gas suppliers do have substantially less detergent. We also know that certain vehicle manufacturers, particularly European, had some engines that were very prone to fouling with fuel deposits so badly that they started to require the use of Top Tier gas (or equivalent) to keep them clean. There are quite a few places that have pix of 100 hour engine tests with Top Tier detergent levels and gov't levels which show a deposit buildup difference.

Here is an article from Consumer Reports, which of course everyone also has a personal opinion of, about the value of Top Tier,or not. Take it for what you think it is worth.

https://www.consumerreports.org/car-...h-extra-price/

There are various theories about where the intake deposits come from, I think, also. All the engines could get them from leaking valve guide seals, or from EGR and crankcase breather sources, it appears. Normal styled EFI engines tend to spray the gas on or very near the intake valve to help atomization and cleaning of the valves, so it would be expected that they could have large benefits from higher detergent levels. I do think that a lot of engines can also get the intake deposits from reversion flow during the cam overlap period, and this type of deposit is more like exhaust valve deposits and harder to clean off than the other intake deposits. High exhaust pressure turbo engines can be very bad this way depending on the cam timing. Direct injection engines don't get the cleaning of the intake valves from the spray, unless they are the dual injector versions that many engines have switched to to keep the valves clean.

For us, we use Top Tier whenever we can, but certainly don't go crazy if we can't always find it. I don't think using 100% of the time would have any significant difference, in almost all engines, compared to 80% of the time. Is it a cure all like some say, not likely IMO, but the years of engine teardowns have shown me just how different the buildups can be, and how they can affect the performance, so any reduction is worth getting the Top Tier.

Of interest at least to me, I think, is the the cleanest engines I have ever torn down were the two twin turbo Chrysler 340CID engines we ran in our 1970 Challenger. To limit detonation and allow higher boost, I had a homemade water injection system that put a water mist into the intake airflow under heavy boost. The water mist, especially at high engine output, cleaned the insides of the engines amazingly well. We are talking stainless intake valves that were still silver at 50K miles and piston tops with hardly more than soot on them. These engines had 1970 and 1989 designed Chrysler heads on them, so certainly weren't the pinnacle of technology, but stayed very clean, especially when compared to normal heads of that design without the water injection.

[Bud]

"As with a lot of things in our world, I think the Top Tier thing will be "discussed" forever without anyone getting convinced to change their opinion of whether it is great or bogus."

Hey booster, I already live my life around an absorption refer! Now I'm going to find special gas? I suppose that if I were purchasing my first vehicle or my dad/mother had raised me on special gas, I would be using special gas. But this year I will have been riding, flying and driving using cheap gas with no consequences for 60 years.

No wait, I did use avgas for about 180 hours. But many more hours with cheap auto gas and 2 stroke oil. Gosh, that engine was awful with deposits squared - several engine outs. Oh well, we can't always land where we want.

Bud

[booster]

Originally Posted by Bud

"As with a lot of things in our world, I think the Top Tier thing will be "discussed" forever without anyone getting convinced to change their opinion of whether it is great or bogus."

Hey booster, I already live my life around an absorption refer! Now I'm going to find special gas? I suppose that if I were purchasing my first vehicle or my dad/mother had raised me on special gas, I would be using special gas. But this year I will have been riding, flying and driving using cheap gas with no consequences for 60 years.

No wait, I did use avgas for about 180 hours. But many more hours with cheap auto gas and 2 stroke oil. Gosh, that engine was awful with deposits squared - several engine outs. Oh well, we can't always land where we want.

Bud

Totally agree, worth the effort is everyone's personal risk/reward evaluation, just like with the absorption frig which, interesting enough was a PITA large enough for us to get rid of very early on. So we are just the opposite of you, we will look for gas if convenient, but you couldn't drag us back to an absorption frig

[SteveJ]

A friend of mine is an engine builder/tuner specializing in performance builds, of late motorcycle engines but in a previous life small block Chevys and Toyotas. He can tell right away who used top tier fuels and who didn't. He said it is starkly evident. I'm in the Booster camp and buy it when available, about 90+% of time. And always for small engines.

Thankfully the use of top tier is becoming more widespread, even Chavez Oil(Citgo) finally changed over.

[VER_1]

As for additives for vehicles they have their place and use if you know how to use them properly. I will put this in simple terms and leave the scientific mumbo jumbo out of it as you can research yourself. Plus tell a story of my life.

Gasoline additives,

Most gasoline additives on the market for years are basically solvents as they are the cheapest and less effective plus can be helpful and not so helpful. As these type predate the 1980's and still used today. Simple enough!

However their is an additive called Techroline that started in the early 80's at the chevron gas pumps and my grandpa would add the bottles to his vehicles when I lived with him in 1986. His experience Korean Veteran and as a chevron dealer, GM Michigan factory worker and mechanic was his resume. He approved of Techroline and stood by it.

I was working at a busy full service chevron station in 1995 as a tech when Techron was introduced as remember those cartoon cars talking. The Chevron station got repainted and badged with all these colorful cars as I liked it.

These are experiences as thoughts and facts will be added as Yes, I may seem alittle biased towards favoring chevron. However I am not as they ended up in the late 1980's ripping the lease from my grandpa so a few years later they could build a larger Chevron gas station with a convenience store. As times were changing for higher volume and no repair shops integrated.

They gave my Grandpa a gold watch at a dinner and thanked him for his service which he proudly wore for the rest of his life and in which he asked what I wanted before his death and I told him nothing. He was alittle wealthy as I told him all I want is that Chevron Gold Watch. My Grandpa was as some would call stingy or cheap as he believed a man should earn his own. But My Grandparents also gave their time to help you any way they could as just not financially. Yes, I did get that watch as he past away about 3 years ago and as grumpy he got as he got older I miss him alot.

[AZ ADVenturist]

I'm a little confused. Thought this thread is/ was about Onan genset running & not!? That said, guess I fall closest into the "Booster" camp of gasoline buying. I prefer- quality, convenience, cost in that order (but nearly equal).
BTW - what tier does Costco gas fall into. Anyone know?
Back to our regular programming...
And I hate absorption frigs.

[booster]

Originally Posted by AZ ADVenturist

I'm a little confused. Thought this thread is/ was about Onan genset running & not!? That said, guess I fall closest into the "Booster" camp of gasoline buying. I prefer- quality, convenience, cost in that order (but nearly equal).
BTW - what tier does Costco gas fall into. Anyone know?
Back to our regular programming...
And I hate absorption frigs.

The thread drifted this way as an outgrowth of the usefulness of Seafoam in Onan generators, or if certain gasoline vendors would do as well or better with just their gas. The symptoms the OP listed could have been influenced by plugging that cleaners might help, although other things would be more likely IMO.

Around here, in Minnesota, Costco gas is Top Tier.

[AZ ADVenturist]

Thanks, Booster. I googled "top tier" and yes Costco is listed as such. In AZ Costco is generally 40 to 50cents lower than Shell, Chevron, Exxon etal.