89 EMERALD 1 GENERATOR KEEPS RUNNING OUT OF GAS

[Matt_C]

Jimmy,

How long ago did you replace the fuel line and did you use an alcohol tolerant barrier type fuel line??

Where I used regular fuel line, the symptoms were just like yours.

On some of my power equipment, I have had fuel line fail in less than 3 years.  But since the size was not what I had in stock, I used Gates barrier hose on some others that has stayed running since I did the work. 

Matt

 

[Henry J Fate]

So I think we have a filter between the fuel pump and the tank? There is a metal fuel line transitioned to new rubber fuel line where?

Issac had some good food for thought as everyone here has. Issac suggested that the vapor seen in the filter before shut down could be gas vapor from a vacuum condition in the suction line of the pump due to a restriction. A restriction should be considered and could be a collapsed fuel line or something blocking the pickup tube in the tank.

If it is air in the filter then as Lou suggested, there must be a fault in the line somewhere from the filter to the bottom of the pickup tube.

Now since you have mentioned the vapor lock issue with the chassis engine and we assume the coach uses the same tank for both the chassis engine and the generator, that fuel tank cap is gaining suspicion.

 

[darsben]

The electric fuel pumps on some Emerald 1's did "vapor lock" when it was hot out. The cure was to move the fuel pump off the Genny and onto a wall away from the Genny.
Could yours be failing when it gets hot?

 

[Henry J Fate]

The electric fuel pumps on some Emerald 1's did "vapor lock" when it was hot out. The cure was to move the fuel pump off the Genny and onto a wall away from the Genny.
Could yours be failing when it gets hot?

Possible but the OP says he has watched the fuel filter (plastic) start full then slowly fill with vapor until the genset shuts down. Could that happen if the  pump heats up?

 

[89 allegro]

i will try to answer all these new replies as best as i can, when the generator shuts off ,i hit the button again ,the filter fills with gas and it runs again ,sometimes 15 min, sometimes until i cut it off.and i have say a gas can beside the generator and ran a line to it and it ran for a hour, no problems at all.as far as the new fuel line its about 3 years old and i used gates fuel line on both ends ,the line i can still see looks just fine,no cracks or anything i can see.the entire setup of my fuel line is, it connect to the generator fuel pump with fuel line, 3 inches , then going towards the tank theres the inline clear fuel filter , then theres steel line all the way to over top of the tank to where there another short piece of fuel line that connects to the down tube into the tank.when the fuel runs out i cant say its vapor, theres just no fuel,its just air and it dont have to be hot outside for this to happen,its done it when its 90 outside and when its been, 40 outside,so at least the outside temp dont seem to matter as far as i can tell, and now the engine vapor lock problem was when its hot only, it runs off the engine fuel pump only in the winter, which is mostly when i use the rv, oct-april and i put my hands on the pump itself and its not overly hot,no more than just the engine heat i would say.now matt said something about bad fuel line, i just used regular advance auto parts gates 1/4 inch fuel line, could that be the issue back over the tank where i cant see it anymore without dropping the tank or would the front fuel line that i can see have the same issues since they were all installed at the same time. as far as the gas cap, is there a way to know if its vented or not??? thanks for all the advice and im willing to try anything just to solve the issue,like i said the company just said i had to move the pump to by the tank,but i just dont understand if thats the way it has to be solved then how did it run and work for the other 25 years before i bought it with it right where it is now.im all ears  people ,keep the ideas coming because it makes no sense to me,especially since its sporadic when it does this  cutting off stuff.

 

[Henry J Fate]

Is that steel fuel line from the filter to the top of the tank original? That steel line could be causing the problem.

Did you run the generator with the cap off or loosened so that air is certainly entering the tank as fuel is sucked out?

How did you connect the portable container of gas to the generator?

 

[89 allegro]

i replaced the entire steel line new when i replaced the hoses,and i did not try removing the gas cap ,that was a new idea that i have not tried yet ,and i just disconnected the fuel line from the fuel filter and stuck another fuel line into a gas can sitting right beside the generator. and this rv is only out in the weather when were out camping in it, other than that its inside a enclosed shed,just for the record.i will try the cap deal tomorrow, i will wait till i see the filter starting to run low and then remove the cap, that should tell , right ?

 

[Isaac-1]

You say regular Gates fuel line, can you get the part number off the fuel line to see if it is a liner style line intended to be used in pressurized fuel injection systems.  If it is a liner style it may be collapsing internally under vacuum.

 

[89 allegro]

i cant get the numbers off it ,but its just regular fuel line because i use the same thing on my riding mowers and i called and asked them  about it and they said thats all they sell is regular fuel line in that diameter ,so that should be the right hose.

 

[Gary RV_Wizard]

It seems pretty clear that air is getting in on the suction side of the pump. Any leaks downstream from the pump would push fuel out raher than let air in, so the problem has to be in the suction side.    If everything between the pump and the vehicle tank has been replaced, the fault must be a joint somewhere.

Try connecting a short fuel line to the pump intake and stick the other end of that line into a gas can and see if the pump delivers a steady stream of fuel to the filter and onward to the generator engine. If the genset runs ok like that, you know the problem is in the fuel delivery to the pump. If not, then the problem is somewhere in the pump to filer section.

 

[89 allegro]

i have already done that before and it ran fine for a hour ,but thats what the pump company said to do to test the pump because it was a shorter run closer to the fuel supply,not because there was a problem somewhere else.i know for a fact all the connections are tight and even have double clamps at the tank ,this is why they told me to put the pump back by the tank because they said it pushes fuel alot better than pulls it.

 

[Isaac-1]

My point is that these days most fuel line sold in auto parts stores is fuel injection line since most modern engines use it.  Only the small diameter small engine line which is probably too small to supply your Onan on a long run is commonly carburetor style fuel line these days.

 

[89 allegro]

i put back the exact same size fuel line ,metal and rubber that was on it when i got it ,and i know the metal line had never been changed and was 1/4 inch .i just think the newer style fuel pumps are not as good as the old style pumps, i do alot of mechanic work and parts today are crap compared to 20 years ago.this pump is only a small pump, i dont remember the gph ,but its not much,

 

[89 allegro]

i found a piece of the fuel line like i put on it and here are all the numbers on it.it does not say gates on it ,but i was told it was gates made in the usa fuel line.this is the same stuff i used on the generator bought from the same place.

1/4" {6.35mm} ID  SAE-30R7  - KX078698506012  - MADE IN THE USA

 

[youracman]

Googled up that P/N and one supplier had the note below.  So it sure sounds like the "right stuff".  Good to know ..... when the day comes I need to replace mine.  Very interesting/educational post; good luck on the fix, allegro. 

Inner tube: Oil-resistant synthetic rubber
SAE 30R7 Fuel Line Hose is Recommended for low pressure/high temperature fuel for passenger car, light truck and small engine applications. Not intended for fuel injection systems.
30R7 is not Coast Guard approved for marine applications.
Use with Fuel Line Hose Barbs
Reinforcement: One layer of Braided Fiber
Outer cover: Hypalon
Temp. range: -40?F to +257?F
Approved by: SAE 30R7

 

[89 allegro]

thanks, i need all the luck i can get .

 

[Gary RV_Wizard]

You seem to have tried all the right things, but the fact remains that the filter runs dry after 20 minutes or so. Obviously fuel isn't reaching it from the pump & tank and there are only a few places/things that could cause that.  You act very sure that nothing is wrong in the fuel delivery system, but the facts say otherwise. I hope you don't take this as a smart-aleck reply, but I've been down a lane like this before. When the facts say my evaluation is wrong, I have to re-think and re-test to determine why the facts disagree with my opinion.

You could test the pump by running 30+ minutes into a big bucket (or directly back into the tank) instead of into the filter. If that's ok, try it again with the filter on the line but the filter output going into that bucket or the tank.  I'm grasping at straws here, suggesting things that might provide an additional clue.
Your genset doesn't guzzle fuel at such a high rate that line diameter or pump capacity needs to be huge. Is there a difference in the 20 minute runtime  if the genset is under heavy load vs idling? I would think so, but it's another parameter to look at.

 

[89 allegro]

i will try next week to have pump pull from tank to a bucket at the generator and see how that goes. that is what your saying to try correct ? no , im open to try anything, its just that its impossible to get back to the rubber fuel line at the top of the gas tank now without dropping it all the way down at this point and its over half a tank of gas now ,and like i said i double clamped each connection so it should be fine , but i mean a rat or squirrel might have gotten to it or something, but i would not think so ,thats why im saying that line should not be the problem and then its steel all the way from that to the generator.im gonna try some of these suggestions this week and see what happens, been cutting trees for last 3 days and im done for a few weeks now ,so i will be doing testing this week and will respond to what i find out, hopefully i find something that makes a change.i just still dont understand why the company told me to put the pump by the tank because the pump pushes better than pulls.thanks and i will let everyone know what i find this week.   

 

[thesameguy]

You could test the pump by running 30+ minutes into a big bucket (or directly back into the tank) instead of into the filter. If that's ok, try it again with the filter on the line but the filter output going into that bucket or the tank.  I'm grasping at straws here, suggesting things that might provide an additional clue.

I like this approach. Check to see whether the problem is the supply or not.

If the filter is emptying, that suggests to be there is an obstruction between the tank and the pump. That scenario is the pump keeps sucking, but there's nothing left to suck. If the pump simply stopped, the filter shouldn't empty. The fact that it runs fine from a gas can further reinforces the idea there is a problem between the tank and pump.

How does the supply line attach to the tank? I ask because 30R7 is rated only for external use... if some portion of the 30R7 is in the tank, it will turn to goo in no time and... obstruct the feed.

Your genset doesn't guzzle fuel at such a high rate that line diameter or pump capacity needs to be huge.

Yes, this. A genset of this size is like 1/2 gph.... a 1/4" fuel line is exactly the right thing, and highly doubtful there could be any scenario where that itty bitty pump could draw a vacuum in a 100 gallon RV fuel tank. Highly, highly doubt there's any sort of venting issue.

I'd bet good money there is an issue between the suction side in the tank and the pump itself.

 

[89 allegro]

the hose on top of the tank attaches to a barbed like fitting similar to the fuel filter that goes down into the fuel tank, it has a round piece with the wires that work the gauge and then 2 barbs, one for the motor and one for the generator.