Running a mechanical fuel pump and a low pressure electric pump

[Rj1]

I asked about this about a month ago but at the time I was going to remove my mechanical pump and go with the electric low pressure pump but decided not to. But know I'm having more problems. First there is never any fuel in my fuel filter. The machine does start up fine and when I pull the line going to the carb it seems like I'm getting enough gas. The past couple times I've had it out after about 30 min it dies on me like it's not getting any fuel and won't start up. If I spray some starter fluid in the carb it starts but dies right away. I'm thinking I'm getting vapor lock so now I'm thinking of putting the electric pump on after the filter and through the mechanical pump but have the electric pump on a switch. I've never ran 2 pumps on any of my atv's would there be a problem doing it? Will the mechanical pump have any problem pulling fuel through the electric pump when it's not turned on ? I don't want to just go with a low pressure electric pump because I think it would be to much on the carb and I would get it flowing out but I think if I have it on a switch for when I need it then that would work but like I said I'm not sure if the mechanical pump would have enough to pull all that way then through the filter then the electrical pump to. Does anybody have this kind of setup?

[Laird]

Did that on a Yamaha Rhino. If it sat any length of time , the bowl seemed to siphon back to tank and took a long time cranking to get it to start. Hit the momentary switch to prime the carb, the bowl would fill and the engine would start right up. Simple vacum pump on the Rhino. You seem to have a multitude of fuel problems. Can not remember if you changed the fuel pump or not. I probably would start there. And check the vacum line to the carb. When I bought the Argo, it came with a simple squeeze bulb because it too would crank and crank till the engine started.

[Avenger Bob]

I was getting vapour lock in hot weather. The machine would not start until it cooled down. I rerouted the fuel line so that the filter was between the pump and the carburetor so that fuel was being pumped through the filter, rather than sucked. Now there is less tendency for the fuel to vaporize in the pump and I have not had the problem since.

[Laird]

Interesting concept. Wouldn't have thought of that. When I put the 23 Vanguard in the 91 Vanguard 6x6, I installed the fuel pump about 8 inches away from the engine. Did that because I couldn't figure out how to mount the pump on the engine as it came with no pump bracket. Seems to run fine even on the one steep hill I had to climb when deer hunting this year. Others have mentioned that they run out of fuel on steep hills. Some may refer to a small mountain as a steep hill so the steepness and height are all relevant to the terrain where you live. Rj1 and others found a lack of power on some terrain with the 16 briggs. I couldn't climb the same hill than I went up with the 23hp as when I had the 16 hp opposed in. World of difference. I will know better when the tracks go on. But so far no lack of fuel issue. Just a further thought, I am using the same pump that the 16 hp calls for. Didn't check but maybe they are all the same. The problems we all have using a general purpose engine in a specific application.

[ARGOJIM]

I asked about this about a month ago but at the time I was going to remove my mechanical pump and go with the electric low pressure pump but decided not to. But know I'm having more problems. First there is never any fuel in my fuel filter. The machine does start up fine and when I pull the line going to the carb it seems like I'm getting enough gas. The past couple times I've had it out after about 30 min it dies on me like it's not getting any fuel and won't start up. If I spray some starter fluid in the carb it starts but dies right away. I'm thinking I'm getting vapor lock so now I'm thinking of putting the electric pump on after the filter and through the mechanical pump but have the electric pump on a switch. I've never ran 2 pumps on any of my atv's would there be a problem doing it? Will the mechanical pump have any problem pulling fuel through the electric pump when it's not turned on ? I don't want to just go with a low pressure electric pump because I think it would be to much on the carb and I would get it flowing out but I think if I have it on a switch for when I need it then that would work but like I said I'm not sure if the mechanical pump would have enough to pull all that way then through the filter then the electrical pump to. Does anybody have this kind of setup?

I think I might try this first though adding an appropriate electric pump will help with the climbing issue Argos have, part of which is the low mounted fuel tank and the amount of lift needed on steep uphills. Also I do not recall if you have changed the 20+ year old fuel line, which could be a problem.

When your machine shuts down immediately open the fuel cap, if you can hear a gasp or not try to crank it and if it starts about 20-45 seconds later you may have a clogged tank vent or pinched tank vent hose as the cap is not vented, if it runs another 30 minutes or so and shuts off the problem is probably there.

I personally had a similar issue that was not constant and became a B to find on my V2, it was not constant and might happen after a couple hours or 15 minutes or 3 trail rides later. I had a ball of varnish in my pick up tube that would get sucked up to the 90degree point in the pick up tube and clog, let it sit it would start back up and run fine til it clogged again. Blowing back in the fuel line helped sometimes but other times the wedge of the ball was too good to be easily determined.

Just a couple thoughts.

[JWW]

If you have not already replaced it I would suggest replacing the pump, second the filter will never be completely full of gas. I have yet to see any small engine with an in-line filter and pump full to the top with full.

You can run an electric pump in line with the vacuum pump if you want but if the vac pump is weak it may not work very well. But like others have said make sure the tank vent is open.

[Rj1]

One of the first things I did was replace the pump and fuel lines back to the tank. Like I said when I check the fuel pump flow it seems like plenty but I'm not sure what it is after the motor warms up. The fuel filter is new to again like I said there's only a trace of fuel I that every time I look at it even with the motor running and most times I see no fuel in it at all. I did test a low pressure pump I believe it's a 3psi one and the flow us great with it but I think if I don't have it on a switch it will over power the carb float that's why I wanted to know if I could keep the vacuum pump on and only use the electric pump when I need it I'll have to check what my fuel flow is like with the electric pump on but not running and the vacuum pump pulling fuel through it .

[JWW]

If I can remember to get a pic of mine while running, it also looks as if there is no fuel in the filter. It runs and pulls fine in every situation and position I have had it in so far. Considering the engine is weak and needs an R&R.

You are correct that even a low pressure pump can/will over power the float in the Briggs carb, it's ability to stop the flow is limited to a really low pressure from my experience. Putting a switch with an electric should work fine or you could check around and see if you can find an in-line pressure regulator. I have not had a need to use one for years but I am sure they can still be had.

Unless the engine is demonstrating fuel issues I wouldn't worry about. I have at 4 different engines/brands (where it is easy to see the filter) that do the same thing, each runs and works like they should.

[ARGOJIM]

One of the first things I did was replace the pump and fuel lines back to the tank. Like I said when I check the fuel pump flow it seems like plenty but I'm not sure what it is after the motor warms up. The fuel filter is new to again like I said there's only a trace of fuel I that every time I look at it even with the motor running and most times I see no fuel in it at all. I did test a low pressure pump I believe it's a 3psi one and the flow us great with it but I think if I don't have it on a switch it will over power the carb float that's why I wanted to know if I could keep the vacuum pump on and only use the electric pump when I need it I'll have to check what my fuel flow is like with the electric pump on but not running and the vacuum pump pulling fuel through it .

If you have the 3psi Kawasaki pump or clone you will probably be ok, as the Kawasaki carbs are sensitive.
However to your point, I do not believe the electric pumps are like the pulse pumps and flow through so you may be able to t the line before both pumps and the t the line after the pulse pump. The pulse pump is flow through but does not back flow, so theoretically you should be able to run the pulse pump normally and then when needed click the switch. You could also eliminate the pulse pump and t the output line of the electric pump to carb and a return line, however that would be a constant run situation.

[Rj1]

I thought about running a return line from the carb back to the tank but I think if I just go with a switch and only use it for a few seconds at a time I should be fine. Today I'm going to check if the vacuum pump will pull fuel through the electric pump when the electric pump is off. If it does then that will be the way I go. Thanks for the help I want to say guys but I'm not sure if any women spoke up so I'll say thanks everyone.

[jerseybigfoot]

Weather you add a electric pump or not. First relocate the pulse pump to the lower hull. the pulse line doesn't care how long it is (within reason). like to the front of the engine low. less time sucking up hill. Alternately use the electric near the fuel tank and add a return line to the tank and tee in at the existing mechanical pump make the return line smaller to give the mechanical pump a slight head pressure. This option works well if you cant find a low pressure pump.

[Rj1]

I never knew that I could move the pulse pump. It makes sense though moving it to a low point I'll try that. THANK YOU.

[Rj1]

I hooked up the electric low pressure pump on a switch. I tried running it before the vacuum pump but with out the electric pump turned on the vacuum pump was not pulling enough fuel. I bypassed the vacuum pump so it will run on the macanical pump and if I need more fuel I can hit the switch for a couple of seconds then go back to the vacuum pump.