New Fuel Pump Not curing problem

[tugboat80]

I posted earlier this Aug of problem dying if I did not keep on the primer bulb. Motor is J15RENM. This has been a good motor for the 5 years I have had it, compressing at 110 psi. It began a problem accelerate slowely, and to die, if not maintained with the primer bulb. I attempted to rebuild the fuel pump not with sucess, so I ordered a new fp. I put it on and the motor starts right up but will only run a short time ( 30 seconds) then to die. What may be my defect now?

 

[flyingscott]

Check the carb and give a good cleaning. Make sure all the fuel lines are in good shape.

 

[jimmbo]

Bad fuel lines, clogged filter(s), clogged tank went.

 

[thumbnut]

Remove outlet hose from fuel pump to the carb. Put on a section of clear fuel line on the outlet hose, making sure the connection is air tight. From above the motor install end of clear fuel line in mouth. Carefully suck fuel into beginning of clear fuel line. Just like stealing gas from your neighbors car...

When/if fuel makes it almost to your mouth put tongue over end of fuel line. Observe clear line for bubbles or any lowering of the fuel in the clear line. Then remove tongue and see if the fuel returns to the tank. If fuel stays in line have someone pull on the lanyard. The fuel should start climbing in the clear fuel hose. If bubbles appear there is an air leak.

One can use a manual vacuum pump if mouth is not available.

Report back to us.

 

[Vic.S]

The first things I would check would be the fuel line end connectors for possible air in-leakage due to bad O rings

 

[Tim Frank]

^^^^ +1
Very common. You could try a known-good tank and fuel line also.

 

[thumbnut]

The test procedure that I described will test all functions of the fuel system including air leaks at connectors and anywhere else.

If one hasn't tasted gas one hasn't lived yet...don't be scared..

If the op has posted before about this issue the op has gotten the tank connector clue and probably has it ruled out..maybe..

 

[James R]

Assuming that the primer bulb is pointing in the right direction, you could have a leak and sucking air, the tank vent is blocked or the pick up tube in the tank is partially blocked. Simple way to eliminate the tank as the problem, fill a gallon jug with fuel, disconnect the hose from the tank and put the end in the jug. Try it out.

 

[tugboat80]

Thanks for the multiple replys. Nice to know people want to help. I got antzy and dropped the motor off at a reliable tech along with a carb kit I had on the shelf. I hope it does not cost the price of a trip to Alaska.

 

[Tim Frank]

Remove outlet hose from fuel pump to the carb. Put on a section of clear fuel line on the outlet hose, making sure the connection is air tight. From above the motor install end of clear fuel line in mouth. Carefully suck fuel into beginning of clear fuel line. Just like stealing gas from your neighbors car...

When/if fuel makes it almost to your mouth put tongue over end of fuel line. Observe clear line for bubbles or any lowering of the fuel in the clear line. Then remove tongue and see if the fuel returns to the tank. If fuel stays in line have someone pull on the lanyard. The fuel should start climbing in the clear fuel hose. If bubbles appear there is an air leak.

One can use a manual vacuum pump if mouth is not available.

Report back to us.

That may work for those with an actual taste for gas....but is not as easy as just squeezing the gas line bulb....that is what it is intended to do.

But more important, your procedure ignores the fact that bubbles in the line is quite normal....and in the nature of any volatile liquid under a vacuum.
Those bubbles would most likely be gas vapour. It is simply inconclusive except perhaps in the case of a catastrophic leak.

PROPER troubleshooting of the fuel system is easily done with a vacuum gauge and a pressure gauge; the procedure is outlined in various on-line locations and every OEM manual...and gives measurable results for comparison to spec.

 

[thumbnut]

You are correct about proper testing procedure. I diagnose and repair water well systems with a compound gauge couple times a month. There is nothing like proper technique and gauges. Sans gauges and such one must improvise. And STP and those gas laws do come into play. Sometimes my clear fuel filter is full and sometimes its half full depending on temp and barometer. Back in the 60's and 70's when I used to snowmobile there was never any vapor in the line but in the summer I would chase "air" in my Hurricane 10.

Just to stay on topic someone on some forum just the other day bought a fuel pump that leaked air out of the box.

A well calibrated mouth can detect flow restrictions real fast and easy though...and air leaks will be a continuous series of small bubbles while in operation while vapor generally is just one void at the high spots of the hose.

Make sure fuel pump is not too high relative to the tank. Then there are check springs in the pump that add to total head. Maybe a spring on the tank filter/check also. And in the primer. That lowers usable suction height. .

I remove check springs in my primer and use a mikuni pump on both of my motors as the mikuni pump doesn't use check springs.

 

[Tim Frank]

Thanks for the multiple replys. Nice to know people want to help. I got antzy and dropped the motor off at a reliable tech along with a carb kit I had on the shelf. I hope it does not cost the price of a trip to Alaska.

Did you try a "known-good" tank?
If not, and the motor comes back with the same problem, don't blame the shop right off the bat.
Check the end fittings on the tank hose for leakage, and make sure that the hose is not reversed.

Those three suggestions were already offered, but you did not acknowledge whether you had tried them.

 

[tugboat80]

Yes my tank is good. It performs very well with a J8RCIC, and a 90hp Mariner. I just heard form my OB teck. My second "new" pump from a large supplier is not keeping up with demand of the motor, 15hp Johnson. Two runarounds from part supplier, now another new pump from a different source,and a couple hours at the repair shop. This could have been done much cheaper if the first "new" pump had been good. Check feed back of your famous national parts suppliers before trusting.

 

[racerone]

A $5.00 diaphragm is about all the original pump would need.--Yes a new diaphragm is available all day long.

 

[tugboat80]

My OB tech shop installed a new third pump and sent me home. I found out it leaks a steady drip, drip, drip... of fuel looking like between the layers of the pump. I contacted a second large supplier and got a fourth pump, put it on, motor runs fine; Pump has a continuing wet on finger of fuel, not leaking quite so much as the three previous BRP pumps. I called BRP to ask if they are having problems other than just my luck. They recommended I go back to the tech shop for another go around at $110 per hour, after they sent me home with a leaking pump as before. I don't have much hair left to pull out.

 

[racerone]

Repair kits at about $15 are available and it is elegantly simple to do.-----Where has the leakage occurred, screw on screen cover for the pump cracked by any chance ?

 

[tugboat80]

I have a jar full of the original FP parts. Many tiny springs and stops, plus thinking upside down in order to reassemble is why I ordered new complete pumps. For safety, I believe I should have no fuel leaking in the engine compartment. This may grow to be a $500 fuel pump replacement job on a $500 motor.

 

[racerone]

Hard to comprehend.-----I find these motors for next to nothing , good working fuel pumps included.-----Those pumps are easy to repair !