New to Board Need HELP

"First of all, thanks for havi

"First of all, thanks for having me!!

Heres the problem. I have a 97 Johnson 115 Faststrike. I have been tackling this for two months, with no luck. Engine will crank fine, but will not idle for more than a few minutes, acts like it is dying of fuel starvation. The first time diagnosing, I disassemble enough of the lower cowling to see the sight glass, appeared that fuel pump was working. Second time, the engine WOULD idle, let it idle for 15 minutes on muffs. Took it out on the water, will not idle. I can keep it idling by pumping bulb. Even got up on plane and ran a short distance with buddly pumping bulb. Now it will not idle for more than a few minutes. Pulled fuel line off of carb and fuel was being pumped out, so appears fuel pump is working. I have changed plugs, fuel lines, primer bulb and thermostats. Also, just this week, the no oil light will come on and steady alarm will sound Please help!! If anyone has any ideas, and can get more detailed, sorry to be such long winded"

"With both No-Oil and need to

"With both No-Oil and need to pump primer bulb, the most likely is a defective air-pump in the VRO.
It may be the membrane, it may be the valve in the housing. You will only find out by taking the pump apart."

"Fuel pump or the pulse line t

"Fuel pump or the pulse line that drives the fuel pump.

Are you saying that you pulled the fuel line at the carb with the engine running and saw gas pumping out, or did you, for instance, just finish pumping the primer bulb, engine off, and decide to pull the fuel line to see if you were getting gas to the carbs? Makes a difference.

My bet is fuel pump. If the scene is this...pump bulb, start engine, engine idles...then few minutes starts to die, pump bulb again, engine idles and a few minutes later starts to die, pump bulb again...etc, etc,etc. You could do that all day long...then fuel pump."

"Hey Mort, are you a fan of ge

"Hey Mort, are you a fan of getting into the guts of a VRO and rebuilding it, or do you replace them? There are ppl that feel it is worthless to try the rebuild."

"Another thing.. the VRO pump

"Another thing.. the VRO pump makes an audible click when working. Idling the engine, you can actually hear the pump click maybe every 4-5 secs.
If yours is not clicking, and it probably is not if the air diaphragm is pin-holed,....bad fuel pump."

"Doug

I pulled the fuel lin

"Doug

I pulled the fuel line off the carb with the engine running for just a minute and had fuel coming out, then shut her off. Figured this was a quick test of fuel pump. Thanks for the quick response"

"Matt...I swear it sounds just

"Matt...I swear it sounds just like a bad fuel pump to me. It that pump clicking...check that out.
You can also "tee-in" a pressure gauge on the output of the pump, I think you must see 3psi @ 800 rpm, no lower, (I think that is the spec...) double check to be sure.
I know you want to be sure before buying a new pump, because those are so expensive."

"Doug

Thanks, I will do

"Doug

Thanks, I will do these diagnostics this evening. If no click and no pressure, ordering the rebuild kit next. Thanks guys!!!"

Please be sure to post what ha

Please be sure to post what happens...I always want to know the outcome. Especially regarding the rebuild of a VRO pump.

"Will do, thanks again!!!"

"Will do, thanks again!!!"

"Matt...one other thing...don&

"Matt...one other thing...don't forget the possibility that the pulse hose that drives the pump may be leaking, or the pulse limiter may be clogged. It comes from under the carbs, driven by pulses from crankcase #4 I think; make sure it is good, seated properly, and is not leaking, pulse limiter clean, hose should be clamped (tie wrapped) at both ends, etc.
Man, I hope I have not steered you wrong..."

"Doug...thanks, I am adding to

"Doug...thanks, I am adding to that to my list of things to troubleshoot this evening before pulling the trigger on a new pump. Yall have been a tremendous help. Will update what I find!!!"

"the vro pump kit is avail,and

"the vro pump kit is avail,and the air motor side and fuel side can be rebuilt w/success,the oil side cannot be rebuilt/not avail to my knowledge...i choose to repl the complete assembly,i have dealt w/hairline cracks,and warped housngs that cause prob's..not always...but many times..."

"Dough:
I have rebuilt quite

"Dough:
I have rebuilt quite a number of VRO's in my time and hardly had any trouble. However one has to find out the reason for the pump breakage, and carefully inspect the whole pump. A 10 year old pump may brake of fatigue and wear, a newer one is normally something else that causes it.
As in all breakdowns it is the weakest link that suffers. 'Sneezing' engines may easily blow the pumps, but the problem might be caused by defective thermostats, clogged carbs or even scored pistons. Watch out for the valve in the air motor housing that gets stuck from time to time, then change housing as well."

"Thanks Mort,
I guess I will

"Thanks Mort,
I guess I will tear one of my bad ones down and do the rebuild and then test."

"Guys

Now I am really c

"Guys

Now I am really confused. Yesterday, I hooked the fuel line up to a tank of premix. At first crank, gave same symptons as before. Cranked up, idled for a few minutes and died. Primed bulb again, and bam, ran for 8 minutes. Turned off, let sit for 10 minutes, cranked and ran for 5 minutes before I turned off. I did find a leak around where the fuel line comes into the bulb. Replaced the fuel line with new, and hooked back into onboard tank. Engine started to die, but noticed I forgot to turn the fuel valve on the tank back on, bulb was sucked flat (fuel pump working, right)? Turned fuel valve on, and cranked up. Ran for 10 minutes before I turned off. Cranked right back up and ran for another 8 minutes before I turned off. My question is can a fuel pump be bad and work occassionally? I went through this a few weeks ago where the engine would idle fine as the fuel pump was working on the muffs. Took out on the water two days later, same symptons came back. HELP!!!!"

"Matt, it looks like it is not

"Matt, it looks like it is not the pump. If it is pulling the bulb flat...it is pumping.
Was it clicking as I suggested?

I am a bit confused by one of your statements...you say the fuel valve on the portable tank was turned off accidentally...that you forgot to turn it on after replacing the new fuel line....my question...how did you prime it with the bulb with that fuel valve in the shut off position?

Also, that air leak at the bulb...when the engine runs and pumps, it will draw air in there, and eventually "run out of gas" as you are experiencing. That air leak may have been your whole problem. I bet that air leak was on the tank side of the bulb.

I am glad you are doing such thorough testing before shotgunning the pump.
I will wait for the experts to add their opinions."

"There are quite a bit 'co

"There are quite a bit 'confusing' in this posting.
My suggestion:
Fill a clear glass jar/bottle with fuel, use 2% oil-mix for safety.
Take the fuel line with bulb from the jar and STRAIGHT onto the pump. (bypass all filters, tubes/connectors).
Start the engine.
If not pumping = pump defective!
If pumping = probably air leak somewhere between pump and fuel line.
If pumping, watch the level of fuel. About every 20 sec the pump should make a 'stroke' (click) and You should be able to see the fuel level drop."

"Mort...I sure hope I haven&#3

"Mort...I sure hope I haven't said anything confusing during this post...
If so, point it out to me because I really do not want to mislead someone on this forum.
Thanks."

"The most 'confusing'

"The most 'confusing' is to establish if the pump works or not.
In the first post You state that when pulling the fuel line to the carb ( I guess You mean the fuel line to the fuel rail), fuel is PUMPED out.
Then You state that You need to pump the primer bulb to make it run. That indicates either a defective fuel pump and/or air leak on suction side.
Finally we have the No-Oil going on, which indicates that the oil-pump part in the VRO does not operate properly.
The VRO consits of 3 units linked together mechanically.
1: The air-motor
2: The fuel pump
3: The oil pump

If the air-motor 'fails', both fuel and oil will fail.
If the fuel 'fails'(internal leaking), the oil should still work, unless there is a mechanical breakage on the shaft system between air motor and fuel/oil pump.
To narrow it down and try to isolate the failing part, perform the test suggested above."

"Thanks Guys

Doug....I turn

"Thanks Guys

Doug....I turned off the fuel valve when replacing the line. I cranked her after replacing the fuel line w/o priming the bulb, fired right up. Noticed the fuel in the sight glass fading and starting to die, noticed the primer bulb sucked flat. Turned motor off, primed bulb and fired right up, running for 8 minutes. Before replacing the fuel line, there were considerable amounts of air in the sight glass, then noticed the leak around the bulb, tank side.

Morten....thanks for the test info, never hurts to have more tests to try. I could not get the no oil alarm to go off yesterday however. I ran it for a godd 30 minutes combined. Last time I tested, it would come on after a minute or so"

"VRO OPERATION
Actually, the

"VRO OPERATION
Actually, the much-maligned pump is very simple and reliable. It consists of four basic sections:

the air motor,
a fuel pump,
an oil pump, and
a "NO OIL FLOW" alarm system.

Cutaway View of VRO Pump Showing Major Components
The air motor converts the pressure and vacuum pulses from the crankcase to a linear motion. These pulses are routed through a pair of check valves above the engine crankcase pulse fitting. One directs pressure cycles to one side of the air motor's piston and an inverted check valve directs the vacuum cycles to the opposite side

Each engine revolution moves the piston incrementally to one side of the air motor chamber and compresses the large spring. When the piston nears the end of its travel, a small spring unloads a poppet valve located in the middle of the piston assembly. The pressure on one side of the piston rushes into the vacuum side as the large spring quickly pushes the piston back to its starting point.

As the throttle is advanced, the pressure pulse gets stronger because of the increased airflow through the crankcase. This back and forth motion of the air motor's piston is what powers the fuel pump and the oil pump. At idle and low throttle settings, the weaker crankcase pulses cause shorter piston movements, which in turn, pump less oil with each cycle. As the throttle opening increases, the stronger crankcase pulses cause greater piston travel resulting in longer oil pump strokes. That means, more oil is delivered increasing the amount of lubricant in the fuel up to a 50:1 ratio.

The fuel pump, which is located in the middle chamber of the VRO, consists of a push-pull piston and diaphragm with a flapper valve and an inlet check valve. A rod connects the fuel pump piston directly to the air motor piston and the two chambers are sealed from each other by an o-ring. As the back and forth motion is generated in the air motor, the double-action fuel pump's piston and diaphragm is pushed and pulled by the rod cycling fuel to the carburetors. Gasoline is drawn into the blue area of the chamber, travels through the piston's flapper valve, and is pressurized in the green section on the following stroke.

The oil pump is directly connected to the fuel pump piston and diaphragm so they work in tandem. As with the fuel pump, oil is drawn in through the inlet fitting and a check valve as the air motor starts its travel. On the return stroke, the oil pressurizes, exits directly into the fuel chamber and is blended while enroute to the carbs."

"Here is how to test it

SER

"Here is how to test it

SERVICING
Since 1991, the OMC factory service manuals include a troubleshooting chart and a section on how to test, take apart, and service the VRO pumps. Besides Torx screwdrivers, you will need a pressure and a vacuum source to test the integrity of the check valves and diaphragms. CDI Electronics' #551-34PV gearcase vacuum/pressure tester work well, as does a SnapOn YA-4000 or the old Stevens pumps.

Even though they are not listed in the parts catalogs, most of the diaphragms are interchangeable. The air motor diaphragm kit is part number 435921 and the fuel pump repair kit is 436095. For those who pre-mix their fuel and oil, these kits allow the repair of the fuel pump section, avoiding the high cost of a new assembly or the re-plumbing and rigging of one or two traditional style fuel pumps.

Do not interchange any of the springs with other pump assemblies. They are calibrated for each model of pump. The latest P/N 5004558 pump is a universal fit that can be used as a replacement for all VRO equipped motors and each part is available for servicing.

When working on a fuel system, check for any restrictions or air leaks which would affect the engine. You can use a clear piece of fuel line connected to the VRO inlet and "T" off to a vacuum gauge. Run the motor at all speeds while inspecting for air bubbles in the line and for any vacuum restrictions above 4-inches Hg. A system with 3/8-inch fuel lines, a clean "spin on" filter, and a quality anti-siphon valve should show between 2.5 to to 3-inches of vacuum at full speed.

Repair and update your VRO or OMS system methodically and by the service manual. Check and test the boat's fuel system for restrictions and/or air leaks, and make sure the oil tank is clean. If you follow these recommendations, you will have a reliable and economical outboard that will keep your boating experiences pleasant.

So, contrary to boat ramp "urban legends", the VRO pump is a simple and reliable oiling system that has been standard equipment on most OMC outboards from 40- to 300-HP for the past 20 years. Most of the misinformation and "scare tactics" about its reliability originate from those who do not understand how the system works, or fail to keep it maintained."

"I think you fixed it in the p

"I think you fixed it in the process of replacing the fuel line and primer bulb.
That air leak can suck in air instead of pulling gas from the tank, and eventually the engine will "run out of gas".
I bet it is fixed."

"if it was indeed an air leak

"if it was indeed an air leak i would go ahead and replace ALL the fuel lines..........just my ......that way you dont go through this again."

David...went ahead and took ca

David...went ahead and took care of that last night!!!! Thanks for the input

"If you are using a portable t

"If you are using a portable tank, is there a screw on the top to let air in? Maybe it's creating a vacuum in the tank which pulls the fuel more than the fuel pump. I had this problem last year, when I unscrewed the air screw, worked fine. Could this be a possibility?"

"Collin...no not using a porta

"Collin...no not using a portable tank. The fuel issue has went away, will idle fine and run fine. However, I still have what I hope is a high jet issue. Motor will come up on pad fine, but once I really get in the throttle will start to surge. I can run around 3500 rpm fine on pad, but any higher rpm's and it will start to surge"

yep....shoulda repl that vro!!

yep....shoulda repl that vro!!!

"Matt...some clarification her

"Matt...some clarification here...last I knew, you replaced the fuel line, found an air leak on the tank side, and I for one thought you had fixed it.
Did you then rebuild the VRO pump?
Or did you do nothing to the pump, neither re-build nor new?

This post is important to me to find out the exact answer, because it is an elusive problem. The "no fuels", "no sparks", "no water out telltale", those are mostly pretty straightforward. But it is the elusive problems that are hardest to solve. Mort and JWB have years of experience to rely on...I am still learning.

I see also that you posted this same problem in Iboats forum. Any help over there?"