1997 60* Evin 90HP OIS. Past 2200 fades and dies under load.

[James R]

Have done all the usual fuel supply tests and no improvement.
There may be more to this story than we know. This motor supposedly has been rebuilt. Comps are normal, sparks are normal. It fires up ok but dies when throttled up. It had a single standard fuel pump fitted in place of the VRO. Decided that it would be better if a VRO were fitted. I have tried to fit a VRO but there is insufficient clearance between the case and the pulse hose connection and insufficient clearance between the case and the fuel in connection. May be able to fit an L for the pulse but there is no L scheduled for the fuel in. Is it possible that the power head is not compatible with the case as a result of fitting a different power head hence the need to go with a standard pump. Can't understand why the original fuel pump was not repaired or replaced with similar. I see that WSM produce a double standard pump set up so obviously a single pump would not do the job.
Any thoughts on this would be most appreciated.

 

[jakedaawg]

One pump is not enough...a vro will fit.

 

[jakedaawg]

 

[James R]

Thanks for the response Jakedaawg. I will post a pick of the problem.

 

[James R]

I hope that the pic will attach. You can see from the pic that the "fuel in" connection almost fouls the hump in the casing leaving no room for a hose. The hose you see is the disconnected pulse hose The pulse hose connection is extremely tight against the shift shaft carrier. Might be able to use an L to access this.

 

[jakedaawg]

That's too busy of a photo. Maybe take one not so close up?

 

[James R]

That would be difficult to do.The motor is mounted on a 'toon. Even with the steering disconnected this is the best I can do with the space available.
.

 

[James R]

Managed to fit a rebuilt VRO pump but real tight. I see the later models have different motor cases with more space.
Tested the motor in the water on the ramp and it starts more easily and runs strong in gear up to about 2500. Beyond that it will die if not throttled back. I dont have the plug in device to set the timing advance etc so I have now set everything to mid position and will run in the tub with the timing light connected to check for spark failure.
Any thoughts on this would be appreciated.

 

[James R]

Ran in the tub and all the sparks are there.
Brought the revs up with the advance and no problem, real easy. It still seems to be a fuel problem. Oh, I did check to see if the revs would pick up when under load at the lake when the primer was activated but it did nothing, did not pick up or choke down. Leads me to believe there is not enough fuel in the VRO reservoir. Any thoughts along these lines?

 

[jakedaawg]

Although it does not exhibit usually the symptoms you describe--- have you checked the diaphragm in the vapor pump?

you said its.not slow system but your descriptions point to it. Do you have access to a known good pack or ois you could swap in as a test?

 

[James R]

Interesting. Have pulled the carbs and there is no fuel in the bowls. The bowls have no trace of fuel mix, completely dry. No residue in bowls, slight residue in the uppers. Usually have to drain the bowls when the carbs are pulled. Any thoughts?

 

[Chris1956]

Are you sure it is plumbed correctly? Gasoline first to the mainstrainer, then to the vapor separator. Next gasoline gravity feeds to the OMS pump, mixes with oil and pumped out to the carbs.

The the vapor separator cover leaks, it will affect the pumping of gasoline. You might as well check the vapor pump as well.

 

[James R]

Thanks for the response Chris.All piped correctly. Did another test. Reconnected the fuel line to the input filter and pumped the bulb. Fuel shot out of the four carb feed holes in the manifolds. Only one carb needle was stuck. Checked that the bowl vents are clear. Reassembled one carb and pumped fuel into it with an oil can. It filled up ok. How can the motor get fuel to start and run without fuel in the carbs? It is getting fuel from somewhere. Could it be that the fuel is leaking past the string seals between the carbs and manifolds? Could it be that fuel is getting past the primer, although the primer appears to be operating normally. Anyone experienced any of these things?

 

[racerone]

The electric primer is a valve.-----It puts fuel into the motor when cranking, not into the carburetors.-----This fuel bypasses the carburetors.

 

[racerone]

The electric primer is not a pump.

 

[James R]

I am aware of what the Primer does and how it works but if it leaks fuel can pass. The motor must be getting fuel from somewhere, certainly not the carbs because there was no fuel in them.
Anyone else have an idea?

 

[jakedaawg]

Leave a bowl drain open, pump bulb, does fuel come out?

trouble shooting is done in logical steps...

if it does not come out bowls when you pump, backtrack by loosening hoses till you get fuel.

there are several places before the carbs...perhaps bad needle and seat/float in the VST

 

[James R]

I removed the carbs for inspection and was surprised by the fact that there was no fuel in them. That led me to testing the piping. the fuel flow to and through the manifolds, the checking of the breathers in the carbs and testing a carb for fuel acceptance. New kits are on their way and will reassemble and check for the fuel in the bowls. Still don't know how the motor was getting fuel to run without it being in the carbs.

 

[jakedaawg]

Could be through a bad vst pump diaphram. Could be through a couple of carbs. Could be through a bad primer valve . I would lean to some carbs getting fuel....

 

[jakedaawg]

I removed the carbs for inspection and was surprised by the fact that there was no fuel in them. That led me to testing the piping. the fuel flow to and through the manifolds, the checking of the breathers in the carbs and testing a carb for fuel acceptance. New kits are on their way and will reassemble and check for the fuel in the bowls. Still don't know how the motor was getting fuel to run without it being in the carbs.

Was there fuel getting to the VST? Answers help folks give better suggestions...