85 Evinrude 90 fuel pressure problem

[Ol Yank]

Hello again all,
I have a 1985 evinrude 90 horse I purchased 3 years ago. When I bought it, I replaced the fuel pump and water pump. The fuel pump was sounding oiler alarm at idle and if you squeezed the oil primer, the alarm would stop. I figured the pump was just getting weak, so I replaced it. Ran fine until this spring. I started getting the same oiler buzzer alarm (1/2 second every second or so). I disconnected and capped oil line, disconnected alarm, and went to premix.
Now, at idle and low rpm, motor will starve for fuel. Pump the primer bulb and it smooths out. at 1/4 throttle or higher, it runs fine.
My question is:
Is it possible that the engine is getting tired and not providing enough vaccuum to the pump, or is it more likely that the 3 year old pump is failing?
How would I go about diagnosing this without spending $320 for another fuel pump?

Thanks in advance

 

[Ol Yank]

Re: 85 Evinrude 90 fuel pressure problem

I forgot to mention that all 4 cylinders test at 95 pounds compression, brand new plugs and wires, all new hoses from fuel tank and under cowling. Proper hose clamps are being used. No leaks that I can detect anywhere. I tried draining all the gas from the tank and used a fresh 10 gallons, no difference.

 

[tashasdaddy]

Re: 85 Evinrude 90 fuel pressure problem

you can replace your vro pump with a standard straight fuel pump. that mounts to the block. +-$60.00.

 

[emdsapmgr]

Re: 85 Evinrude 90 fuel pressure problem

If the engine runs fine at high speed, doubt that you have a vacuum problem with the pump. Possible you have an air leak, or restriction in the line-like dirt in the anti-siphon valve or bad hose bulb. If you pull the hose barb off the engine side of the fuel hose and squeeze the bulb, you should see a strong flow of fuel come out of the hose. If so, you probably don't have a fuel restriction. If you don't see a restriction, I'd be looking at the fuel pump. I prefer to leave the barb off the hose and run the end through the lower cowl, direct to the fuel pump inlet.

 

[Ol Yank]

Re: 85 Evinrude 90 fuel pressure problem

I replaced the primer bulb and all hoses. The primer bulb works fine. I suppose it is possible that the disconnect barb is leaking. I could try by-passing that as you suggest. I still have a hard time believing that it is a bad pump as it may have 100 hours on it.

Thanks for the input.

 

[Silvertip]

Re: 85 Evinrude 90 fuel pressure problem

Pulse limiter may be dirty or malfunctioning at lower speeds. Remove and clean it. That would/could be the original problem and there really is nothing wrong with the pump.