94 Evinrude 112 spl, alot of work still dying

[tbull]

And so the problem continues. As long as keep the throttle at about 3/4 it will not die, but when I open it up to WOT it runs for about 15 to 20 seconds and just shuts down, sometimes the engine dies completely, other times it just goes straight to idle, and when it does go to idle it will not let me give it any fuel. Try to give it gas and it sounds like it is just choked out. And after this happens I have to kill the engine and it takes forever for it to get back to normal. I had 4 spark testers running on the water today, 1 on each cylinder. I wanted to see if it was losing spark when this occured and it IS NOT losing spark. I had this thing running with the spark testers, (bulb type), and it kept spark through the entire bogging down process. Here is a list of what I have done so far:

Rebuilt fuel pump (months back)
Just rebuilt carbs
new fuel lines
new vent line installed
new plugs
link and sync to manual specs
WOT timing procedure done (Joe Reeves procedure)
New primer bulb
new gaskets on electric primer
new fuel line from tank to the engine
New fuel quick connect hookup
replaced rectifier (batteries are charging, but tach still does not work, even tried it again with built rectifier from radio shack, no change.)

This problems seems to be only at WOT, I thought I would see it losing spark when the problem occurs and it doesn't. I am flat out stumped?. Just for the heck of it I disconnected the power to the electric primer, no change. I also ran this thing with the kill wire not connected, no change. The other day ran it in a barrel at about 1000rpms, took a blow dryer and heated up power pack with 4 spark testers, did not lose spark at all on any cylinders. Any other test out there to help me eliminate this, I keep going back and forth between fuel and ignition. I have noticed that sometimes after it shuts down I give the bulb a squeeze and it is very hard. I have disconnected the quick fuel connector from the engine and sometimes the fuel squirts in different directions when I pull it off, like it was under pressure? I remove the line from time to time just to make sure I am not getting a vapor lock, even bypassed the quick connect and went straight to fuel pump, no change. As long as I keep the boat under 30mph it will not die, but when I open her up to WOT it kicks the bucket in a matter of seconds, bogs down straight to idle and then usually dies.

 

[wavrider]

Re: 94 Evinrude 112 spl, alot of work still dying

If you are getting spark during the "bogging down" time then it has to be fuel related.

I would suggest looking at fuel pump, yes you rebuilt it but something is stopping the carbs from having enough fueel to run the engine at WOT.

There is a restriction in fuel system, or fuel pump is not delivering enough fuel, or floats in carbs are not adjusted correctly.

I had basically the same scenerio on two different engines.

1978 115, replaced the complete fuel system, went to 3/8" fuel hose, bypassed the quick disconnect at motor cowl. No more problems.

1973 85hp, starving for gas, ended up someone put a incorrect fuel pump on the engine, not pumping enough gas, replaced with proper fuel pump no more problems.

 

[tbull]

Re: 94 Evinrude 112 spl, alot of work still dying

Thats what I was thinking also, was gonna pull the pump yesterday but ended at at work for 13 hours, guess I am gonna go get another fuel pump rebuild kit tommorow and give it another shot, its the only fuel related component I have not rebuilt or replaced in the past couple of weeks.

 

[tbull]

Re: 94 Evinrude 112 spl, alot of work still dying

One thing though, when we pump the primer bulb the engine still continues to die regardless, could it still be a fuel pump problem?

 

[Dhadley]

Re: 94 Evinrude 112 spl, alot of work still dying

How's the compression?

What spark plugs are you using?

 

[tbull]

Re: 94 Evinrude 112 spl, alot of work still dying

compression 105,106,107,114. champion JC4 gapped at .35

 

[tbull]

Re: 94 Evinrude 112 spl, alot of work still dying

to be more specific that is QL77JC4 gapped at .35

 

[stormtracker]

Re: 94 Evinrude 112 spl, alot of work still dying

I have a similar problem with my 1989 Johnson 88 SPL. I put a clear fuel filter on the fuel line just before the quick connect at the motor and noticed some junk in it after running for a while. Currently I'm looking at the fuel tank, and fuel pick up tube. I've heard that the anti-siphon can sometimes cause fuel delivery problems. I'm looking at draining the tank, and checking for any junk in it. Then removing the anti-siphon valve, and replacing the pickup tube with a copper tube with no restrictions. In my situation, after the motor dies or starts to, I would pump the fuel bulb, and it would start right up and run for a few more minutes, at about 3000 rpm, before dieing again.

Just a thought.
Good luck.
Stormtracker

 

[tbull]

Re: 94 Evinrude 112 spl, alot of work still dying

Forgot to mention I already checked pickup tube there was not any anti-syphon valve present, just a screen, I removed the screen so its just a straight tube now, no change. I plan on rebuilding fuel pump again, I did go ahead and take it apart, no tears in diaphram or anything at all, it looked brand new which it basically is. I am going to rebuild anyway since I took it apart, but it sure looked fine to me?

 

[Dhadley]

Re: 94 Evinrude 112 spl, alot of work still dying

Have you run a pressure & vacuume test on the fuel pump?

 

[stormtracker]

Re: 94 Evinrude 112 spl, alot of work still dying

I found my Anti-siphon valve in the fitting that attaches to the elbow on the pick up tube at the top of the tank. I really didn't even have to take the pick up tube out to remove the valve, and it did seem to be causing a restriction.
If you try blowing air in the fuel line going to the vented fuel tank, and it won't go, then there's an Anti-siphon valve in there somewhere. I also removed the screen at the end of the pick up tube and cut the end of the tube on a slight angle.
Now to get out and try it again.
Keep trying, and good luck.


I not a marine mechanic, but I did stay in a Holiday Inn Express last night.