Interesting Problem (Fuel?)

[azhunter]

'89 Evinrude 175 Crossflow
My 175hp feels like it is taking off in fourth gear. It will eventually plane out and run at around 4800 RPM at WOT but not at the 5500 RPM that it used to run. What is interesting about this problem is that if I kink the fuel line (essentially shutting it off) while trying to take off, the engine will really come alive for a couple of seconds until it runs out of fuel and dies. I kinked the line just on a hunch because of how fast the engine died when I tried pumping the bulb while trying to get moving.

Since this issue has started, I have replaced the fuel pump and rebuilt the carbs. All float levels are 1" from the carb to the lowest point on the float as it shows in the manual. None of this has changed the performance at all.

It is also worth noting that the plugs don't appear to be wet.

I am at a loss as to what to try next. Any ideas?
Thanks,

 

[RogersJetboat454]

Re: Interesting Problem (Fuel?)

Have you done a compression check to see if all holes are healthy, and within 10% of each other?
Checked the ignition of each hole with a spark checker?

 

[azhunter]

Re: Interesting Problem (Fuel?)

Rogersjetboat454,
Thanks for your reply. Sorry, I left that part out but I have checked compression and all are within 10% of each other with an average of 110 psi.
I have also put a spark tester on each cylinder and found that I did have a bad coil so put a new one on. I was certain that would have solved the problem but... No change.

 

[glenn property of pam]

Re: Interesting Problem (Fuel?)

2 strokes run fast and hard when they run lean then they melt there pistons and destroy the engine so it's maybe not a good idea to stave the motor of fuel cause it to run lean.

does the bulb go tight when squeezed with the engine not running?

 

[azhunter]

Re: Interesting Problem (Fuel?)

Thanks for the tip! Definately don't want any melted pistons.
Are you suggesting that perhaps it is running too rich?
The bulb does get tight when squeezed with engine not running.
Thanks

 

[glenn property of pam]

Re: Interesting Problem (Fuel?)

im not suggesting anything yet just trying to rule out things.
The timing plate moves easy with the gear shift ?
correct plugs and gaps?
you haven't changed the prop?
with air cover removed at idle is any fuel being blown back out of the carbs?
has it had a de-carb in the last few years?

 

[azhunter]

Re: Interesting Problem (Fuel?)

The timing plate moves freely with the throttle.

The plugs and gap are correct.

The prop has not been changed.

I will have to check if there is any blow back and get back to you.

It has not had a recent de-carb but I had the heads off a couple of seasons ago to replace the water diversion tubes and there was very little carbon build up.

 

[MattRoar]

Re: Interesting Problem (Fuel?)

Hello, thank you for your time. Just to avoid confusion on this topic and my input - I'm co-owner of the boat.
Couple of other items worth noting on this issue. The motor dies when punching the throttle during take off, so in order to get moving it has to be throttled very slowly. After running for about 15 minutes and shutting down, it is very difficult to start again.
Appreciate your input, don't know where to go at this point.

 

[emdsapmgr]

Re: Interesting Problem (Fuel?)

When you rebuilt the carbs did you pull all the jets out of the carb and visually inspect them? 3 for each throat. Have you checked spark with a timing light on each plugwire, esp when the engine is fully warmed up and is under load? Possible that when the engine heats up to normal operating temp, that some ignition component may be failing-causing a difficult restart. Taken a fuel sample to check for water?

 

[MattRoar]

Re: Interesting Problem (Fuel?)

I did inspect every port,jet I could find in the carburetors. Used low air pressure to ensure all paths were clear.
Have not tried the timing light on each plug wire, but wouldn't the color of the spark plugs indicate that? 5/6 plugs were dry and brown - 1 plug however was only slightly brown and noticeably cleaner than the others. ?
There is a water filter on the fuel line and I did verify no presence of water in the carbs.
Thoughts?

 

[azhunter]

Re: Interesting Problem (Fuel?)

emdsapmgr,
I just wanted to clarify the 3 jets in each throat; there are two throttle jets (high and low speed) and a float "jet", correct?

As far as checking the timing under a load, what am I looking for? Consistency or just verify it's still sparking? Will my standard automotive timing light work?

There is definitely not any water in the fuel. I've had that happen before and that is not what we are dealing with here.

If there is anything else you can think of please throw it our way. We are trying to put together a list of tests to perform the next time we have a chance to get the boat on the water.
Thank you for your thoughts.

 

[glenn property of pam]

Re: Interesting Problem (Fuel?)

pull the drain plug on each carb and make sure it has fuel in all the bowls.

 

[emdsapmgr]

Re: Interesting Problem (Fuel?)

The carbs have 3 jets, not to include the float needle and seat. There is the high speed jet, behind the bowl drain screw, a mid jet inside the bowl of the carb and the idle jet, in the throat of each barrel. The flashes from the gun of an inductive timing light will show the quality of spark. You are looking for intermittent spark, no spark, or weak spark. Check the flashes and compare with all 6 cyls. Be sure to warm the engine up fully, first. There is probably something going on with that one cyl with the odd-looking spark plug. Could even be an internal water leak if the plug looks washed. Was it a bottom (lower) plug?

 

[MattRoar]

Re: Interesting Problem (Fuel?)

All jets/ports are clear. The clean spark plug was in the middle. Am reassembling at this time, have verified all fuel hoses are clear - including the primer solenoid. Will post back as soon as it's running and have checked spark. Thanks.

 

[MattRoar]

Re: Interesting Problem (Fuel?)

I replaced the coil, now all cylinders firing as expected. I also synchronized the carbs via the throttle linkage, top carb was slightly out of adjustment. Took it out to the lake on Sunday, no change in fuel problem. It is still flooding out terribly...no take off power and no top end power. Ate through 8 gallons of gas in about 20 mins at 3200 rpm.
So if I may recap what I have done to this point, as well as verifed, in hopes that it will help pinpoint the issue: New fuel pump, Rebuilt carbs, new coil...confirmed carb floats are adjusted to spec and working properly, all carbs are getting fuel, primer bulb gets hard and stays hard, no leaks in fuel system, no blow back from carbs, no water in fuel.

With all of that done, it seems there is only 1 component left - the primer solenoid. Thoughts? Any other suspect I may be overlooking?

 

[BigBossManDaddyLane]

Re: Interesting Problem (Fuel?)

I am looking forward to the answer to your problem cause I know mine issue has be quite upsetting. It also feels like I have tried everything too. Do you use clear fuel lines or solid black lines?

 

[glenn property of pam]

Re: Interesting Problem (Fuel?)

I replaced the coil, now all cylinders firing as expected. I also synchronized the carbs via the throttle linkage, top carb was slightly out of adjustment. Took it out to the lake on Sunday, no change in fuel problem. It is still flooding out terribly...no take off power and no top end power. Ate through 8 gallons of gas in about 20 mins at 3200 rpm.
So if I may recap what I have done to this point, as well as verifed, in hopes that it will help pinpoint the issue: New fuel pump, Rebuilt carbs, new coil...confirmed carb floats are adjusted to spec and working properly, all carbs are getting fuel, primer bulb gets hard and stays hard, no leaks in fuel system, no blow back from carbs, no water in fuel.

With all of that done, it seems there is only 1 component left - the primer solenoid. Thoughts? Any other suspect I may be overlooking?

its slim but if theres a electrical problem then the primer might be coming on when the key is turned on instead of when the key is pushed in so theres something to check

 

[MattRoar]

Re: Interesting Problem (Fuel?)

I use the normal solid black fuel lines. The parts for the solenoid should arrive in another day, I'll rebuild it then take another test drive at the lake on Sunday. In the meantime, as you said - I will test the electrical component to see if in fact it is still engaging the solenoid after start up. Didn't think of that, thanks.

 

[1NewBoatGuy]

Re: Interesting Problem (Fuel?)

make sure your chokes are not closing while running. It may be causing a greater fuel draw, in turn causing a rich fuel mixture, not enough air and then causing poor take off and wot.
Watch the butterflies on the carbs as it is operating. This really seems like a carb problem. Even though they are rebuilt carbs and I am not questioning your abilities, but I have been known to make things worse before it gets better.
I think I would be focusing on the carb adjustments and operation more than ignition. The amount of fuel usage your getting is comparable to a drag racer. Can't imagine your gas bill ... :faint2:

 

[emdsapmgr]

Re: Interesting Problem (Fuel?)

Reading plugs is a valuable technique. The concern has to the one plug which is a different color. It's either not firing properly or the carb feeding it has debris in one of the jets, (perhaps the main jet)-causing a lean condition. If it's a lean condition, beware. If the piston is not getting fuel, it also is not getting any oil. A bad situation.