Fuel problem continues

[bonz_d]

This is getting silly. I've had 2 other threads trying to sort this out and each time the problem changed. Could be more than one problem?

The motor is a 1978 Evinrude 35hp Electric start remote controls.

Started this because the engine would not idle at closed throttle, it would keep dieing out and would have to be reprimed before it would restart.
Rebuilt the carb and there was some improvement, run it on the water and would act as before. Rebuilt the fuel pump, no change but a test of the pump per the instructions showed that it was leaking pressure on both side. I swapped pumps with another motor and there was a great improvement while running in the tank.

Got it on the water today for a test run and it is much better. Starts right up, idles very nicely, now it accelerates normally until about 1/3-1/2 throttle then bogs out, throttle back and it will stay running.

It did not do this before the carb and fuel pump were rebuilt. It actually ran very well above idle before. So what could I have missed or messed up? The only thing that I had found while the carb was apart was that the float was out of adjustment. It was not level with the throttle body.

So the short of this is that before it would not idle but ran great at WOT. Now it idles great and starts right up but will not run at WOT.

 

[Miroash]

Re: Fuel problem continues

It is obviously a carb issue. I think you need to adjust the carb or you have a plugged main jet. when you rebuilt the carb(s) did you blow the jets out with compressed air or did you just spray carb cleaner thru them?

 

[Cofe]

Re: Fuel problem continues

Sounds like me, getting to know my motor better since I have to work on it a lot.. Anyhow, have you checked where you're spark advance picks up? On my 90 Rude25hp. it is lock collar that makes contact with the plastic block on the timing/carb linkage. There is a procedure in the manual for setting this. Also, it could be you're high speed jet is plugged.... The high speed jet I beleive is behind the gas inlet on the front of the carb. Just take you're hose off the barb, and stick the carb/cleaner straw into the barb and spray. Hope this helps. Also check for air leaks, on tank to engine, the pump bulb should get real stiff.

 

[bustermin]

Re: Fuel problem continues

I have to agree with miroash, as you stated yourself

It did not do this before the carb and fuel pump were rebuilt. It actually ran very well above idle before.

so why go look at something else, look at what you have touched. That will most likely be where the problem is. Try adjusting the carbs, also, make sure the jets are clear (with comp. air).

 

[bonz_d]

Re: Fuel problem continues

I've been through this fuel system so many times I'm seeing it in my sleep!

When I took this carb apart it was very clean inside. So clean I was amazed as it was supposed to have been rebuilt just before I bought it last summer.

The carb cleaner blew through all the passages very well. Both high speed and low speed. I did spray all down very well then blew them out. When I reassembled it I noticed that the float was low when it was inverted and reset it to level as I have done before. When I removed the carb the only linkage that I removed was the choke and the throttle linkage from the carb. No other linkages were touched.

The timing starts to advance as soon as the throttle is advanced. I suppose that linkage could have been knocked while I was removing the starter to get to the carb. But I don't think I hit it.

Also I did find that the hose to the carb is 1/4" were OMC lists a 3/8" hose which I have 3/8" but it fits loosely on the fuel pump. But again it was running fine with that hose before.

Will pull the carb again and recheck the high speed jet and the float.

 

[bustermin]

Re: Fuel problem continues

The carb cleaner blew through all the passages very well. Both high speed and low speed. I did spray all down very well then blew them out.

I'm not sure what you mean by "Blew them out" whether it was with compressed air or with the carb cleaner. the reason people insist on useing compressed air is because while carb cleaner will spray out the other end it will not always remove a restriction, while the compressed air almost always does. it only takes a small restriction to effect the way you motor will operate. but like I said before, the problem is most likely with something you touched, like air/fuel mixture or the like.

 

[bonz_d]

Re: Fuel problem continues

Yes I did blow it out with air. The only adjustment on this carb is the slow speed jet. The high speed jet is fixed.

 

[bolter15]

Re: Fuel problem continues

You spray solvent into all the holes to make sure you soften what ever is inside there gumming things up. You use compressed air as a scrubbing procedure to remove what's been loosened/softened. Take your time and let the solvents work on the passages.

Where did you set that needle valve??

 

[tashasdaddy]

Re: Fuel problem continues

ethanol and carb cleaning here http://forums.iboats.com/showthread.php?t=299680

 

[bonz_d]

Re: Fuel problem continues

Thank you everyone!

TD, I had followed that thread from the begining so I am very familiar with it and even looked for signs of it. When I disassembled the carb the first time it was very clean inside, no discoloration or varnish buildup. All of the passages were clear except the one low speed port towards the back of the carb. Which cleared up actually very easily. All hoses are less than a year old and the feed to the pump actually has an OMC number on it.

As for this carb it only has a low speed needle, the high speed is fixed. I adjusted it 1.5 turns open to start then closed 1/8 after it was running.

Today is pouring rain so I most likely wont be able to work on it unless of course it stops. But I will be pulling it off again.

 

[bonz_d]

Re: Fuel problem continues

Sun came back! Hopefully the Sun comes out tomorrow!

Was able to remove the carb, disassembled it and I think I found the problem.
Looks like the float was stuck partially closed. It's moving freely now so I hope that's it. Started it in the tank and it sounds much better. Also removed that 1/4" fuel line to the carb and replaced it with what Evinrude says is supposed to be in there, 3/8".

Won't be able to test run it on the water until tomorrow, that is if the sun shows up. Right now they're calling for T'Storms in the morning. I'll post back my results ASAP. Wish me luck.

 

[bonz_d]

Re: Fuel problem continues

Took it for a test run today and still no change. Now I'm at a loss as to what to do next. As I stated before, this engine was running fine at WOT before I removed the carb it just wouldn't idle. Now it will idle fine but wont run above 1/3 throttle. As of right now the only thing I haven't changed it the fuel tank.

 

[hidef]

Re: Fuel problem continues

Make sure the fuel line running from the fuel pump to the carb is not kinked. I this happened to me when I re-installed the carb on my 25. It idled fine but would bog down and start to die at anything over a 1/4 throttle.

 

[bonz_d]

Re: Fuel problem continues

Now I'm really disappointed with this. This morning I did a search here and on the web in general and was abosultely amazed at the number of hits I turned up with people having this exact same problem with this group of motors (20-35hp) that no one seems to be able to resolve. Many have even taken them to dealers w/o it being resolved!

So, this carb has been apart 3 times now, it is clean. Fuel pump has been replaced, all hoses have been replaced. I now have another tank being brought over today to try, after that I don't have a clue.

 

[Daviet]

Re: Fuel problem continues

Try to squirt oil/gas mixture into carb while runnig motor as fast as it will go. If RPM'S pick up it has to be a fuel problem. I have also used aerisol spray cans of fogging oil to do this.

 

[tmcalavy]

Re: Fuel problem continues

So..uh, did you do a link-n-synch after you rebuilt and reinstalled the carb? Sounds like your timing and carb are not in synch.

 

[bonz_d]

Re: Fuel problem continues

To quote Ray Stevens, "Everything is Beautiful"!

1st I would like to give a very big THANK YOU to everyone that has responded to my cries for help and especially to bustermin, he hit the nail squarely on the head. Now if there is an IDIOT of the Year award sign me up!

Last night my son-in-law and I removed this carb for the umteenth time to go through it one more time. After we had it off we put a pcs of hose on it to blow through. Couldn't blow air no matter which way it was facing. Opened up the bowl, could now blow air through the hose. Checked the bowl jet, got air. Bowl good. Then we checked the float again. It would not open.

Removed the float and checked the high speed pick-up tube and the low speed tube. Got air. So I went back into the house to get the old float needle and seat which is how we discovered the problem.

At some point during all these tear downs I mistakenly reinstalled the float upside down! So if you all would like to line up and kick me I'll be more than happy to bend over. I guess this is what happens when frustration sets in.

The motor is now running the best it ever has sinse I've owned it. As to all those poor people whos posts I read yesterday and that couldn't find a solution I hope it turns out to be something as simple and stupid as I found.

Again thanks and now let's have some fun,
Kevin

 

[nymack66]

Re: Fuel problem continues

Nice follow up ..Now enjoy the Boat !!