Need advice about possible fuel starvation problem

[Jeb1971]

I have a 1985 Evinrude 235. I took my boat out 2 days ago with this motor for the first time. I had run it a few times with earmuffs.. Didn't notice any problems. New thermostats and good telltale.

I would like to ask some advice about this problem before I haul it over to a shop.

The motor starts fine with a couple bumps of the enritchener and idles fine too. Problem is taking off, and it boggs out like its fuel starved. It seems to bog before I can get up on plane and I have to keep pulling the throttle back down to idle to keep from stalling it, so mid range I suppose. I think these carbs have 3 ranges, Idle, Mid and High..
Anyways, After trying to get up rpms several times, I noticed that when it was bogging that if I bump the enritchener once or twice, it cured the bog and it gets up and goes like gangbusters.

Actually, after going around the lake at 65 or faster, I notice that I can come back to idle and punch it up to high rpms without any bog or need to use enritchener, like the problem went away.
But after I shut the motor off for about a half hour to eat some lunch, when I start it up and try to take off its the same problem.. Its funny, almost like the motor's not warmed up...
I have changed all of the small rubber lines that go between the carbs, used sea foam, etc.
I am running a marine electric fuel pump that puts out a steady 3 pounds of pressure.
I was able to check my fuel pressure gauge 'when it was bogging' and noticed I had good fuel pressure.

 

[fergie]

Re: Need advice about possible fuel starvation problem

have you noticed also having a high idle after running around at full throttle?
If so, i have a johnson 85v4 i had a simular issue my throttle advace was sticking, not moving with the butterflys, if yours is eqipped with a thottle advance, you might want to check that. to fix mine i ended up pulling the flywheel to get it finally freed up, and lubbed so it moves like it is supposed to.

 

[tashasdaddy]

Re: Need advice about possible fuel starvation problem

this is a new to you motor. i would do a linc n sinc, if that does not cure it, it would do the carbs. also when putting new hoses on, it is easy to get a slight bit of trash in the lines, these then end up in the carbs. hope you used B1 rated alcohol resistant hoses.

 

[kenmyfam]

Re: Need advice about possible fuel starvation problem

I would re-build the carb's anyway. It seems to be the number 1 problem of the season so far this year !!!

 

[Jeb1971]

Re: Need advice about possible fuel starvation problem

Thanks.
I recently rebuilt the carbs and blew out the passages with compressed air. The floats seemed to be in fine order acording to my manual. I did the seafoam treatment which I must say is a great maintance operation..

I also removed the intake manifold to inspect the reeds and make sure everything was clean and in good order..I am a Machinist for a major railroad, but was a professional mechanic many years ago.. I'm pretty good at taking things apart and putting them back together, albeit I am not a professional outboard motor man.

Be that as it may, I suppose I could tear down the carbs again since it is apparently something in the fuel supply to the cyllinders in mid range.
I did also do a link and sync as far as the information provided in the seloc manual I use..

I suppose the only thing that I can say that might 'not' be spot on is the timing.. I tried to get it as close as I could to the spec, but cannot say definatly since I dont have a test wheel and tank.

Thanks Tashasdady for the tip on alchol resistant hose.. I think I got the line I have on there now at an auto parts store and didnt verify that it was alchol resistant. I will pick some up and apply it when I rebuild the carbs.

Fergie. Thanks for your advice.. I dont have a high idle problem with the motor, infact, it seems to run like a dream when it is good and warmed up.. All linkage has been carefully inspected and lubricated with waterproof grease.

 

[jonesg]

Re: Need advice about possible fuel starvation problem

Someone as yourself will appreciate the genuine factory service manual over the seloc book of a thousand engines covering the past 60 yrs.
www.outboardbooks.com

per coast guard you need certified marine hose for fuel lines,
these are decent prices,
http://foreandaftmarine.com/FUELHOSECERT.HTM

 

[Jeb1971]

Re: Need advice about possible fuel starvation problem

Thanks, Jonesg for that link to the catalogs. That is a great resource.. Prices are reasonable too. Wish I would have known about that before I got the manual I have now.

 

[Brew2]

Re: Need advice about possible fuel starvation problem

I'm sure you've already checked this given your mechanical experience...however I'll mention it because I had the identical problem with my 140 Evinrude.

Check the fuel lines to each carb body for slight kinks. In my case, one of the lines that was somewhat hidden underneath a carb had a bit of a kink. Idled fine, but whenever you punched it, it would bog down. If you bumped the primer, it would overcome the bog and seemed to run fine thereafter. I assume that at higher RPM, enough fuel got by the kink to keep things running, but at lower rpm, it would drain the carb bowl to empty at any speed above idle.

Good luck!

 

[emdsapmgr]

Re: Need advice about possible fuel starvation problem

Some miscellanous thoughs, since you have most covered. I note that the problem only occurs after the engine is cold, or shut off for a period of time. Once you have it running, it seems that the fuel pump is able to keep up with the engine demands. The engine needs 2.5 lbs fuel pressure to run. The fact that it runs better if you hit the enrichment solenoid indicates fuel starvation. Not sure if you are priming the fuel system well when first starting. Before you start it each time, prime the hose bulb and see if it firms up quickly, or if you have to pump additional fuel into the system. If fuel drains from the system after each use, it will bog upon startup. Usually, you prime the fuel bulb once and you are good for the whole day. Also, possible that your fuel is running back into the tank once the engine is shut off. This is more of a problem if the anti-siphon valve is missing or stuck open, or: check for fuel, air leaks in the fuel system-check all your hose clamps. I have seen problems with the control valves in the fuel primer bulb on the hose. Is this one new? As Brew mentioned, kinks in the hose can be a problem. Another goofy hose thing-make sure the hose bulb arrow is oriented in the "up" direction, and not "down" as it lays in the boat. This engine needs a 3/8" hose line.

 

[Jeb1971]

Re: Need advice about possible fuel starvation problem

Well, all of my fuel line is new 3/8" and well routed. No kinks in the fuel line, the enritchener line or the carbutetor equalization (?) lines. I dont have a primer bulb as I have a marine electric fuel pump which provides a steady 3.5 #'s of Psi which I verify by a gauge I installed inside in the cowl allong the fuel line. This gauge is how I verified that I had fuel pressure durring the bog situation as I ran back to check it.

Its funny because as I said, when the motor was cold, or started after sitting for atleast a half hour, the bog on aceleration happened, unless I bumped the enritchener a couple times.. >>>Then, it got up and went just fine through all throttle ranges.. even after tooling around the lake for a while, the bog problem dissappeared, but let it sit for over 1/2 hour, and the mid range bog is back.

As I said, I had went through thses carburetors and cleaned them out with compressed air and carburetor cleaner and also did an extensive cleaning with sea foam.

What stumps me is that the problem is intermittent.

 

[jtcarter]

Re: Need advice about possible fuel starvation problem

I have the exact same problem, been chasing it for a year and a half. Its not air in the fuel line, i have fuel rails on mine just one main hose that runs to each one, no kinks. I have no anti siphon valve on my fuel line as they have a tendency to stick, then you'll be surging at higher speeds and wondering wtf? Pump the primer bulb after you've been setting for awhile, that tends to help mine sometimes. Other than that keep hitting the choke, enricher and continue to fish until you can unload it on someone else like i'm about to do. If by some stroke of luck or you stumble onto a fix, i'd love to hear it, because this problem doesn't go away.

 

[jtcarter]

Re: Need advice about possible fuel starvation problem

I've heard of people going down a size or two on those mid range jets to just off idle circut. I really never heard the results of that though, as this seems like a fuel starvation deal, just like mine.

 

[Showtime22]

Re: Need advice about possible fuel starvation problem

Is there an acceleration pump in the carb that could be the problem? On my carb you can see the mist blasting out of it when I mash the throttle. (1981 was a very Green year) When the rubber pump seal is cold it may not be working and when it heats up it could be sealing enough to send some fuel. On some carbs you can buy just the pump and some new gaskets to replace it before you do a whole rebuild.

Goodluck

 

[emdsapmgr]

Re: Need advice about possible fuel starvation problem

Would be interesting to try something. After the engine has been shut off for a while, and you are ready to start it back up. Remove a fuel bowl drain plug from the top two carbs. See if they have any fuel in them....

 

[kenmyfam]

Re: Need advice about possible fuel starvation problem

Would be interesting to try something. After the engine has been shut off for a while, and you are ready to start it back up. Remove a fuel bowl drain plug from the top two carbs. See if they have any fuel in them....

Good point.

 

[jtcarter]

Re: Need advice about possible fuel starvation problem

Alright after thinking about this problem a little more i've come to the following conclusion..... If you don't have the anti siphon valve on your motor like i, after letting the motor set for 30 minutes or so the fuel is draining back into the tank. Going to have too treat it just like when you start it first thing in the morning pump the primer bulb. Because it has enough fuel to start, but not enough to put the hammer down and take off, thats why hitting the enricher makes it get up and go. Either that or reinstall anti siphon valve. I don't like those things though.

 

[emdsapmgr]

Re: Need advice about possible fuel starvation problem

It is unusual to have the possibility of fuel siphoning back into the tank so quickly. Even without an anti-siphon valve, I have not had problems during the same day-restarting at any time.... and I don't run an anti-siphon valve on my V6. Wonder if the fact that you have an electric pump causes the fuel to drain back quicker.... I know it's not a problem with the diaphragm pump on any of mine.. I've had problems with the anti-siphon valves before and removed it for that reason. If you reinstall one on your boat, you might want to remove it and clean it annually.

 

[jtcarter]

Re: Need advice about possible fuel starvation problem

It is unusual to have the possibility of fuel siphoning back into the tank so quickly. Even without an anti-siphon valve, I have not had problems during the same day-restarting at any time.... and I don't run an anti-siphon valve on my V6. Wonder if the fact that you have an electric pump causes the fuel to drain back quicker.... I know it's not a problem with the diaphragm pump on any of mine.. I've had problems with the anti-siphon valves before and removed it for that reason. If you reinstall one on your boat, you might want to remove it and clean it annually.

Possible, i installed a electric fuel pump on mine last year trying to cure the same problem, it still did it with the fuel pump or the oms. I have about 7 or 8 foot of line between my tank and bulb. I'm going to try this theory i came up with on mine tommorrow morning. I'll post back with the results, if after pumping the bulb, i'm still having to hit the choke, well then there goes that theory, lol.

 

[Jeb1971]

Re: Need advice about possible fuel starvation problem

Thanks for the thoughts.

I will check the float bowls after a sitting spell and see if they are getting filled.. As I said, with the electric fuel pump, there is a good 3.5 pounds of fuel pressure there all day long, so there is definatly no problem of fuel "supply" to the carbs,
However, As I said, I like the idea of checking the bowls because It is possible the float needles might not be letting enough fuel in albeit I checked the float level to my manual...
But I might mention that before getting underway on the lake I do let it idle for a good long time at the dock..

I know this sounds funny, but it is almost like an old truck with a v8 motor and a manual choke.. If you dont choke that old motor a little, it will bog and stumble until the motor warms up, but it still will idle fine..

This Evinrude v6 motor is pretty cool and sure packs a wallup.. I dont want to offload it yet.

 

[bucket235]

Re: Need advice about possible fuel starvation problem

i have an identical motor with the identical problem. i have not figured it out yet either except lifting the high idle lever before every start seems to help.