Evinrude 115 Won't Idle?

[CLi87]

Hey all, I'm working on a 98 Evinrude 115 60 degree V4 with VRO. My issue is the boat won't seem to stay running at an idle, once it gets some gas going it runs fine. When I first got the boat I rebuilt the carbs and after that it ran fine for quite some time but slowly over time it seemed to have trouble idling or accelerating quickly from a stop and now it's gotten to the point it may idle for a few seconds before dying. I did notice the fuel pump primer bulb seems to lose pressure quickly once the engine is running. Thinking it was the fuel pump diaphragm gone bad I got a rebuild kit and rebuilt the fuel pump, although when I took it apart all the diaphragms and gaskets looked fine, put it all back together and still the same issue. Now I'm thinking I have an air leak in the system somewhere but I checked all the fuel connections to make sure they are tight and didn't notice anything loose or any hoses cracked. Any ideas what else to look at?

 

[racerone]

Trouble shooting starts with a compression test.----Post your numbers here.----You did install a new impeller ?----You have verified that oil injection is working properly?

 

[CLi87]

Trouble shooting starts with a compression test.----Post your numbers here.----You did install a new impeller ?----You have verified that oil injection is working properly?

Compression tested good, all 4 cylinders are right at about 115 psi, spark plugs all looked even and not wet. I did not install a new impeller, I'm not sure why that would matter? And yes oil injection is working properly, i'm getting bluish fuel coming out the carb and my boat has the newer warning system on the dash to let you know if there is no oil in the VRO or if the tank is low. I also checked the timing with the analyzer and it's good. I also noticed it seems to start and idle fine when cold but once it warms up it'll start "coughing" then eventually die.

 

[racerone]

A golden rule for a ----" new to you boat motor " ----Is to install a new impeller.---But sometimes folks will argue that.-----I can not offer any further advice.---Sorry.

 

[CLi87]

A golden rule for a ----" new to you boat motor " ----Is to install a new impeller.---But sometimes folks will argue that.-----I can not offer any further advice.---Sorry.

O I actually do have a new impeller, I just didn't install it because the current one seems to run great, **** stream is very strong and it runs nice and cool even on the hose, I checked with an IR temp reader, I just wasn't sure how that would affect the idling issue.

 

[CLi87]

I did some more diagnostics today, firstly it seems my engine may be "over oiing"? From right to left, first cup is gas that came out the carb, 2nd cup is what came out when I pumped the primer bulb, last is what came out after running the engine for a bit. I also took the main jets out and cleaned them although they already looked clean, no blockage.

I also noticed the engine will stay running if I either keep pumping the primer bulb or if I leave the choke on, which points me toward a fuel problem I would think, but I can't figure out why, fuel pump has fresh rebuild even though the old diaphragm was perfectly fine.

 

[racerone]

The electric primer valve ( what you call the choke ) puts fuel directly into the engine.----This fuel bypasses the metering circuits in the carburetors.----This would make the carburetors suspect.

 

[CLi87]

The electric primer valve ( what you call the choke ) puts fuel directly into the engine.----This fuel bypasses the metering circuits in the carburetors.----This would make the carburetors suspect.

Ok, I'm gonna completely take the carbs apart tomorrow and throw them in the ultrasonic cleaner, hopefully that'll solve the issue, even though it's odd because I just rebuilt the carbs maybe 3 months ago, I didn't put them in the ultrasonic cleaner though, I just used carb cleaner and compressed air to blow the passages out. Would that also account for the engine being able to stay running while I'm pumping the primer bulb? Does that force fuel through the metering circuits?

 

[tphoyt]

If pumping the ball helps it might be worth taking a look at your fuel line for internal deterioration causing an obstruction and checking the tank vent.

 

[racerone]

Operating the priming bulb ( manual pump ) fills the carburetor bowls.-----And it does not put fuel through the metering circuits.

 

[tphoyt]

This is true. For some reason I thought he said it helped to pump the ball but after reading again I was mistaken.

 

[CLi87]

Operating the priming bulb ( manual pump ) fills the carburetor bowls.-----And it does not put fuel through the metering circuits.

Gotcha, thanks for all the info

Operating the priming bulb ( manual pump ) fills the carburetor bowls.-----And it does not put fuel through the metering circuits.

Is the metering circuit part of the plastic carb part or the metal throttle body part? When I rebuilt the carbs I only cleaned the plastic part out.

 

[racerone]

Two steps to take.-----Look the throttle bodies over very carefully.----Check carburetor bowls for warpage.

 

[CLi87]

Two steps to take.-----Look the throttle bodies over very carefully.----Check carburetor bowls for warpage.

I visually looked over everything and it all seems very clean to me, no corrosion or dirt at all, are those little circles with 2 holes the metering circuit?

 

[Crosbyman]

holes... are for venting out or breathing in... otherwise they are plugged !

just make certain they are clean and open ( no crud or varnish etc...)

 

[CLi87]

I got my gaskets and currently cleaning the carbs and had a couple of questions if anyone's able to help.

In the first pic, what is that jet for? Because it sits on the outside of the carb body, is it to let air pressure out or something?

In the 2nd pic, is that the metering system you were talking about? I'm running all the carb bodies through the ultrasonic cleaner but on initial glance they were all clean and I didn't see any debri or clogs

Last two pics, that's the carb bowl, I was wondering what the ball on the outside is for and the silver pin I see sticking through the slot. It leads to a jet at the bottom of the carb bowl, which to me seems an odd place to put a jet because that's where crud will pile up in the carb bowl?

 

[Crosbyman]

holes... are for venting out or breathing in... otherwise they are plugged !
just make certain they are clean and open ( no crud or varnish etc...)...


if that jet does not meter fuel it meters air ....same procedure clean it blow it...
don't worry about the design itself somebody did years ago for you

 

[racerone]

They have had the jet in the bottom of the bowl since about 1950.-----Only time there would be an issue if folks leave fuel in the carburetors.-----Empty carburetors stay clean.

 

[CLi87]

Just put everything back together and I'm positive the carbs are squeaky clean, ran every part in a heated ultrasonic cleaner for 2 cycles of 8 min then blew out everything with air. Unfortunately the same issue is still there, it'll stay running as long as I'm manually pumping the primer bulb but if I stop it'll die within a minute. I also noticed it seems to be misfiring a bit, attached a video to see if it'll help.

 

[racerone]

Sounds like a lean sneeze to me.------Your fuel pump is not working.----Possibly due to tank , hose anti syphon issue.-----Test run with another tank.----Crankcase compression PRESSURE drives the fuel pump.------Cleaned out the vapor separation tank ?----Any other trouble shooting done ?