Falls on face for hole shot?

[Evinrude Trouble]

I have a 70HP johnson J70ELCNB. I took it out yesterday and she was a hard start but i did get it started and it idled fine, shifted in forward and reverse fine. I motoered out of the no wake sone at the marina and hit the gas and it started to take off and then fell flat on its face and died. Put it in neutral and it started right back up. Tired to see if i could duplicate this problem and it did it again. I figured i may be hitting the throttle too fast so i eased it forward and once i hit a certain point on the throttle it died and i never could get the boat to plane out. I tried when it started dying to pump the primer bulb but there was no difference. I went home and checked the plugs, they look normal. The fuel pump looks fairily new, the throttle cam lines up with the second mark which is where its supposed to be according to the manual. I checked to make sure everything was moving freely like the spark advance and when the throttle is moved forward it moves forward smoothly. I cant figure out whats wrong with it. I dont hhave a timing light or i woul do link and sync. Is this a fuel, air, or electrical problem? Do these symptoms sound familiar to any particular problem? The only thing i have done is replace the fuel hose/primer bulb, and i used a small gas can. Will fuel hose diameter have anything to do with it? I have a built in tank but i dont want to fill it up until i get this thing runnin tip top

 

[R.Johnson]

Re: Falls on face for hole shot?

As a guess, it sound's like a fuel problem, such as dirty carb's. They could be dirty to the point they don't supply fuel much above the idle circuit.

 

[rndn]

Re: Falls on face for hole shot?

Hose should be 3/8 ID. Did you install the fuel bulb with the arrow facing the proper direction?

 

[ezeke]

Re: Falls on face for hole shot?

5/16 is plenty large unless you have a very long run of hose, but make sure the connectors match the hose.

Your motor started life with 5/16 hose, part #0320417 which has superseded to 0772564. The connector was 5/16 - part # 123247 which has superseded to # 775640. They used the same hose through the V4 in 1982.


Before anything else, do a compression test - all plugs out, screw in tester. While you have all of the plugs out you might want to test the spark as well.

 

[JB]

Re: Falls on face for hole shot?

Check your fuel tank vent, pickup and lines for restrictions or air leakage.

Sounds exactly like my sons merc when he had a fuel line pinched.

 

[Evinrude Trouble]

Re: Falls on face for hole shot?

I will try to install the 5/16 hose this weekend, as for the tank vent i did not want to leave anything to chance so i removed the lid, the arrows on the bulb are pointing in the right direction. I'll look for a pinched fuel line. As for the carbs, exactly how easy is it to rebuild one of these things? I dont want to get it apart, put it back together and the problem is worse than when i started. Is there anything i can mix with the fuel, or spray down the throat of the carb to clean it? I have heard of sea foam, will that clean my carbs? Could it be a bad fuel pump diaphram or would it not run at all if that had a hole in it?

 

[iwombat]

Re: Falls on face for hole shot?

This could also be a float adjustment, but you're on the right track with fuel I think.

As for rebuilding the carbs - it's a fairly simple procedure. There's not a whole lot of parts to an outboard carb. Hardest part is making the tool to remove the high-speed jets. You'll find posts aplenty on how to make the tool.

 

[Evinrude Trouble]

Re: Falls on face for hole shot?

I really do hope this is a fuel problem because i suck a troubleshooting electrical systems. Do all of these orifices need to be adjusted indivually or do they just seat and thats the end of it? If the engine is starved for fuel and i pump the primer bulb, the RPM's shoul go back up right?

 

[iwombat]

Re: Falls on face for hole shot?

Sort of.

If your fuel pump is faulty and you pump the bulb it will pick up. If the problem is elsewhere in the fuel system pumping the bulb won't help.

 

[HighTrim]

Re: Falls on face for hole shot?

When were the carbs last rebuilt? May be time for a bath and rebuild as stated. Check to see if the timer base (starboard side, under the edge of the flywheel, linked to the throttle lever) moves smoothly without sticking when you advance the throttle.

Take the airbox cover off & observe whether the throttle plates are parallel.

Also, the timer base should start it's travel *before* the throttle plates start to open, else she'll fall flat when you try to accelerate.

 

[HighTrim]

Re: Falls on face for hole shot?

Get a vacuum gauge and hook it inline on the fuel hose before the engine, along with a clear section of hose. Take it for a spin, noting the readings and monitor the fuel flow through the clear hose.

Findings:

-Vacuum of less than 2 inches and air bubbles in the clear hose indicates an air leak into the fuel system
-No air bubbles and less than 2 inches indicates a bad fuel pump
-Vacuum over 4 inches indicates a restriction.

Sample gauge

"http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&sspagename=STRK%3AMEBTOX%3AIT&viewitem=&item=4610113711&_trksid=p3984.cTODAY.m238.lVI"

 

[Evinrude Trouble]

Re: Falls on face for hole shot?

DO i hook this guage up before the fuel line from the tank hooks to the quick connect fuel fitting or after the fitting? Do tanks for small outboards have a flow limiter? I would assume that the 2 gallon tank that i hooked up to the 70hp that i use for my 5 hp evinrude is not used to having that high a flow rate. The quick connect that came witht the boat looks a little bigger than the one on my 2 gallon tank but still fits onto the fuel line connector on the motor could this be my problem? Like i said earlier she will jump out of the hole and then die but if i pull the throttle back she wont die but shell idle. The spark advance moves freely and smoothly when i advance the throttle, the throttle cam appears to be where it should be according to the marks on it.

 

[Yamajoe]

Re: Falls on face for hole shot?

I agree with all posters as well. tear down your carb give it good soak and blow out all orifices and jets, check that the float needle is not sticking, adjustments are your float hieght and idle mixture and idle screws. Take your time and give the carbs a go yourself, it will be worth it and boost to your confidence, let alone the savings.

 

[envader]

Re: Falls on face for hole shot?

Mine does the same thing some times. Just as you go to get on it she dies well i found the problem to be the choke was sticky and causing it to immediatly die but once i wiggle it alittle she planes out just fine. Hope this helps.

 

[Evinrude Trouble]

Re: Falls on face for hole shot?

I took it out today and sea foamed everything and i made an observation. When i throttle up everything moves smoothly but i noticed that the engine starts to bog down after the spark advance hit the stop and the throttle keeps going. I vacuume tested the fuel system before and after fuel pump, no bubble vacuume is normal, replaced quick disconnect fitting, installed correct size fuel line. I pulled the air box coverand watched the butter flys for the choke and throttle during operation. The choke does not stick at all, all butterflys ar parrallel to each other and once the butterflys start opening up for high speed it starts to bog down and die. I adjusted the idle a little to be at what the manual says is the correct RPM's for idle. I had someone else operate the boat while i watched all of the linkage and one time and only one time the trottle was fully advanced and we were nowhere near top speed this happend when i pushed the spark advance tight up against the spark advance stop. Mind you this was not a repeatable phenomenon. As for soaking the carbs do they have any fiber washer packings that i have to worry about or do i just disconnect the linkage, pop off the carbs and soake them. If this is really that easy how long do you soak them for?

 

[ezeke]

Re: Falls on face for hole shot?

ttt

 

[Evinrude Trouble]

Re: Falls on face for hole shot?

ttt? whats that mean?

 

[ezeke]

Re: Falls on face for hole shot?

To the top. Just keeping your thread up there for someone to answer. I'm tired and have company.

 

[Cthom5436]

Re: Falls on face for hole shot?

Have 1977 70hp Johnson. Having similar problem. Runs great, but 2/3rds of the power. We changed the plugs. The middle plug was clean after a drive test. We are getting plenty of spark.

We removed the middle carb. Looks clean. Blew air through it.

Rebuilt the fuel pump.

Any thoughts?

 

[ezeke]

Re: Falls on face for hole shot?

Start a new thread and you will get a lot more help.