Went from running good to not staying running

[wildmaninal]

I have a 1978 85hp evinrude (model number 85895c), that I just got running again the other day. I cleaned the carbs last year just after I bought the motor, I have not rebuilt them. The motor ran fine on muffs before I let it set for the rest of the year. The motor is on the back of a project boat that I just goat finished, now I'm trying to get the motor straightened out. The motor ran good a couple of days ago, when starting it for the first time this year. When I first had this motor running last year it was on an electric fuel pump, sense then I did rebuild the original manual fuel pump and this is what I am running it on now.

What I've done so far.

I've stopped all the leaks I found on the fuel pump and lines going to and from, the bulb will pump up tight.

I've checked the compression again 110, 110, 105, 105 across the board.

I've checked each coil with a spark tester, each had a decent spark. Coils are original from what I can tell.

I've redone the lines going to and from the the fuel filter to get a majority of the kinks out.

I've decarbed the engine today thinking this would make it start easier and run better, but I did it on muffs (which I probably shouldn't have done). I let the motor sit for 2 hours, then tried to run it again, which it seems like it was starting easier and without the aid of fuels mix being sprayed into the carbs, but it will not stay running.

Now what?




Modified by wildmaninal at 4:38 PM 3/14/2008

[Chunder]

The first thing I would do is run a good strong brew of fuel additive/carb cleaner through the motor...let it sit for a day then try again...if that dosen't work clean the carbs again.
I am no expert just a bush mechanic.
Chunder

[ChampioNman]

New gas? Portable tank vent open?

[wildmaninal]

Vent was open, at one point I took the gas tank lid off so I could rule out the vent being clogged up. I did have very little old gas in the tank but put a majority of new gas in, it was basically less then a 1/4 full when I added fresh gas. If I recall right I did have sea foam added to the old gas.

I was thinking that the gas tank could be the problem, it is a 6 gallon plastic gas tank and I have no idea on what the pickup tube looks like in the tank.

I had in mind to run sea foam through it again like I did last year, I put some in a spray bottle and sprayed it in the carbs while running the motor. I don't know how accurate that would be by spraying it though.

It just blows my mind on how it went from running like a champ a couple of days ago to not running worth a flip/not staying running. As of this afternoon I have the control box apart, I seem to have a ball bearing missing out that just to add to the fun, this hasn't stopped me from working on the motor.

I have also put new plugs in this motor last year, now I have't checked the plugs to see if they are all firing, that sorta slipped my mind. I just checked the coils thats all.


Modified by wildmaninal at 7:34 PM 3/14/2008


Modified by wildmaninal at 7:35 PM 3/14/2008


Modified by wildmaninal at 7:35 PM 3/14/2008


Modified by wildmaninal at 7:37 PM 3/14/2008