stumbling like it has a miss

on-going problem still...
1991, omc, 5.8l, 351 ford, cobra

so when i put the boat into the water can stat it up and start putting towards the no wake bouy once i get past the bouy and try to accerate the engine will stumble like its got a miss or something. wait 5-10 seconds and it speeds up to where thottle is set and i can then cruise around just fine untill i fall below 1k rpm again.

things i've done so far;
replaced fuel filter/water seperater
replaced wires and plugs
replaced dist cap and roter
took boat in shop they checked carb and accerater pump [said it was good]
they checked timing said it was off and set it handed me a $90. bill

now what i did forget up untill last nite, was last year i hit ground and it stalled the engine. on that day i was heading in at that point so i didnt notice anything differnt but i've had this problem since then. the prop isnt damaged persay the fins all look decent for an aluminum prop. i took prop off a week ago looking for fishing line or other things and there was nothing around the shaft.

so just looking for ideas, if you say check gas tank vent it shoots gas out at me when i top the tank off so its not pluged. also noticed last night my oil presure was running at 40 idling and about 60 maybe a little higher, at 2k rpm-wot is that normal i was thinking it should be around like 40 at wot.

the engine only studders/stumbles under load if i put muffs on it and lower the outdrive i can put it into gear and thottle up for a few seconds with out a problem[i know thats not good for the engine only did it once for a short time].

Re: stumbling like it has a miss

no advice from any one? i dont have the money to bring it to a shop and say have fun at the prices there talking. although if i can find out what is wrong i may be able to do it myself. a shop near my house has a mechanic that knows omc stuff but again at $75-$100 an hour or what ever doesnt take long to get a $500 bill

Re: stumbling like it has a miss

1 more thing to add to the replaced

accerarator pump[spell check] didnt look that bad the metel was rusty but the rubber was intact still $4.20 and 20 minuites of repair time, and leaning expierence since i've never delt with pulling a 4 barrle carb off an engine.

Re: stumbling like it has a miss

make sure your shift interuptor switch fall into the center detent. if it does'nt it will knock out a couple cylinders thinking your trying to shift into gear.

Re: stumbling like it has a miss

X 2 the interuptor switch. Sounds like it also could be overly rich idle circuit as it loads up and fouls a plug while idleing out, then when throttle is applied it spits and sputters till it begins to fire again, maybe it's time to change the plugs?

Re: stumbling like it has a miss

changed the plugs

replaced fuel filter/water seperater
replaced wires and plugs
replaced dist cap and roter

Click to expand...

whats the best way to check interuptor switch? can i just unplug it or?? if it is bad who sells it?. its that little thing that has a thin piece of metel that makes a clicking noise if i hit it right? about 6 inches from the carb and to the left?

Re: stumbling like it has a miss

Yes that's it, it stumbles the motor (via ignition) when shifting in or out of gear, it takes the pressure off the clutch dogs to facilitate a smooth shift.
Now, if you look at the little roller on the spring arm, it should be riding right between the two humps in the actuator lever, if it's not falling completely down off the bumps you have issues with cable adjustment and a stumbling poor running engine.

Re: stumbling like it has a miss

with the engine running and the engine cover off put the boat in fwd gear. (take all and any safety precautions) When the drive goes "klunk" The shifter handle should be in the handle fwd detent. AND the Shift follow up cam should be centered withe the micro switch actuator in the center. If it is'nt (which I'm betting on) you need to make cable adjustments so it is.
Shut the engine down with it still in gear. DON'T MOVE THE THROTTLE HANDLE BACK TO NEUTRAL!
1. If the handle fell into the detent go to step 2. If not , adjust the top shift cable until it does.
2. Then adjust the barrel nut on the bottom shifter cable until the microswitch falls into the center cam detent.
Then give it a try.
Good Luck
Joe

Re: stumbling like it has a miss

Have you done a compression test on the engine?

if it is bad who sells it?

Click to expand...

I think CDI makes a good replacement.123-7571 ... Like 100 bucks or so.. I used one of their switch boxs on a ol Johnson one time.. Pretty good products...

Unplug the ESA if you think it is suspect...

Check all the wires for it..

Check it out... Iboats sells the sucka... Support the boat forum

http://www.iboats.com/OMC-Shift-Ass...6013728--**********.748249658--view_id.711449

iboats has awesome shipping

Re: stumbling like it has a miss

yah, if i needed sometihng like that unit i would probably support iboats unless i could get the same thing $50. cheaper elsewhere but most prices are stadard give or take a few dollars and shipping.

just went outside the "ESA unit" has 4 little fingers yes? i put muffs on droped outdrive and put it into gear then shut it off. adjusted so it sits in the middle. took 2 or 3 times to adjust foward then reverse but i got it.

by the way there are 2 cables going into the ESA a lower orange colord i didnt touch and the top black one that is the one i messed with as it looked easyer to adjust.

also there is one other black plasic square below the one that i ajusted for do i need to make sure that is lined up to anything?

2. Then adjust the barrel nut on the bottom shifter cable until the microswitch falls into the center cam detent.

Click to expand...

the top mirco switch was kind of self explainitory loosen bolt turn the black nut untill its in desired spot then tighten bolt, but the bottom requires messing with the accual cable and it seems to run fine on muffs, and come out of gear a little easier since i did have a problem sunday it didnt want to come out of gear even when i put it in nuetral i had to wack the shifter towards rev. to come out.

also i noticed i think my automatic choke thing on the side of the carb has gone bad? it seemd to get hot and nothing else was hot. when i shut engine off it makes some noise for 2-3 seconds and then when i restart, the engine wont start unless i pump it 2-3 times. hate when mutiple things go wrong and your trying to diagnois.

gota thank all of you i've been a member on the forums since mid april and i might have just fixed my problem with out buying a brand new merc and alpha. helped a few people with there problems and now a few people have helped me

Re: stumbling like it has a miss

WINNER WINNER CHICKEN DINNER!!! took her out today water was like glass it fired right up and never stalld or stumbled once with in 2 hours of fooling around.
my thank yous go to, a70eliminator and joemomma, for 1 finding my problem and 2 explaining how to fix it. it ran beautifully then i went to the gas station and they kicked me in the balls with $150.02 and the vent didn't spit gas so its not compleatly full. only a few little things to finnish up before shes compleatly ready needs oil changed started to go dark and impellor. running at 3k+ rpm for over 10 minuites she started heading towards that 175 mark, which one point went a little over that so i idled till it went down. but all easy stuff that i know how to do.

Re: stumbling like it has a miss

I love a cheap fix.
The bottom cable goes down to the shift lever in the drive and when its in gear and the tension is off the cable it allows the cable sleeve to put the cam in the center detent.
You may not have been fully in gear. Some times when i tilt my drive fully up it changes the adjustment enough that when I shift to reverse it will stumble. It's the stupidest system I've ever seen. Merc is so much easier .