75 hp runs good for 45 sec, then starts surging.

[jgriner]

75elr79r johnson 75hp 1979 stinger

during a carb clean we knoticed that the needle was sticking on top carb. We cleaned the needle and was able to keep it from sticking. all other carbs were fine.

after the carb clean, we dropped it in the river while trailer-ed she ran full speed for about 1min then it started surging. I brought it back to neutral and went back to wot, she never reached full speed again.

My engine guy thinks that when we backed off of WOT to neutral that maybe we re-jammed the needle and that's why it never reached full speed again.

Would a needle sticking cause this?

also on a carb rebuild kit, do i need to order 3 or does one kit come with enought stuff for 3 carbs?

Also what color is the needle rubber, mine is red/orange, he says he has never seen any color but black, he is convinced that maybe some one ran gummout or something else through engine cause the black to eat off, causing them to stick?

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

bump

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

bump bump

 

[Desertboater]

Re: 75 hp runs good for 45 sec, then starts surging.

jgriner,

I have a 75ELR77S Johnson Stinger motor similar to yours and man I've had my share headaches with it and I'm still trying to get it going to where it's consistant on the water..

I've done the carb kit on it and yes you'll need three seperate kits for each carb. I don't remember the color of the needle rubber the new kits came with but I think my old ones were black and but if I want to guess the new ones were all metal.

My motor like yours starts off good and planes but once I back off it and sit there with the engine running for a few minutes and try to throttle up again it boggs down really bad and it basically crawls for the rest of the day. I don't know if by you discribing the motor to "surge" that your RPM's go up and down. It does sound like your carbs are dirty, might want to check all three.

I'm no expert like alot of these good people on this forum are but I think most of the experts are going to tell you to buy the carb kits to all three carbs and rebuilt them. Soak carbs over night..

Like I said I'm no expert but I thought I would chime in since you hadn't gotten a hit yet. Be patient, the experts will chime in on your question .

Good luck man...

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

The carbs are absolutly clean ive had them off about 6 times now, last time I had them off we noticed the needle on top carb sticking, I would hate to replace them as they look brand new.

I belive that the engine and carbs have been rebuilt a little while before i bought the boat.

how about the fuel pump? it barely pushes gas out, it pumps, pauses then pumps again, small stream, it just flows out (not a squart) Ill take a video of it soon, and post it.

 

[Daviet]

Re: 75 hp runs good for 45 sec, then starts surging.

When you rebuilt your carbs did you remove the high speed jets and clean them out?
If you think your fuel pump is defective, have some one squeeze the primer bulb and see if the starts to run properly, if so you need to replace or rebuild your fuel pump.

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

When you rebuilt your carbs did you remove the high speed jets and clean them out?
If you think your fuel pump is defective, have some one squeeze the primer bulb and see if the starts to run properly, if so you need to replace or rebuild your fuel pump.

nope they are pretty much locked in. tried to remove them several times but afraid i will break them. If i rebuild the carbs they will get replaced if i have to get new bowls, but i can shine light through them and they are completely open. the hole is about as big as the ink tube from an ink pin

ive tried the squeeze test and it does not change anything, i guess im back to needle and seat sticking?

 

[Daviet]

Re: 75 hp runs good for 45 sec, then starts surging.

Are you sure it is a fuel problem? Any chance you are dropping a cylinder, those engines will idle pretty good on two cylinders.
Try squirting some fuel mixture into each carb and see if it picks up, if it floods each cylinder you have eliminated a fuel problem.

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

ive ran that test with only one excption (used starter fueld)
frist time 1carb no effect, 2 would kill engine, 3 slight bog down
2nd time 1 slight bog, 2nd carb kill engine, 3 moderiate bog down
3rd time 1 killed engine 2nd carb killed engine 3rd carb bogged way down

after that we ran it wot to clean out engine it started to surge way up and go full rpm a few times but after backing down on throttle, it stoped surgging up and would onlly run about 3/4 throttle

ps yes i later found out that starter fluid is a no no

 

[Daviet]

Re: 75 hp runs good for 45 sec, then starts surging.

With those reactions it sounds like you have a fuel delivery problem. I would try it again and use fuel mixture, not as volatable, might have different results.
Sounds like the carbs are not preforming properly.

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

With those reactions it sounds like you have a fuel delivery problem. I would try it again and use fuel mixture, not as volatable, might have different results.
Sounds like the carbs are not preforming properly.

thanks will keep playing with needles untill i get paid, then buy a rebuild kit

 

[kenmyfam]

Re: 75 hp runs good for 45 sec, then starts surging.

how about the fuel pump? it barely pushes gas out, it pumps, pauses then pumps again, small stream, it just flows out (not a squart) Ill take a video of it soon, and post it.

Pump should push out strong spurts of fuel. If not something is wrong.

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

Pump should push out strong spurts of fuel. If not something is wrong.

i will video it tommarow and upload it
also noticed that their 2 screen filters in pump, they screens are so fine would not see what would be the point of 2 filters, is it normal to have 2 filters, i have limited info on the history of the motor

 

[Chinewalker]

Re: 75 hp runs good for 45 sec, then starts surging.

The fuel pump should have 1 screen filter under the cap. Two may be causing a restriction...

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

The fuel pump should have 1 screen filter under the cap. Two may be causing a restriction...

thanks

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

http://www.youtube.com/watch?v=AoXYx-Ud9OQ

is the fuel pump strong enough?????

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

last time i tried it, it would only bubble out, i wonder if it was that weaker battery i had

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

bump

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

what do u all think is this pump a strong pump
http://www.youtube.com/watch?v=AoXYx-Ud9OQ

 

[jgriner]

Re: 75 hp runs good for 45 sec, then starts surging.

I found my problem crank case is cracked where it attachs to the intake manafold