At Whits End...1980 70 hp Fuel Issue?

[rustyshakelford]

Hi guys!

My name Brett and I was lucky enough to find this place today!

I have been reading thru a ton of threads thanks to the search feature but i havent found any that really nail my issues, so here goes...

I bought a pontoon boat to use for a business im doing part-time. he started the motor with the muffs on and it ran great...i shouldve lake tested it, but its to late now.

we get home and drop it in the water and as soon as i would put it into gear, it would die...

i talked to a friend of mine that is a paramedic and boat mechanic. he recommended having the carbs rebuilt. i bought everything and he cleaned them up. while he had it, he checked the cyclinder compression:

top: 120
middle:120
bottom: 110

the fuel is good and it has new fuel hoses and fittings.

I got the boat back and tried it again, same problem, but it did start quicker.

I called him and he came with me to the lake today and we worked on it! he double checked the jets and all were clear, adjusted the idle a bit and he told me we had a good spark, the plugs appear to be new.

it starts good and will idle like a champ, but as soon as you place it into gear, it dies. if you get it to idle in gear, it want to bog down and die. we were able to get it out into the lake and open it up. the boat is a 28' pontoon with about 1500 lbs of gear and people and the motor was stuggling, probably about 10-15 mph. im sure the prop had something to do with this but it was seriously underpowered. im not looking for a speed boat but dont want to constantly dog it to make headway.

i disassembled the fuel pump(diaphram)? and it appeared to work. the bowls are full of fuel so we pretty sure its getting fuel?? there are two new powerpacks and the other one is older. do youll have any ideas on what i can trouble shoot? it will run great on the muffs still but any load and it kills it. I need to get it up and running again asap for work but am also getting tired of spending countless dollars. i can also high idle it in the water and it sounds good. please throw out some suggestions if you have them!

thank

brett

 

[DJ]

Re: At Whits End...1980 70 hp Fuel Issue?

1. You're losing a cylinder. It could be spark or carbs, still dirty, float level low.

The best way to check spark is with an inductive timing light. Put the light on each plug wire. You may see one dropping out.

The best way to check for fuel issues is to choke while trying to accelerate. If it picks up, you have a fuel restriction.

Rebuild th fuel pump, you can't tell by looking.

2. Get a manual and do a "Synch. and Link".

3. Get a tachometer and prop the engine down. You will kill it fast by lugging it. It needs to be able to turn a minimum of 5500 RPM at Wide Open Throttle (WOT).

 

[tashasdaddy]

Re: At Whits End...1980 70 hp Fuel Issue?

compression check also, agree with above, did you friend do all of this?
http://forums.iboats.com/showthread.php?t=244013

 

[mthieme]

Re: At Whits End...1980 70 hp Fuel Issue?

Sounds like a fuel issue to me and you've covered the bases except for the fuel pump which will do this.
What brand motor is it? Mercury by chance?

 

[rustyshakelford]

Re: At Whits End...1980 70 hp Fuel Issue?

Sounds like a fuel issue to me and you've covered the bases except for the fuel pump which will do this.
What brand motor is it? Mercury by chance?

it is a 1980 evinrude

tashadaddy

thanks for the link. i believe he did all of the steps outlined.

thanks for all the suggestions, i will pass them on to him and maybe he can get the mess all figured out. definately strange to say the least!

brett

 

[rustyshakelford]

Re: At Whits End...1980 70 hp Fuel Issue?

update

I pulled the prop off and its a 14x19, so i was thinking about droppin down to a 15p prop. the guy doing the work is going to pull the carbs off again on thurs and clean them once again.

he did do the link and sync and said it has a good spark. hopefully its a combination of the dirty carbs and to much prop. its just wierd that it runs fine until you put any load on it...

thanks and if you can still think of anything let me know!

he will also be bringing a tach so we will be able to monitor that

brett

 

[rustyshakelford]

Re: At Whits End...1980 70 hp Fuel Issue?

Hello again!

unfortunately hurricane Ike didn't blow my boat away so im back to trying to figure whats wrong with it still!

I had the boat sold yesterday, but the darn thing wouldnt start. I took it to the mechanic on saturday and he went over it. It has good spark and is getting plenty of fuel. We had it running pretty good.

So fast foward to the next day. before i meet him at the marina, i turn it over and it fires right up. I drop it in the water and it wont start for the life of it. we pull it out, let it sit a min and try it again on the ramp. it fires right up. did the entire process twice more with it starting on land but not the water?

it would start in the lake the day prior but not now? does anyone have any ideas? i need it to be running by first thing tuesday morning for this guy

thanks

brett