Need Help With Boat Problem

[flippin Dan]

I bought a 1978 boat with qa 1978 85 hp evinrude. Have taken it out probably 15 times with no problems then I take it out and it starts and immediately dies twice. My son was starting it so I got in and tried it to no avail. Has good compression (about 120 on each cylinder) and is firing good. Boat shop said clean carbs so i let them do that. First time out I can't get it to run right. Have to keep the warm up lever all the way up and it has absolutely no power, like maybe 3 mph. If you push the throttle on the engine it sounds great and very responsive, if you push the throttle from the drivers seat it dies or barely runs, it also feels stiffer from there than normal. Boat shop thinks timing is not advancing and the engine needs cleaned but I think the throttle cable is hanging and needs replaced. The .boat was used very little in the past year before I bought it. Sorry for the long post but I need some help here. Kind of feel like this shop is trying harder to seperate me from my $$ than to fix it. Thanks for any opinions.

[Way2slow]

My first suggestion would be to find another mechanic. Some of the things you are saying makes me feel he doesn't know his a** for a hole in the ground.

The advance is totally mechanical and you only have to look to see if it's advancing, plus a quick check with a timing light will tell you for sure and how much.

The early carbs are not easy to clean and a pain in the butt to get balanced and complete linc and sinc done, not sure you're guy has the know how to do them.

A motor running good when it's out of gear and being rev'd up means very little. Without a load on one, there is little or no way to tell what it's doing. You are running mainly on timing advance and very little carb.

Not sure how mechancal you are so not sure how much help I could be to you. With a manual and some basic skills I could step you through a lot of the basic stuff but be prepared also to find out you've lost a power pack. There is a lot of other stuff that needs to be done before going that route though.

[BrianinMD]

Is there a fuel filter which may be clogged, or an issue with the gas lines. Any ethanol fuel used may have gummed things up.

[flippin Dan]

We were at the lake trying to look at it last night. I am going to his shop this morning to see what is going on. I think also he don't know a lot about what he is doing so if I can get help here I may go that route or take it to a better shop. It has an electric fuel pump and I chased it from the tank to the carbs one piece at a time to make sure I had a good fuel flow. The pump just replaces the bulb for priming the lines. My dad was a darn good mechanic and at times like this I really miss him. Will keep you updated and probably have more questions.

[Way2slow]

There is no way you should run an electric pump just to keep from pumping the bulb. You either have to run one, or not run one. If the pump is in line, it has to be running or there is a good chance not enough fuel is gonna go through it to run the motor at full throttle. The next problem I suspect is you're talking about one of those cheap pulsing pumps. Many of those are not rated anywhere near enough flow rate or pressure to properly run the motor. Even on that 85, I would run a pump rated for at least 30 gph @ 6 psi. On my V6's I run Carter pumps rated at 74 gph @ 7.5 psi

Even with your setup though, I doubt that's your problem, if it's delivering any fuel, it's not go affect the motors running at idle and low rpm. Now if it idles fine and runs good if you slowly give it a little throttle and then just starts bogging down as you give it more, then you can suspect fuel delivery problems. That's easy enough to check with a cheap 15 psi pressure guage. You should have a minimum 5 - 5.5 psi at the carburators. Remember, any cheap guage will work, pressure is pressure, doesn't matter if it's water, air, gas, etc.

[quanjig]

Sounds like the problem I recently had. A carb jet had some debris deminishing fuel flow. External or internal fuel tank?? Check fuel filter or pick-up?

[flippin Dan]

Went by his shop and showed him that thrpttle was not working right because of cables so we replaced them. He worked it most of the day and sounded good with water hooked up. I met him at the boat ramp after work. Still ran like crap so I made him take it back to his shop. The floats were stuck in one carb so I was running off of one carb. It was pressurised somehow cause we could hear air escaping when we pulled the carb. Possible it was vapor locked?? The carbs were just cleaned so I don't know. Anyway took it back to the lake and now I am ready to go.

[CFFF 1.5]

Sounds like you need to find a better mechanic. He should have cleaned the carbs floats the first time he did the carb cleaning.

[flippin Dan]

Sounds like you need to find a better mechanic. He should have cleaned the carbs floats the first time he did the carb cleaning.

I agree 100%!!

[Way2slow]

I thought you said one of the first thing he did the first time was clean the carbs??

If that was the case, I hope you're not paying this guy much. No way the carbs could have had that crap in them, that quick if they had been previously cleaned. The carbs should have been the very first thing done, and then a good, proper, linc and sync done when putting them back on. I will bet a dollor to a doughnut it's not setup properly.

[flippin Dan]

What about vapor lock?? Is it possible that was the problem, especially hearing air leak out when we broke into the carb?? Was out all day today with no trouble so I am back in the saddle for now. No fish caught though cause I took the wife, kids and a tube instead of fishing poles.

[Way2slow]

Vapoer lock is not a problem with cold motors. This is caused when the fuel in the fuel lines gets so hot it evaporates, causing air pockets in the fuel line. There is another problem caused heat soak, but this was not yours either. Heat soak usually occurs when making a long WOT run and cutting the engine off all most as soon as you get to your spot. The heat of the engine evaporates the fuel out of the crank case. When you get ready to go again, it can cause the engine to be hard to start or bog when you first put the power to it. As I said though, neither of these problems occur on cold or just warmed engines.

As for the air leak you heard, not sure but there should be nothing about the carb that could be holding pressure. The vent hole would have to be plugged and all the jets would have to be plugged and the needle holding full pump pressure in the carb, very, very unlikely for all these things to happen at once.