3.0L mercruiser bogging down at speed

[craigboy]

Hello all, new to the forum. I have a 1990 3.0l Bayliner capri with a Alpha 1. In 2010 I had the carb rebuilt and the seals, water pump, and various other things replaced and then got deployed. The boat stayed in the garage and when i got back, i drained all the fuel from the tank and put fresh in. It started right up and then took it out to the lake. for about an hour, It ran fantastic, better then ever....

This is where the fairytale ended, because all the sudden it bogged down at full throttle, and would not go above idle. We had to troll slowly from the middle of the lake (45 min) and it ran (at very slow speed) all the way back.

so i have taken out the fuel filter and it was the original stone kind from 1990! cleaned that out and put a new felt/AL one in the carter style mech.pump.

My question is, does this sound like a fuel pump issue? should i just replace the pump? (got a new Mallory pump) or do you think it has a less prosaic problem like a clogged carb? Hate to rebuild a carb that has only an hour of runtime from the last.

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

Hello all, new to the forum. I have a 1990 3.0l Bayliner capri with a Alpha 1. In 2010 I had the carb rebuilt and the seals, water pump, and various other things replaced and then got deployed. The boat stayed in the garage and when i got back, i drained all the fuel from the tank and put fresh in. It started right up and then took it out to the lake. for about an hour, It ran fantastic, better then ever....

This is where the fairytale ended, because all the sudden it bogged down at full throttle, and would not go above idle. We had to troll slowly from the middle of the lake (45 min) and it ran (at very slow speed) all the way back.

so i have taken out the fuel filter and it was the original stone kind from 1990! cleaned that out and put a new felt/AL one in the carter style mech.pump.

My question is, does this sound like a fuel pump issue? should i just replace the pump? (got a new Mallory pump) or do you think it has a less prosaic problem like a clogged carb? Hate to rebuild a carb that has only an hour of runtime from the last.

:welcome: to iboats

At first glance it does appear to be a fuel problem. Have a look at the top of this section for Dons adult only section. This area has all kinds of info which should be looked through.

Here is troubleshooting the fuel system
http://forums.iboats.com/mercruiser...ow-testing-your-boats-fuel-system-283269.html

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

I have read the stickeys, I was hoping that someone has had an issue like this and could give me a nudge in the right direction.

I should have asked In the original post, but how prone are the carter style pumps to failing? It seems that the original filter is regarded as a good one( it lasted over 20 years) and I want to get this boat up and running before my 5 hour trip out of town.

I live in Kansas City and have a lake close but they charge 15$ every time I put in.

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

BTW thank you for your service

Carter pumps are good but everything can fail. Have you removed the fuel filter and if so how does it look inside?
Is the fuel filter fuel of fuel?
When you push the throttle forward, can you see fuel being squirted in the carb throat?

Your not getting enough fuel so this is either a restriction, bad pump or clogged carb
Pull the fuel line off the carb and crank the motor over to see if fuel flows freely into a container. If you have a gauge you could run it inline

Edit just noticed you have the filter built into the pump, so disregard the filter question. Still need to remove the fuel line and check flow.

 

[Maclin]

Re: 3.0L mercruiser bogging down at speed

Did you run it again after this... "so i have taken out the fuel filter and it was the original stone kind from 1990! cleaned that out and put a new felt/AL one in the carter style mech.pump."

?

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

No i haven't, but plan to today. Its cold out today though. When i took the filter out there was some gas in it but to my surprise nothing ran out. I did not clamp any of the lines either. I have to say my first impression was that the boat had a "heart attack" like a "clot" hit the system and stopped the flow.

So my best bet at this point is to pull it out and give it a crank. I will report what happens. That way any other guy in the future that has this problem can see the answer.

When i had the carb rebuilt, brand new fuel lines were installed. when the boat was sitting, the remaining gas in the tank was mixed with stay-bil but i used the red, not blue. (did not realize there was a marine version of that)

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

Look forward to hearing what you find. Will mention, if you don't get good flow go back to the tank and check the antisiphon valve, they can get stuck

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

Is the anti siphon valve in tank? Anyone have a part or pic of it?

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

Is the anti siphon valve in tank? Anyone have a part # or pic of it?

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

Is the anti siphon valve in tank? Anyone have a part or pic of it?

It screws into the top of the tank and just looks like a barbed fitting your fuel line is connected to. It has a spring loaded ball inside.

Moeller Aluminum Anti-Siphon Valve

 

[bonzoscott]

Re: 3.0L mercruiser bogging down at speed

Not sure if you found any dirt in the filter : "When i took the filter out there was some gas in it but to my surprise nothing ran out."
Get a clean 5 gallon gas can and a piece fuel line - run from the can to the pump and try her out. That may rule out the pump. Put only about 2.5 gallon in the can and duct tape the hose into the lid.

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

So i pulled the anti siphon valve out and its hollow. I think its a non issue with this boat because all of the fuel lines are above the tank. I think someone down the road got rid of that because if there was a leak, a sipon situation would not occur in this boat. In any case, this was not the problem as described earlier. going to pump out the "old" fuel and use a see-snake to inspect the tank to see how bad the deposits look. May need to retrofit a water filter inline (of course that means that I will need a anti-siphon valve,plus i think it is a good safety idea )

Anyone have any ideas of a good kit for that? Would I/ should I need to go with an electric pump in place of the Carter mechanical?

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

So i pulled the anti siphon valve out and its hollow. I think its a non issue with this boat because all of the fuel lines are above the tank. I think someone down the road got rid of that because if there was a leak, a sipon situation would not occur in this boat. In any case, this was not the problem as described earlier. going to pump out the "old" fuel and use a see-snake to inspect the tank to see how bad the deposits look. May need to retrofit a water filter inline (of course that means that I will need a anti-siphon valve,plus i think it is a good safety idea )

Anyone have any ideas of a good kit for that? Would I/ should I need to go with an electric pump in place of the Carter mechanical?

Get a gas can as Bonzoscott mentioned and try it first.

If the fuel line came off the fuel pump a siphon could start, but not to dive into this issue I'll just say the anti-siphon valve is a requirement for all boats (had one on my 1966 Signa).

A kit like this will work Mallory Filter, Fuel Water Seperator Kit 9-37850

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

Thanks ALLDodge, I will put one on. I was thinking it a good idea to have one. I will pick one up in the next few days. I pulled the fuel out of the tank and just went ahead and replaced the 24YO pump with a new one. The place where the gasket makes contact was corroded anyway and i could not get it off upside down. plus i got this wonderful looking Mallory pump just sitting in the box so what the heck. This way After i am done the only thing left would be the carb as an issue. (still need to check the vent hose that attaches to the back) I wonder if that can let water in the tank?

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

Ok, so i replaced the fuel pump, carb screen, Anti siphon valve, sucked out all old fuel and put ten fresh GAL. in. After some time of priming, it started up and ran smooth for 15 min. in my driveway with the ears on. No leaks, temp normal. Replaced the gas cap, and started it again. Ran fine for 10 min like before. shut it off and cleaned out the boat. worked on the radio. and it started to get cold so i decided to park it back in the garage but before i do, I started it up again.

Then its like its getting no gas. If i spray carb gumout i can get it to start but then it just dies again! Can anyone help because i am about at my wits end!!!

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

First, did you pull the fuel line off the carb and see if you were getting a good flow of fuel?

If your not getting fuel

Second, pull the gas cap off and see if you can get it to run, if it does your tank is drawing a vacuum due to the gas cap.

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

First, did you pull the fuel line off the carb and see if you were getting a good flow of fuel?

If your not getting fuel

Second, pull the gas cap off and see if you can get it to run, if it does your tank is drawing a vacuum due to the gas cap.

I will get in it and let you know. Thanks for the trouble shooting. I will say that the line dedicated for that (runs out the back of the transom) Is patient. I check it. So there should not be a vacuum problem. Can air in the line before the pump cause this? Air bubble that is. still fuel in the tank.

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

I will get in it and let you know. Thanks for the trouble shooting. I will say that the line dedicated for that (runs out the back of the transom) Is patient. I check it. So there should not be a vacuum problem. Can air in the line before the pump cause this? Air bubble that is. still fuel in the tank.

I'm not understanding what you mean by runs out the back of the transom. Your fuel line should run from the tank to the fuel pump, then run to the carb. We need to know are you getting fuel out the end of the line which connects to the carb?

Air air bubble in the line before the pump is not necessarily an issue

 

[craigboy]

Re: 3.0L mercruiser bogging down at speed

On my 20GAL Mueller? tank I have 3 Lines coming out. One is the 2" for refueling. The other one Is a 3/4" ish hose that leads up to the Back of the boat (about 1 foot below the gas cap) and the smallest one goes to the pump.

I'm not understanding what you mean by runs out the back of the transom. Your fuel line should run from the tank to the fuel pump, then run to the carb. We need to know are you getting fuel out the end of the line which connects to the carb?

Air air bubble in the line before the pump is not necessarily an issue

 

[alldodge]

Re: 3.0L mercruiser bogging down at speed

On my 20GAL Mueller? tank I have 3 Lines coming out. One is the 2" for refueling. The other one Is a 3/4" ish hose that leads up to the Back of the boat (about 1 foot below the gas cap) and the smallest one goes to the pump.

OK thanks I understand. I'll go back to wanting to know if fuel comes out of the line that connects to the carb