Fuel delivery issues

[sms986]

So a few months back, I purchased a 1989 Larson DC215 with a mercruiser 305. The block was cracked, so I picked up a 350 short block, changed rings and bearings, and put all of the 305 gear back on it. The tank was full when I purchased it, and I'd estimate the fuel in the tank to be about two to three months old. So I rebuilt this engine, put it in the boat, aligned it and serviced the outdrive/bellows while it was apart. I "rebuilt" the qjet, replacing gaskets and the account pump/check ball only, cleaning the carburetor out vigorously while apart. First start with the new engine in place turned over and fired up instantly. That entire evening I ran the engine for about a half hour, intermittently, setting timing, breaking in cam and lifters, etc. Started fine each time. Had to leave for business and didn't return until 5 weeks later. First thing I did when I got home was try to start it. It would not fire. Accelerator pump didn't squirt anything into the intake tract. Finely poured some gas down the throat and got it to fire. However, I had to repeat this process and fiddle with it all afternoon to run it. Tore the carb apart and found the new accelerator pump had a torn plunger. Replaced the pump and cleaned the fuel line all the way to the tank. While the carb was off I turned it over and got a healthy kick of fuel from the fuel pump. So I got it together and test fired it a few times no problem. Took it out the day after and it started fine. Let it warm up at the dock for 5 minutes, ran at various throttle positions for about 15 more minutes, then shut it off to fish for a bit. Started it up 20 minutes later to go to a different spot. Started fine. Ran for another 20 minutes and when I went to position myself, I shifted to reverse, stopped the boat from drifting forward, and shifted to forward to turn the boat slightly. When I shifted to forward the engine died and wouldn't start up. Went back to check the carb for fuel, and the accelerator pump pushed out no squirts of fuel, just a few puffs of vapor. Pulled the fuel filter off and it was still full. Couldn't get it to start. Put some fuel down the throat and it still wouldn't start right away. I prepared to set up the kicker motor and sat for a few minutes. Turned it over and it fired right up. Ran it for 20 minutes to the dock with no issues. Anyone have an idea? I think it is fuel delivery related. Could have overheated, but highly doubtful. I saw no smoke coming from the engine in any place and when I got it started up again the water temp was right at 140. Could it be something with the red circuit breaker on the fuel filter? (Mounted on engine.) I don't think the fuel is siphoning out of the carb because it started up after being run then sitting, and it died while running. Any ideas? Thanks!

 

[achris]

When it fails, check for spark. If you have no spark, then check the shift interrupt switch, see if it's activated. If it is, lower shift cable needs replacing. If you have spark, then you go back to it being a fuel issue. Maybe rig up a pressure gauge in the line and monitor it.

Chris..........

 

[sms986]

The spark idea crossed my mind too, but I crossed that one off because it behaved the same when cold and hot, and it only seemed to react to fuel being dumped down the throat. What would the shift interrupt cable have to do with it? I am new to sterndrives and not yet familiar with all of the functioning parts yet. Thanks

 

[sms986]

Looked it up and answered my own question. Need to work on not getting ahead of myself... So, assuming it isn't the interrupt switch (which I will also be checking), what else could be causing this? Everything makes sense for the interrupt switch to be the culprit except for the fact that my accelerator pump didn't squirt any fuel into the carb when it died on the water.

 

[alldodge]

I think your fuel pump is failing. Check the tygon tubing and see if your oil level is rising. If those two show no signs, then check pressure (3 to 7 psi)

 

[sms986]

Oil level is still near the same. I think I am going to install an in-dash fuel pressure gauge just for future piece of mind anyway. Now that you say that, I'll probably replace the fuel pump too since it is cheap and easy.

 

[alldodge]

The fuel pump doesn't go out that often, and installing a gauge will be nice, but will have to be electrical. Its your boat, but I wouldn't recommend, things like a water pressure gauge would be better to watch the motor IMO

 

[sms986]

I do have a water pressure gauge on the boat. Learned my lesson on an outboard when my water pump went out and overheated the engine. Only reason I want to watch the small things like fuel pressure is because I go 15 miles offshore in lake Erie and knowing my luck, a brand new fuel pump would likely fail at the worst time. Have a Johnson 15 hp outboard as a kicker but I don't want to have to rely on that to get me home in an emergency.

 

[achris]

... is because I go 15 miles offshore in lake Erie ....

When you have a long trip planned, let me know...

One of my favourite trips is to a place called the Abrolhos Islands. That's over 30 nautical miles straight out into the Indian Ocean. We don't mess around on piddly little lakes..

Chris.......

 

[alldodge]

When you have a long trip planned, let me know...

One of my favourite trips is to a place called the Abrolhos Islands. That's over 30 nautical miles straight out into the Indian Ocean. We don't mess around on piddly little lakes..

Chris.......

Who's boat and what size do you make that trip on?

 

[achris]

Who's boat and what size do you make that trip on?

My own boat (the one in my signature). It's a 20' cabin cruiser... I've only been across once with another boat. All other times, I'm solo.

Chris......

 

[alldodge]

Oh yea, that's off the Ausy coast.

 

[sms986]

You have me beat...

On a serious note, I just want to make my passengers and I as safe as possible. Big waters are still new to me.

 

[alldodge]

When it gets down to it, I know of no boat that can make it home in rough seas in an emergency if a motor stops. A twin engine boat can not plane on one motor. A kicker can not move a boat in high winds. If something breaks, in most cases you will not have the parts or the tools to replace if its needed.

So we do are maintenance, and hope from that we can go have some fun and get back easy

 

[sms986]

Yeah, weather is a no-win situation, but the best I can have for that is my radios. My idea of emergency above is going out on a relatively calm day and breaking down. But, that's why I'm here, rather than trying to troubleshoot a fuel/electrical system that is new to me on my own. Or worse, relying on a shot of gas down the throat to get her started again. I know many people who would take that route, unfortunately.

 

[achris]

.... Big waters are still new to me.

Trust me, it never gets old.

Yeah, weather is a no-win situation, but the best I can have for that is my radios. My idea of emergency above is going out on a relatively calm day and breaking down. But, that's why I'm here, rather than trying to troubleshoot a fuel/electrical system that is new to me on my own. Or worse, relying on a shot of gas down the throat to get her started again. I know many people who would take that route, unfortunately.

Nice to find someone with the right attitude. :thumb: I see far too many people who have 'car' mentality. 'If it breaks down, I'll just call AA'. Yeah, good luck with that! Especially when the nearest tow service has to travel 75 miles to get to you!

On the radio, you have the engine and 'non-engine' electrical systems isolated (apart from the battery obviously)... In the early days, Merc had a 'maximum 35A' accessories feed off the power from the instrument panel. That was all fair in the days when accessories=nav light, bilge pump and a blower. But these days with 5KW sounders, chart plotters, 1000W noise-makers, etc, etc it's no longer advisable to run them from that instrument feed. Yet, I still see boats being fitted out with exactly that. :facepalm:

A few things that will make your boat a little more reliable, and mean you have a few less things to think about...
1. Have a separate electrical feed to a pair of terminal block (one red, one black) for non-engine stuff. That way, one system going down doesn't take the other down with it.
2. Change the main power fuse up under the dash (feeds to the ignition switch). It's currently a glass 3AG fuse and holder. They have a habit of getting a tiny bit of corrosion on the end and going high resistance. Can be very difficult to fault-find. Change it to a water-proof blade fuse holder and fuse, 20A.
3 Carry spare fuses.
4. Most important. Just keep on top of the maintenance. Do your oil and filter changes, service the drive impeller and unis/gimbal bearing annually. And I know this sounds silly, keep your eyes open when you're doing any service work, or your 'beginning of day' checks. You'd be surprised/shocked how many people 'look' straight at a problem and don't see it.

Something worth carrying with you, if you don't want to leave the service manual in the boat... A laminated print-out of the engine and instrument electrical drawings (and a 12v test probe)...

Do you have the Merc genuine service manuals?

Chris........

 

[sms986]

I thought the same thing-this is a boat, not a car. I can't just walk home if something happens. I actually have my radio and chartplotter/GPS on a separate supply. There are two batteries in the back of the boat, and I have a third onboard just for these two things. I also have two battery powered radios and spare nav, anchor, and spotlights (all battery powered) on board, with shrink wrapped batteries. The fuse is a new one .Added to my list.

I have a service manual, which helps with maintainence/service but not troubleshooting, and I'm very mechanically inclined. Have been working on engines all my life. Boat stuff is new to me though, and I'm not afraid/ashamed to ask for help when I can use it. I'm still young and will always have more to learn. I appreciate all the help!

 

[achris]

..., and I'm very mechanically inclined. Have been working on engines all my life. ...

That gives you a great background...

A boat engine is a marinised car engine... So, if you understand car engines, you're on the right path. The main differences are the exhaust systems and the ignition systems. Also marine engines need special head gaskets and brass core plugs. And fuel and electrical systems need to meet 'Marine' standards. Can't use car starters, alternators, fuel pumps, carbs, distributors on boats. You have Thunderbolt IV on that engine, and I have a write-up on that system right HERE... And going through the stickies will yield a wealth of information.

Drives are new to you, so read the manual, read the manual, and ask questions. (that's why we're here.)

I have a service manual

Is it the genuine Merc factory manual, or one of the aftermaket ones (clymer/seloc) that are only useful as a kneeling pad?

You should have 2 manuals for your engine, one for the engine, #9 (GM V8 engine 1985-1989) and #6 (Drives, 1983-1990).

Chris..........

 

[sms986]

I have the outdrive manual only. Still waiting on the engine manual, which I didn't think I needed until last week.

I also read that write-up before, when timing my ignition!

 

[sms986]

So I have another question: how likely is it that the actual shift interrup switch has failed? And what are some other common places to look when the interrupt system fails? The shift cable was replaced in May by the previous owner, with a receipt. When I replaced the bellows I did not do this one. Today I found that the cable bellow has a tear in it, hence why I had a small leak into the bilge. I don't want to buy the switch if it is good, because it is a bit pricey considering all of the money I've already thrown at this thing. I hooked up my timing light and had someone turn the engine over and move the throttle around. Surprise! My timing light only flashed on a few of these trials. I still haven't found why my accelerator pump was only puffing vapor into the throat that day on the water, but I bought a new fuel pump today anyway.