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fatbear

Contributing Member
"Yesterday I installed the Per

"Yesterday I installed the Pertronix ignition kit as suggested in this posting:

http://www.marineengine.com/discus/messages/12486/283242.shtml

It went really well and the engine was running fine, but just as I was finished adjusting the timing the engine died and would not restart. I still had spark (the timing light was still hooked up and it was flashing.)

I suspected a fuel problem. Getting my head down in the bilges I looked at the sight-glass next to the fuel pump and it appears to have really old gas in it, but it's so dirty that I'm not sure. By that time it was getting dark and I had a headache so I just walked away.

But first I was looking in the book and reading about the double-diaphragm fuel pump. Apparently the sight glass goes between the two diaphragms and indicates when the first diaphragm has ruptured. As I understand it, the second diaphragm is there to keep the engine running if the first one ruptures.

So if the gas in the sight glass is really old, that would suggest that the first diaphragm ruptured long ago, so maybe the second one has just ruptured?

But it gets more confusing because I compared the photo in the book to the fuel pump on my engine and I only see a single diaphragm "sandwich" layer. My engine is a 1976 120HP Mercruiser. Did they use the double diaphragm pumps that long ago? If so, maybe someone replaced it with an automotive pump sometime in the past.

I suppose I will replace the pump. If the old engines had only single diaphragm pumps can I still replace it with a dual-diaphragm pump from a newer engine?

Or should I just cap off the fuel pump hole and install an electric pump? Are they reliable?

Thanks,

--Brian"
 
"the glass bowl pumps are long

"the glass bowl pumps are long gone.(and illegal) new mech. pump will have vacuum fitting. you will need to install a fitting on the carb, and a hose. pretty simple, really. an electric pump will require some wiring changes. pump must run while cranking, and must shut off when engine stalls. (K.O.E.O.) plus you must block off the hole for the mech. pump. stick with mechanical, cheaper, and simpler. original pump lasted 30+ years."
 
"If the sight glass is no long

"If the sight glass is no longer legal, that would explain why I cannot find a replacement. The fittings on mine are rusty. If I buy the current pump will it come with the parts I need to adapt it to the carb? If not, how do I know what to get and what to do?

Thanks,
--Brian"
 
Brian it may or may not come w

Brian it may or may not come with what all you need to convert but i doubt it. its one of those things that are like a plumbing job you started out only needing a faucet and had to replace everything part by part if ya know what i mean. im sure the pump is gonna be the most expensive part you'll have to buy just take your time and youll figure it out and im sure you'll get thru it just remember that rubber lines and rad clamps are not (USCG) aproved good luck
 
Point of clarification: Is tha

Point of clarification: Is that rubber lines from the pump to the carb? I can understand that.
What about the line from the fuel tank to the pump? I thought there was USCG rated fuel line for supply. Please clarify. Thanks.
 
"Thanks, Steve. I was kind of

"Thanks, Steve. I was kind of expecting that the pump probably wouldn't come with the extra parts, but I wonder if there is a procedure anywhere. I imagine the pump probably has a hole or fitting for attaching the line, but what about at the carburetor end? Since my old, 1976 carb didn't have this hose, it seems unlikely that it will have an inlet for it."
 
"It just occurred to me that I

"It just occurred to me that I cannot see very well down there where the fuel pump is, but my camera can. So I took this photo:

http://myflotsam.com/Images/BoatProblems/P5294759-FuelSystem-P.pdf

Now I'm more confused than ever. I understood that the sight glass was stuck onto the side of the pump just to indicate if the first diaphragm was bad. But this glass bowl is inline with the fuel line on the intake side of the pump. I cannot find anything like this on a parts list for my engine (1976 Mercruiser 120). Is this just some aftermarket filter that the previous owner installed at some point?

If that's the case, and since the pump has a filter built onto it, maybe I just just toss this glass bowl unit?

Thanks."
 
"Re: Clifford's questions:

"Re: Clifford's questions:
A plastic fuel tank was installed in the boat below one of the rear seats sometime fairly recently. I'm guessing something went wrong with the below-deck tank and this was the easy fix. It appears to have new and proper fuel line leading to the pump. The line leading from the pump to the carb is stainless jacketed. I don't know what's inside of the jacket, but it is fairly new and I hope it is good quality. You can see those two lines on the photo.

--Brian"
 
"It just occurred to me that I

"It just occurred to me that I cannot see very well down there where the fuel pump is, but my camera can. So I took this photo:

http://myflotsam.com/Images/BoatProblems/P5294759-FuelSystem-P.pdf

Now I'm more confused than ever. I understood that the sight glass was stuck onto the side of the pump just to indicate if the first diaphragm was bad. But this glass bowl is inline with the fuel line on the intake side of the pump. I cannot find anything like this on a parts list for my engine (1976 Mercruiser 120). Is this just some aftermarket filter that the previous owner installed at some point?

If that's the case, and since the pump has a filter built onto it, maybe I just just toss this glass bowl unit?

Thanks."
 
"I feel like I am getting on a

"I feel like I am getting on a soap box with the ethanol crap but while retro fitting a new pump I would get the fittings to add a fuel/water separating filter and install it inline before the new pump, that will save you lots of headaches in the future,also there is auto parts stores and some machie shops that make USCG approved hoses any size you need and they crimp on the ends to be exact fit, you need to know the threat size."
 
"Good idea. I will look into

"Good idea. I will look into it. Maybe it would fit in place of that glass bowl? Did anyone look at my photo? I don't want to screw up here.

Thanks for that parts list scan. I've seen it on many websites. I think it must come from a Mercruiser parts catalog. Yes, it will be helpful in buying the new pump, which I hope to do today."
 
"the inline fuel water separat

"the inline fuel water separators are larger than that bowl setup, that's a nice peice and is very helpful for seeing the condition of the fuel. looks like you have some fuel tank issues, and you need to either replace the lines of get them cleaned.

If you dont want it, throw it in a box and send it my way."
 
"Always more to learn. So the

"Always more to learn. So the bowl is just for looking at my fuel? Cool. I will take it apart and clean it up if I can get it apart without ruining it. I suspect that the boat did have "fuel issues" because they disconnected the built-in fuel tank and replaced it with a plastic one under the rear seat. The plastic one is almost brand-new and I doubt that there are still fuel issues. I think that glass bowl is so old that it is just coated with dirt inside and out.

OK, now for the weird part. Last year as part of my winterization I filled the fuel tank and added fuel stabilizer. I know this because it is the first time I have done it in this house and the empty can of stabilizer is still there and the bill for 13 gallons of gas is in my boat file (it's a 14 gallon tank.) My fuel gauge doesn't work (yes, it's on the list) and the boat started just fine when I went to put it in the water a couple of weeks ago, so I didn't think to dipstick it.

Well by now you've guessed the problem: I was out of gas! How did that happen? I'm only 53 and not yet so cracked as to get this confused. The boat spent the winter in a cyclone fenced enclosure, but the barbed wire has been cut two spaces down from mine and they are interconnected. Maybe someone siphoned it. Seems like a hard way to steal fifty bucks worth of gas, but unemployment is high here in NW Oregon.

I filled up the tank and can find no leaks. The engine starts and runs pretty well. I think a carb rebuild is in the near future, but it will get me around for now. The next mandatory project is replacing the hydraulic rams. I took the boat in for outdrive servicing last year and the yard crossed the two of the four hydraulic lines going to the rams. That blew out the two lines going from the pump out through the firewall to the outdrive. (Probably the hardest parts to replace on the whole boat!) After I replaced those I was bleeding (the system, not myself!) and found that one of the rams didn't work. The other did and I couldn't leave the boat sitting on the dike so I launched and used it until fall. But this spring when I went to launch the tilt/trim didn't seem to be working right and now it's totally gone. The outdrive climbs out of the water if I go into reverse - an awkward situation in a marina. It's the same thing that was happening when the hydraulic lines were broken, but mine are all tight and sound and the fluid is not leaking out, the tank is still topped up after lots of pumping up and down.

By now I'm sure everyone is sick of hearing about my old boat, so I'll get back to screwing and wrenching around...

--Brian"
 
"keep at it, there may be a li

"keep at it, there may be a little screen in the glass bowl but that's it.. it'll help you watch for water in the gas, it will look like an air bubble at the bottom, once you clean it.

Does the port tank have a gauge sender on it ? if not that's why the gauge doesn't work, it's still attached to the old tank :)

-b"
 
"It has a sender on it, but I

"It has a sender on it, but I think they just moved the sender from the old below-deck tank to the new, boxy plastic one and it doesn't reach deep enough to register once you've used 1/4 of the gas. It would register full when the tank was full but it's so unreliable that I am just not in the habit of even looking at it."
 
"there are a few choices out t

"there are a few choices out there for senders, just need to know the depth of the tank. about 20-30$ i think,"
 
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