Fuel feed pump issue OR not?

[esarratt]

Originally Posted by a64pilot

Oil diluted with fuel isn't as good a lubricant of course, but a very real danger is if you get enough fuel in the oil, the engine will run away and the only way to stop it is to choke it off by blocking the air intake.

Thanks for the information. I've watched the videos on Youtube, in horror, about runaway diesels. Now where is that board?

[esarratt]

Originally Posted by DougR

One issue with electric pumps is that when your battery dies, so does your engine. You can't even hand crank it to start. At least with an MD7 you can easily start it with the hand crank, even if the battery is toast. (Assuming you have a mechanical fuel pump)

DougR

I hadn't thought about that. Good point.

[Compass790]

I have a similar problem with my yanmar lift pump but it works. I have a spare electric fuel pump ( you can get them cheap off Ebay) as Yanmar wants $360 NZ for the pump as they wont sell you a rebuild kit. The pumps are simple tho if you have some mechanical skills. I'm sticking with the mechanical pump until it fails as its been going for 35 years but I dont have the same faith that a chinese made electrical one will have the same longevity. Will rig a dual circuit to use the electric one as a priming pump as suggested in other posts.

[Nicholson58]

Originally Posted by esarratt

Thanks again for the help! This has been an adventure.

I have been reading my Volvo workshop manual and it mentioned making sure the fuel feed pump (aka lift pump) "squeaked" when you press the manual lever (the bleeding lever).

Mine does not squeak. At all.

Squeaking indicates that the diaphragm inside is in good working order.

First of all, I am going to ignore it (for now) and not rebuild/disassemble it.

What I want to know is has anyone recently rebuilt their MD7A fuel feed pump? The pump for the MD7A (and many of the older Volvos) is a Pierburg, model number 15672.

The reason I ask is because they don't make parts anymore for this model and I have been unable to locate a rebuild kit, or anything, for the fuel feed pump.

Looks like a dead copy for my Westerbeke 1983 6-cylinder. I have two spares and a new rebuild kit. Mine does not squeak either. I would not worry as long as it works. Get a spare or kit. These things are very simple to fix.

[Wotname]

From information you have posted elsewhere on CF, you might be considering replacing your fuel tank; if so, consider a gravity feed tank and do away with a ful pump of any sort.

Last time I checked, gravity was a very dependable system , although you could carry an electric pump as a back up.

[Doug Brown]

Gravity tanks - main or a day tank - are OK until you have a fuel system fire.

Granted, a pretty rare event, but if it happens and if you don't have a remote shut off or a shut off valve outside of the engine room then the entire contents of the fuel tank (one gallon up to +20 gallons) can feed the fire.

Not a good thing.....

If you have a large enough dry chemical extinguisher (at least 5-lb, 10-lb better yet) you can usually - note usually - get the fire out, but you will still have fuel freely flowing into the engine space.

Again, not a good thing.....so have a plan for immediately shutting off/plugging the fuel outlet. After you have shut off the batteries! You don't need damaged energized electrical wiring re-igniting the fuel with you inside the compartment trying to stop the leak!

A fire fighting "trick" that is very handy to know, eventhough it is sort of a "last chance" way of getting the fire out, is to pour water into the fuel tank via the deck fuel fill. Water is heavier than fuel, so sinks to the bottom of the tank - where the gravity fuel outlet is. After a few seconds you will have non-flammable water coming out of the leak instead of a flammable liquid.

Depending on the size of the hole and the shape of your fuel tank, a couple of gallons of water may be enough to do the trick, although you can pour in more to be safe.

You will still need to extinguish the burning fuel that has already leaked out, but at least gravity is not adding more fuel to the fire.

[GrahamHO]

Originally Posted by Wotname

From information you have posted elsewhere on CF, you might be considering replacing your fuel tank; if so, consider a gravity feed tank and do away with a ful pump of any sort.

Last time I checked, gravity was a very dependable system , although you could carry an electric pump as a back up.

My diesel tank is as high as possible under the cockpit floor allowing space for fittings. Previously with a Ruggerini engine when it's mechanical fuel pump failed, as long as the tank was over about half full it would gravity feed with no problems.

That pump failed because the rocker arm pivot developed wear greater than the travel of its actuating pushrod.

Some speedway cars used a hand operated air pump to pressurise the fuel tank instead of a mechanical pump. I have on occasion blown down the vent hose exiting near the tiller to initiate priming ( not specially recommended ). It should be possible in an emergency to adapt the dinghy inflating pump to keep the diesel tank pressurised as long as the filler cap has an O ring seal.

Model T Fords and I think Model A had a gravity feed tank in front of the dashboard and windshield, above the engine. When their fuel level dropped they had to reverse up steep hills to keep the fuel level above the carb. So I was told.

[GrahamHO]

Originally Posted by Wotname

From information you have posted elsewhere on CF, you might be considering replacing your fuel tank; if so, consider a gravity feed tank and do away with a ful pump of any sort.

Last time I checked, gravity was a very dependable system , although you could carry an electric pump as a back up.

My fuel tank is as high as possible under the cockpit floor allowing space for fittings. With my previous Ruggerini engine, when the fuel pump failed it would gravity feed with no problems as long as the tank was over about half full

That pump failed because it's rocker pivot developed wear greater than the travel of its actuating push rod.

Some speedway cars used a hand air pump to pressurise the fuel tank instead of a mechanical pump. I have on occasions blown down the diesel air vent hose exiting near the tiller to initiate priming. It should be possible in an emergency to pressurise the tank adapting the dinghy pump or a bike pump.

Model T Fords and I think Model A had a gravity feed gas tank above the engine in front of the dashboard. If the fuel level was low they had to reverse up steep hills to keep the fuel level above the carb. So I was told.

[esarratt]

Originally Posted by Doug Brown

Again, not a good thing.....so have a plan for immediately shutting off/plugging the fuel outlet. After you have shut off the batteries! You don't need damaged energized electrical wiring re-igniting the fuel with you inside the compartment trying to stop the leak!

A fire fighting "trick" that is very handy to know, eventhough it is sort of a "last chance" way of getting the fire out, is to pour water into the fuel tank via the deck fuel fill. Water is heavier than fuel, so sinks to the bottom of the tank - where the gravity fuel outlet is. After a few seconds you will have non-flammable water coming out of the leak instead of a flammable liquid.

Depending on the size of the hole and the shape of your fuel tank, a couple of gallons of water may be enough to do the trick, although you can pour in more to be safe.

You will still need to extinguish the burning fuel that has already leaked out, but at least gravity is not adding more fuel to the fire.

Good ideas. Thanks! The tank will be mounted above the engine with a shutoff valve just outside the tank.

Nigel Calder, in one of his books has noted, that you can limp home using gravity to deliver fuel to the engine by bypassing the the fuel pump. I just redid the fuel lines so I know what to do and where to splice in.

Thanks for the info on the fires. Interesting trick. I like fire, but I don't like fire on me or my boat.

[esarratt]

Thanks to your advice I have abandoned my fears about my non-squeeking fuel pump.

[Dieseldog]

This is my first post here, but I thought this bit of info was worth sharing.

For the last couple of days I'd been trying to source a new diaphragm for the fuel lift pump on my Volvo Penta 2003 engine. The original fuel pump is now obsolete and has been replaced by a lousy piece of rubbish that is unserviceable. By that I mean you can't take it apart because the pump chamber is crimped together.

The earlier pumps (as shown in the diagram posted by esarratt earlier in this thread) are better made and are fully serviceable because you can strip them down. That's a good thing. What isn't such a good thing is that parts are no longer available.

The diaphragms are usually what fails in a pump. Try getting a diaphragm for a Volvo Penta 2003 from your parts supplier, and they'll tell you they're discontinued. They'll probably try to sell you the crappy new pump, which incidentally has the ports in the wrong place so you'll also need a new copper fuel delivery pipe between the pump and filter. All that will cost you around $400.

Here's the good news. During my research, I discovered that the old version of the fuel pump was made in Germany by Pierburg. They supply fuel pumps to various engine manufacturers and have done for many years. As it happens, some air cooled VW engines used a very similar Pierburg fuel pump to the one used on the Volvo Penta 2003 (and a bunch of other engines). The actuating mechanism is slightly different, but the pump diaphragm is identical.

Go to a VW specialist and buy a diaphragm for a Pierburg pump for an air cooled VW boxer engine circa 1970.

VW specialist Wolfburg West in USA sells a nice double membrane diaphragm for $22.
http://www.wolfsburgwest.com/cart/De...ID=113127141WW

Note that the same pump is used on all Volvo Penta 2000 series and MD series engines up to MD17, and possibly a few others. So the VW fuel pump diaphragm will be applicable to all these engines.

[Wotname]

Welcome aboard CF, Dieseldog. Excellent first post, I'm sure this will be great news for VP owners. That was good sleuthing on your part.

Now if you can do the same for the Yanmar small marine diesels (Y, QM, GM series etc), that would be awesome (just kidding)!

Once again, welcome aboard and thanks for resurrecting at five year old thread.

[Dieseldog]

Thanks for the welcome Wotname. I probably should have observed protocol and introduced myself in a new member thread.

Reading back through this thread, I see that Doug Brown made a brief reference to VW and Porsche fuel pumps, so it seems I'm not the only person to make the connection. Sorry Doug, I didn't mean to steal your thunder.

BTW, the squeak from the pump when it's manually operated is just the non-return valves inside the pump lifting off their seats. The relatively slow operation of the manual lever (as opposed to rapid actuation when the engine is running) and the resulting slow fuel flow causes the valves to vibrate against their seats rather than lifting clear, a bit like the reed in a clarinet. The squeak confirms that fuel is actually flowing. But it's not a reliable indicator of pump condition because some pumps do it, some don't (mine doesn't). A non squeaker can work just as well as a squeaker. They just go about their business without feeling the need to tell everyone how good they are. I suppose they're the quiet achievers of the pump world.

[Compass790]

The other thing you can do if needing a diaphragm is go to a diesel injection place & they often have a selection.
In the case of the yanmar I find a squeeze bulb way better than the silly little primer handle but the pump works fine. Also Yanmars lift pumps look the same as some kubotas so a tractor place is worth a shot as well.

[Dieseldog]

Well, there's more than one way to fix a knackered fuel pump.

The new pump diaphragms that I ordered from USA could take months to get here (Tasmania) with the postal system in Covid overload. Meanwhile summer is on the way and a want to use the boat. So I just replaced the flexible membrane on the old diaphragm. The nitrile material came from an ebay supplier in Australia.

Pump diaphragms usually aren't made to be taken apart, and this one is no exception. The end plate was held on by the end of the shaft being peened over. I had to machine the end off the shaft to get the old diaphragm off. But that left me with a shaft that was too short to reassemble. I thought about making a whole new shaft, but then had another idea that was worth a try. I built the end up with weld metal and turned it back to the original diameter. Re-fitted the diaphragm plates with the new membrane between them and peened the built-up end of the shaft over again with a ball-pein hammer. It worked quite well. Diaphragm is held nice and tight on the shaft and the pump now pumps again.