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Hello to the group.

Engine won't start. It will with starter fluid for 10 seconds. Pressure primed the system with a outboard motor primer "bulb". If I loosen the screw on the top of the fuel filter, fuel runs out pretty good when I squeeze. Disconnected the feed to the injection pump and turned the motor over, just a dribble comes out.

I suspect the fuel pump. It has a lever that when pressed has virtually no resistance. It does not cause fuel to come out of the filter screw. Does that mean it is bad?

Can the pump be replaced with an electric pump? Best price I can find is $170 USD. I guess I should be happy I can find one at all.

Thanks in advance.
Chris, Cal31, Santa Cruz, CA
 

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First of all, DO NOT use starter fluid on that engine. You will do damage!

It is possible the fuel system is vapor locked. Have you tried bleeding the system?

Yes, working the priming lever should build up pressure IF it is pumping fuel, but not if there is air. you should be able to open the bleeder while working the priming lever and have fuel come out.

My last boat had an md7a, and I never had ant trouble finding parts for it. I would be surprised if you couldn't get a fuel pump for it.

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Cape Dory 30
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Mine had all of those symptoms and ended up as a hole in the number one cylinder with no compression. Parts have been oblolute for years so if you find a pump, try grab it. I tried to give away my various parts and could not. Could also be the injector pump or just sucking air from somewhere on the suction side. Bypass everything you can with the squeeze bulb pump right to the injector pump and bleed, keep it pumped tight to the injector pump and give it a try. Cranking to prime with the engine set to decompression. If you are getting fuel to the injectors and it won't fire when you throw the compression lever its something else. Dennis
 

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All of the above was after two mechanics and myself had tried to bleed the system.
A dead give away that there is a hole in the cylinder or a bad ring is when you did get it to fire with starting fluid did a lot of blowback come out of the breather? Fill the engine room with smoke? Pressure blowing into the bottom of the engine.

Starting fluid will not ruin the engine if used correctly. Most have lubrication now, obviously you would not want to run it long on the starting fluid. But we have had diesel tractors on the farm that the only way they will start when cold is with starting fluid. I do give one caution, starting fluid in the bilge of a boat is a bomb! It can be ignited by the glow plugs if an engine has them. It could be ignited by the starter. The glow plugs warm the air going into the cylinder to aid starting. My VWs have glow plugs but I don't think that the MD7A had glow plugs. Good luck. Just my opinion and experience, not everything on the net is true. Dennis
 

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All of the above was after two mechanics and myself had tried to bleed the system.
A dead give away that there is a hole in the cylinder or a bad ring is when you did get it to fire with starting fluid did a lot of blowback come out of the breather? Fill the engine room with smoke? Pressure blowing into the bottom of the engine.

Starting fluid will not ruin the engine if used correctly. Most have lubrication now, obviously you would not want to run it long on the starting fluid. But we have had diesel tractors on the farm that the only way they will start when cold is with starting fluid. I do give one caution, starting fluid in the bilge of a boat is a bomb! It can be ignited by the glow plugs if an engine has them. It could be ignited by the starter. The glow plugs warm the air going into the cylinder to aid starting. My VWs have glow plugs but I don't think that the MD7A had glow plugs. Good luck. Just my opinion and experience, not everything on the net is true. Dennis
There is a big difference between a tractor engine and a small marine diesel. When I was a heavy duty mechanic we used starter fluid to start big diesels. I doubt you will find many marine diesel mechanics that would advocate for the use of starter fluid on small engines. If you feel you must use it, then I suggest you use it very very sparingly.

The MD7 does not have glow plugs, it has a decompression lever that allows you to get the engine spinning fast, then you engage compression and it starts. An Md7 in good condition can even be started by hand cranking with this method.

When my MD7 would no longer start I pulled it out and had it rebuilt. The culprit was a broken compression ring.

First thing to check is fuel. If there is fuel getting to the injectors and it still won't start you may have bigger problems that ether will not fix.

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There is a big difference between a tractor engine and a small marine diesel. When I was a heavy duty mechanic we used starter fluid to start big diesels. I doubt you will find many marine diesel mechanics that would advocate for the use of starter fluid on small engines. If you feel you must use it, then I suggest you use it very very sparingly.

The MD7 does not have glow plugs, it has a decompression lever that allows you to get the engine spinning fast, then you engage compression and it starts. An Md7 in good condition can even be started by hand cranking with this method.

When my MD7 would no longer start I pulled it out and had it rebuilt. The culprit was a broken compression ring.

First thing to check is fuel. If there is fuel getting to the injectors and it still won't start you may have bigger problems that ether will not fix.

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I completely agree, mostly, I don't think you would find any marine diesel mechanic that would suggest an amature spray starting fluid in the engine compartment of a boat. It is why i gave the caution and stated if used correctly. If used incorrectly you could cause a big bang or wipe the cylinder walls dry and you will lose compression. You also can get a heck of a knock with over use.

I knew mine did not have glow plugs (cape dory 1981) I did not know if they never put them on the MD7A. Not sure when they stopped making them.

Curious, how long ago were you able to find rebuild parts for a MD7A? Two years ago two different mechanics could find nothing and neither could I. No gaskets, no rings no nothing. That's before I found the hole and scored piston.

And lastly you are very correct. If you get fuel to the injectors and still no start you have gone about as far as an amature can go. Gets into testing the injectors, injector pump, compression and so on. My story did not end well, I hope yours is something simple. Mine was raw water cooled and had been in the Chesapeake Bay all her life and the corrosion finally ate through to the cylinder. Dennis
 

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I completely agree, mostly, I don't think you would find any marine diesel mechanic that would suggest an amature spray starting fluid in the engine compartment of a boat. It is why i gave the caution and stated if used correctly. If used incorrectly you could cause a big bang or wipe the cylinder walls dry and you will lose compression. You also can get a heck of a knock with over use.

I knew mine did not have glow plugs (cape dory 1981) I did not know if they never put them on the MD7A. Not sure when they stopped making them.

Curious, how long ago were you able to find rebuild parts for a MD7A? Two years ago two different mechanics could find nothing and neither could I. No gaskets, no rings no nothing. That's before I found the hole and scored piston.

And lastly you are very correct. If you get fuel to the injectors and still no start you have gone about as far as an amature can go. Gets into testing the injectors, injector pump, compression and so on. My story did not end well, I hope yours is something simple. Mine was raw water cooled and had been in the Chesapeake Bay all her life and the corrosion finally ate through to the cylinder. Dennis
My engine was rebuilt about 12 years ago and all parts were locally available. Bearings, gaskets, etc. More recently I needed a new exhaust elbow, which was sitting on the shelf at our local supplier, and exhaust manifold gaskets which were brought in from a warehouse somewhere. Of course things like thermostats and pump impellers are easy to come by. I had to replace the oil pressure switch and was able to replace that with a generic switch from an automotive supplier.

Being raw water cooled that engine was starting to get a bit clogged up, but it always started easily with no need for starting aids, although it did take a few seconds of cranking when it was cold.

It was a good engine, albeit with a few idiosyncrasies like those ridiculous compression fit copper water pipes with the retaining clips, and the water pump on the BACK of the engine that required climbing down into a lazarette to change.

I don't miss it though. I did a full servicing on my new boat's Yanmar 3jh4e and it was so easy to access everything I needed to! Water pump on the front of the engine where it can be serviced easily? What a concept!

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I think most of the engine parts that are specific to the engine have evidently gotten used up in the last 12 years. Our MD7A set backwards with a Vee Drive and you couldn't get to anything on it. We replaced with electric as the Beta replacement was going to turn into about 15K to 18K to get it installed. It was nice chatting with you. Dennis
 

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being backwards my water pump was on my front side but the thermostat and belts were on the other end. No I don't miss ours either. Dennis
 

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Lets focus on your symptoms.

Just to confirm the “fuel pump” is on the port side of the engine and has a lever. It is a feed pump. When operating the lever with the bleed cracked you should get a steady flow of fuel. When bleeding you will first get nothing, then some foamy fuel, then a steady flow of fuel.

The lever has a spring return, if that is not working tthen you can force the lever up and down, its a pain but will work.

This pump provides low pressure fuel to the injector pump. If its not providing a steady stream then thats a problem.

My GUESS is that you could set up a test. Get a gallon of fuel and set it a few feet above the engine. Get some clear hose to feed the engine, just past the feed pump. Start a siphon down to the engine. Open the decompression lever and crank the engine a good bit with the fuel connected. Be mindfull you don't pump too much water into the system so manage your water intake. Then clise the decompression lever and try to start the engine.

I have not done this but I believe you should he able to run the engine in this fashion. The pressure head of the fuel above the engine will replace the pump. Excess fuel will go back into the tank return line.

So this is a cheap experiment to show that the engine runs.

The feed pump has some kind of diaphragm. That may be damaged. You may be able to repair that pump.

If you can not repair the pump you MAY be able to substitute an electronic pump. The problem is you need one that can overcome the lift and flow resistance through the primary filter. Many fuel pumps have very limited lift capacity. I would look to Walbro for a suitable pump. They have 48” of lift which can be extended to 120” with a non return valve.

 

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Things that make me go hmmmmm. Do people actually read preceding post before posting. I have often wondered this.
 

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if it will run on starter fluid and not on diesel then you are not getting diesel in the cylinder so it does not run. starer fluid is not the best thing for a diesel but it does show that you have compression. remove the injector line from the injector and run the starter with the compression released. got fuel going to the injector? , I think not. you can use the outboard primer bulb to feed fuel to the fuel injection pump. electric pump is ok but makes the engine dependent on electricity to run. outboard primer bulbs should not to left in the line as the rubber does not hold up well to diesel.
 

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if it will run on starter fluid and not on diesel then you are not getting diesel in the cylinder so it does not run. starer fluid is not the best thing for a diesel but it does show that you have compression. remove the injector line from the injector and run the starter with the compression released. got fuel going to the injector? , I think not. you can use the outboard primer bulb to feed fuel to the fuel injection pump. electric pump is ok but makes the engine dependent on electricity to run. outboard primer bulbs should not to left in the line as the rubber does not hold up well to diesel.
The starter fluid has a much lower Flashpoint than diesel.That is why it is used to get old worn out diesels running when they are cold. The fact that the engine has enough compression for it to ignite is not proof that there is enough compression for diesel to ignite.

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The starter fluid has a much lower Flashpoint than diesel.That is why it is used to get old worn out diesels running when they are cold. The fact that the engine has enough compression for it to ignite is not proof that there is enough compression for diesel to ignite.

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This is correct, mine with a hole in the number on cylinder would fire on starting fluid. But would fog up the cabin with blow by. I think the compression was 150 PSI on one and 350 or so on two. I remember the mechanic saying something like, wow, great compression......for a gas engine.
 

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The guy is looking to prove his fuel pump bad and maybe replace it.

This conversation is interesting but not useful to the problem.
The fuel pump is volvo part number 833323, $99 on Amazon.


OR

$50 on ebay

 

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The guy is looking to prove his fuel pump bad and maybe replace it.

This conversation is interesting but not useful to the problem.
The fuel pump is volvo part number 833323, $99 on Amazon.


OR

$50 on ebay

Well the conversation is also about proving the fuel pump is the problem in the first place...

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and the part is an "indirect replacement" which means good luck! I have found out the expensive way.
 

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Agreed, which is why I suggested a method to assure the engine runs with an alternate source of fuel.

But clearly something is wring with the fuel feed.
1- he has no resistance on the pump lever
2- he is getting no fuel out of the bleed valve
It MIGHT be there is no fuel in the line, say the line is cracked or otherwise there is a serious air leak before the fuel pump.

And I provided links to direct replacements.
 

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Agreed, which is why I suggested a method to assure the engine runs with an alternate source of fuel.

But clearly something is wring with the fuel feed.
1- he has no resistance on the pump lever
2- he is getting no fuel out of the bleed valve
It MIGHT be there is no fuel in the line, say the line is cracked or otherwise there is a serious air leak before the fuel pump.

And I provided links to direct replacements.
yep, all things we all suggested, easy stuff first, bypass everything to the injector pump, stuff he already has and no need to buy, crack an injector line and then you know. The little lift pump acts different depending on where the cam is in relation to the actuator that rides on it. I have been through what he is going through two years ago. I think we all agree that it could just be as simple as a leak on the suction side of the pump, a cracked pick up tube in the fuel tank and so on. But by bypassing all of that will isolate the problem to the injector and engine or the fuel to the system side.
 
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