Volvo Penta md5a fuel not reaching engine after filter change

Sailor96

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Hi, not long ago, I've added a new delphi 296 diesel filter on my boats fuel system.
The old one is the same but is at least 13 years old.

2 days ago I went out on the water with a friend to test everything. After about 5-10 minutes, the engine died on us. I threw out the anchor and began looking and found that when I disconnect the fuel line from filter to engine, there wasn't any fuel.

I checked the fuel filter and it appeared to be leaking on the couplings where you connect the fuel lines.
When I ordered the filter, I didn't notice the couplings had to be ordered seperately so I was stupid enough to use the ones that were on the 13+ years old filter. This obviously started leaking.

Now my question is;
What do you think could be the problem?

I suspect two things myself:
1. Becuase of the air that is now in the system due to the leak, the pump is not able to make the fuel travel to the engine maybe due to not being under enough pressure?
2. The fuel pump died on me.

I've ordered new couplings that will arrive today so if it's nr. 1 that would be easy to fix, install new couplings and purge air out of system.

However, if it's the fuel pump, i'm gonna require some help. I've checked workshop manuals and stuff but can't find if there's an external pump in the system too. From what I can find there's only 1 pump and thats a part of the engine itself. Does it not have an external pump like for example a diesel heater? It's an old md5a from 1982.

Luckily I have a sailboat so I was able to sail back without an engine. Not really into my marina slip, but close enough to get off and leave the boat for a few days.
 
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Scott Danforth

Grumpy old guy who plays with boats
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Fis all the leaks

Refill the filter

Use the manual lift pump to get fluid moving

Diesels are hard to start once you run them out of fuel
 

dingbat

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Nov 20, 2001
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14,380
Your need to bleed the fuel system to get it going again. Bleed instructions should be in the engine manual. Typically a screw somewhere on the injector pump

Heads up… some motors are easy to bleed, others can be a real PIA
 

Sailor96

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Thank you!
Do you guys not suspect the pump itself at all?
Should the lift pump and bleed screw near the injector at nr.5 ? I cant physically find it. Am i looking in the wrong location?
Does anyone maybe have a picture to show me what im looking for?
 

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QBhoy

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All as above and make sure the filter and lines are going the right direction too. Some of these filters are uni directional
 

Scott Danforth

Grumpy old guy who plays with boats
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Do you guys not suspect the pump itself at all?
no, you ran out of fuel.

you must now burp the fuel system (bleed all the air out)

FWIW, run out of fuel on a Cummins 12 valve and you must burp at least 4 of the injectors to get the thing to fire back up at all, and all 6 to get it to run decent.
 

Sailor96

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Thank you everyone.

The couplings arrived. But I have a question. There are 2 nozzles and 2 adapters. I have circled the adapters in the picture. What's the function of those? Currently on my filter the old couplings are without adapter. Do i need to add the adapters? It also screws in without it.
 

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racerone

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Post #4 try loosening / cracking the fitting at the injector.----Crank to get rid of air.
 

Scott Danforth

Grumpy old guy who plays with boats
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Thank you everyone.

The couplings arrived. But I have a question. There are 2 nozzles and 2 adapters. I have circled the adapters in the picture. What's the function of those? Currently on my filter the old couplings are without adapter. Do i need to add the adapters? It also screws in without it.
you have two SAE inverted flare to NPT adapters and two NPT to hose barb adapters

you use the adapters you need.

additionally, these adapters DO NOT WEAR OUT. only the thread sealant would if you removed and replaced. most likely your original fittings would work fine with proper thread sealant. do not use teflon tape.
 

QBhoy

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Thank you everyone.

The couplings arrived. But I have a question. There are 2 nozzles and 2 adapters. I have circled the adapters in the picture. What's the function of those? Currently on my filter the old couplings are without adapter. Do i need to add the adapters? It also screws in without it.
These are insert/adapters. Depending on what suits your installed arrangement.
I’m sure I read a post from you earlier on this. Did that post suggest that your friend said that the engine was self bleeding or something? If it did…I replied suggesting what you need to do, step by step.
Anytime a diesel like this runs out of fuel or takes a gulp of air…99.9% of the time, you’ll need to bleed the high pressure side and injectors.
So to start from scratch, you need to fill the primary filter (the one you have discussed), moisten the seal with oil, then screw her on as tight as your hands can get it. No more really.
Then there will be secondary filter(s) on the side of the engine usually. These are after the lift pump. You need to crack open the bleed screw on top of their housing.
Then you locate the mechanical lift pump on the side of the engine…there will almost always be a manual finger lever on that, allowing you to manually pump fuel through from the tank…through the primary filter and eventually to the secondary filter and out the bleed screw that you have cracked open (as above). Keep pumping until there is definitely no more sign of air at all. Then go again to be sure ! Tighten up the bleed screw (no great force required).
Then you have proven a few things. That your lift pump works, you have no fuel suction restrictions and also that you have primed the system as far as you can before the injectors them self.
Now you need to crack open the injector(s) feed pipe collar a little. Just back her off a wee bit though…not all the way. You’re dealing with a very dangerous and severe pressure of fuel at this stage.
It should be something like a 17mm spanner on a VP around this size. Usually anyway.
So…now with one person cranking over the engine at the key/helm…and the other down at the engine with spanner in hand…crank over the engine until you see definite pulses of a fine spray of fuel coming out each or any injector there is. Once you have that, then tighten up the fitting again. Whilst doing this and depending on how many cylinders there are…the engine may actually start and try and run. Try and avoid this if you can.
Once she’s running (and I’m not officially saying you should), I like to crack open each injector a little bit again and listen…just quickly and to make sure.
Hope that helps
 

Sailor96

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Im glad you say dont use teflon tape as that is what I planned to add. I assume it doesnt go well with diesel? I also considered a rubber o-ring, would that work? I got the exact size oring probably. What would be best to use to seal it properly? Basically the first time I didnt add any sealant at all so thats probably the issue why it leaks now.
 

QBhoy

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Just had a thought there. I don’t suppose you perhaps managed to fit an extra seal to the primary filter, that wasn’t needed, but came in the box and made you think it should be ? Usually the filters for these kind of things come with a couple of seals to make them more universally suitable. More specifically the thick round seal that goes onto the threaded shaft of the filter housing. Often this seal is not required for some housings, but is for others. Just as often, people can fit it to housings that shouldn’t have it, just because it’s in the box. This usually cases a bad or non sealing affect and will draw air into the fuel system. It will not prime like this either.
Just thought I’d mention. Seen it far too many times over the years. Haha.
 

Sailor96

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Just had a thought there. I don’t suppose you perhaps managed to fit an extra seal to the primary filter, that wasn’t needed, but came in the box and made you think it should be ? Usually the filters for these kind of things come with a couple of seals to make them more universally suitable. More specifically the thick round seal that goes onto the threaded shaft of the filter housing. Often this seal is not required for some housings, but is for others. Just as often, people can fit it to housings that shouldn’t have it, just because it’s in the box. This usually cases a bad or non sealing affect and will draw air into the fuel system. It will not prime like this either.
Just thought I’d mention. Seen it far too many times over the years. Haha.
I think the issue is that I didn't use any kind of seal. I threw the old one back in. I could've known it would'nt work but at the moment, laying in a sailboat's tiny engine room I kinda thought it wouldn't be a big deal and I really wanted to get out there and be done with it. Now I made it worse basically. Had I not done that and had I added a proper seal, I probably would'nt have to purge any air out of the system right now.

I just don't know what I should use on the threads to get a proper seal at this moment.
 
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alldodge

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Never liked prefilling a diesel filter, gas is ok but not diesel. The diesel injector nozzle are just really small and one spec can clog it. The manual posted previous it list the motor can have 2 filters not counting the screen filter on the fuel pump. It says to loosen the bleed screw and use primer pump to fill everything

For the most part you shouldn't need sealant so long as the threads are not striped
 

QBhoy

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Never liked prefilling a diesel filter, gas is ok but not diesel. The diesel injector nozzle are just really small and one spec can clog it. The manual posted previous it list the motor can have 2 filters not counting the screen filter on the fuel pump. It says to loosen the bleed screw and use primer pump to fill everything

For the most part you shouldn't need sealant so long as the threads are not striped
Aye. You technically can can leave the pre filter empty…but I can also suggest that doing so, can be a total pain in the bum. Especially to the unaware fella. It can and will give the false impression, on occasion, that you are fully bled with air free fuel from the secondary filter…but what’s happened is that there is still a big chunk of air to come through. You can be there for an age doing it that way…the dreaded feeling of the lift pump just pumping air at your fingers…is a horrible feeling, to the impatient man.
When filling the primary filters on our big princess’s twin Tamd61’s…I always use diesel from the fuel station pump into a gallon can. Pour it in using a filter mesh funnel too. Definitely the way to go for me. Had that old girl for 17 years now. Keeps me in check, does the old girl. Servicing her each year, along with the odd turbo exchange or two !
Although I can get myself by, with the odd two stroke or v8 mercruiser for fun…diesels were and always my thing really. Was a globe trotting marine engineer for a long time…covered head to toe in bloody diesel and heavy oil for most of it !
 

Horigan

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I think the key concern is pre-filling a secondary filter on a diesel. Particles you can't see can clog the injectors. If there is only one filter in the system, I would fill it via the lift pump lever and not pre-fill. An alternative is to fill the secondary filter through the inlet ports only and not the outlet port, if that's possible with this filter. This is possible with a spin on filter by putting a rubber plug in the center hole while filling.

Agree that leaving the pre (primary) filter empty can result in a big slug of air that stalls the engine. Just went through this on one of my TAMD41s and had to crack the injector lines and purge via the lift pump lever to purge the air and get it started.
 

Sailor96

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Dec 31, 2022
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Fortune has not been on my side lately. This morning on my way to my boat in my car, I heard a loud bang and now have a hole in my engine and oil squirting everywhere. Car is done. Work on boat is postproned untill weekend. Will likely update after weekend.
 

Sailor96

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Thnak you for all the help everyone!
I´m so happy right now, my father and I got her running today.
We did bleed both the delphi filter and the bleed screw on top of filter on the engine. After a while she started but died after a few secs. Then after some more bleeding we were able to keep her running idle but she would stall after giving throttle. Then we bled the system some more and she starts and runs fine now. We left her running for about 10-15 minutes at slow idle. We got 30 knots of wind here today so its not the best time to go out for testing.

However, how do I know for sure whether it's fixed now? The last thing I want to happen is her stalling on me again when out on the water.
 
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