Volvo D4-300 cuts out after starting--fuel starved??

[Bruzer]

Our Ranger Tug, a 2020 R/29 S LE, with a Volvo D4-300 (1285 hours) loses its fuel prime. About three weeks ago, the engine would immediately start, run for about 1 minute and then cut out. When I attempted to restart the engine, it took several seconds of cranking before the engine would start. It seemed to be starved for fuel. About a week later, the same symptoms happened. This time I used the priming pump on the top of the secondary filter and it took about 35 pumps before their was resistance. The engine started right away. The fuel filters on the engine have been routinely replaced, but I decided to replace the filters anyway thinking perhaps I had gotten some bad fuel. When I examined the used filters, there was no sign of crud or water in the fuel filter or the fuel that I drained from the filters. This past weekend the engine started right away, but cut out after about 1 minute. Before starting a second time, I opened the fitting on the top of the secondary filter, and it took about 20 pumps before any diesel came out. Once the air bubbles were purged and I had a steady stream of diesel, I closed the fitting. When I started the engine, it fired-up immediately and did not cut out. There are no traces of leaking diesel from the tank to the filters and to the engine. What is causing the secondary filter to lose its prime? Would an air leak on a fuel line fitting cause these symptoms? Any trouble-shooting advice would be greatly appreciated. Thanks.

Full Circle
2020 R29 S LE

 

[scross]

We had a somewhat similar situation on our 2017 C-28 with the D4-260 three weeks ago. Ours would start and run fine up to 1800 rpm. Moving the throttle past 1800 rpm made the engine “cough” and run very rough. Nothing unusual seen in the primary (the one bolted to the bulkhead) fuel filter.
Found air in the secondary fuel filter. Pumped it out with the bleed valve. Tried to run engine past 1800 rpm. Same symptoms. Found air in secondary fuel filter again. Pumped it out again. Tried to run engine past 1800 rpm. Same symptoms. More air in secondary fuel filter.
Here was our fix thanks to Bellingham Yachts. Replaced all the 8 year old fuel hoses. They had soft spots. Replaced the primary fuel filter housing with a new Racor unit. That completely solved the problem.
In our old primary filter housing the check valve at the bottom of the unit had failed open allowing fuel to very quickly drain out of the filter, down the fuel line and back into the tank. So, there was an air leak somewhere in the old housing as well. It’s cheaper to buy the new Racor primary housing than rebuilding the original unit.
Also found out from FM staff that there was a bad batch of secondary filter black rubber pumps used by VP. Don’t know the years but it wasn’t recent. An air leak in the black rubber pump can cause similar symptoms.
Good luck with your troubleshooting.
PS: Bad fuel line hose clamps can also let air into the fuel lines.

 

[Mastercraft]

I put a gallon of Sea Foam a year in 145 gal diesel tank. Put it in before a big trip so it doesn't get diluted by small diesel fuel purchases. This cleans injectors, etc. Available on Amazon. Also use biobor regularly in tank. When you change fuel filter, take the metal filter container all apart. I found excessive crystal buildup there. Don't loosen the bolts on wood backing. You will be sorry since the blind nuts will turn.

 

[AGLyme]

If you do replace the Racor - suggest buying one with the clear bottom. Then, you can "see" if there is FOD in the primary filter. My diesel mechanic also purchased a vacuum gauge attached. I'll take a pic the next time I go to the boat.

 

[Mastercraft]

What does a vacuum gauge do? Where? What should it read?
I also put a drain valve in bottom of filter. Screws into plug hole and put plug on end of drain valve as a removable plug in case valve is accidentally turned on.
Moeller Fuel Tank Shut-Off Valve (1/4" FNPT, Male/Female, Brass ---Amazon

 

[scross]

If you have or are buying a new primary fuel filter housing with a glass bowl at the bottom, ABYC standards call for a metal heat shield underneath the glass bowl. That’s what we bought. Looks similar to this:

 

[Cutwater28GG]

ive had issues with an air leak in the fuel filter caused by heavy heat soak. worth changing the O rings on the fuel filter

 

[AGLyme]

A vacuum gage is like an arm cuff for heart rate. Let's you know if your engine is going to have a heart attack if it is sucking too hard to get diesel through the system.