Yanmar 4JH5E stalls when starting

[Talbot]

Great if that solved the problem.

Another issue (and cheap/easy to check) could be a build up of carbon in the exhaust elbow where the raw water coolant meets the exhaust. Happened to somone I know who was having a lot of trouble with his volvo engine. Engineer was suggesting a rebuild of the timing, and consideration for a replacement engine. My 3YM manual has great diagnostic diagrams, and the exhaust elbow was listed, which triggered a memory of a similar problem. He removed the elbows and they were 75% chocked with carbon. A good clean, new gaskets, and engine was as good as new.

[magique]

We had the same problem wiyh our Yanmar 4JH-TE a few years back when we were in the Eastern Caribbean. We tried everything from replacing fuel filters , bleeding , cleaning the turbo charger , polishing the fuel and it still stalled once in a while under power , it would run forever just idling at anchor. We were in Curacao when we hired a local metal working shop to cut a clean out port in our fuel tank . They emptied the tank ,when he removed the fuel pick up connection on top of the tank he found that it had quite a little blockage there , cleaned it up and have not had a problem since .

[jdaltonpe]

I had a similar issue on a 3GM30 - started intermittent and got worse. I used clear line and diesel jug to trace the air leak - took a couple months to find. It was caused by the Yanmar design where the return line had a T in it sending fuel back to the feed of the injector pump through a check valve. Changed the check valve which solved it but it came back after a while - air was getting in through the check valve. Finally got advice from an experienced Yanmar mechanic who rebuilds them all the time. He removes that connection on every rebuild because it is a troublemaker. Removed the line back to injector pump as he suggested and has run perfect ever since.

[bobatkins]

One other possibility that nobody suggested in this thread - a clogged pickup tube in the fuel tank could cause the same stalling problem.

Some pickup tubes have mesh screens on them that can get clogged by organic growth in the fuel tank. I had this happen on my Hunter 41. Very frustrating to discover after all of the troubleshooting, filter changing, etc. Tanks had a lot of organic matter in them so they were cleaned and the fuel polished and the mesh screen on the pickup tube was removed!

I also installed a vacuum gauge (Racor Fuel Restriction Indicator) on the outlet side of the primary Racor filter to be able to determine if the filter gets clogged unexpectedly.

https://www.defender.com/product3.js...087&id=1737501

That was 12 years ago and not a problem since.

[Sailing Drummer]

Thanks for the additional advise. When I get back to my home port in the upper Chesapeake I think I'll have a look at these other possible issues.

Larry

[nilespf]

Went south from the Chesapeake last year and had issues with the engine stalling when backed down. Turned out to be a couple of air leaks that were observable by looking into the Racor 500. One hose and a second was the packing gland on the manual shutoff valve. You can actually see a fine thread of air bubbles in the glass. Get enough light into the glass and you can see any up stream leak.
If you think you may have a intermittent lift pump check to see if yours is boot strapped by the oil pressure switch. I had to shotgun both the pump and the OP switch just in case.

PN

[Sailing Drummer]

Thanks PN. I'll keep that in mind. So far it's been ok since I re-seated the o-ring in the Racor. But there were never any air bubbles that I could see. The pump has worked without any problems. But your mentioning it reminded me that I want to buy a spare, just in case!

Larry

[UK Ade]

Update to an old post for anyone reading this who is experiencing a similar problem. I had same engine, same symptoms. Fault was the 12v electric priming fuel pump (small cylinder under the fuel filter). From ignition to engine fully running fuel is pumped via this 12v pump. Once engine is running the mechanical pump takes over. Start with higher revs and the mechanical pump can catch the engine before it stalls. Faulty elec prime pump means the engine stalls before the mechanical pump has picked up the flow. $30 replacement cured it. Just for info. Hope it helps someone.

[sailingabe41ds]

Originally Posted by UK Ade

Update to an old post for anyone reading this who is experiencing a similar problem. I had same engine, same symptoms. Fault was the 12v electric priming fuel pump (small cylinder under the fuel filter). From ignition to engine fully running fuel is pumped via this 12v pump. Once engine is running the mechanical pump takes over. Start with higher revs and the mechanical pump can catch the engine before it stalls. Faulty elec prime pump means the engine stalls before the mechanical pump has picked up the flow. $30 replacement cured it. Just for info. Hope it helps someone.

Though my engine is relatively new...2015 I bought one of those as a replacement part.

Abe