Throttle lag on Hylas 54 Yanmar 4JH3-DTE

[boatbod]

Some turbo lag is to be expected. You have a big boat and a lot of mass in the drive train & prop. It's not going to throttle up like a motorbike engine!

When you throw the throttle forward do you get a cloud of black smoke before the engine spools up? If so it indicates the injector pump is putting in the fuel but the engine cannot burn it all yet.

Have you checked the exhaust elbow for obstructions? If the engine cannot breath, the turbo will be slow to spin up.

You might also check to see if the turbo has a waste gate and if so, whether it is operational or stuck open.

Note 1: throttling up out of gear puts no load on the engine and doesn't tell you much other than the linkage is ok.

Note 2: my 4JH2-DTE can be slow to throttle up too. I've always considered it pretty normal.

[sailon46]

My 4JH3HTE did this last week coming into Normans BVI and when I got back to Green Cay marina in St Croix tore into the system and found the cause to be partial blockage with old 3M 5200 that came loose in the fuel tank and got sucked up the diesel pick-up. The 5200 had been used by PO to seal a fuel level electronic sensor he had put there.
FYI Ernie on the Mary Jane.

[AnthonyM]

Hi Mark, did you find the solution to your throttle lag? I have the same engine in a moody 54 and now experiencing exactly the same problem. It initially was just when the engine was cold, but now I have a circa 10 sec delay occurring after putting the engine in idle for a very short period but seems fine going straight back into gear.

[Kenomac]

Originally Posted by Kenomac

Good, then my bet is on a dirty turbo. Have you been revving it once every hour per Yanmar instructions in order to blow out the carbon produced by running at lower revvs?

Originally Posted by AnthonyM

Hi Mark, did you find the solution to your throttle lag? I have the same engine in a moody 54 and now experiencing exactly the same problem. It initially was just when the engine was cold, but now I have a circa 10 sec delay occurring after putting the engine in idle for a very short period but seems fine going straight back into gear.

Have you been revving the engine every hour per Yanmar owners manual?

[AnthonyM]

Thanks, the problem is also intermittent as with the hylas, only seems to occur when really need quick response as when berthing! If I go straight from forward to reverse there is no lag. On start up with cold engine in gear takes circa 30 seconds for revs to pick up in gear, when engine has been idling for for maybe 30 plus seconds takes about 10 seconds to pick up revs. It will then go forward/ reverse with no lag.

[Kenomac]

Originally Posted by AnthonyM

Thanks, the problem is also intermittent as with the hylas, only seems to occur when really need quick response as when berthing! If I go straight from forward to reverse there is no lag. On start up with cold engine in gear takes circa 30 seconds for revs to pick up in gear, when engine has been idling for for maybe 30 plus seconds takes about 10 seconds to pick up revs. It will then go forward/ reverse with no lag.

It sounds like your turbo is loaded up with carbon, we had the same issue. One more thought.... is this a new issue? We also had a problem with our prop having the incorrect blade pitch which exacerbated the turbo issue.

If you tend to motor around at 1600-2200rpms without revving your motor hourly per Yanmar instructions... your turbo is plugged up and/or some of the turbo blades have broken off.