6bta hard starting

[Don Gardner]

My port engine has always taken longer to start than the starboard engine. It cranks fine but it usually takes two tries for it to start. I have taken the fuel shutoff solenoid apart and cleaned it as well as cut the ground wire from the harness and grounded it to the solenoid mounting bolt. Also I cleaned the connections on the mag switch/soienoid. Not sure where to go from here. anyone have any suggestions?

Topic

[Don Gardner]

Rob,
Right now I have a single spin on primary fuel filter/water seperator.FS19934 and an on engine engine filter FF5285.
Don

[Rob Schepis]

What do you have for primary filtration setup? That’s a boat thing, not an engine thing, so there is no way for us to know what you have or what you need…

On engine fuel filter for your M3 6BTA: https://www.sbmar.com/product/fleetguard-ff5285-fuel-filter/

[Don Gardner]

Thanks Tony. I’ll get in touch with my local Cummins marine shop. One other question. I have one primary fuel filter and the on engine filter. Can you recommend the best Fleetgaurd fuel filters for this setup? Thanks for all your help.
Don

[Tony Athens]

Working on a injection pump is over my pay grade..I’d get a 2nd or 3rd opinion too..

Tony

[Don Gardner]

Tony,
Thanks for the quick reply. Is the rack something that can be fixed without removing the pump or do I need to call in the pro’s? I like to do my own work when possible but have no experience with injection pumps.

Don

[Tony Athens]

Loose fuel prime ??

Think of my post “generic” as it applies to many that are having hard starting issues after shut down over night or longer..

Priming your fuel system– Your “squeak” tells you it should be priming right– If you had a PSI gauge on the on-engine “last chance fuel filter, it would be nice to see 15 PSI -ish at the that filter while priming. That is as hard as it gets..

If I were to guess, and for sure that if giving it full throttle continues to make it start quicker , even as weeks & months follow, then I would say that “internally” your Bosch pump has a fuel rack that does not automatically go to full rack prior to starting as it should. ..Think of that s a “choke position” before start-up/during start-up.

Water inlet on the mixer–It looks kinda OK, but there in only one way to know for sure.. Remove the riser and let me “see” inside the turbo exhaust outlet.. There is No Other Way if you want to be sure.

Tony

[Don Gardner]

I think you are responding to Mark Tripi’s questions. What does it indicate if it starts better at 100% throttle setting? Do you think the location of my exhaust water inlet is satisfactory?

Don Gardner

[Tony Athens]

The simplest way to figure out if “loosing prime” is the real issue, install two good ball valves on the engine–One just before the inlet connection. One at the return line connection.. Just shut them the next time you are shutting down for a day or more.. But be sure to open both before you restart.. If nothing changes, loosing prime by fuel siphoning back or out of the system. is not the issue.

Tony

[Mark Tripi]

So I went out to use the boat yesterday and after pumping the primer 10 times I cranked her over, still not firing up after 5 seconds of cranking. I pumped the primer again and after another long crank it kicked over, and I had the throttle at 100% both times. I am loosing prime but just can’t find where. I feel like an injector is leaking down, and allowing fuel to drain back the return line. Can that happen? I did shut off the fuel supply one night and still had starting problems. Any ideas?

[Mark Tripi]

Me too

I was going to post about the same thing with my 4BTAs. Hard starting on one engine, nice puff of white smoke when it does start after a lot of cranking. It is loosing prime for sure. I did shut the fuel supply valve one night after use, the next day after maybe 20 hours it was a pia to start again. I am suspecting the #4 injector, it looks like I see some fuel around the area of the injector mount. I did replace the return line copper there thinking it could be from that leaking but it still happened. I do have a new spare injector that I may throw in this weekend. This is a new problem, and seems to be getting worse as time goes on. I will push the throttle to 100% next time I am out there. Any ideas?

[Don Gardner]

Tony
Here are the pics of the engine and exhaust elbow.

[Don Gardner]

Tony
Never any white smoke from either engine. I pushed the throttle to 100% and it started in about 6-7 seconds. Much faster than starting at idle setting. A little white smoke for a couple of seconds. I will get some pics and send them.

[Tony Athens]

When it comes down to it, it only takes 2 things to start the engine while it is cranking—– HEAT & FUEL.

Heat comes from compression. If one engine cranks at 200 RPM and starts “X-Fast” and then something makes it crank at 150 RPM, all else being equal it will start slower/require many more rotations to build the needed heat to make the fuel go bang…. Of course there are other parts to that heat equation–cylinder & valve condition.

Does the “slow start” engine also have more white smoke once it starts and also it not quite s smooth at first?

Next time the engine has been sitting and you expect a slow start, push the throttle to 100% full stop ( not 90%———100% full stop.. See if that makes it start faster.

Care to post some pics of the engine? Show the exhaust too.

Tony

[Don Gardner]

Return line is submerged in the tank. After initial startup it starts immediately. We were at anchor the other day for about five hours. Did not start immediately but took a few seconds. Yesterday i tried pumping the lift pump to see if that would help. It started squeaking on the first pump. Did not get stiff. Should it get stiff?

[Don Gardner]

If it has been started recently it starts easier. I will check the return line. Thanks for the suggestion.

[Rob Schepis]

So it needs to crank longer than the starboard engine, right?
Does the amount of time the boat is “unused” make a difference?
Do you know if your return line is submerged in the tank?
Could be a slight air leak allowing fuel to drain back.

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