Merc 115 EFI Primer Bulb ?

[tso_privat]

Hi

I am about to install a brand new 115 EFI. The boat is with a built in tank. Is it wright understood that no primer bulb should be mounted?

Cheers Thomas

[jyasaki]

Still need a primer bulb as far as I know. I doubt the fuel pump in the motor would draw air until fuel reached it.

jky

[matt h]

Still need primer

[thomas]

I had a newish 115 EFI that didn't have a primer bulb, spoke to Mark at MB and he said they are useless on them because of the way the fuel pumps work.

[tso_privat]

When I see installation guide it tells that it is no good to have a primer. I am a little confused and thinking how the internal pump can drag all the way from the build in tank with air in the pipes

[uncle al]

there is no primer bulb fitted, if there is it will cause more problems than enough.Contact turbo he will tell you the same, and when you have installed the obm, dont forget it should be checked for fuel integraty, the factory used to say a vacumn test, i plumbed in a pipe of clear plastic and made sure there were no air bubbles.If there are air bubbles it will run weak and again will/can cause problems.

[captnjack]

Clear plastic fuel hose? That's a new one for me. Is it actually rated for fuel? We have nothing like that over here that I've ever seen.

[PeterM]

So no prmier bulb in any EFI ?

Ive got two EFI engines both with prmier bulbs .... both running off portable tanks

[tso_privat]

Interesting

[uncle al]

captnjack, I retired three years ago , but before that all boats that were rigged with new OBMs , were supposed to have a vacumn gauge plumbed into the fuel system to make sure there were no blockages in the fuel system from the fuel tank to the OBM. As taking a vacumn gauge out each time was a bind, I found that a piece of clear plastic pipe, plumbed in by the btm tray(to get it as close to the fuel pump/s as possible)you can see if there are any air bubbles in the fuel going through to the pump, no air no problems, There was a service bulletin issued in the U.K. a few years ago about it.Obveusly the gauge /clear plastic pipe were removed before delivery to the customer. Yes I did find fuel problems in the fuel lines on some boats so I do know from my personal experiance that the clear pipe works.

[captnjack]

Oh I get it, thanks al

[thomas]

Originally Posted by PeterM

So no prmier bulb in any EFI ?

Ive got two EFI engines both with prmier bulbs .... both running off portable tanks

Not sure it is applies to all EFI's, someone will know, I also had a 2011 60 and that did have one, though it was rigged but numpties.

[Jizm]

The 100hp is the same....

[tso_privat]

OK, I will try without. Thanks guys

[diver12]

All the big 4 cylinder 4 stroke Mercury/Mariners have a fuel supply module. If you use a primer bulb with these engines, then it can cause the fuel system to lock up and become unusable until the pressure has been released.
This applies to the 80 through 150hp naturally aspirated 4 strokes and the Verados. Basically if it tells you and primer bulb isn't needed then leave it out.

[Turbodiesel]

Yeap No primer bulb on all L4NA Engines, (4 stroke EFI) It has as said, a Fuel supply module (FSM) which will draw the fuel up via a electric lift pump, the lift pump will time out once the FSM is full. If you hand prime the FSM will be overfilled and go into the return pipe which goes to the inlet manifold. The engine will sense fuel in the return line and it will not let you start, so it wont go down in a ball of fire! It just wont start. So No Primer Bulb!.

[jyasaki]

News to me. Thanks, guys.

jky