2010 Yamaha f115tlr motor knock

[B3njammin89]

Installed new low pressure fuel pump and all of a sudden hear a motor knock. Pulled the new mechanical pump off and noticed it has a round shape. Original had a flat surface. Is the rocker inside the engine( I believe the pump mechanically pumps by the rocker arm), it that piece that the pump contacts supposed to be loose? I can wiggle it with my finger. I tried to install original low pressure pump back on but noise is still there. Just bought the boat and decided to do preventative maintenance. I’m hoping the new pump did not damage something inside the motor since the new one has a round shape rather than flat.

[TownsendsFJR1300]

Which part is round and / or flat? The mounting surface, ???

Here's the parts diagram for your fuel pump:
https://www.boats.net/catalog/yamaha...prd-0510-later

Looks like there's several springs in there to keep things taught. Are you able to push the plunger in by hand and does it return fully?


You didn't mention (probably didn't), but did you pull the pump apart at all?

Is spring #17 installed?

[pstephens46]

What is round? Part #18?

[99yam40]

is the new pump one that should be installed on this motor?
in other words did you buy the one Yamaha recommends for your motor?

[B3njammin89]

TownsendsFJR1300 part 18 has a round top rather than being flat. I bought the assembly new and did not pull it apart. And the plunger goes in and out by hand.

pstephens46 yes, part 18

yes this is the pump I got from a Yamaha dealer @99yam40

[B3njammin89]

Also I forgot to mention I installed a new high pressure pump as well and cleaned injectors. I can wear a stethoscope and hear the noise loudly when I put the probe on low pressure pump area. I don’t know if spark knock can be loud as a engine knock.

[pstephens46]

Post the part number of what you bought. Doesn’t sound like you have the incorrect part.

[B3njammin89]

pstephens46 68v-24410-00-00

[pstephens46]

pstephens46 68v-24410-00-00

The one shown in Scott’s diagram above has the flat end plunger. The part number you have is different and has a slightly rounded plunger. Based on a pic I see when the number is googled.
I wouldn’t keep trying to run it. You may damage the cam lobe that pushes it.....

when did these get so damn expensive? I swear they used to be 65 bucks.

[B3njammin89]

pstephens46 I immediately took the new low pressure pump out after hearing the noise and installed the original back in. I’m hoping I didn’t damage anything internally. But the noise is still there now.

[B3njammin89]

Can a fuel starvation issue cause a engine knock noise at the mechanical pump area? I’ve taken off the intake manifold to ensure I had everything hooked back up but didn’t see anything missing.

[pstephens46]

Can a fuel starvation issue cause a engine knock noise at the mechanical pump area? I’ve taken off the intake manifold to ensure I had everything hooked back up but didn’t see anything missing.

You might need a shop now. I might remove the pump and turn motor by hand, using a flashlight, to try to see the cam lobe. Looking for damage.

I would think fuel starvation would have resulted in running issues.

[B3njammin89]

The motor didn’t want to stay running. It kept cutting off. Before the pump replacements it idled smoothly.


When I took the pump off last night I was able to shake the rocker arm I believe inside the motor. The part that contacts the mechanical pumps plunger. I’m not sure if that’s suppose to be loose like it is. pstephens46

[B3njammin89]

pstephens46 i believe my motor developed a misfire in cylinder 4. Whether I pull the injector plug or spark plug wire for cylinder 4 there is no change in the engine. I tried swapping plugs and injectors and still stays the same. I’m getting power to the injector plug, getting spark to the coil packs. Plugs 1,2,and 3 were dry and filled of black carbon. Cylinder 4 was wet. Even though I’m getting spark to the coil packs, is there still a possibility it can be bad?

I called the boat dealership and they said the low pressure pump I received from them is the right part but doesn’t know why it’s shaped different. I’m thinking that misfire could be a possibility why I’m hearing the knocking noise close to the low pressure pump area. It’s just strange that the motor ran fine before I pulled off the manifold to install high pressure pump and to clean vapor tank.

I spun the motor by hand today and removed the low pressure pump to see if I saw any damage. Did not see any damage. The piece inside the engine that the low pressure pumps plunger touches moves on one end like a flap.

[TownsendsFJR1300]

You have spark at #4 wire, but does the plug itself fire off??