Mercury 115hp 1987 fuel pump inop help

[Thomas coe]

I recently rebuilt my fuel pump and replaced all fuel lines bulb, the motor will start and run until the fuel is our of the floats.pump is not doing anything,I put a hose and bottle attachment on the outlet part of the pump and no flow. I don't know what else to do I do not want to take it to a boat shop. I am a car mechanic not a boat mechanic figured a motor is a motor. Any helpful advice would be much apericaited

 

[Chris1956]

That is a bit of an unusual issue. Fuel pumps usually pump at least a bit of fuel.

OK, since you can push fuel thru the fuel pump (you can, can't you?) using the primer bulb, the fuel pump check valve are installed the right way. That begs the question on whether you have installed the check valves at all. If so, did you connect the two pulse lines to the engine transfer covers? Are those hoses kinked?

Does the fuel pump leak when you prime the motor?

 

[Thomas coe]

I can push fuel thru it seems a bit hard to if that's makes any since. The pump is screwed directly on the motor only have the inlet fuel line and the outlet fuel line so I have no pulse lines it just works off of direct pressure wich I figure is good since the motor runs good once you manually pump fuel into the carbs.

 

[Thomas coe]

No leaks

 

[Zac Penn]

Have you taken it back apart and verified that it does have the two round check valves installed? If they aren't the then nothing will be pumped. Since you can push fuel through it via the primer bulb then they are not installed backwards. You just need to make sure they actually exist and will close

 

[Thomas coe]

O ha did that this morning. There in there,and installed correctly according to might picture I'm going off of. Could I have damaged them?those are the only thing I did not replace.

 

[Chris1956]

You might post a picture of your fuel pump. I would expect your fuel pump is mounted on the lower cowling, on the starboard side, and will have two pulse lines running to the lower transfer cover. There is a different kind of fuel pump that mounts on the block, used in newer and older motors.

Is that an inline 4 cylinder motor or inline six motor?

 

[Thomas coe]

I6 3 carb

 

[Thomas coe]

I have the older style pump no pulse hoses on mine wish I did

 

[Chris1956]

In my experience, IL6 motors have either a single figure-8 shaped fuel pump, with 2 pulse hoses, or dual triangle-shaped fuel pumps, that mount on the transfer plates. The older motors had the triangle-shaped dual fuel pumps. What do you have?

 

[Chris1956]

Can you post the serial number of your motor, as I suspect it is not 1987?

 

[DavidMoore]

In your previous post about the same issue you mentioned the primer bulb was empty after the engine started.

I am not an expert like others that are helping you but this tells me your fuel pump would be pumping fuel if there was fuel to pump, (otherwise the primer bulb would not be "empty").

You connected the outlet to a bottle, what about reversing this, What happens if you connect the inlet side of the pump to a gravity fed fuel supply?

I think you have a significant blockage / leak downstream of the primer bulb, check and double check all the hoses and fittings downstream of the primer bulb, including those inside the tank, and especially the strainer on the fuel tank pick-up pipe.

Good Luck with finding the problem.

 

[Thomas coe]

If there was a clogs how would I have got fuel to the pump?

 

[Thomas coe]

Serial number is 06582453

 

[GA_Boater]

Serial number is 06582453

This is a 1984. You could have either of these two fuel pump - Which one is yours?

New style




Old style

 

[Thomas coe]

Figure 8 style I guess

 

[Thomas coe]

The old style

 

[Thomas coe]

Mine is the old style

 

[Chris1956]

Thomas, That "figure-8" shaped fuel pump should have two pulse lines connecting to the lower transfer cover. Those cannot be kinked when the pump is installed into the cowling.

 

[Chris1956]

Actually, that fuel pump looks to have been modified from what I was expecting. Maybe it mounts to the crankcase or transfer cover? If so, make sure the base gaskets are sealing well, as that is where the pulses should come from.