3 line fuel pump PLUS pulse port on the back

[mayfieldkm]

Question. I have a 1983 Johnson 200GT. I purchased the fuel pump shown in the picture and my outboard has a pulse line (hose) that attaches to the fuel pump. My outboard does NOT have the pulse port on the block that the fuel pump bolts to. HOWEVER, the fuel pump itself has a port on the back and came with a gasket. So...on the fuel pump I've got 3 lines (like shown in the photo) PLUS the port on the back. I've mounted it all up but it seems to still be starved for fuel. It's BETTER than it was before replacing the old, cracked fuel pump. Before, it felt like it was running at about 10%. Now it's running at about 70%. It'll get up on plane but takes about 30 seconds to get there and tops out about 30mph instead of 55mph. My question is...do I need to plug that pulse port on the back of the fuel pump itself?? Am I losing pressure in the pump because I'm using a pulse line and some of the pressure is escaping out the hole in the back of the pump?? If so, what's the best way to plug the hole on the back of the pump?

 

[racerone]

I would say it only looks like there is a pulse port on the back of the fuel pump.-----It is likely not connected to provide PRESSURE to the diaphragm !----Same pump housing casting can be used to make a 2 hose or a 3 hose pump.-----Post the actual compression test values after a test.

 

[mayfieldkm]

I would say it only looks like there is a pulse port on the back of the fuel pump.-----It is likely not connected to provide PRESSURE to the diaphragm !----Same pump housing casting can be used to make a 2 hose or a 3 hose pump.-----Post the actual compression test values after a test.

So even though it was shipped with the gasket needed to mount it to an engine with a pulse port, you think that hole on the back of the pump might not actually go anywhere?

 

[racerone]

Correct.----I would never buy a new pump off the internet.-----I would just install a new diaphragm.------About the only thing that can fail on these pumps is the diaphragm----Simple easy fix here on my work bench.

 

[Crosbyman]

in any event... if you have no pulse port on the engine facing the pulse port on the pump itself, the pump is unaffected.. a dab of JB weld would close it off

Even more so if you mount the gasket since it would have sealed thing up against the engine mounting surface. .

try a new diaphragm on the old pump has suggested. Must be some utubes to see. !!

 

[mayfieldkm]

So even though it was shipped with the gasket needed to mount it to an engine with a pulse port, you think that hole on the back of the pump might not actually go anywhere?

in any event... if you have no pulse port on the engine facing the pulse port on the pump itself, the pump is unaffected.. a dab of JB weld would close it off

Even more so if you mount the gasket since it would have sealed thing up against the engine mounting surface. .

try a new diaphragm on the old pump has suggested. Must be some utubes to see. !!

Great info guys, thank you. I can't believe I didn't think to go ahead and install the gasket to see if that helped my issue. I'm handy enough that I can rebuild the old one with the help of a few YouTube vids as well. I did run the motor long enough to get back to the ramp, 10 mins. Like I said, it was probably running at 10% due to low fuel pressure (the old pump was leaking like crazy). I haven't checked compression since this happened. Do you think I could have screwed something up even worse by running it? It's a 6 cyl. Would the fuel pressure have been low enough where potentially some of the cylinders may not have been getting enough fuel to fire and therefore not have had enough lubrication?? Geeeez, I hope not. It's definitely running better now than it was before I swapped the fuel pump out, but not running like it should.

 

[racerone]

These motors run very well on 5 of 6 cylinders.----See if spark jumps a gap of 3/8" on each lead.----These motors ( with original pistons ) have a history of broken piston rings !-----I can't make you do it , but a wise owner would record the values of a compression test for future reference.----Post your numbers here.

 

[mayfieldkm]

Will check compression, install gasket to back of pump (just in case) and check spark and report back....thanks all!

 

[racerone]

The gasket would be an insulator and seal nothing.

 

[Crosbyman]

agree it seals nothing motor side because there is nothing to seal ... pump side ....it was a suggestion and more of a comfort feeling for OP .