Electric Fuel Pump installation details

[groundloop]

I had a pretty good idea my fuel pump (stock VRO w/ the oil side disabled) was acting up, so I put a pressure gauge on the outlet and sure enough - it would continuously drop down to less than 0.5 then jump up to 4, down below 0.5 and jump up to 4, etc. etc. I'm pretty sure the problem with the engine falling flat on it's face when coming off idle was connected to the fuel pump also (it wouldn't do that all the time, usually only after running for awhile), though I haven't actually witnessed it with the fuel pressure gauge in line yet. Now I suppose I'm back to square one as far as all the work I've done rejetting the midrange and adjusting the idle screws :mad: .

After a little convincing I'm now leaning toward an electric pump, and have a few questions about the installation.

I'm looking at a Carter GP4389 rotary vane Marine fuel pump (6 psi, 72 gph) from Jegs. (engine is a '90 Johnson GT200 w/ no performance mods)

I'm pretty sure of myself on the electrical side (I'm a EE) - get 12V from the the ignition switch (hot only in the run or start position), then through my safety kill switch (it's already got a set of terminals for this) to the coil of a fuel pump relay. Add a fuse for the fuel pump, go from that to a contact on the relay then to the pump.

As far as the plumbing - put the filter/separator before the pump? Is there any reason to keep the primer bulb (like to fill up the filter/separator after changing the filter element)? The specs I could find for this particular pump said it can be mounted something like 16 inches above the tank, so that's why I'm thinking the primer bulb is no longer needed. (I want to mount the pump just above the tank, both because that's the best location and because I don't want to use an anti-siphon valve).

How about a fuel pressure gauge? Are they worth it on a stock lake motor?

[flabum1017]

most guys here prefer the Holley pumps, but Carter is a good brand too. You can put the pump before or after the water sep, but if you put it before, you will need an 80 mesh screen filter before the pump to keep it clean..... You should be able to do away with the primer bulb so long as the electric pump can dry prime..... the vane pumps don't prime so easy and can wear out if dry primed too much. if you mount it low, the pump will stay primed after the initial pime up so long as you don't run out of gas,

[Gorilla0178]

Well I just did mine so its pretty fresh in my head. I went from the + batt fused to the relay, the other side to the ignition and a ground. The ground to the pump went to the - batt. My kill switch has 4 poles one side open one side closed and vise versa, it grounds the magnito so I broke the ground that goes to rely not the hot. I didnt want a hot on one side and a ground on the other. Now there are grounds on both sides just in case the switch messes up. It works good. As far as plumbing I've heard that they push better than pull, so I put a clear inline filter before the pump and the regulator directly on the output of the pump (dont know if you'll need one). Then to the water seperator/filter to the primer ball (just incase the pump fails or I need to prime it). Then there was another small filter at the motor so I left it. Mine is a 110gph free flow and I measured the output at the motor at 6 psi and its only about 75gph so I'm not sure what a 75gph will be at the motor, (i'm sure it depends on how far it has to push fuel, mine goes about 10 feet. Hope this helps.....

[Gorilla0178]

I just reread you other post and my pump did the same thing which is why I went to the electric pump. I found that it was due to the plastic casing that houses the diaphram was coning apart on one side. I snaped it back together and it worked good for a bit, then it happened again and stopped working.

[Forkin' Crazy]

I've been using a screen like this before the pump: http://www.jegs.com/i/Mr.+Gasket/720/9748/10002/-1

And then a spin on water separator after. Been using it like this for several years with out an issue.

[groundloop]

Well I just did mine so its pretty fresh in my head......As far as plumbing I've heard that they push better than pull, so I put a clear inline filter before the pump and the regulator directly on the output of the pump (dont know if you'll need one). Then to the water seperator/filter to the primer ball (just incase the pump fails or I need to prime it). ....


Can you pull fuel through the pump (with it turned off) with the primer bulb?




I've been using a screen like this before the pump: http://www.jegs.com/i/Mr.+Gasket/720/9748/10002/-1 (http://www.jegs.com/i/Mr.+Gasket/720/9748/10002/-1)

Thanks, that looks like a good idea.

[Gorilla0178]

Yes, you can prime it with the motor off, at least I could with the one I got. I'll make sure when I get back to the boat, but I'm sure I had to prime it before I started it up.

[rock]

I am rebuilding an STV and the previous owner had it plumbed from the tank to the seperator/filter to the pump then the Racor screen then the motor. Should the screen be first then pump then seperator/filter then motor. I have never used a screen before and the way this one is plumbed the only thing the screen does is protect the injectors. Seems the filter would stop anything the screen would if the filter was in front of the screen.
Rock

[Gorilla0178]

If it works i'm sure it makes no difference. Only reason I put my filter after the pump is some people said that the pumps push better than pull fuel. So I put a small filter before the pump to make sure nothing gets into the pump, then it pushes fuel through the filter/seperator.

[Forkin' Crazy]

I am rebuilding an STV and the previous owner had it plumbed from the tank to the seperator/filter to the pump then the Racor screen then the motor. Should the screen be first then pump then seperator/filter then motor. I have never used a screen before and the way this one is plumbed the only thing the screen does is protect the injectors. Seems the filter would stop anything the screen would if the filter was in front of the screen.
Rock

I like the screen before because in theory it should be easier to "suck" through. Fuel pumps from what I know like to "push" fuel better than to "pull" it.

[rock]

I'm gonna re-arrange some things.
Rock