MSefi.com read only forum (Jan.15,2018)

Has anyone had a leaky relief valve on their fuel pump?

I had a temporary spike in pressure that caused the pump relief valve to open until I shut the engine off.
I fixed the pressure issue, but now the pump drips every once in a while.
I don't think the fittings are the problem, but I'll check.
I'm almost certain the relief valve is not closing completely for some reason.
Maybe it didn't re-seat properly or a bit of debris got in there.
I'm running the pump inline rather than in-tank, in-tank would be a non-issue.

Any thoughts or experience would be helpful.

Thanks!

It's definitely coming from the pressure relief valve.
Even when it's gravity fed, I can see a very small amount wicking around the pump surface.
I was able to tug on the valve spring to open it manually and let some gas out in hopes that it might re-seat properly.
No such luck. It still seems to leak ever so slightly.

Is this a common problem?

I'm planning on immersing the entire pump in a sealed tank, so the problem will be eventually solved.

Shouldn't the pressure relief be plumbed back to the tank? What kind of pump are we talking about here?

Ken

kjones6039 wrote:Shouldn't the pressure relief be plumbed back to the tank? What kind of pump are we talking about here?

This is a on a motorcycle, so I could not fit the pump in the tank.
I enclosed inlet side of the pump with an aluminum tube.
The outlet side of the pump is exposed, so it's operating like an in-line pump.
If the pump was immersed in a tank as it was meant to be used, any leak from the pressure relief valve would go back into the tank.
Your suggestion of plumbing the pressure relief back to the tank is a good one, but there's no nipple for the pressure relief output, just a hole.
I theory, I could epoxy a nipple on there, but that's not a great long term solution.

My long term plan is to immerse the entire pump in a fully enclosed aluminum tube.
I'm waiting on aluminum stock and O-rings now.

Just one 'off-the-wall' thought occurs to me.....

Couldn't you tee the relief back into the feed line to accomplish the same thing

Just my weird thinking kicking in here, but I can't see why it wouldn't work......

Ken

kjones6039 wrote:Just one 'off-the-wall' thought occurs to me.....

Couldn't you tee the relief back into the feed line to accomplish the same thing

I'm all for 'off-the-wall' ideas. It's the story of my life

As I say, I can't think of an easy way to connect to the relief, it's just a hole.

I had the same problem running an internal pump external. I switched to the suzuki ltr450 pump to solve it.

750essess wrote:I had the same problem running an internal pump external. I switched to the suzuki ltr450 pump to solve it.

Great info!! That removes a number of doubts. I have a second pump that I use for testing.
I was thinking of swapping in case the pump was bad, based on what you say, it won't make any difference.

I've been looking for an ltr450 pump at a decent price. They don't seem to go cheap.
I know I can make a good housing, others have done something similar.
A friend is letting me use his lathe to turn an end cap with an O-ring gland.
That will definitely seal it up. It should also help to keep the pump cool on hot summer days.

You're dealing with an internal style pump that is supposed to run surrounded by fuel for cooling. You hafe the fuel pressure popoff dumping in air. This is on a motorcycle with lots of hot exhaust pipes all over. This sounds like a fireball in the making. Get rid of this thing and get the proper external pump and plumb it correctly before you blow yourself up. JMHO billk