checkmate1996

Ok. This is just a quick tip for anyone replacing fuel pumps. Replace the checkvalve at the same time. I tried getting away with it a year ago and it came back to haunt me just in time for SITM.

Anyway, Big Dave noticed a slight drip coming from the rear and I immediately suspected the checkvalve since I didn't replace it. After I replaced it in the middle of the night at Dave's house by his guest cottage, I swear my gas mileage went from about 11 or 12 to 19 or 20 on the way home.

Also, when I got the new checkvalve, the bag had one wrong sized crush ring out the three. Drew Peelman, Flying Dog verified that something wasn't right as clearly didn't fit over the checkvalve.

Anyway, YMMV!

Sean79 5spd

Why would the check valve improve gas mileage. I replaced my external fuel pump with one that had a check valve built in but had no increase in gas mileage. My current numbers are 1o-12 MPG.

Sean

rixter

check valve can and will improve gas mileage
10-12 mpg is low even for a shark.. you should be in the 17-20 range

AO

When it's leakin a good drip every second... well you do the math.

Glad to hea you got home all right. Pleasure meting you.

Big Dave

Glad you got it fixed, Brad!

(8 mpg improvement = more than a "slight" drip )

checkmate1996

I went from 2.5 tanks to 1.5 on the way home...

Big Dave, Andy...Pleasure meeting you guys too...I'm looking forward to the next gig in Michigan or if we can scrape some 928s here in c-bus...

Andy, keep us posted on the door fix...

Garth S

How so? Agreed that a leak is a leak is a leak - to atmosphere ... regardless of where it occurs: I think Seans question addresses a check valve that may pass (leak) internally - but is not leaking to atmosphere. How would that impact fuel consumption?

Yes, 12 to 20 mpg says 40% of every tank was sprayed to atmosphere ....

BrianG

I'm with Garth. My estimate is that the check-valve prevents drain-back of the fuel lines into the fuel tank to prevent a need to prime the fuel lines on each start-up.

How can this function affect consumption?

Are you referring to another check-valve?

Big Dave

The check valve was leaking fuel onto the ground (or at least the copper washers were). I don't think the valve itself was malfunctioning. The lost fuel wasn't being consumed at all....just dripping to the ground.