Walbro 255 pump
AEM Fuel Rail & FPR
Precision 1000cc injectors
Autolink liquid-filled guage on rail
stock everything else.

Got everything back together on my car from about 6 months of sitting and after I prime the fuel pump the pressure drops right down to zero. If I start the car it is fine and holds a steady pressure @ 44psi. I drove the car for about fifty miles and it runs ok.

No matter how many times I prime the pump the pressure will drop right back to zero after the pump turns off. There are no external fuel leaks anywhere.

Why is it doing this? Bad AEM FPR? Last year it was fine.

 

when my car was running *cough* *cough* and i turned the key to on, the pressure would go up, and slowly fall back to 0 after a minute or so. This is with a brand new aeromotive FPR

PS check my thread

 

yah mine doesnt hold it for very long at all. I have just enough time to turn the key and look around my hood too see the needle drop.

 

Mine does the samething. Never considered it to be a problem. I would only worry if it dropped while the car was on or under boost!

 

yah we'll find out if its really an issue when it goes on the dyno next week. Im bring a spare FPR just in case.

 

i dont think that the walbro pump holds the residual pressure the same as a stock fuel pump. the check valve that does that may be too much of a restriction.

 

my fp also drops off like a brick. after shutting the car down. this is with a weldon regulator. it also did the same with my aeromotive regulator. im also using the walbro HP pump.

 

It's the fuel backfeeding back through the walbro pump. mine does this too.. so it better be ok

I think philipwight was on to something... It's sort of obvious by the size (and someone correct me if I'm wrong) but the stock and walbro are two totaly different style pumps. So I wouldnt compare the way the stock one holds pressure vs the walbro.

If my teacher spoke english I would have been able to describe the difference between the two.

 

Im running the walbro 255, aem rail, and b&m gauge and fpr, and mine DOES NOT drop off like a brick. I will be double checking this once the car is back together.

 

it's s o.k., as long as she holds when the pump is running, stays set were you put it, and doesnt drop off under boost. All is working well. The factory regulator, and pump are meant to hold pressure, so they start on the 1st crank.

 

cool thanks for the info guys... so this explains why I always have to let the fuel pump prime before I start it.