Flyinb1

I bypassed the tank all togather, put a hose right to the pump and in a can of fuel setting next to the truck and still lost presure.

Flyinb1

Well.....I ordered an Air dog pump system...Heck with it, i will redo the the whole darn fuel system Will let ya know how it turns out.

Bruce

Sixpack

Probably a silly question, but did you check your gauge setup with a test gauge? If mech, then the isolator? Electrical connections if electric? Just a couple more ideas that I didn't see mentioned.

Flyinb1

Yea... its not the gauge as the engine will sputter and quit when the pressure drops if i dont shut it down.

bent valves

Flyinb1, hopefully the new pump will restore the pressure but something still bothers me.

With two of the Walbro pumps the pressure will drop to zero after a couple of minutes. In your test you observed the pressure gauge falling and the return line from the regulator increase in fuel volume. The regulator is a spring loaded ball that gets pushed off its seat with rising fuel pressure and this will return fuel to the tank.

If all of the above is true there has to be a blockage somewhere after the regulator and before the fuel pressure gauge or you got two bad pumps or a bad regulator.

I will be following this thread when you put in the new Walbro.

Flyinb1

That was my exact thought as well so i changed the entire line from the pump to the filter housing. Still same problem. I have noticed that when i first start the truck the pressure stays for a longer time~5 to 6 minutes then as the pump runs longer the time it holds pressure gets shorter. Sometimes at first it kinda pulses several pounds up and down then just slowly drops. When i observed the return line it would pulse, when pressure was good very little fuel would come out, then when a lot of fuel started to come out the pressure would drop several pounds. Now i think what was happening is that the pump was barely keeping pressure and when the return valve would open it couldent keep up so when the valve closed pressure would return, Weak pump?

Anyway i am still waiting for my new pump (Air Dog) ,someone droped the ball on that as i ordered it 9/10 and it will be here next tuesday.

Flyinb1

Update....Got my new pump yesterday. installed and all is well. So....it looks like my first Walbro lasted about 5000 miles and the second 75 miles. The pump was the last thing i suspected as it was new and Walbros dont seem to have many issues.

Bruce