FP dropping under boost

[Lobsterbak]

Hi Guys,

Finally got my GN up and going and all seems well...except that the FP drops to the low 20's once and while under boost. The car has an inline pump (unsure of make/model...switching to a 340 once I have funds), and idles at around 39 PSI with the vac. line on the regulator.

The pump is loud as hell, but Im guessing that's only because I'm used to an in tank pump. Could this be a bad regulator (have a Bosch adjustable), a bad pump...or something as simple as a vaccum leak?

Thanks in advance....

 

[turbofrank]

Bad pump,reg,fuel filter,kinked blocked fuel line.
good luck

 

[QUIP'6']

Hi Guys,

Finally got my GN up and going and all seems well...except that the FP drops to the low 20's once and while under boost. The car has an inline pump (unsure of make/model...switching to a 340 once I have funds), and idles at around 39 PSI with the vac. line on the regulator.

The pump is loud as hell, but Im guessing that's only because I'm used to an in tank pump. Could this be a bad regulator (have a Bosch adjustable), a bad pump...or something as simple as a vaccum leak?

Thanks in advance....

if your dropping that low then i would say it is the check valve in the pump causing you to lose volume thus pressure drops. is it stock or a bad walbro 169. if it were a regulator the pressure would drop to the initial 39 psi not 20 also i seen where the clamp came loose on the pump and lost pressure under boost or it had a tear or a weak fuel hose in the tank on the pump

 

[notacarlo]

I don't use a check valve with my in-line A1000, no pressure drops.

 

[vicious6]

I have an in-tank in my GN (Walbro 255) that is loud as hell and doing the same thing. I think it is one of the defective pumps. Have not had time to take it out and see. I have a regulator, pump, sender and tank as well as stainless straps to and filter for the car. Oh yeah, new 42.5s as well. What ever it is I will get it when I get time!

 

[bmackinnon]

That pump is toast, and so will be your headgaskets if you keep 'testing it out'. Drop in FP under boost (increased demand) is primary symptom of bad pump.... stay out of the gas (boost) until you have this resolved....

 

[notacarlo]

+10!

 

[vicious6]

+11

 

[QUIP'6']

I don't use a check valve with my in-line A1000, no pressure drops.

the check valve is in the pump!!!!!!!!!!!!!!!!!

 

[Lobsterbak]

Yeah, I know enough to stay out of the boost after I noticed it....I checked the pumps last night...both were leaking where the fittings were epoxied on. Time to goto a 340.

 

[87GN_70GS]

Since you already have an inline, it will be easiest to replace it with a Bosch 413, Bosch 044, Walbro gsl392 or Pierburg 7.00228.51.0