Okay guys, damn fed up here! Started my car for the first time after full buildup, cars a 85 MonteSS with an 87TPI intake system, When I started the fuel pressure shot up directly to 90psi!!! WTF is the reasoning for this, Where do I start? New Walbro 307, new injectors 22lb, New guage, New Regulator, Help is greatly appreciated. Thanks, Chief

 

What PSI are you aiming for? I would say the regulator, but I am speaking from no experience, just common sense. If it runs then the regulator has to be not doing it's job. Dunno, just trying to jump start the conversation.

BamaZ28

 

Thanks for the reply, I have changed my regulator twice in 2 days! Gone with new replacement stock. Basically I am supposed to be holding 40 psi but only holds for about 2 seconds then shoots up go 90psi. Dont know what I've done. All I hear is the fuel pump sending fuel back to the tank

 

Sounds like a pretty easy problem to figure out by following the fuel system steps. Your pump sends fuel down the fuel lines to the fuel inlet of the fuel rail, then pressurizes the fuel rails up to the set limit of the fuel regulator. Once the regulator sees its set limit the spring compresses and allows the fuel to release out the return line. If your regulator is functioning normally, then there has to be an abstuction in the return line to cause the raise in pressure. Even if I cranked my adjustable regulator as high as it will go, I seriously doubt it would hit 90 psi, so it must be a fuel evacuation problem. Are you sure that the fuel inlet is being fed into the correct line on the ful rail? Fuel should be going in the top rail line and coming out the bottom line.

 

Oh yeah, once you are sure it is plumbed correctly and it still doesn't work, pull the fuel return line off at the rail, then attach a hose and run it to a bucket under the car, and away from any ignition sources. Then fire up the car and see if the pressure has returned to normal. If the pressure is still high, you have a problem with your regulator, and since you said you have tried two already it would probably mean you are not installing them correctly. If the pressure returns to normal then you have a blockage of some kind between the intake and the gas tank.

 

Chief, sounds like you have a whole lotta searching to do Hopefully we can track this down , Good luck today, Mike

 

The regulators are vacuum dependant, how much vacuum are you getting at the regulator?

Is the regulator cap too short or is anything installed between the cap and spring?

What's the fuel pressure with the vacuum line disconnected ?

Is the return line crimped or blocked in any way???

 

I seriously doubt that it has anything to do with a regulator problem. No offence to the guy with the problem but in my opinion it is impossible that a fuel pump can even hit 90 PSI. I may be wrong but I don't think the cabability is even there for that kind of PSI. I would like to hear what you mean by "is the regulator cap too short" 90rocz. It in no way will cause even close to that pressure having the vaccume line disconnected. Just go ahead and do the checks I have described before any other suggestions, and I am sure you wil find the answer,