This is on a 91 5.0 TPI. The first start after sitting takes about 4-5 seconds to start. I have a fuel pressure gauge connected and the car will prim too around 30 PSI. As soon as I start cranking the PSI drops to about 20.

As soon as the car starts it jumps up to almost 40 PSI. If I take the vacuum line off the regulator it idles at 43 where it should be.

The pressure takes many hours to bleed off. If I start the car again after the first it starts right up because its still over 40psi at the rails.

The car has brand new bosch 3 injectors from South Bay and new Wix Fuel Filter. Everything else is stock fuel wise.

Any ideas of what cause this?

 

Weak FP or brush's starting to GO. System holds & maintains Pressure... Initial prime is low.

 

Are you saying the fuel pump is starting to go or the brushes on the starter?

 

Are you serious. I'm sorry. What does your starter have to do with a FP. There is a brushed motor in all FP's

 

Thanks for the lunchtime humor.

 

I never heard of "brush's starting to go" discussed in relation to fuel pressure. The weak fuel pump was the only thing I could think of.

Must be having a bad day? It's Friday man cheer up.

 

I'm as cheerful. As can be. You have never seen. Worn carbon brush. Contacts. Sorry, I tried to help you Diagnose

 

Above is a motor from a GM "delco" - FP. When the brush contacts are WORN = intermittent voltage, Thus weak Pump. Happy Friday!!!!! or the wet Magnets can- de-bond from the CAN = Locked up FP..

 

Kinda like This FP

 

Class.. Dis-missed. See Ya next time...

 

Good to know thanks.