1500 fuel pressure

[spaner]

I have a 1996 gmc 1500 pick up with 5.7 litre v8, 160,000 miles. Has been getting progressively harder to start 1st thing in morning. Cranks over fine but no fire. After it warms up starts fine. Have changed fuel filter, no difference. Have checked fuel pressure. About 55 psi before cranking engine. Is this too low for a cold start? Before starting when engine is warm pressure reads 65 psi (where book says it should be). What tells fuel pump to stop pumping when pressure reaches 55 psi in morning? Fuel pressure regulator? Any thoughts would be appreciated.

[wafrederick]

The fuel pressure spec is 60 to 66 psi and GMs will not run on very low fuel pressure.If you want where I got this from not runing on very low fuel pressure on GMs,a Vetronix rep that is now retired.You can go to the dealer or your nearest CarQuest auto parts store for a fuel pump.Carquest did switch to Delphi for their fuel pump supplier and ditched Airtex whom was thier fuel pump supplier.It does say on the box with the Delphi logal and Carquest did have problems with their fuel pumps when Airtex was their supplier.Stay away from an Airtex fuel pump,they are junk,will not warranty thier pumps calling it installer error.Believe me,put 6 of of them in one Chevy truck.Airtex does make Napa's fuel pumps and Carter is another one to stay away from too.Had good luck with them once and they failed instantly.If it is the fuel pump,change the fuel filter too and it is a must.The old fuel filter is full of dirt and crud which will ruin the new fuel pump.

[spaner]

Response appreciated but I still don't know why the fuel pump is not able to supply the correct 60 to 65 psi for only the first start of the day. If the fuel pump is on the way out wouldn't it just provide a low pressure at all times?

[sechracer]

Originally Posted by spaner

Response appreciated but I still don't know why the fuel pump is not able to supply the correct 60 to 65 psi for only the first start of the day. If the fuel pump is on the way out wouldn't it just provide a low pressure at all times?

Usually, that is what would happen, But the cold may be why its not working as good. I would hook up the pressure guage when its cold out, then carefully pinch the rubber part of the return line off with a pair of vice grips. See where it goes. It should make the pressure jump to around 80psi +. Do it again when its warm. If they are different, I would replace the fuel pump and strainer. However, I would recommend staying away from the after market pumps. I put 4 in my 97 before I said hell with it and bought a gm one. Factory pumps last alot longer where aftermarkets only warranty for 1 year ( I had to replace mine every 12 or 13 months). Figure if your truck has never had a pump in it, the pump lasted 11 years....... Gm is the better bet. Now if the pressures are the same, I would look into the pressure regulator.