Spent

(same post as truck, tow vehicle & trailer forum)
Sub is hard to start when cold, takes 5-8 seconds of cranking to start. New plugs, cap, rotor, gas filter & wires. Only searches on internet I could find suggested fuel injectors are dirty. Anyone have history with this problem. Mileage 75,000, 4x4. Thanx in advance, Bill.

FOUNTAINATLAST

Most likely your fuel pump getting weak. After it sits the system looses prime & pump being weak takes longer to get up fuel pressure to start. These are very common problems on those late 90's Vortec motors. They are trying to push so much pressure they just don't last long.

blkhorse

iTrader: (1)

try looking at the fuel pump relay,do you hear the pump run for 2 seconds when you turn key on? most trucks have a oil pressure operated switch also.which will power the fuel pump when relay fails after getting the required oil pressure which would account for long cranking times

Lmarth

Blkhorse may be onto something here. See if you can determine whether this vehicle has TWO fuel pump relays ($20 each) up front. One is a 'start' relay, the other is a 'run' relay. Ran into this problem about five years ago on a Chevy pickup, albeit with TBI as I recall. I assume it's not setting a code??? You can pressure check the fuel pump output as was suggested. Let us know how you make out.

Lmarth

My foggy memory is coming back to me. The vehicle in the above post did not improve after changing the fuel pump in the tank. After changing one of the pump relays (I believe it was the start relay) you could hear the fuel pump come on as you plugged in the relay. As I recall, the two pump relays were interchangeable. For what it's worth...

blkhorse

iTrader: (1)

the oil pressure switch I am refering to is a mechanical switch(no relay) located I believe above the oil filter or on the rear of the block in the intake manifold area. it's the one with several wires going to it.the oil presure light/gauge sending unit has 1 wire

johnnyboatman

iTrader: (5)

check the fuel pressure valve, should be a vacumn line to it pull it off and see if its wet if so there your problem. the new 5.3l are real bad about that

ratman

if you only have this problem when its cold i would move the truck to florida where we don't have cold starting problems and 11 1/2 month boating season...just a thought, suit yourself

FOUNTAINATLAST

Listening for the pump is good a good idea that will give you an idea weither the relays may be working??? The vortec motors don't run off the oil pressure its all feed through the computer on those only older TBI systems used the oil pressure switch. Hook up a fuel pressure gauge, the port on a big block will be in front by the T-Stat. The pressure for vortecs start up is 58-62 psi after starting settles down to around 55 psi. These systems are very pressure sensitive even if there 10 psi low cold start up will be hard. A cheap try would be listen for the pump, if you here the pump cycle the key on and off 3-4 times to see if it starts easier???

FOUNTAINATLAST

A leaking fuel regulator would give you a hard starting condition when the motor was hot, or after a short sit time. The regulator leaks down and floods the motor causing a flooded type situation...