1996 7.4 fuel pressure?

[Jeeperguy]

1996 7.4 So I'm having a hard start issue, after running around and then letting the truck sit for an hour or more, it cranks for alot longer than normal but does start. If it sits for a long time , say a few hrs or overnight it will start right up as normal?? Just did a duel pressure test and with key off its about 58lbs and drops to 30 in about 20 minutes. Is there a an average of drop off??? Been looking into maybe injector leaking or regulator. Any thoughts or experiences with this would be appreciated.

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[Schurkey]

Mine does about the same thing--starts good cold, cranks longer when hot.

Haven't even started to diagnose it.

I'm told it's a common result when the injectors leak.

 

[Jeeperguy]

Mine does about the same thing--starts good cold, cranks longer when hot.

Haven't even started to diagnose it.

I'm told it's a common result when the injectors leak.

That's what I'm leaning towards, I'm gonna do the upgraded bosch injectors. Mi e actually starts up just fine when hot/warm, it's only after sitting for about an hr it takes longer .

 

[454cid]

Mine was doing that, and it was a weak fuel pump. I never checked the pressure because I was sure it was the injectors and only replaced the fuel pump when it was obvious that it's time was limted..... I had to hit the bottom of the tank to get it going. When I replaced the pump the "injector problem" went away. I still have my original injectors and FPR, and am pushing 300K miles.

 

[stutaeng]

The 3 sources of fuel pressure drop are:

A. Leaky injector(s)

B. Faulty fuel pressure regulator

C. Faulty check ball on the fuel pump

There's ways to test the first 2. If those 2 tests are good then C. is the culprit.

 

[Jeeperguy]

Mine was doing that, and it was a weak fuel pump. I never checked the pressure because I was sure it was the injectors and only replaced the fuel pump when it was obvious that it's time was limted..... I had to hit the bottom of the tank to get it going. When I replaced the pump the "injector problem" went away. I still have my original injectors and FPR, and am pushing 300K miles.

Seeing I'm gonna do probably the whole fuel system anyways, I will probably just start with the pump.

 

[454cid]

Seeing I'm gonna do probably the whole fuel system anyways, I will probably just start with the pump.

I bought a Denso pump through Advance Auto and have been happy with it. I ordered it through their website and used a healthy discount code and free shipping.

 

[Jeeperguy]

I bought a Denso pump through Advance Auto and have been happy with it. I ordered it through their website and used a healthy discount code and free shipping.

Right on!

 

[Jeeperguy]

Right on!

So it's starting to get a little worse, so it's gonna get a full fuel system upgrade, new pump, regulator, bosch injectors, rail. And all the obvious stuff, cap/rotor,wires etc,,, Have a 700 mile trip to the dunes in a couple months and want no issues.

 

[454cid]

So it's starting to get a little worse, so it's gonna get a full fuel system upgrade, new pump, regulator, bosch injectors, rail. And all the obvious stuff, cap/rotor,wires etc,,, Have a 700 mile trip to the dunes in a couple months and want no issues.

Good luck finding a rail. They're NLA from GM. Really you shouldn't need the rail, Though. It's just a hollow tube in a special shape, as far as I know. There are no wear parts, so unless it's physically broken, you should be good to re-use it.