This suggests spark & valve events are just fine, and that it simply isn't getting fuel or enough of it.

Scrutinize the fuel system. Unfortunately, this wouldn't be the first time someone installed a new pump & had a bad one out of the box.

The other component that could come into question is the fuel pressure regulator. Admittedly, I've never had an issue with a FPR, so my experience there is limited. However, I have left the return line off before, to confirm suspicions of a weak pump (pump couldn't generate enough pressure to be regulated).

Here's what I would do: Put a gauge on the fuel rail, turn the key to ON but not run, one cycle. What pressure is on the gauge?

Next, cycle the key repeatedly. ON (wait for fuel pump relay to click off), then OFF, then back ON, wait for relay, OFF, ON, OFF. What pressure is on the gauge?

Now, watch the pressure over time. Does it hold? What pressure does it read after sitting 30 minutes?

Next, start the engine (or try). What happens to pressure while running/cranking? This may require a helper. Although, you may be able to place the gauge on the windshield & watch it from the driver's seat.

Do these tests, and report back. Be specific. The more quality information you provide the better quality of help we can provide.

 

To NotEnoughtTrucks 2014 in response to your thread. the only consistency here is you have been under the tree too long. If you would of read post 2 weeks ago, the truck had no fuel pressure and didn't run. By very appreciative help from others, the truck now has fuel pressure, which was checked with a fuel pressure gauge and runs for at least a minute now which is far better than when I started. Also, never deleted rear fuel tank, replaced rear fuel tank with a new one and deleted the front tank.

 

What port did you connect the gage to? Before or after the regulator?

It seems electrical to me, if the pump primes the system and it runs until the original prime runs out than something that tells the fuel pump to keep running may be turning it off.

I would start by checking voltage at the pump and making sure it has voltage after the initial fire up

 

When testing fuel pressure connected the gauge to the schraeder valve on the rail. When I turn the key off and on 5 times it will build pressure truck will start but then it will quit listen for both fuel pumps and they sound like they are running. Should I check the voltage on fuel pump with truck running? I can keep it running by spraying gas into throttle body. thanks

 

Please test fuel pressure as I explained. I suspect the pump can't move enough fuel to keep pressure up when the injectors are firing. So pressure looks ok when not running. I bet it drops off once started.

If it doesn't have a pressure issue, look to the signal to the injectors, as was suggested by another forum user.

 

Thanks for the info. I will try this tomorrow and let you know what happens.

 

Did the test you suggested GoinBoarding. Turned the key on once and fuel pressure reading was 50. Cycled off and on 5 times pressure went to 55. Let sit for 45 minutes and pressure was 45 cycled off and on 5 more times pressure stayed at 45. Truck started up on its own but then ran out of fuel. Appreciate all your help

 

After the truck started, what did the pressure do? I know you said it ran out of fuel, just trying to be thorough.

 

Stayed at 45 lbs

 

The 12lb/hr injectors are specified to operate at 55-60psi. 45 may be too low. I would be curious if the regulator is blowing open prematurely or if the pump is weak. You could try disconnecting the return line, and see if anything flows out when you pressurize the system (be careful in case it does!). My instinct says weak pump though.

You replaced the in tank pump, high pressure pump on the frame rail, and fuel filter, correct?

Disclaimer: I'm not a 4.9L pro. Sometimes I ask questions that I know have important answers, to aid a more 4.9L knowledgable individual in helping a fellow FTE member.

 

Have you tried checking for any codes yet? You confirmed the injectors are pulsing with a noid light?

 

Rereading RLA's posts here, and others' in the former threads, you may want to move forward with checking the injectors' pulse with a noid light.

Can anyone confirm if 45 psi KOEO fuel pressure is adequate for an 87' 4.9L?

Edit: Leadhead and I were typing at the same time.

 

Thanks for response. I put new fuel pump in tank, fuel pump on rail, fuel filter, new injectors. I will try disconnecting the return line. Be back in touch. thanks

 

Where I eliminated the crossover valve, I checked the return line and had gas. Started truck up still runs for a minute then acts like running out of fuel.

 

Okay, I'd move to injector pulse.

As LeadHead suggested, check for codes too.