Cant get truck fired back up

[blk350on20s]

Hey guys. Just put a new hpfp, hpfp to rail tubes and a new -8 line from my fass. I cycled the key a few times and then hit it to let it do its auto crank. It fired up at the end of the crank. It sounded a little weird so i popped my dash daq on. Frp was going from 5000 to 10000 and slowly creeping up and bouncing around. It made its way to 20000 and then dropped to 1000 and right to 5000. It then jumped back up and creeped to 25000 and thats where i shut it down. Talked to shane and he mentioned the harness could br grounding. I screwed with the outside harness and fired it back up. It took about the same cranking as the first time. This time it idled smooth at 5000 for maybe 7 seconds. It then started chugging and hiccuping until it shut off on its own. The first time it ran for maybe 45 seconds and the second time 30 seconds. It now will not fire at all. Im seeing 55 to60 on the frp. 1960 on the pw while cranking. My first guess is it ran out of fuel and now has all that air in the system. What i dont get is the first set of rp readings. What you guys think. Im really at my end with patience for this truck. Thanks. Ryan

 

[Dzchey21]

most likely its air, it makes the valves in the pump do lots of odd stuff.

Did you inspect or update the harness when you had the pump out? you probably should have noticed an issue with it as well as it should probably pop a fuse eventually too.

Try to start it again im thinking there is just a ton of air in the system that needs to get worked out, the truck probably wont start easy till after you take it for a test drive

 

[78f100]

Wish I could help but I have not changed a hpfp yet.
Good luck getting it going, I know your ready.

 

[blk350on20s]

I put a new gasket/harness on when i did the pump. The only thing i didnt change was the outside connector that goes from the hpfp harness plug to the plug that attaches to the gp module bracket. I searched the forums before i posted and saw that number 74 in the engine bay fuse box would pop. I checked that and all was fine. Worth pulling the waste gate and cracking the supply line? Any other fuses to check? Will a frp sensor cause a no start? Thanks guys. And yes im ready for a working running right truck. Its been all work and no payoff for a while

 

[blk350on20s]

Should i just go and pull my turbos and replace the hpfp gasket/harness with my old one?

 

[black6.4]

I let my fuel pump run for about ten minuets after my build everything was drained/with air and a second hpfp was added took maybe 3 five second cranks and it fired...maybe try that and if nothing maybe plug somewhere not making good connection? Guessing air is the culprit

 

[blk350on20s]

So run a jumper wire to the pump and let it run? The pumps shut off after 20 seconds or so

 

[cory151]

So run a jumper wire to the pump and let it run? The pumps shut off after 20 seconds or so

Or keep cycling the key.

 

[kyle43335]

crank the truck a bit,then loosen the line going to each head 1 at a time,cranking between each.

you will see air bubble pushing back out of each rail.

 

[blk350on20s]

I will try that. The 25k rp at idle has me thinking its hpfp harness related. Can air cause that?

 

[kyle43335]

I will try that. The 25k rp at idle has me thinking its hpfp harness related. Can air cause that?

take a dvom,and resistance test the through the wiring.

if i remember correctly? you should see around 5 ohms in the vcv,and pcv.

ill check a pump i have hear and confirm for you.

 

[black6.4]

I don't think air should make the rp read that also the egt plug will plug into the hpfp plug..so check that.and before I set my cab down I ran the air dog wires to the battery and let it run mainly a leak test ..you can also crack the high pressure line at each head like stated above I would start with that before tearing back into it deep

 

[Cajunhunter67]

Sounds like air in the system. cycle the key about 8 times. Keep a battery charger handy. I have also taken and loosened the fuel bolt at the fuel cooler and bled it there. Keep us updated.

 

[SEABEE08FX4]

Did you prime the pump? In other words run the pump with the motor off till fuel ran out at the HPFP supply line then snug it back up ?

 

[blk350on20s]

No i didnt. I ran the key 10 times prior. Should have jumped the pump. No batts in the truck so i didnt. Can a bad frp sensor cause a no start?

 

[MorganY]

Weren't you going to replace the rp sensor too when you did the pump?

 

[SEABEE08FX4]

Its possible but I bet you have air trapped in the lines.

 

[blk350on20s]

Well im getting decent fuel at the rail to head line when i crack it. Its just spewing out. No ungodly pressure. Sensors only reading 26. Earlier would read solid 55. Im gonna replace sensor and see wat happens tomorrow but i think this pump is screwed and not making pressure. Im so frustrated its unreal

 

[SEABEE08FX4]

Its a cheap part at least to eliminate it as a cause.

 

[Cajunhunter67]

Well im getting decent fuel at the rail to head line when i crack it. Its just spewing out. No ungodly pressure. Sensors only reading 26. Earlier would read solid 55. Im gonna replace sensor and see wat happens tomorrow but i think this pump is screwed and not making pressure. Im so frustrated its unreal

Keep ya head up. Sounds like it may be the pump, but keep in mind the 6.4 doesnt require alot of pressure from the lift pump. Hope the sensor fixes it.