Is the dealer stumped tooo... sounds like the shops in your area just opened with a bunch of guys watching Shade Tree Mechanics on cable....LoL

If you are still getting 50psi of pressure then I would think the pump is ok, a fuel pump will only provide "flow" to the system it is the fuel pressure regulator the provides the proper "pressure" to the system for the injectors to squirt fuel.

 

When you replaced the pump did you do just the pump or the sending unit also?

Might want to look over the TBS's for your truck. I remember something about fuel pump / wires / sending unit .

Might just turn out to be a bad connection back at the sending unit to pump.

I have seen faulty wires act like this. This is why I was heavy on posting about checking the volts from battery to starter. You might have a solid pump but bad wires to it.

Had one truck with a good starter relay / starter / battery / ign everything tested out good. What it turned out to be was the wire from the ign. to the starter, it had an open circut and had damaged the wire. Thought that even though the Ign. relay was new it would not be the cause, but low and behold it was a faulty unit. So replaced it, wire, and made sure the rods from the ign. to ign. relay were straight. No more starting issues.

 

well considering two of the shops are dealers.....

 

And have you looked at the connections on the starter? Corrosion or a loose connection there will also cause a starting issue.

 

That is not true, the fuel pump IS responsible for providing adequate fuel volume AND pressure which should be between 60 and 66 PSI with the pump running. The regulatorkeeps it from rising ABOVE 66 PSI it cannot build pressure it simply "regulates" it. If you only have 50 PSI at idle then the system is restricted (plugged filter etc..) or the new pump is bad, which is NOT uncommon especially if it's an aftermarket pump. But none of this explains why it will start with a jump...that has to be battery/ starter/ wiring related IMO.

 

Its sad that aftermarket items are getting BASHED so much. I have found, in many years of wrenching, that sometimes the aftermarket items are much better then the OEM items (pending on the MFG). Some are just CHEAP junk, but you get what you pay for.

Moonzie:
It does not matter if they are dealerships or not. Its the EXP. that will aid with this.

I have checked with some trusted mechanics locally here that I know (ones that I would let fix things for me and trust me I dont trust many at all to do any work on my rides I am supper picky when it comes to my safety). They agree that the Volts should be check at the pump connection and from the battery to starter. They mainly agree that this falls upon things I have posted already.
STARTER (and starting system)
BATTERY (even new if was on the shelf for more then a year then it could be bad)
CABLES (can never tell what is going on until you test them and prove that current is flowing right)



Good luck


*EDIT: swartlkk* - comments removed...
Thanks swartlkk

 

Well... Now I will have to say that it is quite possibly a faulty connection somewhere along the way and the added boost from the additional voltage via the jump is giving the pump an extra kick in the pants. What is your system voltage while it's running? How far does it dip when you try to start the truck? I really can't see this being a starter or a cable to the starter problem as it still starts when jumped. I even hightly doubt that it is a corrosion issue at the starter either. But I'm assuming that the truck turns over fine when

50psi is barely enough to start the truck and is not where it should be. Is this the pressure that the pump will hold when it is primed up? Has anyone done a fuel pressure leak down test? Has anyone checked the voltage at the pump? Have you pulled the fuel pump relay and checked the voltage supply to the switched side of the relay? These last two questions would tell you if it is the pump or the wiring.

 

It may be that there is a faulty electrical connection at the tank, then with the extra juice from the jump it gives the pump the voltage it needs to get the truck started...

I would go back to the shop that replaced the pump and say the part is faulty since you have taken it to that many shops and have checked all the obvious electrical stuff that is not related to the pump, ie starter, battery terminals etc.. The mechanic might not have gotten the connnection tight enough if it is a nut/bolt connection and corrosion has built up...

 

well i figured it out and it was the one thing i thought of... the FUEL PUMP... if you push the peddle to the floor just like i said before the truck went no where it needed a jump to push more volts to the pump to have more pressure to start..... as soon as i was finished with the pump i primed the pump and it fired right up and i only had like 4 volts on the battery... and when i pushed the peddle to the floor it put me into my seat... so i thank those of you who help me try to figure this problem i had so i wouldn't have to spend 300$ on a new fuel pump...