Okay guys i need some help. Two weeks ago i was driving home for lunch and my truck seemed a little sluggish and i pulled into the driveway. I shut off the engine and went inside to eat, i came back out and she will not start. So i look down at my fuel pressure gauge and i have no fuel pressure when cranking. When i turn the key to the run position it'll kick on and show 12 psi to prime the motor. But then i go to start and nothing and after cranking the lift pump does not run the 20 seconds or whatever like it's supposed to, so i figured bad lift pump, well i had an extra carter so i changed it out and it then fired right up, ran perfectly and showed 16 psi just like it should. About 2 weeks have gone by. Well then last night i went up to the bar. I was there for aboout an hour and was getting ready to home i go out and nothing again, same thing. Key on, LP runs 2 seconds to prime, crank and nothing, the pump doesn't run again, so i got another pump that a friend had to get the truck home, changed it out in the parking lot and truck fired up and ran perfectly fine again all the way home and drives just like normal.

The first pump i have had right at a year and was still showing a good 12 psi. When i had the issue, and then the second spare pump i had lasted me all of two weeks also when i first pump died i removed my powerpuck so no power adders when the spare croaked on me. So my ? is, Was it just a bad LP out of the box or do i need to be looking somewhere else? I'm looking at ordering a new Raptor 100 LP, but if that's not the problem then i need the money for the cause of the problem. Please help if you can

 

If the lift pump, old or new, shows at least 11 psi at cranking and it will not start the problem is in the injection pump. Unfortunately, injection pump failures do not issue any codes more often than not, so it becomes a matter of being sure you have fuel pressure to the injection pump and a no start condition.

 

well that's the thing though, the Lift pump doesn't run while cranking the engine or after bumping the starter. The only time the LP runs is the first 2 seconds when i first turn the key on to prime the engine waiting for the wait to start light to go off. After that it's deader than a door nail. Which is why i thought it was the pump, but then to have a 2 week old pump do the exact same thing is what has me puzzled. I just don't want to buy a new high dollar Raptor lift pump and that not fix the problem.

 

I went thru 2 VP$$ (first one had a defect.) We also ended up putting on a FASS LP (mid-line!!!!!!) If you're putting the new LP back in the engine compartment it's trying to pull the fuel thru, mid-line LP pushes the fuel to VP$$.

 

It'd be good to know if there's any voltage going to the pump when it's acting up...the yellow/brown stripe wire is pos.(+).

 

Wish I could help but I am stupid about such things. Don’t want to change the direction of the thread either but: Will it hurt anything to apply voltage directly to the pump (after disconnecting the harness)? Just to rule out any connector/relay problems.

 

Yeah see that's what i'm wandering. Just becuase i can turn the key to the run position and the LP does the first 2 second prime. It just doesn't run while cranking the engine like it's supposed too. However if it's an electrical issue, replacing the LP shouldn't have fixed the problem. At which a new LP fixed the problem and my truck ran great for two weeks until it did it again. I just wish i knew if it was just a bad Lift pump, or if i'm having some kinda of Electrical problem. If anyone has had the same issue your input would be greatly appreciated. If not then i guess this evening I'm ordering a Raptor 100 and hopefully that will cure the problem.

 

The lift pump doesn't come on during an engine start.
Try turning the keyswitch just enough to "bump" the starter then very quickly release...that should get you The Free 25 Second Lift Pump Run.

 

Do you guys have a problem reading. i've said it multiple times now. My lift pump doesn't run after bumping the starter. It's supposed to run for 25 seconds after you bump the starter, but mine does not. The only thing it DOES is when i first turn the key on the pump primes the sytem, that's it. It DOESN'T run by bumping the starter like it's supposed too. I'm not trying to be a jerk, but all you guys are telling me is things i already know and your not answering the question i asked? I just want to get this figured out because i don't have tons of money to throw into my truck right now with my son being induced to be born tomarrow.

 

Sorry rusty. I am still learning and am no help at all. Hopefully somebody in the know will chime in. Thats also why I was wondering if

 

a suggestion, check the power going to the pump within the 25 seconds after a "bump" that should tell you something

 

Yup, might be an ECM problem since that's where the lift pump gets it power.
I use real thin needles to pierce the pump wiring insulation then connect the alligator clips of my digital volt ohm meter(DVOM). After making the connections, do the "bump" then check the DVOM DC volts in the 25 seconds. Mine shows around 11.5 volts.
If the volts come up zero then you might take the lift pump wiring connector loose and alligator clip the connectors on the lift pump and check the lift pump motor resistance in case the ECM needs to see resistance before powering up the lift pump.

The very best of wishes to your new son and family.

 

Well thank you very much guys, those are some real anwsers of things i can try. Just got back home from the hospital, happy to be home. Staying in a hosiptal two nights is about the worst thing i've done yet. I'm super excited about becoming a daddy, just not ready to go back to work tomarrow, but can't afford to take off anymore time. Thanks for the advice, i went ahead and got a Raptor coming even if that's not the issue, it's not like i wasn't going to get one anyways because the Carter pumps **** and my PSI has steadly been dropping over the past year. Not to mention the warranty is hard to beat. I'm going to pick it up from UPS here in about an hour. Which if i still have issues, oh well, what a credit card is for right. lol.
Also wanted to sat sorry about my attitude earlier in the week, with my son coming it has been very stressful lately and my truck giving me fits was the "icing on the cake." Thanks for the help guys and if a new pump doesn't fix it i'll look into the ECM and electrical connectors.