Archived new lp and still nothing; busted down in West Texas

[mstephenson]

it has been hard to start lately like it was losing its prime and when pulling a full load >10k# pressure went down to 9ish.



started the truck last night 13#. got back into the truck later and 10#. 3/4mile i had 5#. i bought a new lp (this will make 4) waiting for this day so i installed today, but at the quick release before the pump there is no fuel in the line. i have cranked it over for at least 20 seconds many times and still no fuel at the quick release. i cracked the banjo at the vp and fuel comes out while lp is on. i cracked the #3 injector and only a little fuel has bled out so far.



do keep trying to turn it over?

do i check current? i have a volt meter, but don't know the numbers.

and (i hate to ask this question) could it be the vp?



thanks ahead of time.



99 4x4 qc sb 3. 54 185K

 

[EKlem]

I would guess that it is not your VP is there is no fuel in the line before the pump. If you have access to shop air, set the regulator at 15-20psi and pressurize your fuel tank while running the lift pump. When doing this you will need to have a line or bleeder screw(I don't know the 24V's that well) cracked after the pump to let all the air out. As soon as there is solid fuel in the lift pump, you should be all set. At this point, cracking the injector should do the trick. Most pumps will not pump air. I hope that this helps.

 

[RAJohnson]

FYI, I have read in these threads were the pick up tube in the tank can become plugged. If all else fail do a search and check it out. With you losing a total of 4 pumps, something most be causing it.

 

[guava]

you may need to cycle the lift pump many many times to get it to prime. Cracking more than just one line so you know that fuel is getting to all the injectors lets you know your doing it right. It just takes a while. For some people, a LONG while.

 

[TowPro]

I notice you talk about your pressures. What size (and how long) is the line to your gauge?



I had the same problem, replaced the lift pump and it would not start. I messed with it for hours. It would start to prime but lift pump timer would shutoff and fuel would return to tank.



I was using a gauge that had 3' of 1/4"id hose so I could see it from the windshield. Took the gauge off and it primed first try! Seems the additional air space in the gauge hose was more then the system could "prime" during the lift pump cycle.



I also notice you say your "cranking it over". You don't want to crank the engine over as this gets air into the injector lines. Just put the key to ON, then just "bump" to start and release it back to on, you will hear

lthe ift pump start to run for about 20 sec. do that several times and it should start. It will miss and smoke when it does start, but it should start.



If I recall, I think the lift pump actual slows down when your cranking the engine as a fix for a hot start issue the CTD had in the early 24V days.

 

[mstephenson]

ok. i got it started and this is what's happening. 7# at the guage, BUT i have a RR4 and it's reading 0. 55gph at idle (which sounds like good flow as per someone at tdr). the truck sounded o. k. while idling, but i didn't test drive.



is the RR4 reading what fuel the truck is delivering or what the computer is telling it to deliver?



could my guage (diprocol) be bad (it was connected at test port on top of the fuel filter (which was replaced ~1000 miles ago)



thanks

 

[LStanphill]

Have you check voltage at the lift pump while experienceing these conditions?



I have had mine get plugged with debris on several occasions.

 

[RAJohnson]

ok. i got it started and this is what's happening. 7# at the guage, BUT i have a RR4 and it's reading 0. 55gph at idle (which sounds like good flow as per someone at tdr). the truck sounded o. k. while idling, but i didn't test drive.



is the RR4 reading what fuel the truck is delivering or what the computer is telling it to deliver?



could my guage (diprocol) be bad (it was connected at test port on top of the fuel filter (which was replaced ~1000 miles ago)



thanks

FYI, Not sure if this could pertain to your truck, but I have read in different threads where there could be a gasket or o-ring on the inside of the FF, that is blocking the top of the FF where your gauge is tapped at.

 

[mstephenson]

a neigbbor and myself got the truck running. it was all kinds of gremlins. here's the list...



i pulled the quick release and blew air back to the tank. ( i sucked it down pretty low for a period of time )



neighbor discovered a wire on the heater relay was off. (that explains lots of fuel, but no start)

dealership confirmed iat sensor code was tripped.

dealership would neither confirm/deny my accusations of detuning my ecm upon replacement of original lp. he would say that he had never heard of vp44 lasting 185K and attributed it to my claim (if true).



we purged... we purged... we purged the air and it fired off.



in the meantime i had checked prices on vp44 and this is what i found out:



the best price i could find was performancedieselwarehouse.com 1089$ + 400$ core. they also renewed my faith in humanity when they could have sold me a pump, but didn't after hearing my symtoms. i will be doing business with them next time i need something.