Engine/Transmission (1998.5 - 2002) Changed sending unit this weekend, fine for two days, good lift pressure, hard start

[2broke2smoke]

changed sending unit ...



truck ran fine for 2 days ...



last night and this morning VERRRRY hard to start ...



like the first time you put a new set of injectors ...



lift pump pressure is perfect ... 15psi @ idle ... 10psi @wot (0-110 uphill pull)



no smoke ... hesitation ... miss ... etc ... no codes



great power ...



did three 0-110mph wot blasts up long interstate hills ... perfect



any thoughts

 

[blacksheepdiesel]

What sending unit?

Godspeed,
Trent

 

[2broke2smoke]

:-laf



ahhh yeah ...



the fuel level sending unit in the tank

 

[blacksheepdiesel]

Don't see how that could cause a hard start UNLESS the connection for the fuel suction line is not a good one. Might try taking that connector off ( I know, it's a PITA!) and put it back on to see if that corrects the problem. If that is not it then air is getting in the line somewhere else.

Godspeed,
Trent

 

[2broke2smoke]

my fuel pressure gauge reads a steady 15 psi ...



you'de think an air leak would show up there wouldn't you?

 

[ToolManTimTaylor]

No not when the truck is off. See if there is a difference if you park facing uphill or downhill. It should fire right off facing downhill if you have a leak. When uphill lets say you have disturbed the connection at the tank. Air will migrate up to the point of your filter housing (If you still have one I did not look to see if you have a Fass). The air then allows fuel to empty back twards the tank.



Simple way to check for leaks. I got one I have been battleing for a while now (Truth be told I know what it is but I am just a Lazy SOB). Now if an intank pump is used you simply would see a mess where the leak is.

 

[2broke2smoke]

stock lift pump relocated to frame ...



stock fuel filter ...



fuel pressure measured at VP inlet ...



just drove truck for lunch ...



two normal starts ... all hard starts AND normal starts have been on level ground



will try the uphill / downhill thing

thanks ...

 

[icman95]

Barring any electrical problems, I'm with Tim on the air leaks. I had one way back and it took an act of Congress to get it started. Once it was running, ran fine, though.

 

[2broke2smoke]

no consistancy ...



up or down ... didn't matter



1 minute or 10 hours ...



it started fine twice ... rough twice ...



AAARRRGGG



and it may sit for two minutes and be hard to start or sit overnight and start perfect ...



but again there's no consistency ...