Engine/Transmission (1998.5 - 2002) New Fuel Psi Gauge Funny Readings

[ACarola]

Questions maybe someone can help???? got gauge hooked up at idle it reads 15psi then drops to 5 . then when i drive no load or hill running around 70 mph it goes up and down from 15 to 5 then back to 15 will stay there for a few mins then go bavk to 5 on and on. Whats up with this... andy

 

[Joe Mc]

Sounds the like lift pump is on it's way out. My 99 would act crazy (like you describe) and soon after 0#. May I suggest http://www.glacierdieselpower.com/product.asp?pf_id=3929852

 

[ACarola]

thank you joe . Its funny how this works the truck runs great. andy

 

[AggieJustin]

Check your wiring. Had this happen on a friend of mine's, we were thinking LP was going out or FF was clogged, but it turned out to be a connection in the wiring that was intermittent. Wasn't breaking completely to drop it to 0, but would cause it to run low for a while, then it would jump back up.

 

[Joe Mc]

thank you joe . Its funny how this works the truck runs great. andy

Yeah, I know there's no indication if you didn't have a FP gauge that anything is wrong. AuggieJustin has a good point to never hurts to check the simple thing first.

 

[isb360]

My last two failed with same symptoms... .

 

[USMCBay]

Not what you want to hear but that is exactly how mine gauged two days later I could barely get it started... Had to go to the Harley for Transportation. Hee hee... Not a bad option. Had the $70 campaign pump a few days later and moved the LP down south to the Frame Rail. Solid psi now - however this new theory of a clogged tank filter is sounding VERY interesting... I think theres something to it. Looking into High Flow In-Line Filters now... There not giving them away around $45 -$70.

 

[isb360]

I need some education: how would a clogged filter cause bouncy needle on FP gauge? I would think a clogged filter would result in a steady pressure drop across the clog and would be something that happened either slowly as sludge builds up in the filter, or quickly if a piece of sizeable debris gets into the filter and poses a restriction, but bouncy or fluctuating? Help!

 

[USMCBay]

That would be in reference to the "reason" the pump is going out... I see your point but in another thread the idea was kicked around as a constant strain on the LP and in turn causing the cavitation that can shorten the life of the lift pump...

Hey I don't buy global warming so it even puzzles me why I buy this theory... I accidentally ran my LP in reverse after moving it to the frame rail and my psi was at a steady 15psi - now three days later its at a steady 13... I think I backwashed the tank filter...



Just a thought!

 

[ACarola]

Thank you guys for all the input. I was hoping that maybe i still had air in the line with the new gauge. I guess it would be wise to check with a mech gauge right from the vp44 to make sure it is a lp. Just to let you you know i took the schrader valve out because the line that i got from genos the plastic part on the inside got smashed. So i took that out to and am running with no schrader valve. This will be my 2nd lp and also had my vp44 replace already to . andy