Engine/Transmission (1998.5 - 2002) Perplexed....

[chazj]

Came down from over the Sierra's & my nephew kindly decided to wash the salt/road grime off my truck with his Hotsy pressure washer. Upon completion of this task I left and almost Immediately my fuel pressure guage started to wildly jump from -0- to 15 lbs... most noticeably upon any kind of acceleration. NO noticeable lack of response from the engine though.



Ended up changing the "strainer/filter" that is in between the tank and the Fass HPFP (Engine fuel filter had less than 5K since it was replaced). Truck started immediately & fuel pressure seemed to be stable between 12-15 lbs. Ran the engine for a couple of minutes and then shut the engine off for a few minutes and re-checked for leaks. Everything looked "good" except this time the engine would not start! Had to crank it and crank it over, give it a little pedal, and finally it started again and sounded normal.



Drive back to my daughter's house was uneventful (engine response and 12-15 lbs pressure). Truck sat for 1/2 hour and I decided to fill it up as I felt secure enough that the truck would start and not leave me stranded. Return trip from the service station had the fuel pressure guage jumping erratically once again!!! GRRRRRRRRR!



Will try to get it into a diesel mechanic on Monday so he can put a mechanical guage on the VP-44. Am curious if anyone has ever experienced anything like this? And if you think there could be a relation between the pressure wash of the undercarriage and the almost Immediate wild pressure swings I am seeing from my Autometer FP guage...



Just seems coincidental... and of course it has to happen away from home and on a holiday weekend... .

 

[AEdelheit]

I know steam can do funny things to electrical connections, I work for a tractor company and after steam cleaning a tractor there are a few codes I expect to see until it completely dries out. I would suspect steam got into an electrical connector somewhere, I would also check the connections to your fuel pressure sensor to gauge, would not be surprised if the pump and pressures are fine and its just a bad or corroded connection, or a bad connection to the Fass. Would also be a good Idea to inspect any rubber fuel lines, a Hotsy can put a hole in one all to easy.

 

[Bessler]

I keep a tube of Dielectric grease in my truck for that reason. Displace water or clean up corrosion.

 

[chazj]

UPDATE: Took it into a diesel shop and had it checked out. All connections were clean and dry. The truck was driven and a mechanical guage was used to monitor pressure... it never dropped below 13 lbs. Verdict was a bad "sending unit" above the snubber. Apparently not all that uncommon?



I have another one on order. Apparently you just unscrew the old one and unplug the pigtail. Question... will I have an issue with any fuel coming out? Or is it just a simple matter of a little teflon tape and snug the new sending unit up?



Happy New 2011 to "One and All".....

 

[RAJohnson]

UPDATE: Took it into a diesel shop and had it checked out. All connections were clean and dry. The truck was driven and a mechanical guage was used to monitor pressure... it never dropped below 13 lbs. Verdict was a bad "sending unit" above the snubber. Apparently not all that uncommon?



I have another one on order. Apparently you just unscrew the old one and unplug the pigtail. Question... will I have an issue with any fuel coming out? Or is it just a simple matter of a little teflon tape and snug the new sending unit up?



Happy New 2011 to "One and All".....

You should not have a problem with fuel coming out. Maybe a few drops as long as your not running. Teflon tape it, snug it up and look for leaks, plug it in and you should be good to go.



This still does not answer the NO start situation. You must have blow a hole in the fuel line some where, and now air is getting in the system, if your having hard start issues.

 

[TProffitt]

I had something similar happen after a good cleaning with a hose, and finally tracked it down to the relay that you install to power the FASS, water had gotten into it and it was not powering up the FASS full time, the pump was kicking on and off. installed a new relay from Advance Auto and problem went away. Now I have a spare!!!! Your relay may have dried out.