losing fuel pressure overnight ?

[Tractorat]

My 2001.5 set it all the time. DTT said it was from spinning the tires. SnoKing

I wasnt spinning the tires, but i suspect the dealer was gunning the engine a lot trying to speed up warm up to make sure the tstat opened

 

[SnoKing]

Something makes me think he does not have a fuel pressure gauge. I think I remember him saying he has an idiot light. SnoKing

 

[DavidC]

Its about a quarter tank, but Ive never had the problem before, even with less fuel.
No white smoke. Im having an overheating issue that Im having looked at in about a week so I havent tried to stress anything. So, I dont know if there is any performance issue or not. I do show good fuel pressure although is seems like the needle flops around a little more that normat on startup. But that might be because I just hadnt paid that much attn to that before.

He does quote a needle flopping around.

Dave

 

[SnoKing]

He does quote a needle flopping around.

Dave

Got it! SnoKing

 

[Tractorat]

Yup, I have a fp guage. Interesting. It started right up this morning. FP came right up and it started with no hesitation. Can loss of prime be intermittent ? Or can it be a one or 3 time event caused by something else ?

 

[DavidC]

Yup, I have a fp guage. Interesting. It started right up this morning. FP came right up and it started with no hesitation. Can loss of prime be intermittent ? Or can it be a one or 3 time event caused by something else ?

Maybe a piece of grit was stuck in the VP overflow, Fass bypass ?. Did you do anything ?. Mine would only act up if it sat for a while. Sometimes it would start and die or it would not start until the air was purged.

Dave

 

[SnoKing]

A little on how it works. Turning on the key causes the pump to run of 3 sec, bumping the starter causes it to run for 27 seconds.

It is recommended that you disconnect the fuel line between the fuel filter and VP 44 and route a line to a container of a gal or more. Bumping the start should cause the pump to supply a gallon or so of fuel to the container. You should not see a lot of air in the fuel flow in this test. A leak in a fuel line between the pump and the tank cause air to enter the system.

I bad check valve in the pump as noted by others above will cause loss of prime. Is your FASS on the engine or down on the frame?

Chris

 

[Tractorat]

Is your FASS on the engine or down on the frame?

On the frame.

 

[Tractorat]

So after 2 or 3 mornings of a hard start, I took the advice and watched the fp come up when I first started the truck. That morning, and ever since, it has started right up on the first bump just like it always has, just like when brand new and has done so for a few days now.

So, immediately after a coolant service at the dealer, Ive had the initial hard start in the morning and a P0500 code, both of which should not be connected.

Here is my question. If the dealer had been gunning the engine (trying to warm the coolant to make sure the stat would open) and/or spinning the tires or goosing the engine to say 1500 or 2000 rps for a while, could that 1. cause the P 0500 code set, and 2. cause a temporary bubble in the fuel system that might manifest it self or look like a loss of prime for a couple of days ?

 

[SnoKing]

So after 2 or 3 mornings of a hard start, I took the advice and watched the fp come up when I first started the truck. That morning, and ever since, it has started right up on the first bump just like it always has, just like when brand new and has done so for a few days now.

So, immediately after a coolant service at the dealer, Ive had the initial hard start in the morning and a P0500 code, both of which should not be connected.

Here is my question. If the dealer had been gunning the engine (trying to warm the coolant to make sure the stat would open) and/or spinning the tires or goosing the engine to say 1500 or 2000 rps for a while, could that 1. cause the P 0500 code set, and 2. cause a temporary bubble in the fuel system that might manifest it self or look like a loss of prime for a couple of days ?

I do not think so. SnoKing

 

[Tractorat]

I wouldnt have thought so either, but it is rather a strange coincidence.

 

[DavidC]

Something always worked before it broke. As far as the spinning tire syndrome you may have the sensor starting to go bad, a wiring intermittent problem starting etc. As long as the codes clear I would not worry about it unless they come back.

Dave

 

[Tractorat]

Something always worked before it broke.

except in this case the loss of prime seems to have healed itself.

 

[Tractorat]

Will that code clear if I disconnect the batt ?

 

[DavidC]

Probably one of those so many miles without a problem before it clears. Do you have a Brake light and/or ABS light on ?.
Dave

 

[Tractorat]

Nope, just the p0500 and i think it was the 1693 code as well

 

[DavidC]

Kind off odd no lights. Maybe see if you can find a scanner to clear the code and see if it returns. Usually if the speed sensor has problems a Brake light/ABS comes on along with an erratic speedo if it works at all.

Dave

 

[SnoKing]

P1693 means there is a code in the other computer. So ECM is saying the PCM has a code, which is where the P0500 comes from I believe. SnoKing

 

[Tinman]

If for some reason the engine revs without speedometer input or accelerator applied, it will set a P0500 code. I had (malfunctioning now and no replacement) a Practical Diesel Solutions high idler and it would set that code. Nothing wrong with anything, the computer just didn't know what to do with the high RPMs, no speed and no accelerator. Maybe the dealer did something like that to to set the code. If speedometer is working and no ABS light, don't worry about it.

As far as fuel system goes, If I have hard start now, pump runs as its supposed to and fuel pressure promptly up to 15. For what you guys are saying, I'm guessing the fass has bad seal somewhere. I'll give them a call.

 

[Joe Mc]

had the lose prime overnight situation w/mine years back. Ended up being pin hole in the metal supply line that leaves the top of the tank module, went with draw straw = fixed