2nd Gen Non-Engine/Transmission new fuel pressure guage reading low...?

[DLangford]

My 2001 high output CTD is running well right now. A few years ago, I experienced the lift pump starting to fail, and got it in under the warranty with one month to spare. The dealer installed the in tank lift pump fix that Dodge was doing at that time.

This past weekend, I had my neighbor (who is a pro mechanic) install a trio of guages; boost, exhaust temp and fuel pressure. All are Westtach from Geno's Garage.

The boost and exhaust temp work fine. The fuel pressure guage (electric), with the recommended isolater was carefully installed according to directions. My problem is that the readings are low- about 4 or 5 psi if the isolator installed at the injector pump, and 5 to 6 psi if installed at the fuel filter. When he saw this, my neighbor then bled the isolator and guage to make sure there was no air in the line. That did not "help".

He then went on-line, and found a mechanic's "bulletin" from his normal site he uses everyday, that implied that fuel tank mounted pumps in the CTD's will give you falsely low fuel pressure guage readings up near the engine.

Has anyone had a similar experience? Advice?

I am planning on swapping the fuel filter just to make sure that is not part of the problem, but I am sort of nervous with such low readings, even though the truck is running well now, as I said.

 

[DCreed]

pressure at the VP44 MUST BE 5psi min. 15-20psi max. The intank pumps were a band-aid fix from the dealer and work better than the engine mount but now need to drop tank to service and performance is adequate at best. less than 5psi @ the VP can damage the diaphram and cause failure, not to mention fuel is the coolant of the IP and a low pressure/flow rate will not cool sufficiently.

 

[Davcruz]

Something I heard regarding the in tank pump from Dodge is that they no longer use pressure as the guideline, they use flow rate. Apparently the in tank pump is a low pressure but high flow deal... . ??

There is a thread over on Dodgetalk regarding this, I will try to find it.

 

[RJWEST]

Do you have a mechanical gage to verify the Fuel pressure reading of the installed gage... . the mech. should have one...

 

[Davcruz]

Here is the thread I was referring to. Fuel Pres Gauge ???s - Dodge Talk Community Forum

 

[Hammer]

If you would ever get to see one of those "in tank" pump assemblies out of the tank and disassembled you would be quite shocked. The feed orfice for the fuel going to the VP44 is so small one has to wonder what Dodge was thinking when they went to them. The opening to the check ball inside where the draw is taken is no larger than the top of a ink pen insert if one would take a ball point pen apart and look at the top of the ink cartridge. I have seen this setup cut apart as a dealer buddy of mine has had many issues with them. So I could believe that your pressure is "that low" with the in tank assembly.



Anyone who owns a 24v truck and does not go aftermarket(FASS,AirDog,GDP,AirTek,etc etc)for their fuel supply pump is just dancing on borrowed time with their VP 44's. Yes,I do agree that Dodge should have done something better from the factory but since they didn't what would you rather do,pay for the aftermarket fuel pump now or pay for the aftermarket fuel pump and a VP44 later. Thats about what it comes down to with those trucks. As for flow rate instead of fuel pressure being used,think about it,you can have all the flow you want but if the system is designed to be run at a designated pressure rate then what do you feel would happen?..... Andy

 

[Davcruz]

I concur with you Hammer. I do not buy into the whole flow vs pressure thing. Sounds like a typical BS dealer line to me. However, I wanted to let the OP know about it.

 

[DLangford]

Thanks to all for the very insightful posts.

Next step for me will be to replace the fuel filter, and then I will plan on an upgrade, maybe the BD auxiliary lift pump on the frame rail, at least.

 

[Joe G.]

I think you are going to have to deal with the restricted fuel flow problem in the tank as well as install a good fuel pump. On my 12 valve the supply lines are all 3/8" ID from inside the tank to the lift pump. I too have a Westach fuel pressure gauge. I suspected that it may be reading too high so I tested it with a mechanical gauge. It agrees exactly with the mechanical gauge in spite of being 10 years old.

 

[BenCole]

I installed the Vulcan Big Line Kit, and it really helped. My in tank pump only goes up to 8 lbs of pressure. With all the banjo bolts, pressure was very low (1-2 lbs) under acceleration. The Vulcan kit helped tremendously, and now I see 5-6 lbs under acceleration with the big line kit. It was easy to install. The in tank pump is fair, someday I will upgrade it, but it works for now.

 

[Fishin Guide]

You could have a few issues here possibly.



1 Bad gauge or bad isolator. Isolator failures are more common.



2 The pressure is actually correct.



You are correct Dodge switched to flow measurement VS pressure. Most any pump will flow X amount of GPH when dumping into a bucket. I have seen stocker pumps that would easily flow 70+GPH and not hold 2 psi.



I have heard all the arguments. But flow is nothing without some pressure. And even if you increase pressure from say 5psi to 20 psi, that does not mean the fuel will flow faster, it just means there is more resistance to flow. But, if you have positive pressure(to a point), the flow will always match the needs of the pump.



The bottom line is a long term fix is in order if you plan on keeping the truck long term. With the in tank pump, you'll need a draw tube of some sort along with the upgraded pump. Many come with these tubes, some don't but the component is pretty cheap.



And I am a fan of big lines on the inlet of the pump. What you do on the outlet is up to the user.



Dave