Engine/Transmission (1998.5 - 2002) fuel pressure reading

[Huntmastr1]

duaneparks:



The dealer I am fond of is Henson Motors in Madisonville. Sales and service personel are superb. IMO.



I have had good service from Greenspoint Dodge(excellent body shop) and Allen Samuells Dodge for other than engine/drive train issues.

 

[WTBurke]

jtisdale

Your mechanical gauge is it glycerin filled? If not,... . the braided SS line feeding fuel may not have enough expansion/contraction coefficient to "snub" or smooth the oscillations of fluid flow. This will cause your gauge to responde in this erratic manner. Electronic type units have a slower responce time built into the design so fast "spikes" (VP-44 back-wave fluid oscillations) don't show up on the needle.

I work in the "pump" field at 3K to 7. 4K PSI, from . 5 to 6 gallons a minute. I use glycerin filled gauges every day... they are very cool.



William

 

[jtisdale]

magic fluid

WTBURKE-The gauge came pre-filled and sealed with some kind of fluid from the factory with a 30" ss liner that goes to the isolator. Instructions say if some leaks out, re-fill with 50/50 water and glycol. I'll have to check it and see if its full or if it has a bunch of air in it.

 

[RBSOB]

jtisdale,I think WTB may be on to something here. You mention 30inch SS line; from isolator to gauge or injection pump to isolator? I believe most have found, even with electric senders, you need some damping effect if you read pressure at the VP-44. How are you connected VP-44 to isolator? As above I've used 20 inches of "rubber" fuel line VP-44 to electric sender with nice steady results. Keep us posted, Jim G.

 

[jtisdale]

I had a tapped banjo and a straight fitting connected to a 30"ss braided line going from the vp44 to the isolator. On the gauge side of the isolator, I have another 30" ss braided line filled with fliud going to the gauge. As soon as I get my new banjo bolt, I am gonna try it at the outlet side of the filter. I also have a Briar Hopper gauge on the way. We'll see if that fluctuates at the vp44 too.

 

[Ethdee]

I have a tapped banjo at the bottom of the fuel filter. From that there's a 24" SS flexible line going to an isolator. I have 1/8" nylon from the isolator to the gauge, roughly 30". I pre-filled the gauge before installation, and all the air has been bled from both sides of the isolator. I used Swagelok fittings and nylon ferrules on the gauge side so that I could remove the line for bleeding air from the system. After the third time, the bubbles quit returning.



My gauge is responsive enough that I notice a >15 PSI spike every time the ignition is first turned on, but I've never had any needle bounce while it's running.



Typical pressures are 14 at idle, 12 at cruise, and 8 at WOT.



Jim

 

[jtisdale]

Thanks ETHDEE...

EthDee>

I was glad to hear from someone that has a set-up like this that actually works. Before you bled the air out between the isolator and the gauge, did you notice any fluctuation?

Jim

 

[Ethdee]

Originally posted by jtisdale

Before you bled the air out between the isolator and the gauge, did you notice any fluctuation?

Not really. As I said, I pre-filled the gauge. I have a small hand pump, so I filled a length of nylon tubing with my antifreeze mix, and hooked it to the pump and gauge. I set the gauge so that the fitting was pointing up and pumped until the gauge was reading full-scale, then vented the pump. Got the bubbles out of the nylon line and repeated until I got no air out of the gauge.



My isolator had no bleed fittings, so I installed it with the gauge side facing up so that whatever air was trapped inside after I did my best to fill it would migrate up the line. One thing about nylon line - it's easy to see the bubbles in the antifreeze!



So, back to your question... I really can't say whether air in my system caused any fluctuation, as the residual air in the system was a half a cc at most. I didn't have any of the symptoms I read about on the TDR, at any time. Generally, if you're too close to a pump, you'll get pressure oscillations; that's why I went under the filter. Also, I wanted to leave the stock test port in, so that when my lift pump goes out, the dealer has someplace to do what he knows how to do.



Let me know if you notice that pressure spike when you first turn the key on. I don't think I've seen that mentioned before. It's as if the pump is turned on for a fraction of a second, enough to peg the gauge. Just long enough for the gauge to go full-scale and then back to zero. I've got a hunch those with electric gauges won't notice this phenomenon.



Jim

 

[jtisdale]

spike

Yes, I see a spike when the key is turned to the "on" position. It pegs the needle then quickly drops to zero.

When I bump the key without starting the engine, it jumps to 14 and stays there until the pump shuts off, at which time it falls back to 0.

 

[RBallard]

Here is my take

I spent Saturday installing Ray's tapped banjo bolt and the Westach set up. I installed Ray's bolt and new Cummins gaskets and torque the bolt to 18ft/lbs. Installed the 18" grease gun hose to a 316SS Tee. I put the sending unit in one end and the hose in the other and then put a 1/8" x 7/16"-20 TPI adapter with a cap. I used a 4" hose clamp to mount everything to the air horn securely. I let the lift pump cycle twice to bleed out any air through the cap. After cranking the engine twice 10-15 secs each, the truck started and idled fine.



I drove the truck 40 miles Saturday - 14 - 13. 5 psi idle and 10-11 psi highway and 8 psi WOT. After driving the truck another 40 miles on Sunday it just seemed to take more pedal pressure to get it going. On take off, the MPG would dip to 4-6 where as in the past it seemed to hover around 9-10. It just feels different, so after thinking about it some more is it possible that the difference I am feeling is due to the holes in the fuel line matching up directly with a hole in the banjo bolt. I marked the banjo bolt in which it was installed and after removing it I found that the bolt was centered in between the holes, meaning the fuel coming would have to split and go into the holes. I removed the bolt and marked each hole on the nuts hex and reinstalled the nut. 18 ft/lbs again brought me dead center between two holes. I further tightened the nut maybe a 1/6 of a turn to achieve hole alignment. Now the trucks running like it used to. Has anyone else experienced this? Don't get me wrong, it not night and day but it was noticeable to me.



Bob

 

[Steve Campbell]

Bob...

You might be on to something here. I have not checked mine, but now I feel like I should!!!

 

[jtisdale]

I got mail!

I got all my goodies from Briar Hopper (thanks again) and Geno's today. I will be running some tests in the next couple of days. I will post my results.

 

[Summit]

it's fixed

JTISDALE , well i finally made it to cummins today for lift pump, 162. 00 and then staight home for install. it's fixed!! needle is steady, no vibration or fluctuation at all. pre-filter is now 16psi idle, 13psi@65mph, wot 8psi in 3rd gear(lowest in 3rd). bad news is it's lift pump time. i have 81,000 on my 01 and was told not to long ago by stealer that lift pump was o. k. but after your post i decided to go to cummins out of own pocket but i feel was worth it. (didnt have to put up with the bullsh!t).

 

[Huntmastr1]

Well!!!!!!!



Now I have new guages as previously posted, a new transfer pump!!!!!!!



Yesterday My guage starts jumping around?



At idle it is steady at 13#

upon any accelerator activity it moves around. Not fast or jumpy,, just bounces around.



Is my new pump failing or is it the new sender?

 

[jtisdale]

Summit-

Glad to hear you got yours figured out. I have been working a lot of OT lately, and its been raining, so I havent got to work on anything yet.



Huntmaster-

Where are you picking up your reading? I know some guys that are using the electric gauges are using a "rubber hose" like a grease gun hose in between the injection pump and the sender. This will absorb some of the "hammer" that the vp44 has reportedly produced. I had my mechanical set-up hooked at the vp44, and I saw major fluctuation. However, if you are picking up your reading at the filter, it could be the lift pump

I am only going on what I have read here, not first hand expierence, sorry.

Any one else have any thoughts?

Jim

 

[Huntmastr1]

Huntmaster-

Where are you picking up your reading? I know some guys that are using the electric gauges are using a "rubber hose" like a grease gun hose in between the injection pump and the sender.

Jim [/B][/QUOTE]



Jim: I am using a tapped Ray's Banjo at the injector pump with 24" of hose to the sender mounted on the fire wall.

It has been perfectly steady up until now. (3 weeks)

It appears the fluctuations are going lower and lower on the scale.

I shut the engine off and bumped the transfer pump and it held a solid 14#



I guess I am going to pickup a mechanical gauge to hook up as a test rig

 

[Huntmastr1]

NOT THE TRANSFER PUMP

I hooked up a mechanical gauge to the hose that feeds to the sender and the pressures are perfect. Oo.



Guess I have a bad sender or gauge? At least I don't have to go to the dealer



Does anyone think that being connected to the Injector Pump would cause the sender to fail even though I have 24" of hose going to the sender?



I noticed that the mechanical guage shows a solid 15# at idle compared to the 13# with the electric gauge.



Oh well,, guess I need to call for a replacement:-{}





Jeff

 

[jtisdale]

Thats what I did too. I bought one of Briar Hoppers gauges. I was hooking up to the vp44 also, like you mentioned, and I had the same problem. I suspect when I shut the engine off, the fuel would drain out of the line back into the vp44. Then, when I fired it back up, I would have air and fuel in the line. I think a combination of the air in the line, and being hooked at the vp44 was causing my fluctuation. This is only theory as of now. When I get hooked up at the outlet side of the filter, I am hoping the fluctuation will disappear as others have reported. Also now that I have test gauge, I will be able to rule out problems with my isolator or my autometer gauge.

 

[Summit]

i'm big liar to you!!

well it was doing great for about 100mi. and now it's BACK!! stopped to buy a new air filter tonight , shut truck off, B-Sed with the guy for a while and when i left it started fluttering again and within 10 minutes it was as bad as before!!!!!. i dont know what the deal is, it worked great for a day. now i'm thinking it's not the lift pump even though the new one has more pressure. i'm gonna try going to post filter to see if the filter will suck up some flutter.

 

[jtisdale]

Briar's gauge, lift pump, fuel pressure, blah blah blah

I hooked up Briar's gauge at the inlet side of the filter. First, 14 psi @ idle, then it sank like a rock. Held steady at 5 psi cruising. I stopped and shut the truck off and then restarted it. Now its 12-13 idle, about 10-11 cruise, and not less than 7psi WFO. I stopped several more times, and nothing changed. No fluctuation at all, ever. This was with my trailer on. I drove for about 30-40 minutes with the gauge duct-taped to the windshield, my wife had to sit in the back seat cause she was too embarrased. :-laf

I am gonna try it at the vp44 and see what happens. I think I am going to hook my autometer up to the outlet side of the filter, I'll let you know what happens with that too.