Fuel Pressure Question

[Collinst15]

Good afternoon,

 

I have a quick fuel pressure question.  I recently noticed that my FP gauge reads between 14-14.5 psi while driving, it was reading 17psi-18psi a few weeks go.  I assumed that the filters may need replacing, although they only have 2500 miles on them if that.  I have not swapped filters out as of yet, but noticed something odd today.  I bumped the engine over and FP gauge showed 16psi, but when I fired truck up the gauge would fall to 14ish psi.  Would the VP44 drawing fuel cause the gauge to drop.  I have adjusted the Airdog 4G in the past to show the 17-18spi while running.  the gauge "T" with sensor is approx 20 inches away from VP44.   

 

I just think it is odd that a few weeks ago fuel pressure was good and the past few days it has dropped and that there is a drop when engine is running compared to when Airdog is solely running.

 

Any help is appreciated.  

 

I have not checked voltage at the pump yet, plan to hopefully this weekend.

 

Tim

[dripley]

I am the same pump ad you and see the pressure at idle as I do with just the pump running, 20.5 in my case. I would definitely check the voltage and be sure the issue is not there then swap the filter. Though if they are as new as you say they are they should fine unless you got a dirty load fuel. That does happen sometimes. 

 How old is your 4G pump? I have the AD 165 II. Bought it 8 or more years ago. The original failed after 4 years. No problem, AD warrantied it. 2 months ago that one failed. No problem again, they warrantied it. Now I have a 4G like yours, i just hope the problem might not be in the pump.

[Collinst15]

dripley,

 

The pump is just over 1 year old.  I installed it 12/2017 and this is my only issue with it thus far.  I am going to park it until I can check volts this weekend.  It is just odd that the psi would differ 2 psi running and not running.  I don't want to hurt 6 month old vp44 with lackluster fuel pressure or dirty fuel.

 

Tim

 

 

[015point9]

If that style of lift pump has a jam nut on the adjustment screw make sure it's tight.

Edited January 16, 2019 by 015point9

[Collinst15]

It is the style were I can adjust the FP - I adjusted it about a month ago and set it for 17-18spi at idle.  Ill make sure the jamb nut is tight this weekend.  

 

Tim

[Guest 04Mach1]

I have been intermittently seeing odd fuel pressures lately when the engine is idling. The fuel pressure will come back up with a little throttle. @Mopar1973Man Do you have any suggestions? I'm thinking the check ball is wedging itself in the the spring or maybe pump body. I've been busy with the move and new job but figure this is something I should get fixed before I start having VP problems.

 

Here's a little video of it doing it this morning. 

 

[Manimalmother]

04mach1 electric fuel pressure sender?  It may be on the fritz.  My old electric FP gauge would do that also.

[dripley]

44 minutes ago, 04Mach1 said:

I have been intermittently seeing odd fuel pressures lately when the engine is idling. The fuel pressure will come back up with a little throttle. @Mopar1973Man Do you have any suggestions? I'm thinking the check ball is wedging itself in the the spring or maybe pump body. I've been busy with the move and new job but figure this is something I should get fixed before I start having VP problems.

 

Here's a little video of it doing it this morning. 

 

His pump has a pressure regulator adjustable on the outside of the pump just like mine. I have never opened it up to see if there is a spring and ball inside of it, but it is adjustable with out opening anything up.

 

@Collinst15 have you tried turning the pressure up? Is your FP gauge mechanical or electric?

Edited January 16, 2019 by dripley

[Collinst15]

dripley - I have turned the pump up about a month ago and set FP to 17-18psi at idle.  all my gauges are Isspro EV2 electric gauges.  It has been reading 17-18psi with no issues until the past couple days.  I drove truck last night and it was a steady 14.5psi cruising at 55mph. I noticed the FP difference this morning when I bumped motor over to see if it was reading 14.5psi without engine running, only to see gauge read 16psi.  I then started truck up and gauge read 14.5psi. I have parked truck until I can look at it later this weekend. 

 

Tim

[dripley]

42 minutes ago, Collinst15 said:

dripley - I have turned the pump up about a month ago and set FP to 17-18psi at idle.  all my gauges are Isspro EV2 electric gauges.  It has been reading 17-18psi with no issues until the past couple days.  I drove truck last night and it was a steady 14.5psi cruising at 55mph. I noticed the FP difference this morning when I bumped motor over to see if it was reading 14.5psi without engine running, only to see gauge read 16psi.  I then started truck up and gauge read 14.5psi. I have parked truck until I can look at it later this weekend. 

 

Tim

I would get a mechanical test gauge and see if maybe the sensor for the EV2 might be going bad. Do you have any protection for the sensor from the pusles from the VP?

I use a needle valve barely cracked open to protect my mechanical gauge. The electric sensors need this or something similar for the same reason. @Mopar1973Man has the EV2's also, as others and use a different method to accomplish the same thing. 

[Collinst15]

I have a snubber valve that is hooked into "T" then the gauge sensor.  

 

I am going to look over everything hopefully this weekend.

 

Tim

[dripley]

It would be good to get the sensor back away from the snubber from what I read here. My gauge is at the end of 3 feet of line from the needle valve. It is an EV and has served me well for the past 6 years.

[Mopar1973Man]

Sensor needs about 5 foot of tubing from the snubber. The travel distance helps with stability and protect the sensor.

 

Adjustable fuel pressure regulator you want to cycle the screw full loose, full tight, the reset you pressures. Some times the regulator sticks.

 

Check ball and spring. It possible the spring was bent in a manner the prevents the check ball to stay centered. Then you'll get that random drop. I'm currently in this boat.

[Collinst15]

MoparMan - What did you use again for your tubing?  I assume i could use a compression fitting at he end of the snubber then a compression fitting to the appropriate adapter for the sensor?

 

Thanks,

 

Tim

[Mopar1973Man]

3 minutes ago, Collinst15 said:

MoparMan - What did you use again for your tubing?  I assume i could use a compression fitting at he end of the snubber then a compression fitting to the appropriate adapter for the sensor?

 

Thanks,

 

Tim

 

1/8 inch air brake line at least 5 feet.

PTC (Push To Connect) to 1/8 inch NPT.

 

I'm not using compression fittings. PTC fittings are super nice you can just push the tubing into the fitting your done. To remove push the collar back and the tubing is released from the fitting. 

 

Examples...

 

https://www.amazon.com/Numatics-PTC-NPT-FEMALE/dp/B00IOR27TI

 

https://www.amazon.com/Vixen-Air-Connect-Straight-Pneumatic/dp/B0757X9YDJ

Edited January 16, 2019 by Mopar1973Man

[Collinst15]

2 minutes ago, Mopar1973Man said:

 

1/8 inch air brake line at least 5 feet.

PTC (Push To Connect) to 1/8 inch NPT.

 

I'm not using compression fittings. PTC fittings are super nice you can just push the tubing into the fitting your done. To remove push the collar back and the tubing is released from the fitting. 

 

Examples...

 

https://www.amazon.com/Numatics-PTC-NPT-FEMALE/dp/B00IOR27TI

 

https://www.amazon.com/Vixen-Air-Connect-Straight-Pneumatic/dp/B0757X9YDJ

Moparman - Thank you!  Glad you are feeling better also!  Praying for you and a fast recovery!

 

Tim

[Mopar1973Man]

5 minutes ago, Collinst15 said:

Glad you are feeling better also!  Praying for you and a fast recovery!

 

I feeling better just being away from the hospital. I trying to get my doctor to leave me alone for a span of time I was just in on Friday last week and got home late Saturday. Then by Tue already try to schedule another visit. WTH? I can't heal up if I'm being constantly drug around with appointments and never home. Like I just off the phone with the scheduler I told her to back down give me some time. Geez...

[JAG1]

My push lock type fittings had the plastic tabs, not like the ones above. They were all leaking on the isolator and snubber in less than 2 years except the one behind the gauge in the truck. The isolator was causing a bad reading on the gauge, off by 7 psi when tested on the schrader valve under the hood. I decided to not use the isolator and removed it.

 

Edited January 17, 2019 by JAG1

[Collinst15]

Good morning everyone, 

 

My wifes suburban blew brake lines this morning so I have to drive truck to work as she needs the winter rat to get to work.  I spent a few minutes this morning and screwed the adjustment screw on regulator in and out several times then set fuel pressure to 18psi while idling.  I work 2nd shift so I'll see how it does this afternoon.  I also reflashed the XZT+ with a less aggressive tune that still has the high idle feature.   Hopefully this fixes my problems.

 

Tim

Edited January 18, 2019 by Collinst15

[Mopar1973Man]

Adjustable fuel regulators you want to cycle the full in to full out. Then set your pressure. This frees up sticky regulator parts.