Fuel pressure drop?

[Vais01]

Well guys and gals I've been incredibly busy recently. 

Well here is the short story. I recently replaced my pressure side fuel line from the Airdog to the VP44 all is well and no issues with that project. So the pressure starts to fall off only on wide open throttle and is getting worse over time. Any time I go wide open the lift pressure falls from 16 PSI to 13 PSI I've even seen it as low as 12 PSI.

This has been going on since early this month. I have replaced fuel and water separator filters twice and it makes no difference. Also it seems the electrical is having issues. I have rebuilt a section of the harness that attaches the relay into the circuit. All points that were added were soldered in and I don't see any wild voltage drops across the system. 

I am beginning to think the pump motor can't keep up due to worn out brushes. 

If anybody knows anything else that could let the pressure drop and only at wide open throttle let me know?

[gh0stman]

How old is the pump?

[Me78569]

I trust airdog stuff about as much as I trust, well, airdog stuff.  

[Mopar1973Man]

I know there is a lot of people that lost faith in AirDog products. Again I just called and talked to Eric at Vulcan Performance about a AirDog part I need for a job. Again I asked about how many AirDog warranties that have be sent back to him. As for AirDog 100 or AirDog 150 they are stable once again for pump and motors but as for the Raptor line its still shaky.

As for the AirDog series the only thing both Eric and myself agree on is the pre-made plumbing is really of poor quality with the quick connect system. There is a older fitting that is creating a air leak issue. So we both agree that cutting all that off and going back to Push-Loc fittings is the best thing.

I'm fighting with a 1995 Dodge right now and AirDog 150 that has a air leak issue.

[gh0stman]

I know there is a lot of people that lost faith in AirDog products. Again I just called and talked to Eric at Vulcan Performance about a AirDog part I need for a job. Again I asked about how many AirDog warranties that have be sent back to him. As for AirDog 100 or AirDog 150 they are stable once again for pump and motors but as for the Raptor line its still shaky.

As for the AirDog series the only thing both Eric and myself agree on is the pre-made plumbing is really of poor quality with the quick connect system. There is a older fitting that is creating a air leak issue. So we both agree that cutting all that off and going back to Push-Loc fittings is the best thing.

I'm fighting with a 1995 Dodge right now and AirDog 150 that has a air leak issue.

They had to have some perk as to when the pump burnt up that it was easy to replace. I don't get why they would engineer such a fitting onto their pump.

[Vais01]

Ok so the pump is roughly 5 years old and I have rebuilt several sections of the wiring harness in the past 6 months.

So any ideas. I don't have air leak issues or fuel leak issues. Fuel and water separator filters are less than 1000 miles old. Idle 16-17 PSI and wide open down to 12 PSI

Just to clarify this is an Airdog FP-150.

[Buzzinhalfdozen]

Have you tried verifying those readings with a different gauge? What do you have for a fuel pickup in the tank? If it's factory it's possible the screen is getting plugged. 

[Mopar1973Man]

I don't get why they would engineer such a fitting onto their pump.

I asked Eric about that and his simple answer was... Most people couldn't  figure out how to use the Push Loc fittings. We both agree just put the fitting on the floor and use your body mass and push the hose over the barb. Sad to say most of general public had problems with it so AirDog went to the quick connections. (Yuck!)

[Vais01]

Have you tried verifying those readings with a different gauge? What do you have for a fuel pickup in the tank? If it's factory it's possible the screen is getting plugged. 

Nothing factory for sure it has a half inch pick-up in the tank. The water separator is also the pre-filter for the pump and it is only 1000 miles since the install.

I don't believe the sender has died in less than 6 months. I do have a precision mechanical gauge for this I can Tee into the line but to confirm it against the electrical sender requires some additional plumbing. 

[Vais01]

I asked Eric about that and his simple answer was... Most people couldn't  figure out how to use the Push Loc fittings. We both agree just put the fitting on the floor and use your body mass and push the hose over the barb. Sad to say most of general public had problems with it so AirDog went to the quick connections. (Yuck!)

Well to add to the partial hijacked post quick-connect fittings come in various forms. My quick-connect fittings are sold by two different companies but are from Legris. Eric sells them for the best price. Even the Dorman Chrysler/GM fittings are better than the ones Airdog used. I personally like JIC/AN fittings and traditional reusable hose ends. Push-lok fittings in my opinion can damage the inner liner (the tube) of the hose which shortens it's life span. 

[dripley]

FWIW i have had my AD with quick disconnects for 5 to 6 years with no problem from the quick disconnects. The pump crapped out about 4 or 5 months ago and they replaced no questions asked. Maybe I am just lucky on the fittings.

 As far as your fuel pressure drop, what were you seeing pressure wise before? Mine idles at 19 and wot is 16. That is a 3 psi drop and not out of line with what you are seeing.  

[Mopar1973Man]

As for the quick connect fittings there is two styles of fitting one with a long male fitting is the trouble maker as what I understand.

[jlwelding]

This is the connections I have and I think that could be the problem I am having. Fuel pressure is 16 and will drop to 13-14, and it acts like it is running out of fuel. I still have not got around to pulling code from ecm. But my thought on that is if it was a vp death code it would show on the dash with the key trick. It will start dying off and pick back up and do this until I let of the pedal and get back into it, it will either be fine or I have to do it all over again. It my be fine for two weeks and do it again the next hour or so and then go for a month. 3 apps and all three do the same thing. It has 1693 stored just have not found a good scan tool. These cheap ones show nothing. I am leaning towards air in the line, but have no issues with fuel pressure.

[Vais01]

As for the quick connect fittings there is two styles of fitting one with a long male fitting is the trouble maker as what I understand.

That is known as a Jiffy-Tight fitting and yes they are notorious for having problems.

FWIW i have had my AD with quick disconnects for 5 to 6 years with no problem from the quick disconnects. The pump crapped out about 4 or 5 months ago and they replaced no questions asked. Maybe I am just lucky on the fittings.

 As far as your fuel pressure drop, what were you seeing pressure wise before? Mine idles at 19 and wot is 16. That is a 3 psi drop and not out of line with what you are seeing.  

Well that's interesting. I do have a new return ball and 17 PSI spring. I will be replacing them and seeing if that helps. 

I wish I had a flow monitor to tell me the true GPM. GPM of the pump should be 2.5 and should not drop more than 20%. Pressure drop of 3 PSI will show a drop in flow. In hydraulics flow is speed and pressure is the result of doing work (work or resistance to flow creates pressure). Flow is a fixed value unless the motor turning the pump slows down or the pump loss is too much. 

I believe the pump and motor may be dieing just due to age. If I find this to be true I will install a FASS TITANIUM 150 in its place.

[dripley]

My AD has a regulator to increase/decrease pressure with. Cant you just stretch the spring to increase the pressure and see if that helps?. You are seeing a little more pressure drop than me but I would think if you can keep the wot pressure 14 or above you would be ok. At least from what I have learned anyway.

[Vais01]

On Thu Oct 29 2015 21:00:25 GMT-0500, dripley said:

My AD has a regulator to increase/decrease pressure with. Cant you just stretch the spring to increase the pressure and see if that helps?. You are seeing a little more pressure drop than me but I would think if you can keep the wot pressure 14 or above you would be ok. At least from what I have learned anyway.

Well according to Airdog I should replace the factory overflow valve with a new one and go from there. 

I replaced my pressure side hose with 1/2" rigid aluminum and some 100% bio rated hose never did get the opportunity to pull the return line during the replacement of the pressure side line.

[CSM]

I have seen similar lately with my FASS HD 150.  I am thinking it may be due to crud in the tank... I am putting a draw straw in.  The rest is 3/8ths line with push lock fittings to the pump.  On my truck, I don't think the pressure drop is a flow restriction in the downstream side, as it never had a problem holding pressure in the past.  However, lately i've been getting some cavitation in the pump if the tank isn't full.  So I am thinking it's upstream (suction) related. 

[Vais01]

7 minutes ago, CSM said:

I have seen similar lately with my FASS HD 150.  I am thinking it may be due to crud in the tank... I am putting a draw straw in.  The rest is 3/8ths line with push lock fittings to the pump.  On my truck, I don't think the pressure drop is a flow restriction in the downstream side, as it never had a problem holding pressure in the past.  However, lately i've been getting some cavitation in the pump if the tank isn't full.  So I am thinking it's upstream (suction) related. 

The suction side on my system is 1/2 inch and it has a draw straw already in it. So my issue is up stream of the pump. It used to hold 15 PSI at wide open but not lately. Filters are not clogged either.

[CSM]

8 minutes ago, Vais01 said:

The suction side on my system is 1/2 inch and it has a draw straw already in it. So my issue is up stream of the pump. It used to hold 15 PSI at wide open but not lately. Filters are not clogged either.

It could be several things then.  My list if the draw straw doesn't fix my problem is as follows.  

-Check the return spring and flow passages in the filter & pump housing for debris that could be blocking something open

-Call fass and see about a rebuilt motor/pump, as mine is an OLD Fass. 

-Check the condition of my lines internally at the connections... For air leaks or I am thinking that perhaps there is a restriction or some deterioration of the lining of the fuel line itself.  

-Check gauge against another.  However, regardless of its calibration, I am still losing 4-5 psi once in a while and most initial startups.  

Edited November 26, 2015 by CSM

[Vais01]

4 minutes ago, CSM said:

It could be several things then.  My list if the draw straw doesn't fix my problem is as follows.  

-Check the return spring and flow passages in the filter & pump housing for debris that could be blocking something open

-Call fass and see about a rebuilt motor/pump, as mine is an OLD Fass. 

-Check the condition of my lines internally at the connections... For air leaks or I am thinking that perhaps there is a restriction or some deterioration of the lining of the fuel line itself.  

-Check gauge against another.  However, regardless of its calibration, I am still losing 4-5 psi once in a while and most initial startups.  

Is your issue only on start-up?