Jump to content
AlCorr

Fuel 2-3 psi

Recommended Posts

Went out this morning and only had 2-3 psi. I drove it to the store and back, no problem. It was cold last night and I'm due for new fuel filters, maybe some waxing on the dirty filters. Maybe it's my Holly Black fuel pump, it's been in there for about 5 years now and it looks like it is weeping a little on the bottom. I have a rebuilt Holly Black under the back seat. Not sure what to do?

Share this post


Link to post
Share on other sites

How cold was it last night???

 

With my Walbro pump;  I actually see higher/increased fuel pressure according to my gauge in the winter than in the summer. Usually 3-4psi increase when it really cold.  I've never had a "gelling"  problem or a frozen fuel line due to water.  The fuel is more viscous when it's colder out, hense the increase in pressure……………..probably due to the filter media it's trying to pass thru.

Edited by dorkweed
  • Like 1

Share this post


Link to post
Share on other sites

Thats kind of strange. I always see lower pressure in the winter time. Might be different because of pressure sender locations maybe. For every 10 degrees F lower than 20* i usually drop about 1 psi or so. Could just be the old raptor doesnt like the cold too..

Share this post


Link to post
Share on other sites

Thats kind of strange. I always see lower pressure in the winter time. Might be different because of pressure sender locations maybe. For every 10 degrees F lower than 20* i usually drop about 1 psi or so. Could just be the old raptor doesnt like the cold too..

 

My "sensor" is pre-OEM 7 micron filter in the stock housing.  It then goes to a 2 micron GDP filter set-up before the CP3.

 

It's always been this way for me…………7+ years now IIRC.

Edited by dorkweed

Share this post


Link to post
Share on other sites

What sort of pressure do you usually see? I put a tapped banjo in the CP3 and see very little pressure (under 2psi) on it according to my CTS. Stock fuel system, and that was installed with brand new filters. I've never verified the reading with an analog gauge but that's been on my list to do forever...

Share this post


Link to post
Share on other sites

My "sensor" is pre-OEM 7 micron filter in the stock housing.  It then goes to a 2 micron GDP filter set-up before the CP3.

 

It's always been this way for me…………7+ years now IIRC.

That may be why then. I have my sender tee'd in right before the VP so I know what kind of pressure is getting to the pump. It has to get pushed through my BF1212 and the stock filter before it gets to the sender. I probably see low pressure because that chilled fuel has to get through 2 filters.

Share this post


Link to post
Share on other sites

I'm using a Baldwin BF1212, 9 micron near the fuel tank and a Baldwin PF7977, 5 micron up front in the drop-in.

 

It was in the 20's that night but has warmed up and it still only reads 2-3 psi.

 

The next 2 days it will be pushing 50 so I'll be on my back in the driveway changing out the Holly Black pump for another Holly Black. I'll be changing the filters also.

Share this post


Link to post
Share on other sites

OK, it's 42* today so I changed the 2 fuel filters and it reading 4-5 psi. Not good, this truck always read 14-15 psi. Down to 9-10 at WOW.

 

I can hear the Holly Black pump running and the truck seams to be running ok, maybe it's the fuel pressure sensor going bad, it is a Quadzilla Commander.

Share this post


Link to post
Share on other sites

I installed a rebuilt Holly Black fuel pump, works good, at start-up it reads 20-21 psi, driving around town 17-18 psi, the highway 14-15 psi.

 

 The pump I just took out was a used Holly Black and I got 4-5 years out of it.

 

I'm not sure if I should pick up another pump or try and rebuild this one myself. Anyone ever rebuild a Holly pump, any advise?

Share this post


Link to post
Share on other sites

A coworker with an 03 cummins and Fass system had to leave his sit in the shop at work to warm up and get a ride home, his Fass wouldn't build any pressure, my HPFP150 would be like that when it was below zero too, had to restart it a couple times or drive it a couple miles and then restart it to get any fuel pressure to build.

Share this post


Link to post
Share on other sites

I installed a rebuilt Holly Black fuel pump, works good, at start-up it reads 20-21 psi, driving around town 17-18 psi, the highway 14-15 psi. The pump I just took out was a used Holly Black and I got 4-5 years out of it. I'm not sure if I should pick up another pump or try and rebuild this one myself. Anyone ever rebuild a Holly pump, any advise?

 Nice to have a spare. Can you adjust the pressure on that pump? I would drop it to 15 at idle if you can.  

My "sensor" is pre-OEM 7 micron filter in the stock housing.  It then goes to a 2 micron GDP filter set-up before the CP3. It's always been this way for me…………7+ years now IIRC.

That's why your pressure increases, it's showing you the restriction of the cold fuel in the filter. Monitoring the pressure just before the CP3 would show a drop in pressure with cold fuel. I see a 1-3 psi drop with cold fuel, and can tell when the fuel heaters get everything warmed up as the pressure comes back up. Why did you choose to put your sensor pre-filter? Not wrong, just not common.

Share this post


Link to post
Share on other sites

 Nice to have a spare. Can you adjust the pressure on that pump? I would drop it to 15 at idle if you can. That's why your pressure increases, it's showing you the restriction of the cold fuel in the filter. Monitoring the pressure just before the CP3 would show a drop in pressure with cold fuel. I see a 1-3 psi drop with cold fuel, and can tell when the fuel heaters get everything warmed up as the pressure comes back up.Why did you choose to put your sensor pre-filter? Not wrong, just not common.

With the GDP Walbro fuel pump system I bought years ago, there's a machined aluminum block with 3 "ports" in it. One port takes the brass "push lock" fitting that the rubber fuel line from the Walbro  connects to. Another is an identical "nipple" with rubber O-ring that fits into the back of the OEM FF housing where the OEM lift pump was mounted………re-use the OEM mounting bolts on the block.   The 3rd "port" is on the top (as viewed) and that's where I screwed the sender for my fuel gauge.

 

The machined block looks very similar to the one Richard @GDP uses in the "Fuel Boss" kits now. It may be identical;  but it's difficult to tell from the picture.

 

http://www.glacierdieselpower.com/product.aspx?pf_id=FB-03045

 

It's the part in about the 6:30 position in the kit picture. It was convenient, so I used it!!!

Share this post


Link to post
Share on other sites

Easy is good!

 

 

With the crazy cold we've/I've had here North of Chitcago, my FP gauge has been "maxed" out……….30+psi.  Normally in normal temperatures, it runs 24-26psi.

 

That's in FRONT of the 2 fuel filters in my set up………for those that are new here.

 

My truck has  been running just fine…………so far.   I've been driving in temps this year as low as -15*F.  I will admit though, that my truck is kept in an unheated garage over night……………..but for the first time in the history of me living at my house………………a water bottle froze in the cab of my truck whist being housed in my garage!!!!!!  An attached garage also…………not a free-stander.

 

Anyhow, I just thought it would be of interest to let y'all know what the "fuel pressure" is "PRE-FITLER" for those of y'all that run FASS,

AD, Assassin, etc.  I think I see more variation in lift pump pressure than most here based on where my FP sender is.  Colder=thicker fuel=higher lift pump pressure…………………….for me

 

For most of y'all………………..you have you FP gauge at the the injection pump, and after the fuel filters………………….in the cold weather, with the "thicker" fuel, after it get forced thru the fuel filters, the pressure will be LOWER than normal…………………..JUST THE OPPOSITE OF WHAT MINE READS!!!

 

Just saying, not arguing!!

Share this post


Link to post
Share on other sites

Just a thought here..

 

Isnt the pressure that the injection pump is getting the most important one to see? Maybe not with the CP3? I know with my VP truck we need to see what the VP is actually getting. I am just curious as to why put the sender before the filters. I feel that the pressure there is not important....

Share this post


Link to post
Share on other sites

dorkweed... you need to turn your pressure down. The CP3 only wants 15 psi max and 12psi is optimal.

 

 

I do believe you're referring to the VP44 pumps in that regard.

 

The CP3 can handle up to 60+psi IIRC…………………….and YOU must remember that my FP sender is "PRE" filter of any kind.  So if'n I'm seeing 30+psi in the coldest of cold we've had here,,,,,,,,,,,,,,,,,…I'm guessing that the pressure PRE-CP3 is way below that.

Share this post


Link to post
Share on other sites

Nope, that is the CP3 range. VP44's want 14-20 and don't do well under 14. A CP3 has a range of -5 to +15 (direct from Bosch, I called) and when you look at HPCR specs for marine motors (same CP3) is 11.x psi. Most agree keeping the pressure positive is better than using the bottom end of the range.

Yes you are pre filter, but even with a pair of plugged filters you would be higher than recommended. Next time you change the filters adjust the pressure to 15 at idle, that should be about 13-14 post-filter. A clean filer will have less than 1 psi drop, and most filters are "plugged" with ~4 psi of restriction.

Share this post


Link to post
Share on other sites

Nope, that is the CP3 range. VP44's want 14-20 and don't do well under 14. A CP3 has a range of -5 to +15 (direct from Bosch, I called) and when you look at HPCR specs for marine motors (same CP3) is 11.x psi. Most agree keeping the pressure positive is better than using the bottom end of the range.

Yes you are pre filter, but even with a pair of plugged filters you would be higher than recommended. Next time you change the filters adjust the pressure to 15 at idle, that should be about 13-14 post-filter. A clean filer will have less than 1 psi drop, and most filters are "plugged" with ~4 psi of restriction.

 

Not arguing, just saying here………………but I recall reading that it was "flow" and not "psi" that was important for CP3 function……………as the CP3 can "pull" fuel if needed…………………….unlike the VP44.

 

I'm pulling this off the top of my head from a guy that went by the name of "super duty" on CF or DTR…………….I don't remember which.

 

He was even more anal than you are (in a good way) about filtration, pumps, flow etc.  His research said the the plastic cover on the OEM filter housing was good to about 60psi iIRC.\

 

My truck runs good in temps as low as -20………………..why would I want to change things……………….????

Share this post


Link to post
Share on other sites

Yes flow is more important than pressure to the CP3, hence the low pressure requirements. Too high of pressure can be hard on the FCA.

The factory filter cover starts to leak at about 30psi.

My truck runs great in the -20 to -30 range as well, not sure what that has to do with it? I run about 6-8 psi 90% of the time.

Saying it runs well out of spec is like saying 1600 hasn't melted a piston yet, so why go off of what is spec'd.

Not arguing, just putting the info out.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×