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· Needs more hours per day
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Discussion Starter · #1 ·
I've had a chance to put some miles on the new injectors with the big fuel feed setup and Bosch 044 pump. What I have observed has now got me pretty irritated.

In the 80, 100, and 120 settings, fuel pressure is dropping badly under hard acceleration from 60 psi down to below 20 psi. :( However it seems to only recently have started doing this, so I don't know if all the air is finally out of the oil rails and the injectors are working properly or if the pump is already failing me after less than 3 months of use.

A new 2 micron element was put in the Dahl 150 (which Bob tells me will flow 100 GPH - more than B Codes require) when I put the fuel pump on, so there should not be any contaminants in the pump. I've also got a fused 12 GA wire directly from the battery to power the pump, using the stock fuel pump wires to activate a relay - so the pump should be getting plenty of voltage & amperage.

Even if the pump is failing, I plan to replace it. Originally, I was told the 044 will flow 80 GPH at 72 psi. I have since found out this is incorrect. At 65 psi, the flow rate is more along the lines of 54 GPH - a far cry from 80 GPH. Here's the flow rate graph of the 044 pump: http://jayracing.com/images/BFP-044_flow_chart.jpg

This is quite frustrating! Back to the drawing board.
 

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Is the filter before or after the pump?

Tom
 

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Discussion Starter · #4 ·
The Dahl 150 is pre-pump. It's a suction type filter and the water seperation would not happen if it were under pressure. There's an Aeromotive 10 micron inline after the pump, that was also new with the pump.

David, I'll give you a call tomorrow. I need to start checking out my options.
 

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My Plan is still to run two pumps... with a pre pump water/prefilter and a post pump 2 micron filter... and delete the fuel bowl...
 

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:stupid:

2mic is waaaay too small for a pre pump. I just today switched from a 1212 filter, which is rated @ 4mic I believe, to a much larger FS1000 filter rated at 10 microns. I immediately noticed a difference, including idle quality, smoothness, and the weak stock fuel pump can actually keep up a little better now.

For a simple experiment, completely eliminate your prepump, bypass it and see what happens. Should tell ya real quick :D :ford:
 

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Discussion Starter · #9 ·
But, that 2 micron pre-pump filter is rated at 80 GPH optimum and 100 GPH max, according to Bob at Dieselsite. That shouldn't be causing a restriction. Bypassing it wouldn't be that difficult though and at least give it a try.

I can't swap the filters, or I'll lose the water seperation ability of the Dahl. With no fuel bowl, I need to have a water seperator on there somewhere.
 

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But, that 2 micron pre-pump filter is rated at 80 GPH optimum and 100 GPH max, according to Bob at Dieselsite. That shouldn't be causing a restriction. Bypassing it wouldn't be that difficult though and at least give it a try.

I can't swap the filters, or I'll lose the water seperation ability of the Dahl. With no fuel bowl, I need to have a water seperator on there somewhere.
Jeremy, just a simple experiment to see what's going on. Not saying I wouldn't believe Bob, but it's better to try for yourself and see what works for you.

I know the Baldwin version of my filter (I had the fleetguard) was rated 4mic @ 90 GPH, and it was still causing a restriction.

You also have to consider whether that rating is on the suction side, or pressure. A filter can boast a high flow rate on the pressure side, but in reality flows much less under suction.
 

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Originally, I was told the 044 will flow 80 GPH at 72 psi. I have since found out this is incorrect.
The 044 flows 300 L/hr (80 g/hr) at 0 psi and 200 L/hr (52 g/hr) at 5 atm or 72 psi. Somebody got their numbers mixed up. I agree with Bob that a clean 2 micron filter in the Dahl 150 is likely not the source of restriction. Could you have gotten some dirty fuel? What does the bottom of the Dahl bowl look like? Any junk or water there?
 

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:stupid:

2mic is waaaay too small for a pre pump.
Nope. I have measured the restriction with a 2 micron filter pre-pump and it is about 10 inches of water at the pump inlet. That is less than 0.7 inch of mercury (Hg). I meticulously removed sources of restriction from the pickup to the pump. The filter rating, 2 micron to 30 micron, did not make any difference at OEM flow rates. That was with 3/8" id hose and an OEM pump. My new fuel system will be very similar to JTH's with 5/8" pickup, 5/8" hose to Dahl 150 to 044 pump and 1/2" from pump to Hy-Pro glass filter and to y-block with 3/8" to each head. OEM filter housing is deleted. HOWEVER, I am not running B-codes.
 

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At 65 psi, the flow rate is more along the lines of 54 GPH.......
What kind of fuel delivery do your B-codes require at WOT? Nearly a gallon per minute is a ton of fuel? Maybe I am way off here but if an injector fires once every 2 revolutions, then at 4000 rpm, 8 inj x 2000 inj events per minute x 250cc per injector per 1000 injector events would be 8x2x250cc or about 4 liters/minute which is 1.05 gallons/ minute. The only reason the pump can keep up is as the pressure drops the volume output of the pump increases. Me thinks you need a bigger pump.
 

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Discussion Starter · #15 ·
Glad to know those flow number of the Dahl have been checked. The bowl in the Dahl is spotless, no water, no dirt. I'm not sure on the exact flow rates, someone may know though - DDP's with .0075 EH PSD tips.

However, this morning gave me some ineresting data - like the pump is working perfectly now. I put the chip on the highest setting, did a WOT run from 20 MPH to 70 MPH, watching the fuel pressure the whole time. It dropped maybe 1 or 2 psi, that's it. Yesterday, I could just tip into the throttle on the 80 setting and watch the FP drop quickly to around 20-30 psi.

I have no idea what's going on now. :shrug: I wonder if it's heat related somehow, causing the FP to drop? I noticed it yesterday after I had been driving around all day in 80* temps. This morning, it was in the low 60's when I started the truck, and ran the WOT run(s) after maybe 30 minutes of driving around. I've got a bunch of driving to do this afternoon, so I'll see what happens as the air temp comes up, pump get's warm, and fuel in the tank get's warm.
 

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cavitation maybe it then that fuel is thicker when that much cooler
 

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cavitation maybe it then that fuel is thicker when that much cooler
I doubt it is cavitation if it is worse when warmed up. I could measure the increased restriction between cool fuel (more viscous) and warm/hot fuel.
 

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I wonder if it's heat related somehow, causing the FP to drop? I noticed it yesterday after I had been driving around all day in 80* temps.
JTH, I wonder if there might be an issue with your relay. How many amps is it rated for? These pumps draw a fair amount of current?
 

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Nope. I have measured the restriction with a 2 micron filter pre-pump and it is about 10 inches of water at the pump inlet. That is less than 0.7 inch of mercury (Hg). I meticulously removed sources of restriction from the pickup to the pump. The filter rating, 2 micron to 30 micron, did not make any difference at OEM flow rates. That was with 3/8" id hose and an OEM pump. My new fuel system will be very similar to JTH's with 5/8" pickup, 5/8" hose to Dahl 150 to 044 pump and 1/2" from pump to Hy-Pro glass filter and to y-block with 3/8" to each head. OEM filter housing is deleted. HOWEVER, I am not running B-codes.
HNH, I just know the particular filter I was using caused a restriction when it was "supposed" to be rated at well beyond the minimum.

I do have a weak pump though, probably just band aiding the weak pump by using a higher mic filter. I might go to 100 mic next. All I care about pre pump is effective water seperation, and somekind of filter to stop large particles going into the pump, all we had before was the screen in the pickup.

The Dahl *should* be up to the task, and then some, I agre 100%. But there's one way to eliminate it on his setup: bypass it.
 
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