Observations about Walbro/Racor/In-Cab Fuel Pressure

[Matt Bachand]

Its been a few weeks now since my fuel system refinery overhaul has been done, and I wanted to share a few thing's I've noticed about doing this.

1. Not sure if its the Walbro, or the fuel pressure gauge, but seeing strong fuel pressure in-cab at all times has given me a super strong sense of confidence in the rig.

2. When engien ins't warm, fuel pressure is generally 1 psi less than once the engine warms up. This could be due to the filter manager getting heat soaked, thus thinning the diesel, - OR - to be fair, it could be due to the electric fuel sender heating up, and reading differenctly (the sender is mounted far corner, driverside by the brake systems, where it would remain cooelst, and opposite of fan wash). So I think its the filter mgr heating up. Curious to see what winter temps do.

3. Walbro noise levels have increased a little whre I can now hear it click at WTS times, just like everyone else mentions they can hear their Walbro.

4. Walbro seems to output the most PSI when its a consistent flow. Before IP I idle at 3-4cold, 4-5 warm, and 41/2 consistent on the highway or anytime holding 2200rpm.

5.Stewart Warner guage is nice, and cheap, but the illumination is not up to par with my ISSPRO gauges, wehre as the needles and the numbers do not allow light to pass - through. Just a ring of illumination around the outside bevel.

6. Extrememly important to mount gauge directly in front of the IP as my 4 month old flt mgr filter was clogged up, leading me to read 6psi at T-Valve, but only 2psi idle, with instant drop to 0 with throttle applied. I would have driven like this another 6 months or so had I changed the flt on 15000mi intervals, or yearly.

7. Racor with clear bowl at the bottom is priceless. It catches all sorts of rusty drops of who knows whats... Visual view of the conidition of my fuel at all times, including cold weather properties. The built in heater is just an added bonus.

8. I was originally going to mount in-cab Fuel pressure gauge under dash, but decided to put it on a pod on top of the dash righrt next to my a-pillar gauges. I love it there, even though it doesn't match my ISSpro's. LIke I mentined, real sense of confidence in the rig having that there.

I'm sure more observations will come to mind next time I road trip...

 

[DieselCash]

Do you have pictures posted of everything?

Thanks for the great information! :thumbsup:

 

[Matt Bachand]

Pix... Tossed one in of my 100% covered gloss back 'down there' picture!

 

[buddy]

Did the spring change in the Walbro help? I got my springs, and they gave me a new bowl to replace the one that cracked.

I finally got camera charger, so will go take some pics later today.

 

[DieselCash]

Pix... Tossed one in of my 100% covered gloss back 'down there' picture!

Thanks for the pictures! :thumbsup:

Is that your Elmo or your daughters?

 

[Matt Bachand]

Thanks for the pictures! :thumbsup:

Is that your Elmo or your daughters?

Mine... when she behaves I let her play with him! :thumbsup:

 

[Matt Bachand]

Did the spring change in the Walbro help? I got my springs, and they gave me a new bowl to replace the one that cracked.

I finally got camera charger, so will go take some pics later today.

It did help. I went from 3-4 at t-valve to 6 or so at t-vavle... the flt mgr takes a few PSI outta it, so Now i get 4-5 after mgr. Still would like more, but she runs awesome and never dips under 4 during normal driving.

 

[Matt Bachand]

The Racor separator has to be a far better design than the sealed units without separate/drainable bowl. It seem anything that is heavier than diesel, IE Water, RUST, CRUD and anything else sits in the bowl, and is easily drained out, instead of taking place inside the filter element.

Now I just need to find a mating pigtail for the racor's fuel heater. Searched googles but no luck, Seems it should have come with my unit perhaps, but didn't.

 

[Acesneights1]

I'm not sure if it makes a difference with the 6.5 but on Cummins you need to use a fuel pressure "snubber" and a 30" ext hose to get consistent readings otherwise the spikes cause by the IP are all over the place and eventually burn out the sending unit. I am assuming your FP guage is electric in cab(I hope).

 

[Acesneights1]

Which Racor did you use ? I want to upgrade my FF on my CUCV. It has those worthless plug in ones. I don't like it.

 

[Matt Bachand]

I'm not sure if it makes a difference with the 6.5 but on Cummins you need to use a fuel pressure "snubber" and a 30" ext hose to get consistent readings otherwise the spikes cause by the IP are all over the place and eventually burn out the sending unit. I am assuming your FP guage is electric in cab(I hope).

I see some fluctuations, but it seems more of that of the walbro. No IP spikes. Sender is about 18" away from the T in the valley.

SmithvilleD has a high quality mechanical gauge, and he sees high spikes and ip pulses. Not sure if its cuz my gauge is cheap, or electric vs mechanical, but I don't see those spikes.

Electric sender for in cab gauge, yes.

 

[Matt Bachand]

Which Racor did you use ? I want to upgrade my FF on my CUCV. It has those worthless plug in ones. I don't like it.

From Ebay search PBTXXX ended up getting the 490r30 w/heater for about 60 bux after shipping. He deals with refurbished, but it sure looked and acts new. His ebay store always has a listing of variable racors. Always at super cheap prices.

 

[Acesneights1]

try a snubber. Autometer sells them for like 30$$. Autometer will not warranty a FP gauge if used on any diesel without one.

 

[Acesneights1]

My mistake, only in Cummins.
http://www.autometer.com/cat_accessoriesdetail.aspx?vid=212

 

[SmithvilleD]

I see some fluctuations, but it seems more of that of the walbro. No IP spikes. Sender is about 18" away from the T in the valley.

SmithvilleD has a high quality mechanical gauge, and he sees high spikes and ip pulses. Not sure if its cuz my gauge is cheap, or electric vs mechanical, but I don't see those spikes.

Electric sender for in cab gauge, yes.

On my Autometer mechanical 0-15 psi fuel pressure gauge w/ isolator, the gauge reacted quickly w/ every lift pump pulse. Resulting in constant needle bounce indirectly proportional to fuel demand. With a stock-type '93 spec lift pump, the needle pulses at idle were ~ 0.5 - 1 psi. Swapping to the Walbro FRB-5 showed a much stronger pulses - max bounce (2-4 psi) at idle, smoothing out as throttle/inj pump fuel demand went up.

The solution was putting a restriction orifice in the gauge's pressure feed line to limit how much of these pulses the gauge actually see's. Doubt this is a problem except for quick reacting, mechanical type fp gauges.

I removed a fitting in the feed line & brazed the internal passage shut, then drilled out a smaller orifice. First few guess at how large the orifice should be were too large, but each step in a smaller orifice lessened the degree of gauge needle bounce. Wound up going to the smallest drill bit I had, #60 - 0.040", which has the pulsation showing on the gauge dampened to less than 1/2 psi swing at idle which quickly smooths to a steady reading with most any application of throttle beyond idle.

 

[buddy]

They call that a snubber, common for fuel pressure gauges. Are you measuring on the drain line or the actual IP feed line?

 

[SmithvilleD]

The gauge feed comes from the inj pump feed line.

Understood. The 2 ready-made snubbers I tried did attenuate the pulsation some, but still too much needle bounce - enough to prompt concern about gauge longevity.

I got to this 0.040" orifice size last Fall, but wanted to go thru winter fuel temps/higher viscosity, so I'd know gauge response was still quick enough in those conditions, before posting.

 

[Matt Bachand]

Probably only an issue in your super sensitive high quality gauge.

Glad you resolved it. Must be a nice feeling seeing that thing nice n steady.

 

[bison]

I got that needle flutter too on both trucks,the one is worse than the other,but have exactly the same mech setup,only 1 truck has the gauge in the dash(worst flutter),the other on the tunnel.I thought it might be caused by air trapped in the line to the gauge?
It differs from one day to the next,sometimes they're steady, other times just a blur

 

[Matt Bachand]

Problem is fuel recirculates all the time so if truck is on its going through filter so some particulates will get caught. But then again too if you are adding fuel to tank more often more particulates are added to the system. So MPG does make a difference.

I read the Black color comes the fuel being hot/warm and the "asphalts" seperating and being filtered out. Heavy work or hot will increase black color on filter. The regular crud dirt and particulates I think can be any shade of brownish to black color. So color may not be the only indicator. Also look for rust colored crud indicating dead algae iirc.

Also one bad batch of fuel could plug filter at any time. I run a fuel gauge and go anywhere from 12-20 K miles depending. I probably should change it more often but if I have adequate flow (> 1-2 psi at all conditions) I figure everything is ok. Closer to 4-6 psi is better and usually what I get when filter is new.

I just installed a Racor Filter INdicator works on suction looks like the air filter indicator we have.

Now With my mouth I get that thing to spring down easily. When I crimp the line past it, the indicator trips (ratcheting style like up to -7hg vacuum)...

Anyhow. The Walbro Doesn't trigger this one but, and my fuel pressure is down to 4 with 1-2 working..

Since my filter indicator isn't tripping, I swapped out my FFM filter.

Still have crap pressure, so I tossed in my OTHER walbro pump.

Same thing. Even worse as this pump stinks for PSI, but maintains same hardflow PSI. But I'm a PSI junky, so NFG in my book.

ANYHOW. Still no filter indicator action, so I think the walbro is just too ***** of a pump to suck enough to trip it.

I'm going to swap out the filter, but Pissed about my 55 dollar indicator I at least want to make sure that is the problem.

Then, I think I'm going to install one of the walbro's as a 'pusher' pump to go pre-racor, and switch from my 30micron to 10micron filter that I have.

I will leave the mesh screen trap (70 micron) in the ass of the walbro of the pre-Racor unit, and remove it on the post. It's easy enough to empty and drain mounted on fram rail.

Take that fuel PSI.