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Ds4 fitting for fuel pressure gauge

Will L.

Will L.

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I been hollering long enough that Mark at Mod Mafia finally sells one. Not sure if he found an existing one that happens to work, or is having one made. Either way, here it is. Since there is no current vendor here that offers it, I think it’s ok to post a link. Gonna do a picture also just in case. I haven’t used one, since ds4 is the devil, and I only one db2 rigs.
modmafia.com

Fuel Pressure Tap (FPT)

This item makes it very easy to add a fuel pressure gauge to your 6.5 equipped vehicle.
modmafia.com modmafia.com
 

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is this for the DB or DS pumps? I could be wrong, but this looks as if it has #6 jic or -6an male and female ends. I suppose an additional #4 male o-ring boss to #6 male jic adapter would be needed to be able to use this fitting along with a female #6 jic to 3/8" hose barb for the DS style?
 
Thread says its for DS4, site says it's for 6.2 or 6.5, which suggests both DB2 and DS4 as 6.2 was only DB2. I am curious as to where exactly it's supposed to thread in, as the DS/DB pumps have different inlet fittings to begin with, and most hot rodded DB2 pumps have a nose cone threaded for a larger ORB fitting than the puny 1/4" brake line type fitting on the GM DB2
 
That would be for a ds4. They are not good at proper labeling.
I am not sure if this is stock 5/16 or for 3/8. They just posted it today on thread, I think the rushed getting it online because there are several folks on the hummer forum looking to add the pressure gauge currently. I think they will soon get labeling corrected- just call them with questions.

Still surprised no one here ever did this yet. I guess $5 a fitting profit isn’t worth a lot of effort, but I figured a complete kit would be desirable. Just my theory.
 
@Will L. is there a fuel pressure fitting you recommend for DB2? I really want to get a fuel pressure gauge installed once I convert to DB2, have a whole host of mods waiting to get done in the meantime, always room for one more part to add to the pile 🤣
 
I have the fuel pressure fitting that Leroy sells, fits in the top of the FFM filter.
I am not sure of where in the flow chart this fitting that I have takes its reading from. I am thinking it would be prefilter.
So, if it is pre filter pressure, then with this new fitting, I could run two sending unit, switched, and be able to toggle from one sending unit to the other one. Like what someone else has suggested. I dont rememer whooom though. 🤷‍♂️😹
 
@DieselAmateur Db2 just needs a “tee” that has 1/8 top female, and either 5/16 or 3/8 on the male & female ends that go straight through depending if you are stock fuel line or upgraded to 3/8”. Use stainless preferably. I usually pop into a shop and tell them what I need, they show me a few options/ prices and I get one. One like this should be in the $25 range. Just install it in between the existing barb fitting and ip inlet cone.
3114683D-0D7A-4C55-ACC0-C0375CC7EDED.jpeg
 
MrMarty51 said:
I have the fuel pressure fitting that Leroy sells, fits in the top of the FFM filter.
I am not sure of where in the flow chart this fitting that I have takes its reading from. I am thinking it would be prefilter.
So, if it is pre filter pressure, then with this new fitting, I could run two sending unit, switched, and be able to toggle from one sending unit to the other one. Like what someone else has suggested. I dont rememer whooom though. 🤷‍♂️😹
Click to expand...

The fitting Leroy sells is cool, and way better than using nothing. But the bleeder screw is pre filter, and obviously pre fuel hose to the ip. What I advocate is using a fitting like the one Mod Mafia is selling that will go in between your ip and existing line.
Then you mount the sending unit right there. This will read the actual pressure at the ip. This becomes important when the fuel line gets damaged before the ip. If your line just before the ip failed like the one in the following picture, what happens is you will read great pressure where your current gauge is tapped, or if tapped on the wif drain line. If you did volume flow test- plenty could come out. And before you know it you are installing a new ip. Unfortunately the new ip will mess up also, because the hose is still bad and you have no idea it is $5 worth of fuel hose.

What my plan is this time around is have a pressure gauge sending unit at the ip inlet by using a T like above. Another sending unit pre filter like how yours is (except I will probably replace factory ffm) then the two wires go to a switch and one wire from the switch to my gauge. So switch in normal position and I read the ip pressure. Flip the switch and I read pre filter pressure.
Simple flip of the switch and by knowing the normal difference between the two, I can tell when I need a fuel filter. If I loose pressure, flip the switch and see if filter or fuel line is plugged or if no pressure is coming from the lift pump.
 
When I worked at the dealership- in the gm/ stanandyne testing kit- it had a fittings like these 2 tees (along with other parts of course).
Before condemning an ip under warranty- installing one of these fittings (that had a quick disconnect on the end) and getting the readings was required. The fitting was longer than the one in this pic that MM is selling, but no clue why they made it so long.
 
I sorta thought it was You @Will L. that had the idea of having two sending units hooked to one gauge with a switch.
Your system and idea of how it needs to be is what I want to incorporate into My truck.
 
Only thing that could make a system like that real sweet would be wireless sending units and gauges. Have to be different frequencies though.
Just because running wires can be a PIA sometimes.
Although, when I installed the RR cylinder head temp gauge, I did run enough wire to fill the other two holes on that three gauge pod. 😹
With two sending unit wires out into the engine compartment and enough length of wire to reach about any thing under the hood.
 
We put the pressure tap back at our fuel filter re-locations since the reverberation pulses back thru the supply line on the DS4 pump can kill gauges and electronic transducers. Be mindful of that if this goes directly on the injection pump inlet.
 
quadstar87 said:
We put the pressure tap back at our fuel filter re-locations since the reverberation pulses back thru the supply line on the DS4 pump can kill gauges and electronic transducers. Be mindful of that if this goes directly on the injection pump inlet.
Click to expand...
Someone might need to come up with some sort of a springloaded accumulator device that could absorb the shock waves. 🤷‍♂️👍
 
quadstar87 said:
We put the pressure tap back at our fuel filter re-locations since the reverberation pulses back thru the supply line on the DS4 pump can kill gauges and electronic transducers. Be mindful of that if this goes directly on the injection pump inlet.
Click to expand...

We did a ton of testing at the fuel company- including experimental fuels.

On the mechanical side of gauges- not really a concern. I had around 40 in the fleet when we did different fuel types testing that all went over 400,000 miles. All but 1 made it the entire time. It started with exactly 50 trucks, but around a dozen of them were eliminated from testing in the first year. The ip and injectors had to be replaced many of them very often from damages from the fuels, so my guess is the one gauge that I replaces (which started seeping in the cab) had issues from the fuel itself.
By the time the shockwave goes through the fuel very far in the line it is mitigated. We could see needle vibration in the gauges way more when the gauge is directly on the fuel line. We noticed the closer to the lift pump it got the more radical the pulses were on the gauge- and farther away from the lift pump the more steady it was. But if you want to see the average of the gauge not the pulses, just get a liquid filled gauge or use a damper. For diagnostics, seeing how bad pulses are can be helpful.

None of the electric ones failed.
Then we had 12 trucks (3 for each type of the most likely to use fuels) that we did with constant recording on, so they were all electric with the regular 4-20 signals. This is where my 1 pre and 1 post sensor thing comes from. The fuel commission mandates over a million miles testing done. We had pressure read on both sides of lift pump, both sides of filter, and both sides of ip, and at return sides of injector returns, along with flow meters before and after ip, and on injector return. Granted these were more expensive than regular sending units, but they were the cheapest ones that Omega (iirc)sold back then. The monitoring and recording set up itself was crazy expensive, so thats why it was only done on the final trucks under scrutiny. Amazingly none of the 12 got in wrecks so bad we couldn’t fix them- so they all finished. All had bearings and rings, etc every 200,000 as allowed in the standard. When ip, injector, piston, valve etc failed- we had to record it and all parts identified and saved, then sent in with reports to the commission.

I started with electric gauges on my truck, but my electric oil pressure gauges would always fail and my mechanical ones never did. Usually it was the gauge itself not the sending unit. So after that I just went all mechanical for my added gauges for decades afterwards.
 
Burning oil said:
FYI Fuel Pressure Tap. Buy the original here https://leroydiesel.com/products/leroys-fuel-pressure-tap-fpt/

Ive never heard of a hose between the FFM and IP collapse or have any problem, with our FTB kit it would be exceedingly rare!. If someone wanted I could add the fitting like pictured above, its a generic fitting not a special made fitting.
Click to expand...

Outside of fuel line or filter failures or plugged filters- yup your ffm tap is a great idea, and convenient.
Remember folks- Will is still fighting aspects of ocd. So 3% of an added gauge not working for intended purpose is unacceptable to me. I get too critical sometimes. For most this set up is fine. But for me and for a few others...

I know your kit uses the push to lock system. I know some of the brands are not rated for ethanol, guessing yours is because you know it’s a problem and I know you never wanna sell sub par stuff. I haven’t seen sae30r9 that can work on push to lock- but there are some hoses without that rating that are still ok for ethanol. But not everyone has your kit, some diy, some dont ftb.

But here is a few pics, the two pics that show the cable tie as a pointer to the flap which was intermittently blocking flow for this guy who seems to not want to share it here- replaced his ip because he had “good pressure to ip” when infact his failed right at the barb fitting of the ip. New ip, same problem. He is not alone, I have seen this many times- and TWO different members here not counting the guy that sent me these pics- had this happen but didn’t want to admit it on the forum because they feel silly over spending big bucks over a few dollar hose. Then the count on the hummer forum is TWO. so that is 4 people in the last few hears that did ew ds4 and didn’t need it. I got bit by this on a db2 way back, His (the picture supplier guy) was db2, but when this occurs I have seen it both db2 and ds4- and it seems always at the ip fitting becomes intermittent. When at the lift pump or filter- then plug constant- so maybe something about the thing John was saying has different effect close to the ip- he obviously onows more about ip than I ever will.
Note the condition of the rest of the hose. Only the thin inside layer is coming apart. The rest of the hose looks and feels absolutely perfect. No signs of damage that would ever be suspected. I can’t remember how old he said this hose was/ mileage in this picture- but my experience seeing this so many times, I would suspect 35,000-40,000 miles.

The other pic random shot of ethanol problems to fuel line, other shows proper condition.F0D6384D-AA4C-4AE3-A36C-C4D51B1FA8F8.pngC61EFD15-68A2-42FC-A430-926395D85A44.pngF675F490-E756-4306-A388-6CA3259DCBA7.png28F52D42-3DF5-485C-B03E-3D27FF90D1F8.png
 
Well thats not a proper hose (fuel injection hose) so yeah its going to fail possibly. Even so Ive never seen or heard that it was even a thing. Use the correct parts and should never have a problem.
 
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