12 Valves Are Hanicapped

[Ted Jannetty]

Don't get me wrong I love my 12 Valve, but I recently experienced a stumble while lighly accelerating which prompted me to start digging for the problem and I found something disturbing.
I installed a fuel pressure gauge at the injection pump and went for a ride, only to find the fuel pressure fluctuating Violantly 0-60 psi so fast you can't even read it, I thought the gauge was going to explode!
I replaced the lift pump and it only got a little better, 0-40 while driving but settles down a little at idle and swings from 18-35 psi.
This got me thinking, Maybe this accounts for the big differences in fuel economy that all these truck see.
These constant pressure spikes can't be good for the injection pumps ability to give smooth and even fuel delivery to each injector.
So I came up with the Idea, to install an electric fuel pump that will keep a steady 23 psi at the injection pump at all times.

I have high hopes for this system, to increase the efficiency and performance of the MIGHTY 12 valve Cummins Turbo Diesel.

Testing is currently being run, will keep you posted.



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Ted Jannetty, Owner President, Jannetty Racing Enterprises, Inc.
97 3500 4x4 club cab 5spd. RED, JRE custom power kit, JRE 4" exhaust
JRE 1/2 inch fuel system, Bosch 300 hp injectors, Prime loc,
Cummins chrome kit, US Gear 20% over drive, 3. 54 posi, Autometer
Ultralite 50lb. boost, and Pyrometer, BD exhaust brake.
Horton fan clutch

99 Ski-Doo 800 Formula III Pipes, reeds, studs and clutching 172 hp
99 Honda Forman 450 ES jet kit, pipe, lift kit, 27" Mud Runners
2001 Ski-Doo MXZ 800 X stock for now 140 hp
2000 TransAm Ram Air WS6 Flowmaster, K&N, Granatelli Mass air meter, LS1 Lid 370 hp
1973 Camaro Rally Sport Street Strip 850+ HP

 

[drawson]

Sound good, let us know how this comes out. I think you are working down the right track.

 

[illflem]

Ted,it would be great if the electric pump helps things,seems like a smooth flow would be better,especially on the overflow valve,it has to be pulsing as much as the gauge,but the pulsing you see is common with most mechanical fuel pumps. I don't think the pulsing is as violent as the gauge registers,but agree that the gauge won't last long with it. My gauge settled down while accelerating and at cruising speed though. Later I installed a gauge snuber before where the sender is attached at the IP banjo bolt on mine to protect the gauge. It's just a male/female coupling with a very small hole though it,smoothed the pulses down to zero, cost $12. Be interesting to see what your experiment yields,there must be a reason that most newer rigs,gas and diesel,have gone over to electric pumps,but it could be cost.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(work truck)
95 3500,5 speed 3:54,BD E-brake,Driftwood,Banks&Psycotty,34,000 GCVW apple and tractor hauler(works harder truck)

[This message has been edited by illflem (edited 03-02-2001). ]

 

[C-Series-Man]

I would not get that excited about the pressure peaks generated by the lift pump. It is after all just a piston pump. The internal flow characteristics of the P7100 are pretty wild themself. Some of the pressure peaks you see on your gauge are from the internals of the pump. Everytime a plunger goes up until it closes off the fill port in the barrel you get a back pressure wave. I am simply saying that I would not blame the whole issue on the lift pump. You have just discovered a known characteristic of the B and C series engines. This problem is also agrivated tremously by higher pressure bypass valves in the injection pump. I have seen suck high pressure relief valves used they caused the lift pump to basically lock up. This is bad for lots of reasons. Your injection pump does not get the flow it needs for cooling. It also causes the lift pump piston and tappet to seperate. This itself is not all that bad, it's when the two parts come back in contact like they are suppost to be. You can hear a ticking noise and after a while the lift pump tappet and the piston start to deform. Extreme cases will cause the lift pump piston to crack and break up. I have also seem internal lift pump pressure so high they leak raw fuel into the engine block. BAD STUFF. Moral of the story: You really don't gain that much performance by jacking up the pressure in the injection pump fuel gallery. You usually only get more problems.

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95 Ford F-350 4x4 Ext Cab, Cummins 6CTAA 8. 3, Fuller 9 Speed, Big Rig Heart in a Pick-up Truck

 

[Ted Jannetty]

I already knew that there are pluse waves generated by a mechanical lift pumps, heck we check fuel pressure first on every driveability problem and have seen it many times before but not this wild.
Happy to report the new lift pump did fix my stumble problem.
So the next step it to collect data with the electric pump installed.
I will give it a month of city driving and highway towing to evauate the system, have data to compare to collected over the last few months.
I have no intention of raising pressure above factory spec of 21-23 psi.
I only want to give a steady flow and pressure so that all the plungers and barrels will see the same pressure all the time.
In theory, this should smooth out these beasts, and hopefully improve fuel economy to the levels of the 24 valves that run right.
My current fuel mileage figures are mid 14's city and mid 17's highway, and that is in double overdrive, not too impressed.

Always looking to improve on anything.




------------------
Ted Jannetty, Owner President, Jannetty Racing Enterprises, Inc.
97 3500 4x4 club cab 5spd. RED, JRE custom power kit, JRE 4" exhaust
JRE 1/2 inch fuel system, Bosch 300 hp injectors, Prime loc,
Cummins chrome kit, US Gear 20% over drive, 3. 54 posi, Autometer
Ultralite 50lb. boost, and Pyrometer, BD exhaust brake.
Horton fan clutch

99 Ski-Doo 800 Formula III Pipes, reeds, studs and clutching 172 hp
99 Honda Forman 450 ES jet kit, pipe, lift kit, 27" Mud Runners
2001 Ski-Doo MXZ 800 X stock for now 140 hp
2000 TransAm Ram Air WS6 Flowmaster, K&N, Granatelli Mass air meter, LS1 Lid 370 hp
1973 Camaro Rally Sport Street Strip 850+ HP

 

[illflem]

C-Series Man,what I think you are saying is back pressure from the IP is overcoming the transfer pump pressure,right?If so I wonder if the lift pump problems the 24 valves always seem to have is related to this?Seems like an electric pump would be more susceptible to becoming damaged from this. Maybe locating an electric pump closer to the tank could isolate it from this more?Another problem with changing to an electric pump I'm seeing is that the mechanical pump should be disabled so it doesn't self destruct from running dry or a plate should be put in it's place. Ted you might want to beware of this. Just my 2¢

 

[Jones]

Good point on pump location there illflem.
We learned early on that electric pumps like to push a lot better than to pull, so back close to the tank is a good place. I even think a lot of the late stuff has tank mounted pumps. As soon as we went over to elec pumps and decided they were doing the job dependably we pulled the mech pumps as they came in and put on block-off plates.
My 2cents too. Jones

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Jones
'84 Ramcharger w/CTD, non-gated 12, torqflite, NP205, Dana 60 and 70 w/ 3. 07s. Looks more or less stock.

 

[Mel Fuelling]

Ted, your posts are always worth reading, observation tempered with experience is a powerful troubleshooting tool. There are several other alert, inventive minds who can be counted on to shine a practical light on a problem also. It will be interesting to see if this solution works out. If an electric pump doesn't smooth delivery out enough, it almost seems like a pressurized accumulator might help if a size small enough for the application is available.

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93 Maroon/Gold D350 CC Dually,5sp,LE trim, A/C,Raven cab height w/contractor side windows, PW inj. , K&N in OEM housing w\altered added inlet, class IV receiver hitch, Maroon cloth 60/40 '97 F150 bench seat, KYB shocks,& behind the seat,not yet installed: Moog upper & lower ball joints, PST poly graphite upper & lower control arm bushings and Praise Dyno Brake pads & shoes.

 

[Brandon]

for what its worth I have installed a mess of spa's and some on fuel pressure. My problem started with 2000-2001 and we were reading fuel press at the injector pump, not on schraeder but a 6an test port as truck already had lines on it. Well to make a long story short the guage moved so vilolently we troubleshooted the gauge -20 to +20 it was wild. . The bottom line is we moved the press sensor underneath the fuel filter (upstream) about 10 inches and the problem was gone, very consistent reliable readings. . For me at least it appears I can not get reliable reads directly at the pump, it must be about 10 inches away(yes its still post fuel filter) and all my funky readings went away. . Probably to many backpressure fluctuations directly at the pump. .
Sooooo yes I have seen the spikes to and they are on the 24valves as well, ps this happened to me on two 24 valves and i talked to a man at sheids and he had seen it too on a 12v, he thought maybe because it was digital, I advised him no, try it downstream

Also I thought of a pulsation dampner, but moving the press sensor 10 inches
B... ... ... ... ... ... ...

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END THE OPPRESSION FREE HVAC NOW
Danelle's Dodge

 

[DieselB59]

Ted,
I had the same problem with my 97 2500 and I fixed it with one of Dave Mitchell's own overflow valves and that caused a hammering in the transfer pump which eventually led to its failure. I acquired a new OEM overflow valve and tweaked the spring slightly to get 30 psi at idle. The problem went away. We went on to eliminate the transfer pump all together on the race truck and plumb in an electric pump which is mounted rearward near the fuel cell.

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Chris Timochko
AUTO WURKS DIESEL R&D TEAM
1997 5sp 4X4, Rhino Linings, Espar Heater, A. W. D. HX40 turbo, ATS 3pc Manifold, BD 4" Brake, Marine Compression, A. W. D. Custom Tuned Injection Pump, A. W. D. Intercooler, A. W. D. 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, A. W. D. Water Injection, NOS Diesel Kit, A. W. D. 6" Chrome Exhaust System, BD No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. 15. 50@97mph on Goodyear All-Terrain tires.
****************************************************************************
Project U96 - 1996 3500 2WD racer. A. W. D. Marine Ultra Low Compression, A. W. D. Teflon-coated Pistons, A. W. D. High Lift Camshaft, Ported and Honed Cylinder Head, Intake and Exhaust manifold; A. W. D. HX40 Turbocharger, ATS 3pc Exhaust Manifold, A. W. D. Water Injection, A. W. D. Custom Fabricated Fuel System, Race Spec A. W. D. /BD P7100 Injection Pump, A. W. D. Custom High Flow Fuel Injection Nozzles, BD Auto transmission and Custom TC, Weld Draglites, Goodyear Eagle Drag Slicks, 5" Single Stack Through The Bed, Mag-Hytec on Rear and Transmission. 11. 54@115mph

 

[Ted Jannetty]

I already have all the components to eliminate the stock lift pump, block off plate and all.
I intend to mount the pump right in front of the tank.
I have located a pump that is rated for continuous duty at 25 psi and has an adjustable regualtor mounted right on the pump housing, so we can set the line pressure where ever we like.

Chris, Did I read your post correctly? you said that the overflow valve caused the dimise of your lift pump?
Increasing the opening pressure on the overflow valve agrivates the problem of pressure spikes, that is why the spec. is 21-23 psi no more no less.

With an electric pump and a constant pressure we will be able to experiment with different pressures and the effects on driveability.

I expect that more pressure will increase fuel delivery with out any losses in smoothness.

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Ted Jannetty, Owner President, Jannetty Racing Enterprises, Inc.
97 3500 4x4 club cab 5spd. RED, JRE custom power kit, JRE 4" exhaust
JRE 1/2 inch fuel system, Bosch 300 hp injectors, Prime loc,
Cummins chrome kit, US Gear 20% over drive, 3. 54 posi, Autometer
Ultralite 50lb. boost, and Pyrometer, BD exhaust brake.
Horton fan clutch

99 Ski-Doo 800 Formula III Pipes, reeds, studs and clutching 172 hp
99 Honda Forman 450 ES jet kit, pipe, lift kit, 27" Mud Runners
2001 Ski-Doo MXZ 800 X stock for now 140 hp
2000 TransAm Ram Air WS6 Flowmaster, K&N, Granatelli Mass air meter, LS1 Lid 370 hp
1973 Camaro Rally Sport Street Strip 850+ HP

 

[C-Series-Man]

60 PSI with the stock lift pump?

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95 Ford F-350 4x4 Ext Cab, Cummins 6CTAA 8. 3, Fuller 9 Speed, Big Rig Heart in a Pick-up Truck

 

[DieselB59]

It was a different overflow orifice valve that was probably from a different application all together and it didn't open at 20-25 psi like the stock one, but at 60-70 psi. It was good for keeping pressure in the injection pump, but it killed the internal seals in the lift pump and fuel began squirting from the primer button. Also, a hammering noise was heard from the lift pump area and it sounded like rod knock. Upon re-installing an OEM one with a slight tweak to the spring, the noise went away and hooking up a pressure gauge to it for the test drive revealed that it was completely functional and carried a steady pressure of 27-32 psi. It's somewhere in my toolbox where it can't do anymore harm. I think it was originally developed for tractor pulling.

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Chris Timochko
AUTO WURKS DIESEL R&D TEAM
1997 5sp 4X4, Rhino Linings, Espar Heater, A. W. D. HX40 turbo, ATS 3pc Manifold, BD 4" Brake, Marine Compression, A. W. D. Custom Tuned Injection Pump, A. W. D. Intercooler, A. W. D. 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, A. W. D. Water Injection, NOS Diesel Kit, A. W. D. 6" Chrome Exhaust System, BD No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. 15. 50@97mph on Goodyear All-Terrain tires.
****************************************************************************
Project U96 - 1996 3500 2WD racer. A. W. D. Marine Ultra Low Compression, A. W. D. Teflon-coated Pistons, A. W. D. High Lift Camshaft, Ported and Honed Cylinder Head, Intake and Exhaust manifold; A. W. D. HX40 Turbocharger, ATS 3pc Exhaust Manifold, A. W. D. Water Injection, A. W. D. Custom Fabricated Fuel System, Race Spec A. W. D. /BD P7100 Injection Pump, A. W. D. Custom High Flow Fuel Injection Nozzles, BD Auto transmission and Custom TC, Weld Draglites, Goodyear Eagle Drag Slicks, 5" Single Stack Through The Bed, Mag-Hytec on Rear and Transmission. 11. 54@115mph

 

[DieselB59]

Ted,
I cannot tell you if it really were the direct reason as to why the lift pump's seals failed, but it did fail and it failed within an acceptable amount of time for me to say that the 60 psi of the overflow valve was too much for the lift pump.

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Chris Timochko
AUTO WURKS DIESEL R&D TEAM
1997 5sp 4X4, Rhino Linings, Espar Heater, A. W. D. HX40 turbo, ATS 3pc Manifold, BD 4" Brake, Marine Compression, A. W. D. Custom Tuned Injection Pump, A. W. D. Intercooler, A. W. D. 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, A. W. D. Water Injection, NOS Diesel Kit, A. W. D. 6" Chrome Exhaust System, BD No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. 15. 50@97mph on Goodyear All-Terrain tires.
****************************************************************************
Project U96 - 1996 3500 2WD racer. A. W. D. Marine Ultra Low Compression, A. W. D. Teflon-coated Pistons, A. W. D. High Lift Camshaft, Ported and Honed Cylinder Head, Intake and Exhaust manifold; A. W. D. HX40 Turbocharger, ATS 3pc Exhaust Manifold, A. W. D. Water Injection, A. W. D. Custom Fabricated Fuel System, Race Spec A. W. D. /BD P7100 Injection Pump, A. W. D. Custom High Flow Fuel Injection Nozzles, BD Auto transmission and Custom TC, Weld Draglites, Goodyear Eagle Drag Slicks, 5" Single Stack Through The Bed, Mag-Hytec on Rear and Transmission. 11. 54@115mph

 

[Ted Jannetty]

Just an update!
For Those of you thinking about trying it at home.

It seems the Fuel heater can't take being under pressure, Normally on the suction side of the lift pump.
It leaks fuel out of the electrical connector with the electric fuel pump turned on, Not a Good situation.

I have a solution, making the necessary changes, I will keep you posted, NO Data to report Yet.

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Ted Jannetty, Owner President, Jannetty Racing Enterprises, Inc.
97 3500 4x4 club cab 5spd. RED, JRE custom power kit, JRE 4" exhaust
JRE 1/2 inch fuel system, Bosch 300 hp injectors, Prime loc,
Cummins chrome kit, US Gear 20% over drive, 3. 54 posi, Autometer
Ultralite 50lb. boost, and Pyrometer, BD exhaust brake.
Horton fan clutch

99 Ski-Doo 800 Formula III Pipes, reeds, studs and clutching 172 hp
99 Honda Forman 450 ES jet kit, pipe, lift kit, 27" Mud Runners
2001 Ski-Doo MXZ 800 X stock for now 140 hp
2000 TransAm Ram Air WS6 Flowmaster, K&N, Granatelli Mass air meter, LS1 Lid 370 hp
1973 Camaro Rally Sport Street Strip 850+ HP

 

[DieselB59]

We don't have the fuel heater in the truck we race, just braided Earl's line and -AN fittings and an adapter from -AN to NPT to plumb directly into the fuel filter where the banjo fitting would come from the fuel lift pump. Thankfully we don't live in the Great White North.

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Chris Timochko
AUTO WURKS DIESEL R&D TEAM
1997 5sp 4X4, Rhino Linings, Espar Heater, A. W. D. HX40 turbo, ATS 3pc Manifold, BD 4" Brake, Marine Compression, A. W. D. Custom Tuned Injection Pump, A. W. D. Intercooler, A. W. D. 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, A. W. D. Water Injection, NOS Diesel Kit, A. W. D. 6" Chrome Exhaust System, BD No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. 15. 50@97mph on Goodyear All-Terrain tires.
****************************************************************************
Project U96 - 1996 3500 2WD racer. A. W. D. Marine Ultra Low Compression, A. W. D. Teflon-coated Pistons, A. W. D. High Lift Camshaft, Ported and Honed Cylinder Head, Intake and Exhaust manifold; A. W. D. HX40 Turbocharger, ATS 3pc Exhaust Manifold, A. W. D. Water Injection, A. W. D. Custom Fabricated Fuel System, Race Spec A. W. D. /BD P7100 Injection Pump, A. W. D. Custom High Flow Fuel Injection Nozzles, BD Auto transmission and Custom TC, Weld Draglites, Goodyear Eagle Drag Slicks, 5" Single Stack Through The Bed, Mag-Hytec on Rear and Transmission. 11. 54@115mph

 

[C-Series-Man]

The stock lift pump uses a spring to pump the fuel. The cam shaft only pushes the lift pump piston out, the spring pushes the piston back in towards the engine and pumps the fuel. You are extemely lucky your truck is still around. The fuel filter is not rated to handle that kind of pressure. If you bust the fuel filter canister, it is almost certain to start a fire and roast your truck. The clicking sound you heard was the spring not being able to pump the fuel (lift pump in hydrodynamic lock). Anytime the overflow pressure is greater than the spring force divided by the lift pump piston area, the pump ticks. Prolonged ticking leads to cracking the lift pump piston and seal damage. The last thing you want is a significant volume of raw diesel in your engine. If the fire hazard does not get your engine, the reduced lubrication will. We are dealing with incompressable flow here, trust you will not gain enough to make a very big power increase to justify the risks. In my book, your are lucky to get away with what you have - 60 psi.



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95 Ford F-350 4x4 Ext Cab, Cummins 6CTAA 8. 3, Fuller 9 Speed, Big Rig Heart in a Pick-up Truck

 

[Mopar-muscle]

brandon , i had plumbed the SPX/Miller tools fuel pressure gauge ( what DC uses ?) onto the schrader valve on my 24V IP and did not see any gauge fluctuations , is this being dampned out by the valve ?

 

[Brandon]

I got the same miller tool too, but I have not tried driving with it, buuuuut try the very fast reacting and huge pressure fluctuations, I dont know what to make of it, but there is something to it and even a tech at scheids had the same problem with digital, peaks and valleys, well I think more R&D to really understand pressures in the injector pumps are needed, I am wanting to wire spa to the return line as well just to see what I get, I have discussed this with csutton who I think is doing a good job r&d ing the bigger lift pumps

B... ... ... ... .....

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END THE OPPRESSION FREE HVAC NOW
Danelle's Dodge

 

[DieselB59]

Yep, got a fuel system going that eliminates the entire transfer pump, prefilter and fuel heater assembly. Guess my 12 valver got out of its wheelchair now. You can check out more in the Products/Accessories forum where I have a post all about it.

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Chris Timochko
*Association of Diesel Specialists Certified*
AUTO WURKS DIESEL R&D TEAM
1997 5sp 4X4, Rhino Linings, Espar Heater, A. W. D. HX40 turbo, ATS 3pc Manifold, BD 4" Brake, Marine Compression, A. W. D. Custom Tuned Injection Pump, A. W. D. Intercooler, A. W. D. 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, A. W. D. Water Injection, NOS Diesel Kit, A. W. D. 6" Chrome Exhaust System, BD No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. 15. 50@97mph on Goodyear All-Terrain tires.
****************************************************************************
Project U96 - 1996 3500 2WD racer. A. W. D. Marine Ultra Low Compression, A. W. D. Teflon-coated Pistons, A. W. D. High Lift Camshaft, Ported and Honed Cylinder Head, Intake and Exhaust manifold; A. W. D. HX40 Turbocharger, ATS 3pc Exhaust Manifold, A. W. D. Water Injection, A. W. D. Custom Fabricated Fuel System, Race Spec A. W. D. /BD P7100 Injection Pump, A. W. D. Custom High Flow Fuel Injection Nozzles, BD Auto transmission and Custom TC, Weld Draglites, Goodyear Eagle Drag Slicks, 5" Single Stack Through The Bed, Mag-Hytec on Rear and Transmission. 11. 54@115mph