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Technical Info: 2nd Gen 24 VALVE DRIVETRAIN Technical discussion of second generation (1998 - 2002) 24-valve engine and drivetrain questions, solutions and upgrades.
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  #1  
Old 6 Days Ago
Junkman Junkman is offline
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Default Long crank

Truck has been getting harder to start over the last couple of weeks. It seems to be cranking a little slow. Batteries usually are 12.6 volts. When they sit a while they drop to 12.4.

I had the starter out to change the CKP. Starter contacts were replaced a while ago and are almost new. Bendix moves in & out as it's supposed to when I hook the starter to the battery with jumper cables and bridge between the battery terminal and small terminal.

Absolutely no sign of fuel leak and the return line banjos and T were replaced a while ago. Fuel pressure gauge is the same as always. key on and the fuel pressure goes to 12 or 13 then returns to 0. Once started, fuel pressure stays at 12-13. Internet lore says 10-20 # and arguments are all over the place. I'm running an old AirDog and it has been the same for years.

VP was changed a while back and there is no indication that it is bad. Injectors are probably original at 230,000 mi. Injector tubes are original too.

What do I check so I don't throw parts at this thing?
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2000 Quad Cab,Longbed, NV4500, 410 Gears, 4X4, ISSPro gauges, Thuren 3rd Gen Trackbar (beautiful), AGR Steering Box - box works - NOPE, spoke too soon. Never AGR again. 2 dumped fluid & lost brakes & steering, 4th is too loose. AGR = pp quality control & long wait for replacement (doing something different. Will update with what works), DSS Steering Brace, AirDog 100 = 13# solid, Rusty Doors (POR15 at the bottom for now covered with color match Rustoleum)
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  #2  
Old 6 Days Ago
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cougar cougar is offline
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Slow cranking can be a couple things. Starter dying. Batteries dying. Bad battery cables and/or battery terminals. Hard starting can be fuel drain back. Fuel supply restriction. Or a bad injection pump. Your fuel pressure is good, though a little more pressure would be better. I like to stay just over return pressure so fuel circulates through the IP keeping the electronics cool at low RPM.
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RIP 1991.5 1991.5- 8/14/2013
92 W250 Xcab 4X4, HD 47RH with Compushift, Scheid Lightning VE, moded H1C 62mm/60mm/16cm, 7X010 DAP injectors, DE 4" exhaust, 60# valve springs, home made cooler tubes, and the usual gauges.
01 2500 Q cab 4X4, stage II auto, fresh VP-44, HX35, B T E and F gauges, FASS 95 adjustable.
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  #3  
Old 6 Days Ago
Junkman Junkman is offline
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Thanks for helping me think through this.

I have an AirDog that has been working for years. The pressure gauge is tapped in where the fuel goes into the VP and the gauge is functioning the way it always has. That leads me to believe that fuel is normal up to the VP.

There is no leak where the hard lines attach to the injection tubes. It's possible that there is an internal leak between the injection tubes and the injectors. How do I confirm that or not? I don't want to spend $150 on tubes as a guess.

So, how do I test for an internal leak at the injector tubes or injectors themselves? One thing I read said to remove the hard lines and crank the engine. If any injector tubes move outward, replace them. Is that an actual test? That wouldn't be difficult.

The batteries charge to 12.6 measured at the battery terminals. I'll go have them load tested just in case. I measured voltage drop starting at the terminals then moving the probe out 1 step at a time - ie battery terminals, move out to cable clamp, move to other end etc. There was no indication that the cables or terminals are bad. I have some new military terminals that will be installed because the old terminals are misshapen even though they still clamp well.

The VP usually throws a code. I'm happy to buy whatever parts are necessary but don't want to spend $1000 to change a VP that is good.

I need to adjust the valves and can do a leak down and compression test when I do the adjustment. Will removing the hard lines completely from the VP stop the VP from spurting fuel?

There is also no evidence to condemn the starter. Bench testing and even pulling the bendix out by hand showed it to come out freely and spin as what seems normal. I know the solenoid contacts are good.

I put the battery charger on the highest jump setting and still had the long crank. The extra uumph should have fixed the slow crank if it was the batteries.

When you have a problem and everything tests out as normal, you missed something - but what?
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2000 Quad Cab,Longbed, NV4500, 410 Gears, 4X4, ISSPro gauges, Thuren 3rd Gen Trackbar (beautiful), AGR Steering Box - box works - NOPE, spoke too soon. Never AGR again. 2 dumped fluid & lost brakes & steering, 4th is too loose. AGR = pp quality control & long wait for replacement (doing something different. Will update with what works), DSS Steering Brace, AirDog 100 = 13# solid, Rusty Doors (POR15 at the bottom for now covered with color match Rustoleum)
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  #4  
Old 5 Days Ago
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CaptainCummins CaptainCummins is offline
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What is the engine speed while cranking? With the charger and without? Cranking the engine with low batteries or excessive voltage drop will overheat and burn even the best solenoid contacts in a hurry.

Did you measure the starter cable voltage drop while cranking?
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Old 5 Days Ago
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If you have an internal fuel leak it will end up in the oil. Check your oil for signs of fuel.
Is that 12.6V with the engine running? If so, you have other electrical problems like a bad alternator, regulator, or battery. If not running, I'd suspect a battery problem. Voltage should be a little higher unless the temperature is very cold.
A wire may carry voltage without a load, but can't carry current under a load. A check with the volt meter doesn't show this unless you check the voltage drop under load.
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RIP 1991.5 1991.5- 8/14/2013
92 W250 Xcab 4X4, HD 47RH with Compushift, Scheid Lightning VE, moded H1C 62mm/60mm/16cm, 7X010 DAP injectors, DE 4" exhaust, 60# valve springs, home made cooler tubes, and the usual gauges.
01 2500 Q cab 4X4, stage II auto, fresh VP-44, HX35, B T E and F gauges, FASS 95 adjustable.
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  #6  
Old 4 Days Ago
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smokediver smokediver is offline
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With my 99 it was an air leak...somewhere.
If your fuel pressure returns immediately to zero I'd be suspicious...I think.
My vp truck's been gone a couple years now, but best I remember the fuel pressure kinda fell slowly after the "bzzzt" at key on.

Does it make any difference if you do the starter bump and let it run the 20 seconds before cranking??

I replaced all the hard lines with clear plastic ones so I could see what was going on, and after sitting overnight the lines would be empty.
Note: after 2-3 years those clear lines get hard and brittle.
Don't remember right off where the air leak was..
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'07, megacab, 2WD, Dually, 6.7, auto,
H&S XRT, ETE tranny, 500k mi and counting !!
'09, quad cab, Laramie, 2WD, Dually, 6.7, auto.
H&S mini maxx, something fell off under the truck 270k mi
My Other Truck is a Fire Engine!!
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  #7  
Old 4 Days Ago
Junkman Junkman is offline
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This is mostly on hold until after Thanksgiving.

There is no evidence of fuel in the oil and this engine has never used much oil between 10,000 mi (full synthetic) changes. It may be time for injectors anyway and I'm considering but would prefer to fix the problem 1st. There are a lot of WhileImA**** if I have to get into injectors or a VP. I'll look into what sensors can be tested while in the car.

Batteries measurements have varied. They don't seem to be taking a full charge. One was at 12.4 and the other slightly lower this morning at 30*. I've got a fancy schmancy charge that is supposed to desulfate the batteries. I'm charging the batteries and running the "repair cycle" on the charger.

I have a friend that wholesales and will get me a new pair for $180 cash plus the old batteries. I'll likely replace the batteries regardless if they are questionable and out of warranty because I'd rather rub the problem with dollars than deal with bad batteries during the winter.

Other than batteries, I'll be back on this project after this Friday,

Have a good holiday.
__________________
2000 Quad Cab,Longbed, NV4500, 410 Gears, 4X4, ISSPro gauges, Thuren 3rd Gen Trackbar (beautiful), AGR Steering Box - box works - NOPE, spoke too soon. Never AGR again. 2 dumped fluid & lost brakes & steering, 4th is too loose. AGR = pp quality control & long wait for replacement (doing something different. Will update with what works), DSS Steering Brace, AirDog 100 = 13# solid, Rusty Doors (POR15 at the bottom for now covered with color match Rustoleum)

Last edited by Junkman; 4 Days Ago at 09:01 AM..
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  #8  
Old 4 Days Ago
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cougar cougar is offline
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It is normal for the fuel pump to come on with the key then turn off after a couple seconds. If you bump the starter the pump will stay on until you turn off the key.
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RIP 1991.5 1991.5- 8/14/2013
92 W250 Xcab 4X4, HD 47RH with Compushift, Scheid Lightning VE, moded H1C 62mm/60mm/16cm, 7X010 DAP injectors, DE 4" exhaust, 60# valve springs, home made cooler tubes, and the usual gauges.
01 2500 Q cab 4X4, stage II auto, fresh VP-44, HX35, B T E and F gauges, FASS 95 adjustable.
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  #9  
Old 4 Days Ago
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smokediver smokediver is offline
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Technically, a 12V battery is 6 cells at 2.1V each 6x2.1=13.2.
Might make sure the alternator is putting out 13.4 or better. Usually close to 14.0
Bumping the start should cause the lift pump to run for about 20 seconds and stop regardless of key on or off. That's what mine did.

I have seen trucks turn over without enough voltage to wake up the computer.
An M11 will roll over at 10V, even down to 8, but the computer won't tell the fuel to inject, so it won't start.

I Have seen a couple 5.9's that would take up to 30 seconds after the key was turned on for the initial fuel pump "bzzzt", and they would not start until that happened. Engine would turn over, but not fire up.
I know one been doing that for 10 years but still runs.
__________________
'07, megacab, 2WD, Dually, 6.7, auto,
H&S XRT, ETE tranny, 500k mi and counting !!
'09, quad cab, Laramie, 2WD, Dually, 6.7, auto.
H&S mini maxx, something fell off under the truck 270k mi
My Other Truck is a Fire Engine!!

Last edited by smokediver; 4 Days Ago at 09:25 AM..
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