Engine/Transmission (1994 - 1998) 98 12 valve needing help

[myoldodge]

Hello everyone

I have an early 1998 12 valve 2500 club cab 4x4 with 178,000 miles. Its completly stock from bumper to bumper. I have some problems that have just started.



Problem 1: With the pickup in drive, if i just bump the gas and let off the truck dies.



Problem 2: Once the engine is to normal operating temp while driving, my oil pressure gauge will zero out when I stop at a stop sign. And will return to normal pressure when I start driving again. What would be causing this?



Problem 3: Over time my truck has started taking longer to start. I have to crank it over 8 or 9 times to get it to start.



Thanks for your time

Tyler

 

[KBurgoyne]

your high pressure oil pump for the injectors is probably bad. that can cause starting issues and if your oil pressure is falling to zero you should really have it checked asap.

 

[hsmith]

Hold on now pardner, this ain't no Power Choke he is talking about. The Cummins only has one oil pump and it is solely for lube of moving parts.

Look at this solution to problem #1 & #3. If you adjust the idle speed up a tad, minimim of 750 in drive with ac on, both problems may be taken care of.



#2 problem may be solved simply by replacing the oil pressure sender, on the drivers side of the block just at the p/s pump.



Give these a shot and i think you will be pleasantly surprised, and the wallet will not be empty.



And, the oil pressure sender can be had from NAPA for a pittance, around $30.



Good luck

 

[myoldodge]

LOL, thanks guys..... I will look into the idle speed and an oil sending unit.



Thanks again

Tyler

 

[snappy]

If the fuel supply and return lines are original. it would not hurt to change them out. Larry B has a marine grade hose kit.

 

[DieselDoghouse]

Here's my insight - Hsmith and Snappy got ya covered, they nailed it!!

 

[fest3er]

The others have you covered. I'll just put notes with your Qs.

Hello everyone

I have an early 1998 12 valve 2500 club cab 4x4 with 178,000 miles. Its completly stock from bumper to bumper. I have some problems that have just started.



Problem 1: With the pickup in drive, if i just bump the gas and let off the truck dies.

This is most likely idle is too low. Find diagrams, then feel for the nut to loosen to increase idle speed. It's there, you just can't see it. Bump the idle up to about 800 in D or 950-1000 in neutral/park.

Problem 2: Once the engine is to normal operating temp while driving, my oil pressure gauge will zero out when I stop at a stop sign. And will return to normal pressure when I start driving again. What would be causing this?

A long standing issue. DC's response was to reprogram the PCM to make it display a 'longer-term' average pressure, so that if you truly lost pressure, you might not know it for a while. It's nice to know NAPA's dropped their price to $30 or so. They wanted $130 the last time I checked. Cummins Atlantic near here still has the best price.

Problem 3: Over time my truck has started taking longer to start. I have to crank it over 8 or 9 times to get it to start.

You have air leaking into your fuel lines. Either a rubber line is leaking or a hard line has rusted through. It only takes a tiny pinhole. Given its age, replace all the lines, hard and rubber, from the hard line at the frame to the injection pump and pre-screener.



When I did mine, I carefully removed the plastic form the lines on the frame and used high-pressure rubber fuel lines from there to the engine block.



Don't 'save time' or kid yourself. Replace them all. If a hard line has rust on it, replace it. If there's a rubber line, replace it. Don't piece-meal it the way I did 'to save a little money'. Rip the old stuff out and replace it. And if the lines continuing back to the fuel tank show rust, replace them as well. Looking back, I jury-rigged mine; I didn't truly *fix* it. It'll come back to haunt me in due time.

 

[charlessmith]

The others have you covered. I'll just put notes with your Qs.
...
You have air leaking into your fuel lines. Either a rubber line is leaking or a hard line has rusted through. It only takes a tiny pinhole.
...

To add a bit to this solution, which IS correct. The reason even a tiny air leak causes really long cranking times, is that the air leak is in the suction side lines.

The pinhole doesn't leak fuel, BUT when the engine is off it lets fuel drain back to the tank. So you end up with an empty fuel line and you have to crank a long time to suck fuel back into the line all the way from the tank.

Another symptom of air in the fuel lines, is a burst of white smoke when it does start.

You DO want to replace the return lines at the same time as you fix the suction lines. A leak in the return line will mean you are spraying fuel all over the underside of your truck and the road. The most likely place for this is the rubber line from the pump back to the metal line attached to the body.

Don't ask me how I came by this knowledge half way up the AlCan Highway.

 

[RVPILOT]

oil pressure

My oil pressure gauge zeroed our two years ago after replacing the sending unit 3 times. I gave up and have been running since with no oil pressure. boy do I have confindence in these motors. stormy

 

[myoldodge]

Thanks for all the information. You guys nailed it with the air leak in the fuel lines. I also raised the Idle to 750 while in gear and the a/c on and problem solved. Replaced the oil sending unit and oil pressure is right where it needs to be. This has been the best forum Iv ever been a part of.



Once again I can't say thanks enough for all the help.

Tyler

 

[rrl989]

myoldodge,



Can you give me the oil sender part number, mfgr etc ? What tool is needed to replace. Did the new one fit directly, or come with an adapter, how much did it cost ?



Thanks

 

[surfbeetle]

I got my sending unit from Napa. All you need is a wrench or very deep socket, can't remember the size, nothing special.