Archived 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 i have had to crank the engine over more and more to start it. Now i have to turn it over 8-9 times before it starts.



Thanks for your time

Tyler

 

[HCannon]

What is your idle speed? If slow, it could cause it to die. I have a 98 12 valve and the oil pressure gauge does the same thing. The problem with mine is the sending unit on the motor. I have a new one but havent put it on yet. It is behind the starter and is hard to replace so I been told. Two of my friends have had to change theirs.

How long has it been sense you changed your fuel filter? The slow starting could be your fuel filter. I am not a mechanic so this just some ideas that it could be.

 

[myoldodge]

Thanks for the info... ... I have just changed the the fuel filter and air filter along with all fluids. The Idle is about 750rpm, is that high enough? I will change the oil sending unit as soon as possible and will let you know how it does.



Thanks again

Tyler

 

[rrl989]

on #1 - You should be checking your idle in gear, A/C on, engine hot, foot on brake. Are you just reading 750 in idle, no load ?



#2 - Sounds typical, I started have the same issue like many with the oil pressure sender. I recently wiggled the connector on the sender and the problem is gone and the pressure reads higher. I'm sure I'll be looking for a sender at some point.



#3 - Has not happened to me yet, but a common hard starting issue is the fuel return line, doesn't always leak, but can take in air making for hard starts especially when parked on an incline. I'll be changing both lines soon.

 

[myoldodge]

My idle is at 750rpm while in park with no load on engine. What should it be while in drive and foot on break?

 

[birddog]

the other suggestions are good, but with that amount of miles the start and die could very well be the bellcrank mechanism on the throttle/fuel plate, simpler terms would be throttle linkage components. my 97 12 valve had a recall on those parts, so may your 98. I have seen this problem numerous times with ppumped equipment in the fleet i work on.

 

[KB0OU]

I think you need to adjust the idle speed up some, check the manual, I think 750 in Drive with the AC on is low, let alone in Park etc.

I think the Manual says about 850 in Drive with AC on.

 

[GOTSOOT]

Oil pressure problem is probably in the PCM,changed sending units on quite a few trucks with no cure,forget about the ga. on the dash ,and put a mech. ga. in. problem solved.

 

[rrl989]

My idle is at 750rpm while in park with no load on engine. What should it be while in drive and foot on break?

Just as I wrote above, 750-800 for the auto. Fix the low idle before moving on to other possibilities.

 

[myoldodge]

How do i adjust the idle?

 

[Cooperman]

Idle adjustment

There is an idle adjustment screw at the end of the linkage. It is either viewable, or reachable, but not both at the same time. You can manually move the linkage at the front of the engine, and follow the linkage to the back.



Reach in to the block in front of the brake cylinder, and you will be able to feel the linkage moving. There is a screw with a 10mm nut on the bottom. Loosen the nut, then while holding the linkage off the screw, you can just unscrew it a small amount. One full turn will give you at least 100 RPM increase -- so don't do too much.



When satisfied, simply tighten the locking nut.



P. S. I leave mine set to about 350 RPM in the winter, and set it up more in the summer when I have to have the air conditioner running. Right now it is set to run at 750 with air on and in gear. I don't like it that high, but at least the truck keeps running when I have the air on and turn the steering.

 

[rrl989]

I find it easiest to depress the go pedal with a stick during the adjustment, it keeps the linkage out of the way.

 

[Cooperman]

I find it easiest to depress the go pedal with a stick during the adjustment, it keeps the linkage out of the way.

I just included all that so he could actually FIND the screw. He asked how to adjust, so does not know where the screw is located. Without working the linkage and feeling where it is, you cannot find that screw. Once you know where it is, then jamming the pedal is the way to go!



Thanks for the reply.

 

[HCannon]

You may fix the slow start when you raise your idle speed. The idle speed on one of mine is around 700 (standard trans) and if you dont mash the fuel a little when starting it struggles to go.