1998 Dodge Dakota Intermittent no-start

Tiny
SILVERBULLET91
  • MEMBER
  • 1998 DODGE DAKOTA
  • V8
  • 4WD
  • AUTOMATIC
  • 270,000 MILES
Just bought this truck recently and have found in the morning after sitting overnight or for a day it occasionally won't start. This doesn't happen every time it sits and doesn't seem to be related to temperature or moisture. What is constant is that if it starts first thing it runs great all day.

The starter and battery work great because they crank the engine over quickly but it doesn't cough, sputter or anything when it won't start, just cranks and cranks. This problem occured before I changed the air filter, spark plugs, wires, cap and rotor and still occurs with equal frequency after the tuneup. On one occasion I pulled a spark plug and grounded the electrode with the wire hooked to the plug and there was a strong, bright spark every second or so of cranking so it appears the ignition systems works as it should. The fuel pump primes when the key is turned to ON so the relays that power the ignition and fuel pump seem to be doing their job.

I replaced the fuel pump (which is a combination pump, filter, pressure regulator, check valve) and it started and ran fine the day I changed it but this morning it would not start again.

I got my hands on a fuel pressure tester and found that when the ignition key was turned on after depressurizing the system it went to 46psi (book says 44-54psi is "normal") and when I finally got the truck started it ran steady at 50psi at idle. After I turned the truck off it went down to 46psi. I waited 5 minutes and it was at 44psi. Now, almost an hour later its at 40psi. (The Haynes manual says you have a leak somewhere if the pressure drops below 30psi in 5 minutes, but my pressure is holding much longer than that, although I don't know how well a "normal" system holds pressure.)

I plugged the block heater in this morning (it was about 40F, 10C, not cold) and the truck eventually did start (sometimes it starts later in the day at random, not sure if the block heater does anything or not). At that point my Scanguage told me the coolant temp was 96F. None of the fuel lines, rail, injectors leak externally that I can see by visual inspection (though I'm no expert there) and I'm at a loss as to what else the problem could be.
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Monday, October 25th, 2010 AT 12:18 PM

11 Replies

Tiny
RASMATAZ
  • MEMBER
Hi silverbullet91, Welcome to 2carpros and TY for the donation

Do below immediately to determine if its fuel or spark problem don't wait for nothing and get back with some testing results. Something has to give-let me know

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine at least 3/16 away from ground -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/COP/coil packs, coil's resistances, distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it.
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Monday, October 25th, 2010 AT 1:11 PM
Tiny
SILVERBULLET91
  • MEMBER
Thanks for the quick reply! On the ignition side, I don't have a helper handy to help test the spark, but I may be able to do that later. Just to clarify, its the plug boot I want to hold 3/16" from a ground and watch if a spark jumps from the metal part inside down to ground? There's quite a recess in the rubber before the metal part starts.

I believe I've eliminated the fuel pump, filter and pressure regulator as culprits since I replaced the whole assembly and still have the same problem as before. On the fuel side that leaves me with clogged or leaking line, or leaky rail or injectors (that I can think of) does that rate of pressure loss indicated by my pressure tester sound normal?
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Monday, October 25th, 2010 AT 1:51 PM
Tiny
RASMATAZ
  • MEMBER
Your fuel pressure sounds good to me-lets check for spark-remove the sparkplug and hook it back to the wire and ground it-let me know later when help is on hand
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Monday, October 25th, 2010 AT 1:59 PM
Tiny
SILVERBULLET91
  • MEMBER
Hi, sorry for the delay. Have been busy with work and haven't been able to look at the truck.

There is spark at the plug while cranking, I tested the ignition coil with the Haynes manual and the secondary resistance is within limits. The primary resistance though is 1.4ohms but it should only be 0.96 - 1.2ohms (although my meter gives me 0.4ohms of resistance when I simply touch the testing tips together). Does it sound like that ignition coil is bad or is the high reading simply the fault of the meter?

I also disconnected the cam position sensor wiring harness (CPS is under the distributor cap on my truck, may also be called a distributor pick-up coil) and it does get a 5v signal as it should when the key is turned to ON. To further test the cam or crank sensors the book indicates I need an analog multimeter but I only have a digital one handy. If it sounds like the coil is or may be ok, I can go get an analog MM and test the cam and crank sensors.

The truck does get an RPM readout when cranking (140rpm), I assume it gets this information from either the cam or crank sensor so hopefully that information proves at least one of them is OK!
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Wednesday, November 3rd, 2010 AT 3:44 PM
Tiny
RASMATAZ
  • MEMBER
If you're getting spark the cam and crank sensors are okay -check if you're getting fuel
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Wednesday, November 3rd, 2010 AT 3:52 PM
Tiny
SILVERBULLET91
  • MEMBER
With the plug out you can smell fuel after its been cranking. I checked the fuel pressure and, after being depressurized, the pressure goes right up to 46psi when the key is turned ON and after a downward spike stays at 50psi throughout cranking it.

The only thing I'm unsure about is the strength of the spark. It's white, not blue but is visible in daylight and sparks every second or so while cranking.
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Wednesday, November 3rd, 2010 AT 4:24 PM
Tiny
RASMATAZ
  • MEMBER
Zero the meter and retest the coil if its coming up with the same reading substitute or replace the coil-but before you do that verify the valve and ignition timing
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Wednesday, November 3rd, 2010 AT 4:42 PM
Tiny
SILVERBULLET91
  • MEMBER
The book says the ignition timing is not adjustable on my truck (computer controlled here, my old car would allow me to rotate the distributor to change the timing). How does one check the valve timing? This problem is intermittent in nature, so if the valves are off for whatever reason it should never run, right?
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Wednesday, November 3rd, 2010 AT 4:56 PM
Tiny
RASMATAZ
  • MEMBER
It doesn't matter if its computer controlled its only the ignition timing is being controlled when to fire the coil by using the CPS input signal-if the valve timing is off -meaning the camshaft and crankshaft alignment you can get fuel and spark all day it won't fire up

Then again like you said its an intermittent problem that takes it out of the picture-test the ASD relay if okay-replace the coil
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Wednesday, November 3rd, 2010 AT 5:09 PM
Tiny
SILVERBULLET91
  • MEMBER
Fair enough! To test the ASD, I checked for 12v going to the ignition coil with the key on (yes, for a second) and also when the truck was cranking. It also got 12v while cranking which I think means the ASD is working fine. However, it's getting dark here now and when I got my girlfriend to crank it over I could see a spark jumping around the outside of the ignition coil, just about where the base of the distributor wire's terminal is. I guess it wasn't dark enough for me to see that before. New ignition coil ordered, lol.

Thanks for all the help! I will let you know how it turns out!
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Wednesday, November 3rd, 2010 AT 5:37 PM
Tiny
RASMATAZ
  • MEMBER
I'll be waiting-Good Luck
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Wednesday, November 3rd, 2010 AT 6:07 PM

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