Engine/Transmission (1994 - 1998) Hard Starting to No start

[AKington]

1997 Dodge Ram 2500 diesel 12v

I was having a hard time starting my truck in cooler weather. Later in the day when it warmed up a little bit, it would start fine. It was cranking fine no matter what the temperature. So I decided to check my fuel shutdown solenoid. The boot was gone and it was not moving up when you try and start it. So I used my hand to move it up where it would stay. Then had my nephew crank it over and sure enough it would start every time. I then tested the voltage to the three wire connector and had him crank it over. Voltage was good the first time, I then had him try it again. This time it will not crank over at all. I put the connector back together and still no crank. What did I do that would cause it not to crank? I also noticed the fuel shutdown solenoid will no longer stay up when I do it by hand.

 

[surfbeetle]

Before you buy a new solenoid for about $200, you need to make sure that you have proper power to the solenoid. Also you can remove it, clean it and put a new boot ($25. 00) and see if that works.

 

[EBansberg]

I believe there is a relay that works the solenoid. As you've figured out, there is a pull and a hold portion of the solenoid. If the engine will not crank at all, you might have bad starter contacts or lost the starter relay. I can't think of anything you might've done just testing it with a multimeter but maybe all the cranking caused something to finally go that was on its way out anyway. Make sure you check the voltage for both the pull and the hold portion of the solenoid and definitely fix the boot if it turns out the solenoid is good.

 

[AKington]

I was going to check the fuel shutdown solenoid and relay to try and see which one was faulty, but then I ran into the new problem of the truck not even cranking over. Is there a fuse I should be looking at? Could checking voltage at the connector of caused the no cranking issue? Any suggestions are appreciated?

 

[Dave M]

Go to this site for more info on how this all works:



Starter FAQ



Here is your fuel shutoff relay on the firewall nearest fender (there are 2 relays side-by-side):



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Here is the blue fusible link that hangs off the drivers side positive battery post:



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All these parts plus the starter play a role in your problem. Fuse 9 in your glove box supplies 12v to the fuel shutdown "Hold" solenoid. Check to see if it is blown. This is likely considering when you pull the solenoid up it doesn't hold.



The fuel relay on firewall gets 12v from the starter circuit on pin 85 to energize the relay and pin 30 (the real 12v for the "Pull" circuit) of the relay gets it's power from the blue fusible link off the drivers side positive battery post. If the fusible link is bad then the "Pull" circuit of fuel solenoid would not work. To test the relay you could temporarily swap them. The fuel relay is 70 amps and the other is 30 amps but a quick test may not hurt.



Check all fuses in glove box and PC under hood. Another culprit could be the starter relay in PDC which supplies 12v to the starter solenoid and the fuel relay on pin 85.



I know it doesn't make sence but the starter contacts if corroded can cause the 12v to fuel relay at pin 85 to not get there.



Study the schematics I gave you and good luck. You may need to pull your starter to check the contacts depending on results of testing.



Dave

 

[AKington]

I switched the trailer relay for the starter relay and still no crank. I will try some of the other suggestions tomorrow. The fuel shutdown relay has nothing to do with the no crank issue right?

 

[Dave M]

I switched the trailer relay for the starter relay and still no crank. I will try some of the other suggestions tomorrow. The fuel shutdown relay has nothing to do with the no crank issue right?

I don't think so. You might verify you have 12v at the starter solenoid (brown wire I think) and starter (Big red wire). The fuel relay is tied to the starter solenoid signal thru the pin 85 of the relay so the wires or relay may effect it. They are tied together. Verify the brown wire to starter solenoid is not shorted and verify your fuses with ohmeter not by sight (trust me on that). Your neutral/safety/park switch is in the starter circuit also but is not shown in these circuits for clarity.



If you have power to starter (when crancking) and nothing is happening then you need to pull the starter... . contacts are probably burned... . very common.

 

[hsmith]

Are the batteries ok? Particularly the driver's side positive terminal which is where the solenoid gets it's power. Remove the small wires at the terminal, paying close attention to the blue wire and it's terminal. It will break just at the crimp and cause all kind of starting problems.

 

[AKington]

Does the blue wire have anything to do with the starter not cranking or just the fuel shutdown solenoid and relay?

 

[hsmith]

Just the solenoid. Bad connection there on the main terminal can cause other starting problems.

 

[Dave M]

One of the big fuses in the PDC supplies power to the start relay for the starter. Make sure all those fuses are good..... they can fool you visually so use a voltmeter if you can. I forgot which fuse # it is. Also the park/neutral safety switch is involved with the starter relay in PDC but checking at the starter for 12v on brown wire while cranking will prove all that good if you get 12v down at the starter solenoid brw wire while cranking.

 

[Dave M]

PDC fuse 2 supplies power thru the starter relay in PDC, out the BRN wire which splits and one BRN wire goes to the starter solenoid at the starter and the other BRN wire goes to the fuel shutdown relay on the firewall.



Check for 12v while cranking (clutch in or in Park) and verify you have 12v at the starter solenoid and 12v on the big red wire to the starter motor. If you do then pull the starter... it's bad.



It should be noted the power to energize the starter relay in PDC comes thru the ign switch and then the park/neut switch and then to starter relay.

 

[AKington]

Thanks for all the ideas everyone. I will try to find a helper, and hopefully figure this thing out. It is not fun when you narrow down the fuel problem and then end up with a truck that wont even crank over.

 

[AKington]

I checked voltage to the starter wire(Big one) straight from the battery and got about 12. 2-12. 3, same as the battery usually is. The solenoid wire(brown small one) only had 11. 60, is that normal? while I was checking voltages it actually cranked and tried to start once when I was checking the solenoid wire. So I am going to clean that connection. Fuses all look good. Fuse 2 I put in the horn spot and the horn worked fine. I also checked continuity to fuse 2 and it was good. Fuse 9 and 15 also good continuity. I tried fuse 15 because I think it goes to the park/neutral switch. all other fuses I pulled out seemed good. One other piece of information, I think the fuel shutdown three wire connector is still getting juice, even though no crank still. Any other ideas?

 

[AKington]

Ok it's cranking again. The starter solenoid wire, at the starter, was not getting a good connection I guess. Cleaned it and tightened it down, and good to go. Back to the original problem. With the key in run, I manually push up the fuel shutdown solenoid and it stays up by itself and then starts. So when checking the three wire connector do I have to check each wire for voltage? I just checked the middle one like in the geno's picture. From what I read on the geno's article, if there is power it is likely the solenoid is bad. Does that sound about right? Once it started to get a little colder is when I started having problems. If it's a warm day I can usually start it. Thanks for the help everyone!

 

[Dave M]

There are 2 functions of the fuel solenoid... . Pull and Hold. It sounds like the high current "Pull" function is not working but the lower current "Hold" function is good since when you PUll it up it HOLD's ok.



The fuel relay is in the circuit only during the "Pull" function. The Hold function is powered by fuse 9 directly into the fuel shutdown solenoid... which is working in your case.



Before you assume the fuel shutdown solenoid is bad verify the voltages are getting to the fuel relay on firewall. The fuel relay could be bad. You could unplug the relay and test at the connector for these tests. When you are cranking the engine verify you have around 12v on the BRN wire which is pin 85 of the relay. That is the voltage used to energize the fuel relay (as long as the BLack/tan wire has GND which is pin 86 is good).



Now the 12v voltage source for the relay to pass 12v to the fuel solenoid "Pull" circuit is the relay Red/Black wire (pin 30 of the relay). I suspect this is your problem. Without this 12v the Pull solenoid will not fire. This 12v at pin 30 comes from the Blue fusable link off the drivers side battery positive post that was mentioned earlier. The voltage for the "Pull" circuit starts from the battery thru the blue fusible link (so this 12v is not switched but is always Hot) and then to the fuel solenoid "Pull" circuit (Red/Violet wire) of fuel solenoid. If there is not 12v here at pin 30 of the relay then you found your problem. Temporarily jumper 12v here and you can test that way to see if it will fire the "pull" solenoid.



Again, check the blue fusible link is good by checking the voltage where it supplies 12v to the relay on the relay Red/Black wire. This blue fusable link can fail and are a typical problem with our trucks.



Also, you could temporarily swap the other relay on firewall to test for a bad relay. If truck runs then order a new relay.



Dave

 

[Dave M]

If you continue to have starting problems I'd recommend replacing your starter contacts with the heavy duty ones form Larry B's or Geno's. Those contacts sure can cause problems and they will be pretty worn when you replace them.



Edit: If you have all the voltages at the relay and swapping relay does not fix it then it is either connections or a bad fuel solenoid. At that point I'd disassebly it and clean the bore and lube it with silicone spay and try that... . that fixed my intial problem and later my relay failed. It's around $200 for a solenoid from Larry B's or Geno's.

 

[Dave M]

To test the voltages at the fuel solenoid, disconnect it and do the following:



To check the fuel solenoid connector look for 12v (when cranking starter) on the Red/Violet wire (this energizes the "Pull" coil of the fuel solenoid). The Light Green/Blk wire of the fuel solenoid will have 12v to fire the "hold" coil but this is working in your case. Also the Blk/Tan wire of the fuel solenoid needs to have a good GND for the solenoid to function.



An easy test for a good ground is to put your red postive lead of the voltmeter on a 12 v signal (like the positive battery post) and then put the black voltmeter test probe on the suspected ground signal (like the Blk/tan fuel solenoid Gnd). If the ground is good you will read the 12 volts on your voltmeter. If bad you will read nothing.



Dave

 

[Dave M]

Well!..... any update on this! Did you get it fixed?

 

[norcalram]

This is very strange. I am having the same problem on my 98. just started today. When I turn the key to start, nothing at all happens. batteries are more than fine. i ran a jumper from the battery to the starter and it engaged fine but engine would not start. i checked the starter relay and have proper voltage. i also swapped some relays around and still when i turn the key nothing happens. will the shutdown relay or solenoid actually keep the started from engaging or just keep the engine from firing due to no fuel. also if it is the Park/neutral switch, where is this what color wire do i look for?



Thanks.