12 valve won't start

[Signal73]

When the starter is activated the pull coil is energized to lift the plunger then the hold coil takes over to keep it raised. When key is switched to off the solenoid is de energized and it shuts fuel off as it returns to the down position.

 

[Crowhurst]

That's a good reminder, thanks. I haven't been in the USA to work on my superb 12 valve since before Covid. as I've had brain surgery, so my memory is not what it was. In the past I've replaced the torn rubber boot and cleaned the solenoid. The 1998 12 valve would still be my choice today. What a great machine!

 

[BigPapa]

Turn your ignition on, pull the lever up, and see if it stays up.

 

[Crowhurst]

Turn your ignition on, pull the lever up, and see if it stays up.

Will do, thanks.

 

[Crowhurst]

I've now realized that for the past 25 years of maintaining the truck I've not properly understood the function of the fuel solenoid. I had assumed that when not energized by ignition, no fuel could flow past the solenoid, as if the fuel solenoid operation was similar to the operation on my Yanmar marine engine, where pulling on a wire directly stops the flow of diesel, and the engine. I've now re-read Joe G's excellent article from 2008, in which he states:
"Fuel solenoid.
The fuel solenoid is actually not part of the fuel supply system. It pulls a lever on the side of the
injection pump. However, if there is a problem with it the symptoms are similar to problems with
the fuel supply system. Another thing to remember is that the fuel solenoid does not open or close
a valve. It parks the rack so that no fuel is sent to the injectors. Fuel will still flow through
the injection pump to the return line regardless of the fuel solenoid rod position."

The full article is at Joe G's fuel system writeup | Cummins Diesel Forum
Now I understand this, our next action to get fuel through the P7100 is simply to pull on the "fuel shut-off lever" on the driver's side of the P7100 pump, and manually operate the fuel lift pump to get some 911 fluid into the p7100 and through the injectors. I've attached a diagram for those like me who were unaware of the existence of the fuel shut-off lever.

 

[Timd32]

Just a positive suggestion here call a mobile diesel tech in to give you a hand with this.

It's worth a few bucks, also someone might want to go over this rig and refresh all the fluids and do a safety check at a shop if it's been sitting around for atleast 5 years and just starts up a few times a year. A not maintained Diesel is the gift they keeps on giving, especially pulling a trailer.

If able build it into your gift for your granddaughter along with a subscription to the TDR and a Genos catalog.

I may take some slack for this but with a wedding, surgery and not a mechanic your son is doing awesome but the weather and conditions, schedule could be a ton of stress for him. I am sure he loves the time working with you, but it's a lot. I have a 2022 and no way I'm trying to force that in the super cold it was -6 here yesterday, I have other vehicles and no need to force that rig to run, it's just so cold out. -14 is no joke. You really need to have a use to run and operate spare rigs and summer rigs in this weather.

He will be chasing this for a bit still once he gets the fuel flowing.

 

[Crowhurst]

Thanks, Timd32. I agree with everything you say. Nick.

 

[Crowhurst]

The truck starts with the HP pump fuel lever pulled forward. With the lever in the shut-off position, the truck will not start and the solenoid will not fire. However, with the SS70a fuel relay shorted out, as shown in Larry B's excellent video, the solenoid fires and the truck starts, so a replacement relay is on order from Geno's. As Timd32 suggested, the truck will be serviced with all the fluids changed before the truck is delivered to the young lady in MD in the Spring.
Fuel Solenoid Relay Location & Adjustment: A How-To from LarryB's

 

[BigPapa]

So, the solenoid won't pull up unless you short out the relay on the fire wall?

You can get a relay that will work from O'Reilly's, part number 25-0102. It doesn't have the hood or the bracket, but it will work.

 

[Crowhurst]

Thanks, Scott. Yes, if the relay is shorted out the truck starts. We are in no hurry, so we'll wait for the Geno's relay, but it's good to know that there's an alternative.

 

[BigPapa]

We are in no hurry, so we'll wait for the Geno's relay

Sorry, I thought you were in a rush.

 

[Crowhurst]

We were, but the truck wouldn't start, so we had to fly the bridegroom back to MD from MN as he had to get back to work, so we missed that deadline. We'll try again when the weather warms up. The wedding is in the autumn, and the plan is for the bridegroom to fly back from MD to MN and drive the truck back to MD, 870 miles. Before that my son will use the truck as a daily driver for a couple of weeks before booking his flight, which is what we should have done the first time.

 

[Hootguy]

replace that crappy solenoid set up with a manual cable set up like the old days,and it will NEVER let you down,i did this after loosing power on a busy highway pulling a race trailer in the middle of the day,put in a manual.and never worried about it again,

 

[Crowhurst]

I agree. A fuel stop cable from something like my Yanmar 1GM10 or a tractor would do the job. One would have to make a bracket to go on the HP pump. The other end would need careful placing in the cab, as the end fitting would stick out when the fuel is on. Photos and description of such a system would be very useful.