After reading here on the forum, I decided to install the widely mentioned relay to delay the LP while cranking when I have hard starting issues. To clarify, I am on a newly installed rebuilt VP with only a few thousand on it, which in actuality replaced a perfectly good VP, but that's another story. It may or may not be something to do with the newly installed injectors, but I kind of doubt it as it was having these symptoms before them.

Before getting into the thread's title, has anybody living on the coasts ever had hard starting issues when parked by the water's edge, salt water that is? This is the second diesel I have ran into that problem with of longer than normal cranking to start. Previously was on a 7.3L Stanadyne pumped naturally aspirated. A friend of mine said it happened to them all the time when at the bay. Not sure if it has something to do with the moist air, the salt content, or what? The weather is warming up and I'm not wanting to be stuck at the boat ramp any longer than I care to.

Alright, back on subject, and why I titled as I did. After multiple stops at the local parts stores, nobody seemed to grasp what kind of relay I was looking for. They kept referring me to the ones used for offroad lighting. Those switch the main power spade (30) to both of receiving spades (87 and 87a). I finally found at the local truck stop what is packaged as a "latching relay", and it has the circuit printed on the relay itself.



After trying to decide where to tap it into, I found myself looking at the trucks starter relay. It was then that I found it shared the same function as the one I just purchased after checking with an ohm meter.



But the factory did not intend to use its full capability, so it left the unused spade's connection empty. This is when I decided to use what has always been available, only that it would take a little bit of work and the addition of a female spade inserted from underneath.



I happened to have an extra relay socket kit that had the connector needed. The crimper is a D-sub type. Even though it did the job securing the wire to the connector, I went for overkill by adding some solder.



Safety first. Traditionally the battery would be disconnected. I opted for a quicker way, still being safe, and also found that it worked to help gain access to the underside of the power box. The electronic harness was also removed to facilitate access. Take care when doing so, the screw is only snug tight. This made it easier to lift the top half of the power distribution box.



Once the box was separated, all the undersides of the sockets could be seen to have a small white plastic keeper, or cage if you will, around them. Not having any removal tool, Southern engineering proved useful by snipping the ends of four small pieces of electric fence wire to a chisel angle and inserting from top side to release the four corners. Sorry for not showing in use, but you can see what to do on the two facing you by looking underneath, then repeat.



Once the cage is lowered, the spade and wire can be inserted. There is a small tab that can be seen from top side when looking down into the cavity. The spade is orientated so the top side, or the side that has the two halves roll in towards each other, slides over that tab. It's what keeps the connector from falling back down when inserting the relay. You can look at the third picture from top and see how it's supposed to face. I used some small needle nose and curved tip pliers from one of those hobby style tool kits to push it in.



Once in, I pushed the plastic cage back up with my fingers. Then routed the wire to exit with the others. That was a little easier said than done, as they're in a tight bundle and didn't want to damage the insulation on any of them.





Plugged original factory starter relay back into it's socket, with the addition of an extra spade. Then removed existing fused wire to battery positive that was feeding the LP relay, and leaving fuse inline, attached the new power lead that is constantly on until the starter is engaged. Not to leave out that the original LP wiring from ECM is the switching wire on the LP relay that has been in use all along. It does the same as has been suggested here on the forum by adding an additional relay. Only this uses an already existing one. Credit goes to those who posted the original idea. I'm only offering an alternative route if one so desires.

If this link works, here is the end result. I bumped the starter to put the LP into continuous mode before starting. You can see the momentary drop in pressure as intended.

If this has already been posted, I apologize for the repetition. I did do a search on here and did not find any mention of it.

 

I haven't spent enough time to go thru your post line by line to see exactly what you did. I doubt that you are using the term "latching relay" correctly. The starter relay is not a latching relay but just a 5 pin relay.

If I understand your post corectly, you are now feeding youir LP battery voltage from your starter relay. So you have constant power to the LP whenever the ignition is on, except when actually cranking. So, why did you have to bump the starter to put the LP into continous mode?

The delay relay is for those running high pressure pumps. With your Vulcan relocation kit I assume you are running the original pump. For these pumps, the factory has already provided circuitry to reduce LP pressure during cranking.

I doubt you will see any improvement in starting with your mod.

 

Before I go any further, I want to apologize for not having all the pictures up that I originally intended. I jumped the gun and didn't wait for their approval before writing the post. As soon as they clear, I will reinsert them if they do not do so automatically.


First off I did not misuse the term, it is what the relay was labeled and packaged as, hence the use of the quotation marks.
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And you said yourself that you did not read the post line by line, but if you read the ending, it clearly states it is feeding a relay that is switched by the ECM's original LP wires. The power wire to that relay was taken off the battery and substituted with the hot wire now off the starter relay. So no constant power to the LP until switched by the ECM. The starter was bumped to simulate high pressure starting issues, to show that it did work as it should. And when the starter is engaged, it is stopping supply to the relay until the key is moved back to the "on" position.

The original carter pumps do not produce 20psi, so no, it is not the original. And again, it is running through a relay, so factory circuitry does not apply to reduce pressure.

That is to be seen. Not all those who have done the same with an additional relay are running high pressure pumps. And it was also mentioned to be a fix to a glitch DC did not want to address. So either way, no harm done.

 

Hello, FFMike! I recognise your name, you helped DieselDan post his VP44 video on Youtube.

Song Chuan relays are good quality relays. I bought a whole bunch of ISO280 relays from DelCity for less than $3 each.

Here is the Song Chuan brochure on the 896-1CH-D1 relay.
http://www.songchuanusa.com/wp-content/uploads/896h.pdf

It is a simple SPDT relay, with 87a powered always unless the coil is energized, in which case 87 becomes energized. With a latching relay, once the coil is energized (and then de-energized), 87 will remain powered until the coil is energized a second time.

Here is what Wikipedia has to say on latching relays
A latching relay has two relaxed states (bistable). These are also called "impulse", "keep", or "stay" relays. When the current is switched off, the relay remains in its last state. This is achieved with a solenoid operating a ratchet and cam mechanism, or by having two opposing coils with an over-center spring or permanent magnet to hold the armature and contacts in position while the coil is relaxed, or with a remanent core. In the ratchet and cam example, the first pulse to the coil turns the relay on and the second pulse turns it off. In the two coil example, a pulse to one coil turns the relay on and a pulse to the opposite coil turns the relay off. This type of relay has the advantage that one coil consumes power only for an instant, while it is being switched, and the relay contacts retain this setting across a power outage.


I read your post line by line and you seem to be implying that the Ram starter relay is a latching relay. I know of no vehicle that uses a latching relay as a starter relay.

 

As I read it he states he found one with the proper circuit on it at a truck stop that was labeled as a "latching relay" no where do I see him calling the Starter relay anything but a Starter relay.

 

Thank you Larry, you summed it up. I'm giving up on george, as I included a picture to better help him understand, but still it's a dead end. He may have his tuque on a little too tight. And just so he knows, I already knew what an actual latching relay was. I didn't study electronics in college for nothing.

 

Well, this is how I interpreted the above statement - Mike purchased a latching relay and checked it with a multimeter and found it ( a latching relay) to be functionally identical to his existing starter relay.