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Fuel pressure at idle and WOT

Hmmmm why do I have to use 87a? Couldnt I splice into the gray wire coming from the OPS and run that wire to a switch inside the cab and then run the switch to a 12volt fuse and when I push the switch in it sends 12volts to the relay on peg 86 and cause the relay to lock in and give 12 volt power to the LP? I have a Bosch relay mounted by the previous owner on the drivers side close to where the wiring harness from the OPS is, I think it had something to do with his brake controller, and convenient to the battery, I also have a push button switch off the Mercedes that was a manual glow plug hookup that was not necessary that I can use to prime the pump. Got lots of crimp connectors etc and wire and silicone tape. I know I am making bricks with very little straw and making silk purses out of sows ears but thats what I got, well I got no money! LOL So can this work, I think the bosch has the diode n it doesnt it? If I power the 87a terminal with my 12volt switch am I pulling in the relay or am I supplying 12volts direct cause if so I would need a heavy circuit from the fuse block wouldnt I? Verses splicing into the OPS would only need a small amount to excite the relay?????
 
Yes you could do that, but either way use a momentary contact sw. IMO it would be just as easy and cleaner to hook up to pin 87
 
orrum said:
Here is another try at the wiring diagram being big enough to read.
Click to expand...

Should work fine.

If you use a momentary switch as Leroy mentions, you don't have to do a double relay circuit.

You would need to power the momentary switch from a 12v source seperate from the ops if you want to use it for priming the filter manager.

You're proposing to run it in series with teh OPS if I read your diagram correctly. All that will be good for is to kill power to the lift pump.

With the engine not running, there's no oil pressure at the OPS so there will be no continuity. That's why you'll need to power it from a 12v source.

87a is the normally closed circuit in the relay, 87 is the normally open.

IOW, if you want current to flow through the relay when it is off, use 87a. If you want it to flow when the relay is on, use pin 87.

If I read your diagram correctly, you've drawn the same circuit I did except with the switch in series with the OPS:

img028web-1.jpg


With momentary switch:

img027reduced-1.jpg
 
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The way you want to hook it up will work just fine, with a switch providing alternate source to the relay coil. If you were to use an ignition source thats when you should use a momentary switch or diode in case you leave the switch on, because otherwise OPS could allow vehicle to keep running after key is off. Thats what Aces was saying earlier. But if you just use a battery source then make sure to not leave it running to drain the battery :)

The lift pump will pull just a few amps, which is not a big deal for wiring, just that it causes the crappy OPS contacts to fail. Thats why its not a big deal to run switched power through 87a.
 
OK so lets say I use the push button switch I have, u push it in and when u release it it comes back out and breaks the circuit. Yall r all saying to hook it to 87a and to get the power 4 it I can hook it to the battery or the fuse block in the dash. Any sugesttions which fuse to hook it to cause it seems that way when I cut the ignition off it will kill the power to my momentary switch, this would be a double safety right??? Therefore I am gonna hook it to a fuse, now tell me which fuse to hook it to please. Thanks guys, in cowboy talk we gotta "git er done"! Tommorow would be good if I can find out which fuse to use, remember I am going to use the radio fuse to make my resistance wire injection heater relay kick in. Progress people we r makin PROGRESS!!!!!
 
Yes Great White ur diagram helped a bunch n thanks. I really wanted the glow plug LP thing to work but I dont have the relays to do it that way Buddy, maybe when I go to the junk yard. I found one about thirty miles from here where u just go in and get what u want and then pay for it, they said a lot of things like little relays etc r free. Can I get the fuel pump relay off the firewall that is factory and use it for my resistance heaters and double relay glow plug setup? Is there a LP on any trucks I can get @ the junk yard that will be better than my stock electric LP? Is there a fuel filter system on anything in the junk yard that I can use for spin on fuel filters that will use a 6 micron or so filter? How bout a 10 micron or so that I can use as a pre filter to my LP when I get a good LP off Leroy. This place is supposed to be plumb full of old chevy n GMC trucks and suburbans. I value all of ur knowledge and thanks again.
 
Here it is my newfound friends!!!!!! Pics of my first fully complete mod!!!!! Thanks Great White, Buddy, Handcannon, Leroy and all the rest. Got that muffler out and that thing does muffle. The ole girl has a sorta unique sound now, not irritating but its a sorta drone mixed with a tonal whine @ low speed and then at cruise speed she has a nice lil beller, I like it, as u speed up she talks to u! And yes I am gonna get some black paint that sticks to plastic and paint it! LOL Sorry the pics r dark it was almost dark when I got it finished.
 

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U know gettin the muffler out of the way makes some room to fab in a mount area for my 6 micron fuel filter too so thats on the list too! i know I write too much, I talk a lot in real life too.
 
If you put the momentary switch to battery you can prime without a key in, and before the glow cycle with key. The advantage from the ignition is as you say, making sure you aren't leaving it running, but with the momentary switch you have a good assurance you wont be able to do that. And with the momentary switch I think you are also just as safe to connect it up just like you were planning, with two voltage sources to contact 86. More than 10 ways to skin this particular animal :)
 
Buddy thanks a bunch, couldnt have done it without u. But which fuse to hook it to? I think 12volt to the 87a would be the best since that way its impossible to backfeed two sources to the OPS, ie. if for some reason the momentary switch were to send voltage to 86 while the OPS was sending a voltage to 86 then I might burn up the OPS and u oughta see what a ordeal getting to that OPS to replace it is going to be. I would rather replace the fuel pump if I send a double voltage accidentally or would the relay burn out and save the fuel pump from a 24 volt fiassco!
 
Hey Leroy somewhere on here I saw a thread where u put a lil vacum meter gauge thing on to measure something about ur air filter???? Anyway I dont want to get too many irons in the fire but could I use that to somehow measure the amount of air flow I am getting to my air filter at highway speed to see if my air ram idea that I am using increases the air to the filter and subsequently the engine? I want to put a aluminum sheet behind the grill to direct more air to the intake to the inside of the fender where the snorkle use to be. Or perhaps the behind the grill area works like a great big tub facing the front of the direction traveled and air bleeds thru the ac condenser/radiator and also shoots thru the opening behind the headlite into the opening in the fender? Seems like I saw a air gauge on my friends Dodge diesel that told u when to change the air filter.
 
The gauge you saw operates off a vacuum. It gives an indication of filter condition. You could possibly mount one on yours. "IF" the air cleaner lid creates a seal on the inside diameter of the filter you could pop a hole in the lid and install one there. Im thinking in the area close to the studs that are holding the lid on now.

On the OPS relay, I like to have a momentary sw in engine bay also, so I can bleed air from filter.
On your spin on filters idea you can use the Wix base (witch I also sell :D) with a filter is appox $65. Can't think of any junk yard cars that would have anything usefull.
 
It's a long shot, but if you run across an 82 or 83 GM vehicle that had the 6.2 in it they had two different size spin on filters on them. I have them on my 83. The larger one was on the firewall as the pre-pump filter, which also had an air bleed built into the filter canister.

The other one, smaller, was bolted onto the back of the intake manifold and was plumbed in between the fuel pump and the IP. I'll get you some pics of them this evening.

I've been outside doing yard work and had to set down to give my back a chance to rest and now have to get back out there.

Don
 
Thanks Leroy, I can cut another switch into the wire under the hood when money is available, right now I am gonna get the OPS mod and priming button done and finish my fuel pressure gauge, right now I am baling hay here @ Trails End Farm 2day and 2moro with my friend that runs his John Deeres on wvo, we changed a filter this afternoon! LOL He has to change about one a month. Great White I was thinking big transfer trucks 4 sure for fuel filter mounts, big ones! LOL Hey Handcannon I researched ram air setups on the net last nite and here is what I found, now this was on a forum in England but it was on the GM 6.2 diesel. The folks built some very simple, really ugly too but functional air rams and hooked em to their non turbo 6.2 and they used a vacuum gauge like Leroy is talking about and with the ram air there was so much air in the breather that the gauge would not register anything but if the ram air was blocked off the gauge would pull a vacuum. Even very dirty the ram air still put the air to the engine @ speed and no reading on the vacuum gauge, speed for them was a minimum of 40 mph. So then they did some testing and a basic add on turbo to the 6.2 would need about a 1/8th to 1/4 turn up of the IP, air ram could use a 1/16 to 1/8 turn up of the IP. Now I understand the vacuum deal but I have no idea how significant turnin up a IP 1/16 to 1/8th is ????? Anybody want to chime in on this?
 
Leroy another question. My friend that runs wvo in the tractors was looking @ my 1991 6,2 and he has been bitten by the diesel bug, he is real big on chevy gas trucks but is quite impressed with my economical lil 6.2 so now he wants one to replace his aging farm truck. He might also experiment with wvo in it. I need to know what years were turbo from the factory 6.2 or 6.5 and were mechanical IP setup, I think it would be better for wvo to not have the electronic IP. Also he would take a non turbo too if it was available, this truck aint goin to the mtns or anything, he wants that good diesel mileage that the older ones get. Which trucks will have the 4l80e tranny cause its the best stock tranny isnt it? Your truck that runs on wvo is a 1995 isnt it? My thinking is probably 1991 thru 1995 but once again I am green as a gourd on diesel trucks and just think the lord looked out for me with my 6.2 cause I am tickled with it. Thanks in advance for the advice.
 
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