My Ongoing Repair Thread for my 93 - Lots of Pics, Vids, and Details. Please HELP!

[Classified]

the solenoid is under a cover? I thought it was just right on top, you unscrew it and thats it. Maybe im not following you correctly

 

[buddy]

The solenoid on electronic pumps is right on top, just unscrews. You can check voltages/signals on yours without taking it apart, check to make sure there isnt any voltage on the pink wire when the ignition is off. There shouldnt be, and that would mean you have to open it up. If there is someone did something stupid and you have to wire it to an ignition source, or a relayed engaged by the ignition.

 

[buddy]

As fopr testing injectors, who can do that? and is it ok to just replace bad injectors with new ones? or do you get them rebuilt?

Also, I see alot of people recommend heath diesel but im trying to keep this as cheap as possible and ssdiesel has way cheaper prices. is there a reason for that? Much of thier pricing is 30-40% cheaper than HDP. The IP that ss sells is $700 versus HDP at $1900. Thats a HUGE difference. I dont need this truck to last forever, a good 2-3 years would be great, after that it will just be a backup truck.

The diesel fuel in the tank is a couple months old but it acts no different in the summer when it gets used every day.

You can put in new injectors no problem.

SSDS has lower prices, and good email technical support, and phone customer service, but they get you on the shipping costs, $6 shipping when adding a 2 ounce $4 part kind of crap, not much added efficiency when buying a lot. Otherwise their stuff is good and good service. Heath is a place known for performance and a brand name with good stuff too.

Make sure to add some lubricant to the diesel fuel if its #2. I have had great results putting 2-stroke oil in, I put in a quart when I put in 15-20 gallons.

 

[Turbine Doc]

If you want even better prices check out Pensacola Fuel Injection on ebay, good guys buddy of mine works there, still backing of the Heath name goes a long way and worth the extra $$$. SSD is not on the first round draft choice for many of us, PM if interested on knowing why.

 

[Classified]

Thanks for the explanations!

I forgot to charge my camera over the weekend so I dont have any pics today but I dont really need any to eplain todays progress.

First thing I did was to pop in the new GPs. 6 are new, one I couldnt get too because I already clamped on the the downpipe and its barely holding on as is so I didnt want to mess with it. I pulled out one of the GPs with the tube around it and it was pretty much brand new. No corrosion and hardly any carbon on the tip so I put it back in.

Then I tested the lift pump. I opened up the T valve and turned the ign to on but not running. Nothing came out, good news! So I jumped the relay by powering the E wire and I heard it pump! good news! So then I put in the new relay figuring it was bad, no dice, still didnt turn on the LP. So I tested the wires that power the coil and the purple/white wire was not switching the coil on to power the pump. I traced the wire into the cab and into the glovebox. Then from there it goes over to the drivers side, I looked around for it but didnt want to split open all the taped wires so I just cut the purple/white wire and wired it to IGN. That worked. So I went to fire it up, started on the first try! VERY little smoke and sounded much better and ran smoother. The high idle kicked in right away. I let it run for about 10 mins, then romped on it a few times to see if I get that puffing smoke. NOPE! was all clear. Figuring it was too good to be true, I put the truck all back together and took it for a little spin, it ran great but It was so loud I couldnt hear anything (I straight piped it since the muffler was shot. I need to put another one back on, thats for sure) and I didnt want to romp on it since it was so loud. It ran real smooth though and when I got back to the shop, still no puffing. The only time I get smoke is a bit at startup and if I romp on it in park.

So I might be lucky enough to return the LP, OPS, and LP relay.

As for the shutdown switch, it gets power with IGN so its working properly. I went one step further and while the engine was running, it unplugged that pink wire and the engine stopped. So Its probably a problem with the key cylinder or elsewhere.

The next major project is getting the speedo to work and figure out that wiring mess. Right now, if your cruising on OD and then it needs to downshift into 3rd, it will but it will stay in 3rd or below until your turn the truck off and then back on. It was like that the whole summer but I delt with it since im just on local roads the whole time but towards the end of the season it went one step further and if it needed to go to 2nd, it wouldnt go back into 3rd until a restart. Im not sure if its related to the VSS not funtioning or not but the new VSS comes in on wednesday so Ill know then. Im hoping that is it or I will be very lost after that and not know what to do next. Any ideas on that one?

 

[buddy]

Your LP is not supposed to work with ignition on, only when cranking, with 96+ years the PCM would run the LP with ign. Thats why it wasnt working for you. Although with the ignition helps a lot if all the fuel gets sucked up with an engine running after you shut it off. Now your system is being primed like its supposed to.

 

[buddy]

Im not sure if the relay is meant for constant duty, seems like a large durable one though. After cranking the power through the relay is supposed to be absent and the power comes through the OPS.

I think it was all working correctly before, except your IP isnt shutting off with ign, so your system isnt primed when you go to start it.

You might try putting LP on a switch with the ign source you put to it, so the OPS can do the job after you start it up. And its best to change the OPS to trigger a relay that powers your LP from a battery source, instead of having the OPS powering it through less durable contacts.

 

[Classified]

really so the LP is only supposed to be on while cranking? Is it ok to run with IGN? Thats probably why like you said, I thought it wasnt working, hard to crank and test the voltage at the same time. What controls the LP then? or is it simply wired to the starter wire? Or did I misunderstand you all together? LOL

 

[Classified]

your 2nd reply wasnt there before I typed mine.

So is my OPS possibly bad?

 

[Classified]

Also, this is the first time I heard the sound of the LP so im not sure if it ever worked before or not.

 

[buddy]

Its not audible over the engine, and only audible to me when its building pressure because my IP shuts off, so its already filled the filter assembly and all the lines so it gets noisy. I only ever hear mine when engine shuts off and the OPS is still powering it because oil pressure is still above 4psi for about 10 seconds.

The way you have it seems OK, but you dont have the benefit of the safety OPS feature. If you roll the truck nothing will stop fuel from pumping unless you can turn the key off. Since you know where the LP is, you can just touch it to see if its vibrating, humming quietly while engine is running. Then cut the ignition line you put to the relay and see if it keeps going, that would mean the OPS is working.

 

[JiFaire]

If you can hear it, you should be getting fuel, Doug. Wiring the LP to the ignition is not that good an idea... if you get in an accident, the OPS is designed to shut down your fuel pump when the engine quits so you don't keep pumping fuel on the fire. I would put the wiring back, were I you.

Then, put the truck in gear and have somebody turn the key to the start position... it won't crank over (not in neutral) but the LP should start pumping.

You can take the drain hose off the T-valve and put a gauge on that nipple... you should have 4-8 psi on that when idling, and even under wide open throttle (when driving) the pressure should never get to zero.

Jim

 

[Classified]

Its not audible over the engine, and only audible to me when its building pressure because my IP shuts off, so its already filled the filter assembly and all the lines so it gets noisy. I only ever hear mine when engine shuts off and the OPS is still powering it because oil pressure is still above 4psi for about 10 seconds.

The way you have it seems OK, but you dont have the benefit of the safety OPS feature. If you roll the truck nothing will stop fuel from pumping unless you can turn the key off. Since you know where the LP is, you can just touch it to see if its vibrating, humming quietly while engine is running. Then cut the ignition line you put to the relay and see if it keeps going, that would mean the OPS is working.

So if the LP stops when I remove the IGN wire that would mean the OPS IS bad then? I will have to try that tomorrow.

If you can hear it, you should be getting fuel, Doug. Wiring the LP to the ignition is not that good an idea... if you get in an accident, the OPS is designed to shut down your fuel pump when the engine quits so you don't keep pumping fuel on the fire. I would put the wiring back, were I you.

Then, put the truck in gear and have somebody turn the key to the start position... it won't crank over (not in neutral) but the LP should start pumping.

You can take the drain hose off the T-valve and put a gauge on that nipple... you should have 4-8 psi on that when idling, and even under wide open throttle (when driving) the pressure should never get to zero.

Jim

the IGN was kinda temporary anyway. I just wanted to drive it around the block and start it a few times to see how much different it operates. I would return the wiring back to the way its supposed to be if its not working with the engine running tommorow then im not sure what I should do then? The wiring is a NIGHTMARE on this truck. WAAAAAAY to many cooks in the kitchen in the past. I have ground issues galore in the cab and the trun signal makes my volt meter in the dash drop to 9 volts everytime it flashes. :mad2:

I need to buy a pressure gauge, I never needed one of those before or I would have pressure tested it today. I was just doing what I could without it.

 

[Classified]

OK another question, so when the OPS takes over control of the LP, does it control it through the relay on the firewall? Or is it wired directly to the LP?

 

[buddy]

The OPS is wired directly to the LP. The OPS is a relay, triggered by oil pressure over 4psi. The OPS is under the GP relay/controller. It should have an orange wire battery source and the output to the LP is grey.

I dont think an ignition soucre to the relay is a bad idea, since its that way in 96+ for this hard start specific reason. However you want it to change to the OPS after its running. Thats why a dash switch would be good. You might want to make sure that purple and white wire you cut is covered because there will be voltage when cranking.

And yes, if the LP stops when you cut the IGN line to the LP relay then the OPS is likely bad.

 

[Classified]

The OPS is wired directly to the LP. The OPS is a relay, triggered by oil pressure over 4psi. The OPS is under the GP relay/controller. It should have an orange wire battery source and the output to the LP is grey.

I dont think an ignition soucre to the relay is a bad idea, since its that way in 96+ for this hard start specific reason. However you want it to change to the OPS after its running. Thats why a dash switch would be good. You might want to make sure that purple and white wire you cut is covered because there will be voltage when cranking.

And yes, if the LP stops when you cut the IGN line to the LP relay then the OPS is likely bad.

Ok excellent! I will check the wires tomorrow and everything else there. I kinda hope the OPS is bad since that will be easier to replace than tracing down a wiring issue

 

[tracy]

the solenoid is under a cover? I thought it was just right on top, you unscrew it and thats it. Maybe im not following you correctly

I think what you are describing is the cold fast idle solinoid its on the drivers side of the pump. On the passanger side of the pump is the TPS (throttle position sensor for the trans.) mine has 3 wires coming out of it. And in the center top of the pump cover should be two wires one for the shut off and one for the cold advance.

 

[Turbine Doc]

The OPS is wired directly to the LP. The OPS is a relay, triggered by oil pressure over 4psi. The OPS is under the GP relay/controller. It should have an orange wire battery source and the output to the LP is grey.

I dont think an ignition soucre to the relay is a bad idea, since its that way in 96+ for this hard start specific reason. However you want it to change to the OPS after its running. Thats why a dash switch would be good. You might want to make sure that purple and white wire you cut is covered because there will be voltage when cranking.

And yes, if the LP stops when you cut the IGN line to the LP relay then the OPS is likely bad.

Not zactly Buddy, time to hit the GM manual some more; IGN is not what turns on lift in 96+ (it begins the logic process monitored by the PCM);and never a good idea to have ign on being the controller, listen to Jim he knows of what he speaks.

96+ has 2 power paths relay/ops as in earlier years, and PCM have to lose both to lose total power sort of a backup feature to make sure lift pump is providing fuel to IP to keep PMDs alive longer. On edit I'll have a look at the OPS/Lift thread to see if I can splain it in more detail there.

OPS is not a relay, it is sort of like one, OPS is a switch closed with oil pressure to close contactor and complete the path of trons to the lift pump, a relay uses a electrical coil that when energized from control signal closes load side contactors, sending high curent trons to the device needing the them.

Best/safest is to restore factory wiring, or if you want to add reliability, let the OPS control trons to a separate relay coil, and let that relay carry power to the lift pump, the contacts of an OPS tend to be light duty and fail, even though it still provides output to the dash gage.

 

[daustin]

'93 lift pump operation

Hi guys,
According to my GM manual, it will energize the lift pump relay when the "WTS" (Wait to Start) light is on (that's when it cycles the glow plugs), "START" is true (starter is turning over) AND when the OPS is "true" (Oil Pressure > 6lbs). These early models with the mechanical IP are a little different than the '94 and up. I had read up on it a lot on several other sites, and mine wasn't working like it was stated for the ODB-I type machines. I then got out my GM manuals, and read every scrap of info i could find on it. Found out my '93 was working just like the book said it was supposed to. The mechanical IP powers the lift pump when the WTS is on, START is "true" AND when the OPS is true. My estimate of 3-5 seconds was a little off, it's tied directly to the "WTS/Glow Plug" operation, thus it varies somewhat. I'm a control systems engineer so i'm always interested in how things work thus i research things in detail, one of my faults according to my wife. lol My '93 has about 205,000 miles on it, original engine/heads..etc (Tranny was rebuilt at 202,000) and runs like a top. Very very happy with it. I don't let any shop touch any of my cars except for front end alignments, tire installs or things like that which i don't have the specific tools to do. I think they are all screwing me every time. HAHAHA My hobby is restoring 50's-70's musclecars i built a 1200 sq ft shop in '01 to mess with my stuff in. All my friends & neighbors come over and we mess with my cars and theirs when needed. Hope that helps explain things with the lift pump, ops, WTS..etc for the '93's.
Don

 

[buddy]

Thanks for the info Daustin, that helps with the AND condition, so it will only power it after cranking a little, which is worse than in 94 even. So I think leaving it tied to a switched IGN source is not a bad idea then. Or have it activate with the GP relay to prime the system for a like 5-15 seconds depending on engine temp.

Not zactly Buddy, time to hit the GM manual some more; IGN is not what turns on lift in 96+ (it begins the logic process monitored by the PCM);and never a good idea to have ign on being the controller, listen to Jim he knows of what he speaks.

OPS is not a relay, it is sort of like one, OPS is a switch closed with oil pressure to close contactor and complete the path of trons to the lift pump, a relay uses a electrical coil that when energized from control signal closes load side contactors, sending high curent trons to the device needing the them.

Symantics really, the 96+ turn on when the IGN is in the ON position, triggered by direct feed to the PCM from the IGN. A relay is a switch, a switch can be a relay, not much difference in definition, and the OPS meets definition of a relay better anyway.