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1994 k3500 Lift pump relay

12K views 56 replies 8 participants last post by  jrsavoie 
#1 ·
Hey all, I tried to use google and the search function here but I cannot seem to just get a clear picture showing me where the lift pump relay is so I can jump it with a peice of wire so I can prime my truck and see if it's at least working.

Long story short I bought a 1994 k3500 Crew cab dually with 207k Miles on it. But hey, can't go wrong for 500$.

The reason why it was so cheap was cause the truck started to misfire on one of the cylinders and then the owner let it sit since 2004...yes sadly for 12 years it has sat. Now he sold it to me but it doesn't even run anymore. Cranks over but doesn't even attempt to run and doesn't get fuel to cylinders. How do I know this?

Well I don't, it's just a assumption based on the fact when it's cranking there's absolutely no smoke from the tail pipe at all. So I'm assuming there's no fuel getting to the cylinders.

The last owner said it's cause the fuel lines under the intake between the injection pump and fuel bowl where leaking and cracked.

Well it's at my house now and I removed the intake manifold and I can tell there was small leaks from the fuel lines and from the bottom of the fuel bowl but no lines where broken completely.

Now I plan to put all new lines back on and Google a fuel bowl rebuild kit (need the little o-ring in the side and the big o-ring on the bottom) and put it all back together but once it's back to tether I will need to know exactly where the fuel pump relay is so I can prime the truck without cranking it for a half hour. Now I know my 1997 had the relay in the drivers side fuse box and was simple enough. I also know that the relay for the 1994 is somewhere on the passenger firewall but I'm not sure exactly what to be looking at. So to sum up my very lengthy story. Simple question is does anyone have a photo pointing it out for me? Thank you in advanced.

P.s any input on my overall dilemma is appreciated.

P.s.s I hope it isn't the injection pump, cause all the lines had diesel in them when I removed them, so some fuel HAD to have made it to the cylinders but hey didn't. :(
 
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#2 · (Edited)
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#3 ·
The O-Rings you need to rebuild your FFM are:
Fuel Filter Heater O Ring - GM: 12511962
Water In Fuel O Ring - GM: 12511959
 
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#4 ·

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#5 ·
Thanks! You guys are awesome! So I tested it and the lift pump is working epically! So now I must move on to my next issue is why it doesn't fire or even attempt to. No smoke from tail pipe or anything noise of firing.
 
#7 ·
Try changing the PMD with another "known working" PMD w/resistor.(make sure you have a resistor installed!)
Change the Fuel Filter and clean and check the screen manager down inside of the bottom of the Fuel filter manager.
Batteries must be a matched set of equal cranking CCA's and fully charged.
Also, try unplugging the coolant temp sensor on top of the coolant crossover to fool the PCM for longer glow time.
If the vehicle starts, be sure to plug it back in immediately .

If still no start, Open your fuel cap then disconnect the Fuel line at the lift pump and blow Compressed air in the fuel line that goes to the tank to clear out the tank sock.
Then reconnect the line, leaving the fuel cap off and try starting the vehicle.
 
#6 ·
After sitting so long you will mostly likely need to rebuild the entire fuel system. Probably everything but the tank and injection pump. If you get it running you'll be chasing issues until it is rebuilt. Start with those soft lines and install a clear line off the top of the ip (1/4" id clear)
 
#8 · (Edited)
I'm willing to put in the arm work and money to do that, as long as it isn't the injection pump that's bad, the cost of a new pump is just outrageous.


okdually said:
Try changing the PMD with another "known working" PMD w/resistor.(make sure you have a resistor installed!)
Change the Fuel Filter and clean and check the screen manager down inside of the bottom of the Fuel filter manager.
Batteries must be a matched set of equal cranking CCA's and fully charged.
Also, try unplugging the coolant temp sensor on top of the coolant crossover to fool the PCM for longer glow time.
If the vehicle starts, be sure to plug it back in immediately .

If still no start, Open your fuel cap then disconnect the Fuel line at the lift pump and blow Compressed air in the fuel line that goes to the tank to clear out the tank sock.
Then reconnect the line, leaving the fuel cap off and try starting the vehicle.
Well good news is I have a new FSD Pmd and relocator kit that I'll pop on real quick.

But speaking of Batteries, I don't have a single 6.5 that cranks over "fast" they all have a "eh" cranking speed. Just Fast enough where you don't think your batteries are dead but not as fast as lets say a gas engine or a new diesel I.e Duramax whips over with two new batteries.

But yes the batteries are brand new and both matching (850 CCA)

Again, thank you all for your detailed and quick responses. No other form has been this helpful or "alive" ha-ha
 
#9 ·
The stock Delco MT28 Gear Reduction starter likes to be taken apart, cleaned out, greased and re-installed. Then your starter will spin much faster. http://www.jatonkam35s.com/CUCVTechnicalmanuals/1M-128.pdf While you are down there, make a custom 2g/0g battery cable to the solenoid.

Larger positive, cross over, and negative battery cables, 2g/0g will allow the electrical system to work easier.
 
#10 ·
It actually has a brand new starter and what looks like home made big cables. But I'll verify if the correct starter is even installed. But I do have grim news and it looks like my injection pump is bad. I cracked all the lines to make sure no air and for laughs and giggles I wanted to see what pressure the lines made so I took one off a injector completely and turned it over and it just spits out a tiny drop in a very pathetic manner every now and then. I'm assuming there is no way this is enough pressure to work the injector
 
#11 · (Edited)
The "homemade" starter cables may be one issue....

If you cracked open a fuel injector line and got a dribble of fuel you are in the ballpark. It is not going to Flow out of those lines..

Did you try another Known Working PMD w/resistor???

The IP should be the absolute last thing ever to condemn on your engine..
 
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#18 · (Edited)
And Do not forget the resistor. It does not automatically come with the PMD..
The only vendors that I am aware of including the resistor in the purchase price is Leroy Diesel and Badger Diesel.
 
#21 ·
It is inside the PMD connector. Go to leroydiesel.com or search here. I am sure there are pictures of a resistor someplace

Massive heat sink is a good thing. Where is it located?

If you need an extension cable to mount it in your bumper, do not cheap out. Get a good quality made in the USA
 
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#20 ·
Fill out your signature so people know where you are and what you have without back checking the posts.

You can also run the return line from the front of the injection Pump / IP to a container. If the return line is plugged, the truck will not start.

If you have good measured flow from the T drain, then I doubt you have any tank sock issues. You can jumper the lift pump and leave it jumpered while you try starting and while doing diagnostics.

I sometimes jumper the lift pump and turn the key to run and check for a dribble of fuel out the IP return line>

I have installed a fused toggle switch on all of my 6.5's so I never have to look for a jumper.

On a 94 you will want to do the dual lift pump relay upgrade. Or just order one from leroydiesel.com

His comes with the prime feature and an on/off switch. It's plug and play.

If you make your own dual lift pump relay upgrade, order the connectors and make yours plug and play also.

Use 14 gauge wire.

While you are running new lines install a T with an 1/8" NPT out the side, between the Fuel Filter Manager / FFM / Fuel filter bowl, to have a permanent fuel gauge. It's very handy for diagnostics and to see when your filter might be plugging up or your lift pump going bad.

There are several gauges to choose from. This is the gauge I ordered: https://www.amazon.com/gp/product/B0095Z7G94/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
 
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#26 · (Edited)
You can order any PMD brand and use it if you are in a pinch. You just have to make a small modification to the harness for it to connect..

Be forewarned, If you hunt for PMD's on Ebay you will find a lot of China "tested good" junk and may waste your money buying them!
Buy from a reputable source like Leroy Diesel or Badger Diesel.:HiHi:
 
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#28 ·
Don't hate on Ebay too much! Go thru some of my posts and you'll see it can pan out when you are an educated buyer.

You did good buying it for $500. You have way more than that in parts value :bigglasse

Read some of my threads and get a plan before you buy too many parts. For example, instead of a $100+ lift pump relay setup, you can splice a $10 relay into the under hood wiring of a '94 and solve your issues in 30 minutes (Assuming your OPS is functioning somewhat and can still trigger the relay)

I always suggest pulling the glows on a project like this since it most likely needs them anyway. Can be a PITA so get them sprayed down in advance and take your time...but it'll make bleeding the system very easy. You'll see fuel mist out the holes once it's primed and won't burn up your starter and cables trying to crank it over during diagnostics. It can take up to 30 seconds of cranking even with the glows out to get it bled...especially after it sat that long.
 
#32 ·
The complete block heater replacement cord isn't much more than a good plug.
 
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#33 ·
it is worth more just to get the new plug assembly for it, there cheap and easy to get
 
#35 ·
Okay so it's the weekend again and back to my little project. I decided to start by fixing up the battery cables and the truck turns over a bit better now. So I'll set that issue aside for the moment. I also decided to pull any codes if there where and I'm getting just three codes currently DTC 29,49 and 57 now 29 explains why the glow plug light randomly stopped coming on. Now 49 has me puzzled as to exactly what it means but 57 is concerning to me. But I did order a new verified working PMD wig resistor so it's on it's way but I'm guessing code 57 means my current PMD is fried. Am I correct in assuming this?

Also here's what I got from google when I looked up the codes,

DTC 49 - Service Throttle Soon Lamp Circuit Fault

DTC 29 - Glow Plug Relay Fault

DTC 57 - PCM 5 Volt Shorted
 
#36 · (Edited)
Go through all of your grounds!
link i provided in post #2 will help you find them all
 
#40 ·
What browser are you using? The pics are working for me..
 
#42 ·
If you can't get the pics to appear with the laptop let me know.
 
#44 ·
to access the passenger side grounds best you'll need to jack up the vehicle,remove the passenger side tire to be able to get to them properly
 
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#46 ·
Okay I got side tracked, I took the passenger wheel off and there are two ground straps bolted to the frame, well 1 of the two is snapped off in half, is this a truck specific part or can I some how make a ground strap replacement
 
#47 ·
You can make a replacement for it. Just use the proper stuff.
 
#49 ·
I run a ground wire direct from the battery to the frame. I also add a few other grounds to each vehicle
 
#51 ·
I'm not sure exactly what your question is.

I do the battery bolt mod on both batteries - I get rid of the battery csb;r bolts and install 1 1/4" or 1 1/2" stainless 3/8-16 Allen screws in the batteries.

If I am re-using the OEM cables - not so much anymore - I am replacing the original cables as a maintenance issue - I put 3 stainless washers inside the rubbers so I do not ave to cut them off - then Use a 3/8" nut to secure the cables to the battery>

If the Allen screws are tapered, I cut the ends straight. The tapered ends will strip out.

The alternator has a cable going to one battery already. I find another OEM cable off of about any vehicle and run it to the other battery.

The extra cable makes a noticeable difference. Others just add a bigger cable and fuse. M way is cheaper easier and faster. Both ways work.

I add several grounds. One from the right / Passenger side to the frame. There is no reason that you could not add the ground from the other battery to anyplace else on the frame.

I also add a body ground on the right side to the battery box bolt - to augment or replace the screw ground on the inner fender.

I use a lot of baking soda on the battery boxes before installing the batteries.

I add a ground from the heater blower to the dash mount bolt just a few inches away and to the stud at the back of the engine where all the little grounds go. I use 10 ga stranded wire for the added grounds.

Here is a good thread on battery cables
http://www.dieselplace.com/forum/63...22818-making-new-battery-cables-93-6-5-a.html
 
#57 · (Edited)
I would make or buy new cables before you proceed. Take your starter in to be tested. If it's good I would re-use it.

In future, be picky about electrical parts for your 6.5. Check the starter threads

I also sometimes add a white ground from the battery all the way back to the trailer plug
 
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