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6.5 has me lost

I would recommend one step at a time. You should have codes from the Assembly Line Diagnostic Link (ALDL). Grounding test terminal "B" to terminal "A", ignition switch "ON". The Service Engine Soon light on the instrument panel will flash with the code, One flash - pause - and then two flashes means code 12, which is not a fault codes but starts the diagnostic sequence. wright down any and all codes to find out what the computer sees from sensors and components.
 
Okay after a long few weeks I’m back at it! Installed a fuel gauge with the leroy diesel fitting. I’ve checked the gauge install and it’s all correct but I’m getting a zero fuel pressure reading along with zero on the boost gauge
 
no fuel pressure! that would indicate your lift pump down on the frame is ether not getting power or it's working and not pumping any fuel. that can kill the injection pump in a hurry! you should be seeing around 8 psi if you have an OEM LP. things to check is first the fuses, then see if there is power to the oil pressure switch. that switch has three wires. one power in, one power to the LP and the third is just for the oil pressure gauge in the dash. the dash gauge can still be working and it not passing power to the lift pump. Those oil pressure switches are a common failure. the tiny contacts in them burn out, weld them selves together or worse, burn out the LP. if you have to replace it, get GM DELCO. I went though three of them from the auto parts stores before I ordered the Delco one. all the auto parts sell that cheap aftermarket chineesium junk.

this is where your gonna want to get a relay mod installed. Leroy one of the members here sells a complete harness that is a fairly easy install for it, or you can make your own it your handy with wiring and what not. I made my own and even wired it in such a way that the LP will run to prime the pressure up while the glow plugs are warming up. 95 and earlier didn't have the self prim feature where I think 96 up did.

on the no boost pressure. if you still have the factory vacuum pump installed, check to see if it's got vacuum. or if the tiny brittle tubing from it to the solenoid on the drivers side valve cover isn't cracked. there should be a tiny plastic tube that runs from the vacuum pump over to that solenoid and then back to the actuator on the turbo. trace those lines and look for any cracks or broken tubing. most just replace that hard brittle tubing with some rubber hose. If your truck has an EGR on the top of the intake, there will be two solenoids and some tubing to the EGR too.
 
dbrannon79 said:
no fuel pressure! that would indicate your lift pump down on the frame is ether not getting power or it's working and not pumping any fuel. that can kill the injection pump in a hurry! you should be seeing around 8 psi if you have an OEM LP. things to check is first the fuses, then see if there is power to the oil pressure switch. that switch has three wires. one power in, one power to the LP and the third is just for the oil pressure gauge in the dash. the dash gauge can still be working and it not passing power to the lift pump. Those oil pressure switches are a common failure. the tiny contacts in them burn out, weld them selves together or worse, burn out the LP. if you have to replace it, get GM DELCO. I went though three of them from the auto parts stores before I ordered the Delco one. all the auto parts sell that cheap aftermarket chineesium junk.

this is where your gonna want to get a relay mod installed. Leroy one of the members here sells a complete harness that is a fairly easy install for it, or you can make your own it your handy with wiring and what not. I made my own and even wired it in such a way that the LP will run to prime the pressure up while the glow plugs are warming up. 95 and earlier didn't have the self prim feature where I think 96 up did.

on the no boost pressure. if you still have the factory vacuum pump installed, check to see if it's got vacuum. or if the tiny brittle tubing from it to the solenoid on the drivers side valve cover isn't cracked. there should be a tiny plastic tube that runs from the vacuum pump over to that solenoid and then back to the actuator on the turbo. trace those lines and look for any cracks or broken tubing. most just replace that hard brittle tubing with some rubber hose. If your truck has an EGR on the top of the intake, there will be two solenoids and some tubing to the EGR too.
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I was just assuming it was a failed lift pump, I installed it 1yr ago it was a cheap after market pump off eBay . I no power didn’t even cross my mind but that’s the first thing I will check
 
1995 and older needs the lift pump relay upgrade. If you make your own, make it plug and play - like Leroy's.
No cutting and splicing as you might find in some older instructions.

I may have posted the connectors needed a long time ago.

The prime feature dbrannon79 described is important.

I also prefer mountable relay sockets to mountable relays.

I also mount a toggle switch for an on off switch. I find it handy for diagnostics and priming.

I have ran a couple vehicles, for years, with the relay upgrade, that had bad ops - they put out enough juice to trigger the relays, but not enough to run the lift pump.

Use 14 ga wire.
 
Soun
jrsavoie said:
1995 and older needs the lift pump relay upgrade. If you make your own, make it plug and play - like Leroy's.
No cutting and splicing as you might find in some older instructions.

I may have posted the connectors needed a long time ago.

The prime feature dbrannon79 described is important.

I also prefer mountable relay sockets to mountable relays.

I also mount a toggle switch for an on off switch. I find it handy for diagnostics and priming.

I have ran a couple vehicles, for years, with the relay upgrade, that had bad ops - they put out enough juice to trigger the relays, but not enough to run the lift pump.

Use 1
Click to expand...
 
So I used a power probe. The lift pump does work when I give it power. There is no power going to the lift pump. So I’m guessing it’s the oil pressure switch. Not sure I want to spend the money on mods so I’m gonna change the ops and see what I have
 
Loosening and tightening the OPS is a real joy if you don't have the correct socket. One technique that worked for me is a basin wrench. A lot of 1/2 and 1/4 turns but, it worked without damaging the switch.
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Hammerhead said:
So I used a power probe. The lift pump does work when I give it power. There is no power going to the lift pump. So I’m guessing it’s the oil pressure switch. Not sure I want to spend the money on mods so I’m gonna change the ops and see what I have
Click to expand...
You may well have to change the ops to do the upgrade anyway.

Sometimes the ops will send enough juice to trigger the relay and you don't have to change the ops to do the upgrade. I had a couple vehicles run for years like that .

You can jumper the lift pump under the hood to get it running.

It helps to fill out your vehicle information on your signature.

So people don't have to check back to see what you're working on.

I must have something set wrong or something changed.
I'm not seeing any signatures now.

If you have voltage at the lift pump plug with the engine running, you may be able to get away with just doing the lift pump relay upgrade, without messing with the OPS.

I don't have a clue how much the vendors are charging for the lift pump relay upgrade these days.

Only use AC Delco to replace the OPS.

Aftermarket ops is just asking for trouble in the future
 
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Hammerhead said:
That makes since. I have already dumped more money into this truck than it’s worth. I trying to get this running right as cheap as possible before the snow starts flying.
Click to expand...

Be Frugal NOT CHEAP!!!

Plenty of cheap garbage parts out there: Knock-offs, wore out painted scrap sold as reman, bent, not rebuilt correctly... So be careful and best to ask on here first esp. for fuel injection parts.

What is the condition of the body and interior? What would it cost to go buy a new pickup? Used runs and drives pickup? I doubt the inexpensive repairs you need are close to that. So what is this truck worth to you when it runs and drives given the cost to "get somethin else"?

Do not be cheap on lift pumps or brakes. Even Frugal is iffy for these parts.

As you broke a glow plug ... depending on blowby and compression loss you need glow plugs, ALL EIGHT WORKING, even in a Phoenix, AZ summer. This is some of your white smoke till the precups get hot enough to light diesel off from compression heat.

Boost ... This only gives you a number under engine load. This is your black smoke if the vac system is INOP. It holds the wastegate closed on the turbo. No vac to wastegate = KITT saying "No Turbo Boost, Michael."
 
WarWagon said:
Be Frugal NOT CHEAP!!!

Plenty of cheap garbage parts out there: Knock-offs, wore out painted scrap sold as reman, bent, not rebuilt correctly... So be careful and best to ask on here first esp. for fuel injection parts.

What is the condition of the body and interior? What would it cost to go buy a new pickup? Used runs and drives pickup? I doubt the inexpensive repairs you need are close to that. So what is this truck worth to you when it runs and drives given the cost to "get somethin else"?

Do not be cheap on lift pumps or brakes. Even Frugal is iffy for these parts.

As you broke a glow plug ... depending on blowby and compression loss you need glow plugs, ALL EIGHT WORKING, even in a Phoenix, AZ summer. This is some of your white smoke till the precups get hot enough to light diesel off from compression heat.

Boost ... This only gives you a number under engine load. This is your black smoke if the vac system is INOP. It holds the wastegate closed on the turbo. No vac to wastegate = KITT saying "No Turbo Boost, Michael."
Click to expand...
You are not wrong. I’ve learned my lesson on the cheap parts. The truck isn’t in horrible shape but it is a old work/ snow plow truck.
 
are we talking fuel pressure or boost? the main thing first is getting ample fuel pressure up to the injection pump. on the stock lift pump, pressure will drop down to around 3-5 under load due to the pump not keeping up with the demand of the IP. you never want it to go into a vacuum situation under WOT (wide open throttle) that means the IP is starving for fuel.
 
dbrannon79 said:
are we talking fuel pressure or boost? the main thing first is getting ample fuel pressure up to the injection pump. on the stock lift pump, pressure will drop down to around 3-5 under load due to the pump not keeping up with the demand of the IP. you never want it to go into a vacuum situation under WOT (wide open throttle) that means the IP is starving for fuel.
Click to expand...
Sorry that was fuel pressure. I’m guessing the cheap eBay lift pump isn’t pushing the pressure. Ordering a AC delco pump to replace it. As far as boost goes at 70 mph gauge still shows zero boost. So gotta figure that out but already I’m going in the right direction from where I started
 
AC DELCO EP158 and only from an AUTHORIZED DEALER. Delco has multiple lawsuits ongoing with places (especially online) that are selling knock offs that come labeled and boxed as the real mccoy.

You are seeing the effect of not enough supplied fuel - proven by getting a difference of a couple psi. The best the Delco pump will do is 8-9 max and maybe 6ish under hard acceleration. Because you are using this as a beater- decision comes hard.
But just like the investment of a top notch lift pump pays for itself on the dmax, that is normally the answer for the 6.5.
The ideal pressure is 8-14 psi- but the EP158 never hits those numbers. FASS or similar quality keeps the ip alive longer- but you obviously have a worn ip and it will not give you another 100k for sure.

The Delco will give you 20,000 miles or so before it is worn enough to need replacement. Most ds4 will survive but wear quicker at lower pressure, By the description- you need to stay above 5psi minimum to have any chance at getting decent miles from the ds4.

Strongly consider having it run ok and sell it now while it runs. Ya might get a few grand running but when that ip dies - scrap weight because everyone that knows 6.5 realizes the ip has to be expected to be replaced. And 6.5 fans like us don’t pay top dollar when we want another project.

If you choose to keep it around for another 50,000 miles- invest now in a high end lift pump and expect to replace the ip. The 6.5 is only economical when you set it up for the long haul, otherwise it will nickel and dime you to death.

Consider some of the other mandatory repairs- new ac delco harmonic balancer and belt drive pulley (the cheap ones fail ridiculously fast). Oil cooler hoses. Whatever maintenance/ repairs might be needed for cooling. These are all critical points of failure for this engine that there simply is no room for error.

Now, since this is a plow truck and depending where you live (dmv requirements)
If you are a serious diy guy - do the good lift pump and start buying parts to do a db2 conversion. Then when the ds4 dies- you can do low cost fuel like black diesel.
Running alternative fuel is one of the huge reasons so many people became fans of this engine but the ds4 kills that.
 
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