Well I had some fuel gel up on me the other day, so when I was changing the fuel filter I noticed my fuel was really dark and looked like it had oil in it. So I'm guessing I've got an injector o-ring leaking even though they were just done last December by the previous owner. So my question is, the truck has 226000 on it and I know for sure they are the oem injectors. Is it worth putting injectors with 226000 miles back in? If I'm replacing should I just go with another set of stock injectors or should I upgrade to bigger injectors? I'm actually pretty happy with the power I have now but would maybe like it to pull just a little better. I pull 10-12000 pounds pretty regular from April to October and then through the winter I pull my dump trailer with a load of firewood regularly.

I would assume I'd see an increase in performance just from a new set of injectors compared to ones with this many miles on them.

The other thing I'm debating is which hpop to get, I'm between a Bosch from diesel o-rings or one from CNC fabrication. I usually always try to stay as close to or oem as possible but have heard good things about cnc. The price is basically the same.

Current modifications are in my signature, let me know what you all think. Oh and this is for the late 99 not the excursion.

 

The OEM HPOP seldom goes bad. It can, and does, but seldom.

 

Like Dan said, you should verify you've got an issue with the HPOP before spending money on a new one. A working stock HPOP can handle slightly bigger injectors, so unless you're planning for big power in the future, no need to change it.

Get Torque Pro, and make runs to check it's performance. If it's low, it could very well be a poorly working IPR giving it bad instructions. There are plenty of threads where folks compare IPR%, ICP, and FIPW for you to see whether your HPO system is up to snuff.

 

And unless your injectors leak or look like this poor fella's Crusty Injectors, a little cleaning and new o-rings should be fine. Just be sure your fuel system is clean.

If you're thinking of upgrading, there's a lot to think about and you really should plan it out, instead of hopscotching along the way. So for now, keep it stock and running well, get it to 100% while stock, and that way you can really see where you need to go when upgrading.

 

The hpop issue I am having is the oil is draining back from the reservoir. When I've checked it, it is about 2-3 inches below the port in top where you check it.

My excursion since posting this I believe we have diagnosed a bad hpop. It won't make over 950 icp and has the IPR maxed out to do that. Going research a little more on this before ordering one. We're using a snap on Modis scanner to monitor and check this stuff.

As for the injectors, I'm not sure which route I am going to go yet. Seems like after 226000 miles the wear parts like nozzles and the plunger etc would be wore and possibly affecting performance by now. But the truck does seem to run pretty good overall so maybe not. Just hate to do all the work to pull and reseal just to do it again in 75000 miles. Kinda like to do stuff once.

 

You'll just have to replace them somewhere between 275,000 and 350,000 miles. 165 CC/ 80% single shots rock...

New HPOP should also yield better MPG (marginally if you can keep your foot off the skinny pedal)

Adrenaline HPOP is awesome.


Agreed.

 

I had the opportunity to rid in Mecdac's Ex recently and it hauls ***, there is no doubt about that. Another no doubt situation is the Adrenaline HPOP. Although, I am partial to CNC because I have dealt with Corey (CNC owner) on more than a few occasions and frankly I would send my business to him before Diesel Site. That is only personal preference though, and both HPOP's will get the job done well beyond your expectations.

The Terminator T500 has been popular over the years because it was a great value for a great performing pump. Although, there seem to have been some issues as of late that I have not seen any resolution for. The history of the pump speaks for itself though.

The fellas are right too, the OEM HPOP is capable of a lot, but if you have a fault, you should consider your options carefully.

 

My personal thoughts....

Not that changing injectors is a hard or super time-consuming job, but with 226K on stock injectors and adequate funds, consider just replacing them if you plan on keeping the vehicle. They're going to need to be replaced soon anyway regardless if you throw new o-rings on them ($10-$12 bucks a hole wasted) right now because you'll not be able to reuse them later for any reason.

 

Bad injector o rings will also bleed off ICP. See what the ICP is after the new injectors. Or you can test for leaks by putting air pressure to the HPOP hose fitting on the head, listen for leaks. Often called a Cody test on this forum, search for that. Yeah, that ^^ guy.

 

Will bad injector o-rings cause the hpop reservoir to leak down though? I think the hpop is working fine per my tests with wide open throttle runs and hooking my 9000 pound horse trailer to it and watching icp. It makes 2900ish icp with leaking injector o rings. That tells me it's probably working ok. But I think it's leaking down causing the recent hard starts I'm experiencing. Is that check valve replaceable?

 

No. This will only reduce operating ICP, give you smoke and a black fuel filter.The check valve is replaceable, but I don't think it can cause a draining reservoir. In the below image, I believe the check valve is labeled the Short Circuit Device, and it's just inside the front of the driver's side head, below the valve cover. But no matter what, the top of the standpipe inside the HPOP reservoir should be the lowest level in the HPOP. If it's draining, then maybe it's the base of the standpipe that's leaking internally, or the reservoir gasket. I don't know if the standpipe can be removed without removing the reservoir itself, but if it's sealed by the HPOP reservoir gasket between the HPOP reservoir and the engine cover, then you'll have to remove the HPOP and the reservoir to fix that.

 

So based on that info and diagram, replacing my hpop isn't going to fix the reservoir draining down anyway.

 

I don't know anything about the internals of an HPOP. The gear drive goes through that big hole in the front of the block into a space in the front cover, so I suppose there could be a path for the reservoir to drain through the HPOP into the engine cover and straight down into the oil pan, but someone else would have to chime in for specifics. Or even whether there's enough clearance for a such a leak to even be possible overnight.

 

I had expected one with more knowledge on this would have found it by now. My understanding is that bad injector O rings will let the HPOP drain down but I add the disclaimer that I am not 100% on this. There is also a check ball under a plug in the top of the block right behind the HPOP reservoir on the right side of it. It has a 3/8" square drive recess in it for removal. Under that plug is a spring and a check ball that purportedly can get a piece of dirt lodged in it and prevent it from sealing. If you remove that plug I would recommend cleaning the area first and blowing the loose debris out of the area with an air hose to prevent contamination. I found the location of the plug makes reinstalling it a bit tedious as it is too close to the reservoir to just use a 3/8" extension and put it it, I ended up using a large screwdriver to get it started back in. AFAIK those are the two places where the HPOP can bleed down.

 

Negative!

The upper square O rings will allow the hpop reservoir to drain if they’re bad. The upper rings usually fail near the gap in the steel ring.