Continuing to work on my truck. Have it running pretty good, during normal driving, you wouldn't think anything is wrong. However, when I punch it, there's a slight hesitation and stutter.

I think the four injectors I replaced are doing fine - It passes the bubble test.

Put in the blue spring upgrade, and it needed it. The old spring was all gunked up.

Took out the HFCM today and cleaned it out - it was real nasty inside; the reservoirs almost completely clogged with gunk.

Unfortunately, I don't have a scanner. Got Torque Pro but I'm waiting for my adapter to arrive from Amazon.

I'm thinking that the fuel pump may just not quite be providing enough pressure at high load. It's definitely working, but maybe just not enough pressure. Since it and the regulator were so gunked up, it seems logical. However, I hate to buy one if that's not the problem (I've wasted so much money already on non-fixes).

Dealer mechanic did a $250 multi-point diagnosis and said the FICM was fine and only recommended the injector, blue spring, and a fuel pump, but admitted that he only included the fuel pump because there had been a recall on mine years ago.

Am I missing anything simple? Just changed to 5w40 Rotella today from 15w and that seemed to help a bit, but the hesitation is still there.

 

Thought I would add my 2cs, have you or do you know if Bio fuel was used ? being all gunked up as you say, I would pull the Tank and check the pick up socks a Buddy has a 7.3 and the truck would Idle just fine get on the petal for some load and it would starve. ended up killing the #8 Inject too . hook up a fuel pressure gauge and drive around Remember below 45 is not good .

 

Yeah, I posted a thread asking for any fuel gauge recommendations but didn't receive any. It would be a roll of the dice spending $80 or so on a gauge vs. $270 for a new pump. I hoped the Torque Pro app would tell me the fuel pressure, when the adapter for it finally shows up...arrrgh.

I've only had the truck a couple of months and don't know if the previous owner used biofuel. I don't think I have - do the gas stations make it real clear that you're buying bio vs reg diesel? Don't recall ever seeing the diesel I've bought labeled that way.

 

Harbor freight has some gauges and tubing with all the fittings to build one it would really give you some readings before you drop the tank. most bio fuel hoses are yellow and truck diesel are green . all the way down cali/Az 10 freeway stations have B-20 I steer away from running Bio for a lot of reasons Especially trying to make it.

 

I threw A glow shift 3 in 1 gauge in my truck last yeah (boost, egt, fuel psi) and would highly recommend it vs throwing expensive parts at your truck. It's an added bonus since there are no factory sensors for the egt's and fuel psi so a scanner will only get you so far but is also very useful.

 

Aaah, I've seen those yellow pumps. Thought they were for gas cars that use FlexFuel.

I'll check out HF asap.

 

Thanks for the info. So, TorquePro won't tell me fuel psi...drats.

 

Take the MAP nipple off the intake and make sure
that it and the hose to the sensor are clean.
Any gunk there and your going to get slow response.


Sean

 

Thanks! I will check that out in the morning.

 

I don't believe our beloved 6.0L's were ever equipped with the pick up socks in the fuel tanks like the later 7.3L's were, so that would eliminate dropping the tank for now. It is possible that it could be stiction on the other injectors; you might could try hot shots stiction eliminator before you start throwing expensive parts at it and maybe stanadyne's fuel system cleaner and lubricator... I have used both and they seem to be legit! Stanadyne is made by a company that manufactures injectors and pumps and from what I understand they were not satisfied with the available fuel system treatments for lubricity and cleaning so they made their own. Hope this helps and good luck.

 

Well, I put a good fuel pump on and it didn't solve the problem. Looked at the MAP sensor and hose and they were dry as a bone. Now I notice, however, that you said the MAP "nipple," which I assume is a fitting that screws into the intake. I'll take that off and see what it looks like.

Dang, wish I had my scanner adaptor already.

Based on all the gunk that came out of the old fuel pump and regulator, and the original symptom of bad injectors, just keep thinking it's fuel related. But, I guess that gunk could have gotten in the engine and plugged up a sensor as well.

 

The pick up tube in the tank can still be an issue. It depends on how much fuel was kept in the tank and if the tube has come loose, or deteriorated somehow. I think you may still be wanting to pull it and check it out. Also, when you changed the new HFCM, did you back blow the lines from the engine and the line up to the tank? If there is gunk in there it will really restrict flow, or block am orifice, make the pump work hard. This chit can be frustrating, keep the faith.

 

I didn't blow back the lines - great suggestion. Where would I blow from the engine?

 

I would disconnect from the HFCM on the frame rail and blow back to the tank, both main and return.

For the lines to the secondary filter, I would take off the cover on the secondary filter on the motor (do a blue spring if you don't have one after this) and blow from the secondary filter lines back down to the HFCM. You can disconnect the lines where they go into the top fuel filter module, but make sure you use two wrenches so you don't twist the lines. Any larger stuff or debris should come back out where it came from best. There should be much in there because the primary filter should trap all the June before it gets in these lines.

You need a fair bit of compressed air and you need to be careful with the pressure on the other end. I have a rubber tipped blow nozzle that fits snug into a line and will get a lot of pressure into the line. Make sure there is something, like a empty 2 litre pop bottle on the other end to catch what you blow through on the top lines. Can really do that with the lines into the tank but it is wortha try to get them clear too.

Now, I would think a blue spring is necessary, and you might as well plumb for that fuel pressure gauge. This is the only way you are going to rule low fuel pressure out of the equation moving forward. I have not had to do any of this on my 6.0, but I have had this problem with other vehicles, tractors, sleds and motor bikes. Hopefully chez it or mechanic will chime in if they see any issues or tips they can add to this.

 

No data reader will read fuel pressure because there is no fuel pressure sensor on the truck ...... Unless you put one on it.

Fuel pressure and EGT are two sensors that would have been great to have as OEM.