Normal Load % for Basically Stock Truck?

[LorenS]

Around 118. I think the ECM was doing a lot of pulse width modulating because the pressure would go up and down with a fair bit of regularity, 14 to 17. Then sometimes it would go up to 18-19 for a few seconds. I could not deduce the pattern looking at IAT, boost, load %, fuel temp.

 

I almost tied my relay into the wire that IBMobile recommends if the ECM loses the lift pump circuit, but really didn't want to put a splice in a perfectly good wire.

[Mopar1973Man]

Typically on my truck the IAT and fuel temp run the same temps. 

 

[LorenS]

I get that, but our trucks are about as different as they are similar, so I don't know how much stock to put in comparing temps.

The big differences are that I've got dinky injectors at stock pop pressure, a dinky turbo, a slushbox, and operate in a sea-level sauna compared to Idaho. My truck has also been used and abused before I got it (36k pound plates?!), whereas I recall you bought yours new and surely took care of it. And yes, I'm running giant 3rd gen stock tires with my 0.69 overdrive.

 

We have so many differences it's hard to know why my fuel temps are reported as high. For all I know the sensor is bad, my return line is restricted, or since my injectors are small the solenoid has to be energized longer each injection cylce and thus puts more heat in the fuel. Most likely if I did the IBMobile mod the temp would come down.

 

Maybe my relief valve isn't up to snuff.

 

 

[Mopar1973Man]

8 hours ago, LorenS said:

The big differences are that I've got dinky injectors at stock pop pressure, a dinky turbo, a slushbox, and operate in a sea-level sauna compared to Idaho.

 

Oh... Idaho you think is cooler? HA! It was a 100*F here yesterday typically I see 115 to 117*F in Riggins, ID. Elevation ranges from 700 feet in Lewiston, ID to 9,000 feet at Heaven's Gate (Riggins, ID). Looking at what temps are around the VP44 intake is more dominant about fuel temp than block temperature typically. Being the intake temps roughly what fuel temp will be. Injectors wise depending on how old / miles could be the pop pressure is low. OD on an auto makes the final ratio smaller just by a bit more. 0.75 vs 0.69. Then I can throw in rotational mass as for every 1 pound of rotational mass you can ditch is like 8 pounds off the frame. Bigger and heavier tires will make for higher engine loads. Hence why I ran the other direction away from large tires down to smaller tire to reduce engine loading. Gives me better efficiency all the way around ditching extra rotational mass that just only looks cool, and steals power. Being Iv'e got grades around here that most don't think about. Several roads are between 10 to 16% grades around here. 

 

 

Just like I've gotta head back to Anatone, WA to finish my injection pump project on a CASE C580 back hoe. That trip is nothing but up and down mountains. Running as high as 4,000 feet and dropping to mere 700 feet above sea level. Temperatures on my last trip were around a 100*F in Lewiston, ID during the day. Other than some mechanical differences climate wise its pretty close. 

 

 

Edited July 28, 2020 by Mopar1973Man

[dripley]

8 hours ago, LorenS said:

I'm running giant 3rd gen stock tires with my 0.69 overdrive.

Your 265 70r 17's are the same size as my 265 75 16's. A little larger than Mike's but most folks here are running larger also. 

 

Which @IBMobile mod are you speaking of that might bring down temps?

[LorenS]

I didn't say cooler, I was referring the humidity we have here when I said sauna.

 

It seems you agree our trucks are very different.

 

@dripley

The IBMobile mod to which I refer is where the lift pump relay is triggered by a wire (orange and black?) from the PDC that will cut power in the event of a crash, instead of being controlled by the ECM. My fuel pressure rises and falls around 13 to 18 as I drive, but if I shove a jumper in the wiring to power the pump it's consistently up around 18-19.

[dripley]

9 minutes ago, LorenS said:

The IBMobile mod to which I refer is where the lift pump relay is triggered by a wire (orange and black?) from the PDC that will cut power in the event of a crash, instead of being controlled by the ECM. My fuel pressure rises and falls around 13 to 18 as I drive, but if I shove a jumper in the wiring to power the pump it's consistently up around 18-19.

Sounds like you are not getting steady power until jump it out. Maybe something wrong with relay?? Not sure how to check that though. 

[Mopar1973Man]

20 minutes ago, LorenS said:

I didn't say cooler, I was referring the humidity we have here when I said sauna.

So do we... Started out at about 81%. Then reaching 98*F outside. Ugh really rough to work in.

 

22 minutes ago, LorenS said:

My fuel pressure rises and falls around 13 to 18 as I drive, but if I shove a jumper in the wiring to power the pump it's consistently up around 18-19.

What size plumbing do you have on the truck? 3/8" hose or 1/2" hose and fittings? 1/2 inch hose and plumbing gives the most volume per amount of pressure. I typically only see about 2 to 3 PSI drop from idle to WOT.

[LorenS]

I have 3/8 from tank to stock filter, then 1/2 from filter to IP, all banjos removed.

 

Since the pump puts out great and consistent pressure when jumpered, I believe the ECM is "pulse width modulating" the pump for some reason. For my 400 mile drive home I plan to jumper it just to see what happens. Fuel got to 151 today and it was only 88 degrees out.  IAT was 125. Flat Iowa terrain.

[dripley]

Mine is 1/2" from the top of the tank to the oe filter and 1/2" from there to the IP. My pickup is only 3/8". I see 4 to 4.5 psi drop. Thats on the same pump as Mike has.

[Mopar1973Man]

7 minutes ago, LorenS said:

I have 3/8 from tank to stock filter, then 1/2 from filter to IP, all banjos removed.

 

Need to upgrade to full 1/2 inch lines you'll get more volume through the VP44 keeping the fuel temps down. I'm 1/2" from the DrawStraw in the tank, to the AirDog 150, then up to the stock filter and then finalize with 1/2" between the stock filter and the VP44. I struggle to get past 120*F fuel temps. 

 

This is my last trip to McCall ID with temps in the high 90's. Climbed a 7% grade and did my shopping and came home again. 

[LorenS]

If the ECM isn't triggering the pump to operate, I could have 3" pipe and still not have 18 PSI.

[Mopar1973Man]

Well I guess you need to send the ECM out to Auto Computer Specialist and let them repair that. 

[Mopar1973Man]

Just for info... Just drove 3 hours to Boise. It is 103°F out and my IAT and Fuel Temp match. The whole way here.

 

 

[LorenS]

I knew the ECM would modulate the lift pump, but I just looked up the standard operation in the FSM and learned it only does that during cranking! I incorrectly assumed it had an algorithm to know how much to pulse.

 

Before I assume that part of the ECM is dead, is there anything else it could be, like a pressure relief valve that has a "hitch" in it?

 

If not, I'll be doing the IBMobile modification - I currently don't have an operational backup vehicle (1986 military Blazer has sat a long time).

[Haggar]

Loren,

 

Hook a cheap volt meter up to the pump leads and watch it just like you watch pressure.  (make the leads long enough to put it in the cab.)

 

See if there is a change in voltage that would lead you to believe that there should be a corresponding change in pressure.

 

If you have pressure changes without voltage changes, you can more likely assume that something is wrong in the pressure regulating side of the pump and no issue with the ECM.

 

HTH
 

Hag

[Mopar1973Man]

14 hours ago, LorenS said:

s there anything else it could be, like a pressure relief valve that has a "hitch" in it?

Not really. The only one is the overflow valve which you can test with compressed air. I've never seen a bad overflow yet.

[NIsaacs]

On 7/27/2020 at 12:46 PM, LorenS said:

I don't believe the new pump helped much. Fuel temp reached 141, and it's 10 degrees cooler out. I did have an extra 1,000 pounds in the bed, so the test is far from definitive.

 

 

I just changed out my Raptor 100 for a 150, no change in fuel temps. After a 5 hour 3 trip haul, easy down hill loaded, I am at 153*, 2/3 tank of fuel, 95* ambient.  I have it set at 17 psi, it helped a lot on cruise psi but WOT dropped to 8 psi.

[Mopar1973Man]

Are you full 1/2" line between the fuel tank and VP44?

 

I just did a 414 mile trip to Anatone WA to install a injection pump on a Case C580 backhoe. Never got over 120*F fuel temp and even coming home only had about 3/8 of tank of fuel still stayed under 120*F the entire trip. 

 

AirDog 150 with 165 Pump. Full 1/2" from tank to VP44

Idle 17 PSI

Cruise @ 65 MPH - 16 PSI

WOT - 15 PSI.

 

I do need to change my fuel filter getting close to 60k miles on these filters. 

Edited August 13, 2020 by Mopar1973Man

[LorenS]

I did another 400 mile trip today, home from Minnesota.  Started with a full tank.  It was about 88 degrees the whole way, according to overhead console - and humid.  It took the whole trip, but fuel temps finally got over 150 degrees.  IAT was generally around 125.  Any time traffic slowed to 55 MPH for several miles, the fuel temp would drop several degrees, then we'd get going again and soon the fuel temp would be up again.

Fuel pressure on ISSPRO would be consistent 16-17, then sometimes climb to 18-19 and then would fall to around 13, then go right back to 16-17 again.  To me that sounds like a relief blowing off when I'm at 16-17, then shutting for several seconds so pressure rises to 18-19, blowing wide for several seconds to drop to 13, then finally the spring partially shutting the relief.  But as Mike stated, relief failure is rare.  This climb and then drop isn't very regular, and has nothing to do with engine load, throttle position, a head wind, or anything I can easily observe as a correlation.

 

On my way to Minnesota on Monday I essentially hot wired the pump at the relay (load terminals, not the signal wire).  The pressure wasn't any more consistent, it behaved the same way.  It was very nice weather, only 68 degrees, so the fuel never got near 150, but was still 50 degrees hotter than ambient.

 

Unlike you guys with a decent amount of fuel going to your filler neck, all my fuel just goes in a circle, right back to the factory sump/sending unit, so could it be that that fuel is just slowly getting super hot from that?  I haven't measured the temperature of the fuel elsewhere in the tank, nor double checked that the computer isn't lying about the temp.  It's not lying in the morning, reported fuel temp is near ambient.

 

Should I plumb my return back to the filler neck?  I rather hate to do that as it adds more splices and could entrain air in my fuel as it splashes back into the tank, and also in the winter that warming of the fuel has to be a good thing, right?  I bought the $300 DDRP before I found this site, and don't really want to drop another $650 on yet another fuel pump just to remove air.  Of course, there are a lot of things in life I don't want to do, but do anyway because it's better in the long run.