Engine lost Power

USN_Green_Addict · Aug 11, 2024

During my road trip, half way through I noticed a lack of power, or what I perceived as a loss of power. When I had my M35A2 in Colorado I would be constantly be watching the EGT gauge, I never needed to floor the go pedal and after my intake swap it was go 60mph on 12.00-20s up gradual hills. Now that I'm in Georgia it feels like it struggles to go up hill, and I don't think I have enough power to install the Waterloo overdrive. I have checked the newer parker lift pump and it's humming just fine. I've changed the fuel filters, and last month I rebuild the hydraulic head. I do have a leak coming from the boost pump area. I'm debating taking out the entire IP to see if there are any issues or if the boost pump is bad, unfortunately I'm trying to find information On how to tell if the boost pump is bad. Previous owner installed a tiny air filter that was really bad making very high EGT, I installed a M52 filter and it dropped EGT significantly, and I was able to achieve better performance. Now when climbing any hill the truck struggles, however with my foot to the floor the EGT will never go above 1050 degrees. Or if the change in altitude and humidity affects the engine performance. Altitude was 5400+ ft in Colorado, now I'm at 305. Humidity is now in the 60+ every day. I'm not sure if I need to perform a valve clearance adjustment, or how to tell if it's needed. Blow by is very minimal out the slobber tube.

Anything else I can check?

gringeltaube · Aug 11, 2024

USN_Green_Addict said:
Anything else I can check?

Sounds like your engine is starving for fuel.

I'd recommend downloading and study this TM....
(Best step-by-step guide to help determine what is causing that lack of power of your Multifuel.)

USN_Green_Addict · Aug 11, 2024

gringeltaube said:
Sounds like your engine is starving for fuel.

I'd recommend downloading and study this TM....
(Best step-by-step guide to help determine what is causing that lack of power of your Multifuel.)

Thank you,

The only thing I forgot to mention is I have the spin on fuel filter adapters. I use Donaldson water separator and Fleetguard fuel filter.

I'm not sure if these restrict flow. One is 2 microns the other is 5 microns. However I just replaced these.

cattlerepairman · Aug 11, 2024

USN_Green_Addict said:
Thank you,

The only thing I forgot to mention is I have the spin on fuel filter adapters. I use Donaldson water separator and Fleetguard fuel filter.

I'm not sure if these restrict flow. One is 2 microns the other is 5 microns. However I just replaced these.

I got bitten by the "but I just replaced these" a couple of times. Who knows...several fillups and hours of vibration might have shaken some crud loose you didn't even know you had in there.
I strongly agree with re-visiting the basic culprits before tearing into the complex stuff!

Sent from my SM-G991W using Tapatalk

USN_Green_Addict · Aug 11, 2024

cattlerepairman said:
I got bitten by the "but I just replaced these" a couple of times. Who knows...several fillups and hours of vibration might have shaken some crud loose you didn't even know you had in there.
I strongly agree with re-visiting the basic culprits before tearing into the complex stuff!

Sent from my SM-G991W using Tapatalk

Good news I have a spare IP, and injector nozzles. I've been pondering replacing all of the fuel lines anyway, I figure after 58 years it might be time. If I do I probably will take off the filter bases and clean those passages too.

USN_Green_Addict · Aug 11, 2024

cattlerepairman said:
I got bitten by the "but I just replaced these" a couple of times. Who knows...several fillups and hours of vibration might have shaken some crud loose you didn't even know you had in there.
I strongly agree with re-visiting the basic culprits before tearing into the complex stuff!

Sent from my SM-G991W using Tapatalk

Any idea where I can find the fuel flow rate needed for the M35A2 LDT?

cattlerepairman · Aug 11, 2024

USN_Green_Addict said:
Any idea where I can find the fuel flow rate needed for the M35A2 LDT?

Yes, it is in the TM. I know there is a table in the engine rebuild TM.

Sent from my SM-G991W using Tapatalk

USN_Green_Addict · Aug 11, 2024

cattlerepairman said:
Yes, it is in the TM. I know there is a table in the engine rebuild TM.

Sent from my SM-G991W using Tapatalk

Ok I found the table, however I'm not understanding unit of measurement to GPH or GPM.

HDN · Aug 12, 2024

USN_Green_Addict said:
Ok I found the table, however I'm not understanding unit of measurement to GPH or GPM.

Perhaps I can help with this and include a math lesson for those who need a refresher

The answers are in green if that's all you want

According to Hometowne Energy, diesel fuel weighs about 7.1 lbs/gal. It seems you need GPH or GPM. I'll start with GPH here since the units in the TM are using hours. We'll use the 90 lbs/hr figure in this example:

90 lbs/hr * gal/7.1 lbs = ?

I flipped the 7.1 lbs/gal to gal/7.1 lbs because we want the lbs to go away since we're interested in the gallons. This way the lbs cancel each other out (this is easier to show as fractions on paper!). We're also multiplying fractions here, which involves multiplying the numerators and denominators together. Remember that multiplication like this isn't just with numbers, but also with units. It's algebra at work!

90 ~~lbs~~/hr * gal/7.1 ~~lbs~~ = ?

So we now divide 90 gal / 7.1 hrs and get 12.7 gal/hr

Now if you need gal/min, we want the hrs to go away and put mins there instead, so it works like our first conversion from lbs/hr to gal/hr:

12.7 gal/hr * hr/60 mins = ?

The hrs cancel each other out and you end up dividing 12.7 gal by 60 minutes:

12.7 gal / 60 mins = 0.2 gal/min

Note that when units cancel each other out, a number "1" sits in place of the units, so that ultimate gal/min answer is really figured out by multiplying 12.7 gal/1 * 1/60 minutes. Multiply the numerators and denominators together to get the answer.

This hobby involves math sometimes. Gear ratios and fastener torque conversions are especially fun! I hope this helps to get you back on the road! :driver:

USN_Green_Addict · Aug 12, 2024

Thank you I appreciate it. I'm used to dealing with math on the electromagnetic spectrum, just not fluids and flow/hydraulic or pressure.

HDN · Aug 12, 2024

USN_Green_Addict said:
Thank you I appreciate it. I'm used to dealing with math on the electromagnetic spectrum, just not fluids and flow/hydraulic or pressure.

Different math for different things! For my line of work I do a lot of unit conversions. kWh to MMBtu to therms to gal per MMBtu, and across different types of fuel... People deal with energy in a lot of ways!

ANYWAY for the LDT it looks like you need 64 lb/hr. So that would be 9 GPH or 0.15 GPM.

WillWagner · Aug 18, 2024

USN_Green_Addict said:
Thank you,

The only thing I forgot to mention is I have the spin on fuel filter adapters. I use Donaldson water separator and Fleetguard fuel filter.

I'm not sure if these restrict flow. One is 2 microns the other is 5 microns. However I just replaced these.

There might be an issue with these two filters. 2 and 5 micron are VERY fine. A micron is 1/1000 of a MM. Normally, a primary filter is 15-25 micron and sometimes there is a secondary that is a 5 - 7 micron. Cummins deemed that a 10 micron filter, FS1000, was sufficient enough to clean the fuel at the pump. I believe that that thinking is still in use. If the filters are that fine, the filters will plug quickly.

Did you change/clean the screen filter under the alternator?

IIRC, the spin on filters I had were a Fleetguard FF182 or a NAPA 3336. Those were 17 micron rated.

JATONKA kits come with a Wix 33405 primary, the one under the alt., rated at 10 micron. That filter is equivalent to the FS1212 or FS1000.
His spin on kits come with WIx 33336, which is FF182, rated at 17 micron.

I'd change filters and see what happens.

In theory, the way John has the filters set up, one would only need to change the primary due to it being finer than the secondary filters. This can be an issue, it should be a rock catcher as a primary, to get the chunks out, then a finer micron before it gets to the pump.

A way to keep an eye on things would be to install a vacuum gauge at the outlet of the primary and when you feel a power loss, check the restriction. Don't know what the multi engine can handle for restriction onto the lift pump, but on a similar sized Cummins, the C8.3, it was no more than 4 inches of restriction at the frame mounted primary and 4 psi drop across the pressure side, secondary, filters. I imagine the LDT/S is about the same.

USN_Green_Addict · Aug 18, 2024

WillWagner said:
There might be an issue with these two filters. 2 and 5 micron are VERY fine. A micron is 1/1000 of a MM. Normally, a primary filter is 15-25 micron and sometimes there is a secondary that is a 5 - 7 micron. Cummins deemed that a 10 micron filter, FS1000, was sufficient enough to clean the fuel at the pump. I believe that that thinking is still in use. If the filters are that fine, the filters will plug quickly.

Did you change/clean the screen filter under the alternator?

IIRC, the spin on filters I had were a Fleetguard FF182 or a NAPA 3336. Those were 17 micron rated.

JATONKA kits come with a Wix 33405 primary, the one under the alt., rated at 10 micron. That filter is equivalent to the FS1212 or FS1000.
His spin on kits come with WIx 33336, which is FF182, rated at 17 micron.

I'd change filters and see what happens.

In theory, the way John has the filters set up, one would only need to change the primary due to it being finer than the secondary filters. This can be an issue, it should be a rock catcher as a primary, to get the chunks out, then a finer micron before it gets to the pump.

A way to keep an eye on things would be to install a vacuum gauge at the outlet of the primary and when you feel a power loss, check the restriction. Don't know what the multi engine can handle for restriction onto the lift pump, but on a similar sized Cummins, the C8.3, it was no more than 4 inches of restriction at the frame mounted primary and 4 psi drop across the pressure side, secondary, filters. I imagine the LDT/S is about the same.

I have the 33336 on order and am going to order the 33405. Yesterday I mounted a pressure Guage for the lift pump, it's at 7 PSI with the engine off, haven't checked it with the engine on. I have two more on order for after the primary a after the secondary. I plan on keeping them permanently installed. I only changed out the primary filter about 150 miles ago. As far as filtration, I'm running WMO with a direct drive centrifuge. I run it at 10 gph.

Valley Rock · Aug 18, 2024

If you went from 5400' to 305' you need more fuel .

It's a pretty simple procedure just take that cover off and turn that screw out one full turn and see what difference it makes then go from there .

WillWagner · Aug 18, 2024

WMO will clog filters fast.

And I forgot about the deuce having an in tank pump, so, yeah, low pressure gauge pre and post primary. One can be installed at the tank fitting, IIRC, there is a 1/8NPT plug there, and after the primary.

Sometimes WMO, WTF, etc can be too much. You can try thinning the tank you have with gas or diesel and see if the power comes up.

The idea of "Multi Fuel" was designed so that the trucks could get out of harms way by using the available stuff to use as fuel. They were not intended to use alt fuel as a primary source. Your issue could be caused by your mixture.

I do remember that the "other" Will Wagner had issues on one of our trips that was caused by his choice of fuel. He had used WMO, WTF, gear oil to top off. He had cleaned out his and his Dads garage. By the end of the 100 mile trip to our destination, he had fallen back several miles. We topped off with some fresh "diesel gas", still free since I got it from FedEx, and he was back up on ponies and no more issues for the 4 days in the desert and the 100 miles home.

I miss DirtBag!

USN_Green_Addict · Aug 18, 2024

Valley Rock said:
If you went from 5400' to 305' you need more fuel .

It's a pretty simple procedure just take that cover off and turn that screw out one full turn and see what difference it makes then go from there .

I need to read about how to adjust the fuel screw with a EGT Guage. Mine is pre-turbo.

USN_Green_Addict · Aug 18, 2024

WillWagner said:
WMO will clog filters fast.

And I forgot about the deuce having an in tank pump, so, yeah, low pressure gauge pre and post primary. One can be installed at the tank fitting, IIRC, there is a 1/8NPT plug there, and after the primary.

Sometimes WMO, WTF, etc can be too much. You can try thinning the tank you have with gas or diesel and see if the power comes up.

The idea of "Multi Fuel" was designed so that the trucks could get out of harms way by using the available stuff to use as fuel. They were not intended to use alt fuel as a primary source. Your issue could be caused by your mixture.

I do remember that the "other" Will Wagner had issues on one of our trips that was caused by his choice of fuel. He had used WMO, WTF, gear oil to top off. He had cleaned out his and his Dads garage. By the end of the 100 mile trip to our destination, he had fallen back several miles. We topped off with some fresh "diesel gas", still free since I got it from FedEx, and he was back up on ponies and no more issues for the 4 days in the desert and the 100 miles home.

I miss DirtBag!

I switched from 50 diesel/50 WMO to pure. I think I might switch back.

Valley Rock · Aug 18, 2024

One turn on the screw won't burn you down, but it will give you an answer, you can always hook up your guage after .

I dump all my old used motor oil in my Deuce, then when I'm out on fires I just take out straight diesel because I don't want to deal with that oil mess out in the woods, I've never had any running issues or plugged filters because of it, I run all my waste motor oil through a paint strainer to remove pine needles golf balls etc.

WillWagner · Aug 19, 2024

Valley Rock said:
One turn on the screw won't burn you down, but it will give you an answer, you can always hook up your guage after .

I dump all my old used motor oil in my Deuce, then when I'm out on fires I just take out straight diesel because I don't want to deal with that oil mess out in the woods, I've never had any running issues or plugged filters because of it, I run all my waste motor oil through a paint strainer to remove pine needles golf balls etc.

Pine needles!

LowTech · Aug 23, 2024

Full time WMO burner here and been doing it for a decade. 100% in the summer and 10gal gas mixed w/ 40gal WMO in the winter. I filter through 2 -20 micron filters, 1 - 10 micron and sometimes a 5 micron before adding it to my tank. Pressure gauges on all filters so I only change out the one clogging up.
I know when I'm using "emergency fuel" (pump diesel) because the truck is weaker pulling grades than when it has it's standard WMO fuel.

Engine lost Power

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