M915A1 rough idle - Steel Soldiers::Military Vehicles Supersite

rcflyer70 · 03-07-2011, 20:50

What is the correct idle speed for the M-915A1? Mine is set at 500rpm and idles rough. At this rpm, it is also slow to accelerate. Any information would be appreciated.

Brian

R Racing · 03-07-2011, 20:52

Check your fuel filter . It maybe plugged up.

wreckerman893 · 03-07-2011, 21:03

Injector pump may need adjustment....my first M915 wasw a dog...AM General bought it and made a big truck out of it.

AMGeneral · 03-07-2011, 21:16

Mine idles about 550 to 600 cold,and about 700 warm,it has that Cummins"lope" cold but it smooths out when warm.

As far as the low power condition,after you change the fuel filters and are certain it is getting plenty of fuel flow to the injectors, and the injectors,valves,and Jakes are adjusted properly,then you may want to look at having the IP rebuilt,it cost me about $402 from a reputable shop,and that included a new 24V fuel solenoid and mounting gasket plus a new drive spider.

It made a 110% better driving truck,lots of power and virtually no smoke,these 915A1s aren't shy on power by any means,just gearbound with 4.41s,so 63 mph is about it.

If you floor it from a standstill,hang on,it WILL push you back in the seat.,DO NOT engage the diff lock on wet pavement bobtailed,it will spin around in the road with you!!

rcflyer70 · 03-07-2011, 22:25

I put a new fuel filter in today along with Lucas injector cleaner. I also removed and cleaned the IP screen. Can the IP pump checked at a specialty shop?
Once the motor is accelerated to 1000rpms or more it sounds smooth (nothing like an injector issue).

Brian

Monkeyboyarmy · 03-07-2011, 23:06

The few 915's and 916's I've seen all have been dogs. I think they were de-tuned because of the cat tranny. I'm sure a pump adjustment would help alot.The 915A1's seem to be tuned up more.

Floridianson · 03-08-2011, 00:40

I bout the same as AM General when it's cold maybe 500rpm but after it's warmed up 650. Mine is real strong and is an A1. I did open up the fuel 1/2 turn at the throttel shaft.

O that's a TP and I would run it awhile if you just put in the fuel additive. It's not going to happen in 30 seconds it might take a tank full who knows.

Bighurt · 03-08-2011, 01:08

Anybody have a NAPA part number for the fuel filters? Or all PM filters for the matter? I plan to do an initial fuel filter swap, and another after the first tank.

Thanks

rcflyer70 · 03-08-2011, 01:25

The NAPA fuel filter number is 3405. These are the numbers I've taken off the filters on my truck (I'm also in the process of replacing every filter, after the power issue is solved). Coolant - LFW 4701 Oil Filter - LFP 670 Air filters - V250C127 & V250C128. I haven't gotten the numbers off both transmission filters, spin on and internal. Will post tomorrow if someone hasn't beat me to it.

Thanks to everyone who has given advice on what to check - keep it coming

. Once I have figured out the problem, I will post the solution(s).

Brian

AMGeneral · 03-08-2011, 17:20

I use Fleetguard on mine,the numbers are as follows,

Primary oil LF 670
Bypass oil LF 777
fuel FS 1000 or FS1212
trans HF 6243 or HF 6318

I think the water filter is a WF 2071.

I don't believe there is a fleetguard cross for the internal trans filter.