M915A1 rough idle

[rcflyer70]

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]

Check your fuel filter . It maybe plugged up.

 

[wreckerman893]

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

 

[AMGeneral]

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]

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]

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]

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]

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]

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]

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.

 

[rcflyer70]

I found a local diesel shop that will check my fuel pump. One last check, suggested by Memphis Equipment, will be to put the last section of fuel line to the fuel pump, in a bucket of diesel then start the motor. This was suggested to eliminate the possibility of air getting into the fuel line. If this doesn't shed light on the issue, the pump goes to get checked.

Brian

 

[Floridianson]

Yes if the air was entering from the lines. The advantage of you having the PT rebuilt I would think would be they can tweek it a bit. Raise the rail pressure, tweek the AF. Never hurts to rebuild these PT if it's never been done I would think. You get alll new seals and should be good for a long time. I pay about the same here in Gville 400.00

 

[rcflyer70]

I was quoted $250 to $650 depeding upon what they had to do it - well worth it if my issues are solved!

 

[rcflyer70]

Looks like I got lucky!!! On the advice of my local parts store owner (I think he has parts for every vehicle and tractor ever made in stock), I tried Lucas injector cleaner before diving into my fuel pump - I'm glad I did. I put the entire container in 10 gallons of diesel (I had about 10 gallons in the tank already). After idling the truck for about 1/2 hour, it started running much better. I ran the truck up and down the road in front of my house about a dozen times - the truck runs great now! I'm sold on Lucas injector cleaner.

Thanks again for everyones help!

Brian