Engine/Transmission (1994 - 1998) Starting problem

[mothertrucker]

'97 3500 Bone stock 12 valve 150,000 miles.

Recently developed a starting problem.

Excessive cranking required to start the motor... but if I step lightly on the accelerator while cranking it fires right up.

Any ideas of what may be causing this ?

Thanks for any ideas.

 

[GAmes]

What is the idle rpm, operating temp, A/C on, in drive if an automatic?

 

[GrantP]

... but if I step lightly on the accelerator while cranking it fires right up.

It will always start faster with a little throttle. It took me a long time to get out of that habit once I bought my 3rd Gen. But to your problem, check your idle speed as GAmes suggested.

 

[mothertrucker]

I was suspecting idle adjustment.

Owned the truck for 18 years & have never had to step on the accelerator to start it.

Correct if I am wrong but idle adjustment should be done with truck in Drive {auto} & AC on.

 

[GAmes]

Correct if I am wrong but idle adjustment should be done with truck in Drive {auto} & AC on.

No, it should be checked in those conditions. The idle speed adjustment is done with the engine off. It will probably take less than a half revolution of the adjustment bolt to get you in spec.

 

[GAmes]

IDLE SPEED ADJUSTMENT
The high idle stop screw is factory sealed and cannot
be adjusted. Low-speed idle can be adjusted.
(1) Use an optical tachometer such as Snap-on No.
MT139 or MTE (Cummins tool division) No. 3377462
to read the engine rpm.
(2) Bring the engine to normal operating temperature.
(3) Adjust the low idle speed at the low idle speed
screw. The screw and locknut are located at the rear
of the fuel injection pump (Fig. 37).
LEVER STOP
FACTORY
SEAL
HIGH IDLE LOCKNUT
STOP SCREW
LOW IDLE
ADJUSTING
SCREW
J9414-103
Fig. 37 Low idle Speed Screw
(4) Loosen the idle screw lock nut (Fig. 37). Adjust
idle screw to obtain specified rpm (Fig. 38).
(5) Tighten the locknut after adjustment.
LOW IDLE SPEED H I G H IDLE SPEED
With automatic transmission...
750-800 RPM with transmission
in drive and air conditioning on.
Do not attempt to adjust
high idle speed. High idle
speed adjustment screw
is factory sealed. Breaking
seal will void injection pump
With manual transmission... warranty.
800 RPM with transmission in
neutral and air conditioning on.
* With engine at normal operating temperature. Refer to text
for idle adjustment procedures.
r J9414-66
Fig. 38 Idle Speeds—Diesel Engine

Cut & paste from the manual doesn't work well. Page 14-85 in the '96 FSM.

 

[BigPapa]

The head of the idle screw and throttle lever have probably worn quite a bit over time. I had to remove my idle screw and grind the head flat again before I could get it to adjust properly. The lever will wear a groove in the head and when you turn it just the least little bit the idle jumps up a lot because it's no longer in the groove but on top of the un-worn head.

That said, a little pedal pressure to start quickly is not unusual. Mine will start immediately if I lay my foot on the pedal but with no pressure on the pedal it takes a second or two of cranking to start. It's always been that way.

 

[GAmes]

I have my idle set a little high (900) because the A/C work better while in traffic. I still unconsciously give it a little throttle when starting. I do love to just barely bump the starter and bring it to life when there are Ferd & Chebby owners around. :-laf

 

[GrantP]

I do love to just barely bump the starter and bring it to life when there are Ferd & Chebby owners around. :-laf

Or even a 3rd gen owner. ;-) I do miss that.

 

[DVolk]

Sucking air from a fuel supply line

 

[MLee]

Has the return fuel line been changed? air get into the fuel system, creating a start problem especially when cold after sitting over nite. some thing to think about.
Did the above suggestions help any?

 

[GAmes]

Sucking air from a fuel supply line

I doubt it. Sucking air wouldn't result in "... but if I step lightly on the accelerator while cranking it fires right up."

 

[fest3er]

Is the starter turning the engine fast enough? If not, it mayn't be generating enough heat fast enough to ignite the fuel.

 

[Missouri Mule]

It mite be your starter. When the starter starts to go you have to push down on the go pedal.
When my original starter went it just went (15 years old).
The napa life time warranty junk starter they put on started to wear out in 2 1/2 years.
I started to have push down on the go pedal. So I started a search of the symptom files in my head while driving to the produce market.
Soon a thread came to mind with the same symptoms the starter was the problem. Six months later the starter died, lucky for me Mule was in my driveway.
Unfortunately I put another napa junk starter on. Plan on having original one rebuilt or trade it in for an other denso.

























f
i

 

[Missouri Mule]

Napa junk starter died Monday. Last start at market. Monday night turned the key nothing. Quick diagnosis confirmed starter.*
Had shop put reman denso on Wednesday.
Several cranks before starting. *I see how it does tomorrow morinig when I am at the markets.

 

[mothertrucker]

Update

Low idle speed compounded by a tired starter was the problem.



Set idle speed to 850 in drive with AC on.

Installed a new Denso starter.

& as long as I was working in the area.... I replaced the original lift pump with a new Cummins pump.

Everything is working great & it fires right up without touching the go pedal.



Thanks for the help guys.



.

 

[sgmans]

My '94 behaved the same way. Had some fuel pump work done and the starter wouldn't spin fast enough to prime the injector pump worth a darn. The starter finally quit and I bought one form Summit Racing that had really good reviews. Once I put it on the truck fired up better than it ever has. I'm weary of the parts from the autoparts stores. I went with this because of the reviews, glad I did.

https://m.summitracing.com/parts/pwm-9053

 

[BFurton]

When mine went out several years ago, it got replaced with a 1.4Kilowatt unit. It didn't last to long either, maybe 6 months. Did some research in the -96' FSM and it calls for a 2.7 kilowatt unit for diesel applications. Currently running the NAPA 2.7 kilowatt unit now for >9 years.