Engine Trouble

[OutbackDiesel]

My friend has a 97 Cummins Dodge with a low speed/Rpm problem. His truck will sort of lurch and hesitate for a few seconds as you leave a stop light. Or early in the mornings. It feels as though it isn't getting any fuel. Then once the RPMs are up, it doesn't do it any more. I was wondering about a fuel transfer pump and I bought one, just haven't put it in yet. However, the more I read, the less confident I am that the pump is the problem. I read that the mechanical pumps rarely go out. His truck has 125000 miles on it. Any Idea what may be causing this? Thanks in advance for any help. .

 

[illflem]

Idle is too low.

 

[HoleshotHolset]

Speaking of low idle... .

How does one know where there idle should be without using a scan-tool? In other words... . at curb idle where should the needle be in relation to the 1krpm mark on the stock tach?



I think I have mine just right now... but I'm still unsure.



Matt

 

[illflem]

Matt, I used a laser tach that read off a piece of reflective tape on the lower pulley, fanless of course. 700 rpm on the laser was right about where you'd figure 700 to be on the dash tach. A/C needs to be on and auto transmission in Drive.

 

[HoleshotHolset]

illflem, that's a cool way to do it.....

With no access to a laser tach, I'll just look at the stock tach and guesstimate.

With the idle set to where it is... I don't have to give the truck any throttle to start it in the AM... not like I used to have to do. It fires within 1/2 revolution everytime now. Gotta love direct injection without the PITA of a HEUI system like the Flowerpoke... ... they won't start if the crank speed is even just a little too slow... ... darn $1600 high pressure oil pumps and $3200 injectors... . HAHAHA!!



Matt

 

[illflem]

Matt the laser tach has come in handy a few times, especially when I'm fabricating unique pieces of equipment. Measures from 0. 1 to 25,000 rpm, $39 from Harbor Freight.

 

[HoleshotHolset]

illflem, you seem to have a lot of tricks up your sleeve.....

That's cheap for a neato tool... . I may just pick one up!



Matt

 

[R.Brooks]

Hey Illflem,



You got a P/N or manufacturer on that tach?



Thanks!

Rodney

 

[diesaldual]

Outback, doesn't look you got your answer!

Chech thye idle speed, in park with a/c off and lights off you should idle around 850-900 rpms. give or take a few. Then when in drive it should idle around 750-800 rpms.

If this is not the problem, it could be thr preboost. Has anyone been screwing with the AFC or fuel cam plate?

 

[OutbackDiesel]

Yeah the cam plate was replaced with a TST #5 I believe. As well as new injectors. I think the injectors are a little bigger than stock. I will check the idle... if not that, then what do I look for as a remedy to the pre boost problem you mentioned?

 

[illflem]

RBrooks, The laser is a Cen-Tech DT-838. I picked it up on sale but the regular price wasn't much more. I was wrong about the range, it's 0. 1 - 99,999 rpm, that's some major spinning

 

[HoleshotHolset]

WOW! You could da*n near check the RPM of a turbo that wasn't spooled all the way..... 150,000+ happy little revolutions per minute that put smiles on our faces for hours!!



Matt