Hello guys, new to the fourm.
First off want to say hellp. SO Hi everyone..

Now heres my problem.
I bought a rollback towtruck with a 98 12V cummins and a 5 speed.
200,000 miles It was just converted into a tow truck within 10K miles. (streched and suspention beefed up)

The guy i bought it off of said it has a new injection pump and 330Hp injectors.. ( i seen the recepts also) It was done within 5k miles.
The problem is it has NO POWER! I even put a #100 fuel plate and adjusted the star wheel with little to NO differance. It lost power i think.. When its cold it starts fine but when it warms up you have to hold the throttle to the floor for it to start in a timly manner. Also when warm has slight miss on one clyender. When you8 get in to the throttle a little the miss comes out. I really doubt the miss is the motor its self. It has no blow buy and don't smoke at all.
after the fuel plate I really think i lost some more power.. Like it literly wont get up to hwy speeds IE: 60MPH.. I put a pair of vise grips on the fuel retorn line to the tank anx pinched it off. It helped a little bit. It smokes a little during low rpm driving with foot to floor. Ive had many 12Vs and never has a this issue... Could it be a timing issue?? would that make it miss on out though?? Its not a all time miss.. Just under light throttle of no throttle.

I have done, ( checked for )
pinched return line,
checked the fuel shutoff,
air in lines..

Im leading toward timing.
maybe they didnt time it i correctly when the pump was installed.
With 330HP injectors ot should poor some smoke with the fuel plate i put in it.
It seems like if i have vey light throttle pressure it feels like it wants to go. However when i go 1/4 throotle or more it feels as if its trying to dog down.

Please give me some insight,

God bless.

 

Hello and Welcome

What you are describing sounds like fuel restriction. Have you replaced the fuel filter? Replaced the strainer in the fuel heater? Could be cracled fuel lines letting air in. Was the overflow valve replaced when the injection pump was reworked.

I would start by checking the above and the fuel pressure at the injection pump.

John (DH)

 

This sounds like a fuel problem. Have you checked your fuel pressure? You might have a bad lift pump. And then 330HP injectors and a #100 fuel plate with a stock turbo! That will push the heat up to the level of the Sun for pulling. Without the head being O-ringed I wouldn't set the timing past 16 deg. A much more realistic set up for pulling would be a set of 75HP injectors and a #10 plate. And without cut delivery valves or 191's you probably have way to much injector with 330's JMHO

 

I found that the wastegate was not hooked up and the WG was fully open.
well the plunger thing is rusted up I tryed blowing air ( air comprssor) in the line to make it push out so I wired it shut. It made a slight difference. in the power. But only with the vise grips on the fuel return line. I can hear it spool a little now but still dont even spool like a stock 12v though Its not a bad turbo. It has no shaft play and spins great. Im just not getting enough fuel..

Well i changed my filter, It had a extra B.S pump on the back by the tank and a inline filter. The pump didnt work and the filter was removed.
I didnt check the inline screen at the heater. I didnt know where it was to be honest. So where do i look? I Dont know of the overflow falve was changed or nnot.
If i put vice grips on the return line i can drive it like that and its " ALRIGHT" power. Like a little less than like a 94 12v stock.. some smoke below 1300rpm. I find it hard to beleve that it has 330 inkectors. The truck is weak!
It will haul a car but it really slows down on hills. It has a miss at low throttle pressure and at idle. when its cold it wont miss.. warm it will miss. above 2K rpm i cant feel it miss.

I beleve that its maybe a junk injector causing the miss.
Well ill try to check pressure at the pump.
I really think its maybe timing...
Maybe not though... Your the masters. Im here to learn.

what elese can i check for.

 

her ya go this explains it all
http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

 

oops posted it twice

 

Oh, think you very much johnber...

 

My miss is getting worse. its 2 clienders not hitting at low rpm and light throttle when i get in to it will bring in one of the missing clyenders amd only one is missing. If i shut the truck off for about 10 sec or so and start it it idles fine. If i try and drive it and let it go back to idle it misses on one agan and so on.

Im trying to find out wich one is missing.. hopefully just two injectors will fix it.

If i take the vice grips off the fuel return line it will bearly pull its self and i get quite a bit of blue/white smoke at any rpm including idle.

How much fuel pressure am i sopposed to have?
I checked all the obvise including the pre screen and everything.
It must be out of time or low fuel pressure. I check the overflow valve and couldnt blow air through it by mouth. I streched the spring just a little to give it a little more PSI, Even though i have the return line totaly blocked off.


Any help would be wonderful.

 

Before getting too carried away with the fuel system, I'd give it some sort of a compression test to be sure it isn't an engine problem. At least disable the shutdown solenoid so it can't start, then crank the starter and listen to each cylinder's contribution. You'll be able to hear a weak one while it's cranking.

 

I tryed that, It was the fist thing i thought of. with my luck it should have has at least one of two holes that were low but they all sound even.
HOWEVER, when you shut it off its not as abrupt as my other 12Vs
It kinda just stops like gasser.. Not off like a light switch and that little churp thay make. This one makes no churp..

 

Well, Im at a loss... Any more help?

 

Im Thinking my rebuilt Pump is going out...
If its cold it runs fine. Starts missing after a cople miles.
even at idle. If i shut it off for 10 sec and start it no more miss at idle. ( or until i try and give it throttle)

It has new lift pump, injectors, and the psi is good to the pump...

 

Did you ever end up checking fuel pressure? You should see in the 20 psi ish range at ide and maybe even to to 30.

 

Ohh ya at wot you should see no lower then 10 psi and also maybe should inspect the lines from injection pump to frame rail those are really normal to crack. I have found even if they are not externally leaking they can still get air sucked in. Good luck

 

ill go over all that again.