CTD shaking/vibrating... DV's?

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I don't know how many of you guys know 12V's but I have a 94.... The truck in my sig... When i bought the truck I noticed that the truck would start shaking or vibrating heavily in 5th gear when i get down around 40 MPH. I figured it was just because it was lugging it slightly. When i pushed into the pedal a little bit more it would clear up and power through it. I recently put 75 HP injectors in the truck from DDP and it has gotten a little worse. it will do it even at 45 MPH and when its cold even at 50 MPH, but it doesn't only happen in 5th gear now either. In 4th you can sometimes feel it but not as severe. It also seems to cackle a lot in the lower RPM range from around 1000 to 1400 but i think the cackle is just because of the exhaust that I am running... I remember hearing somewhere that Delivery Valves helps take away chatter (shaking/vibration?) with bigger injectors and didn't know if this was the same problem that they were talking about because it happened BEFORE i had my injectors too... it makes the truck more of a nuisance to drive, especially when the truck is colder. Any personal experience or knowledge is greatly appreciated!

Thanks
 

ramhunter9

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Struggling for fuel , you need a lift pump . Bigger injectors are going to make it worse ... If not kill the stocker . Sounds like the stocker was going south anyway .

I think I told you this at one point :Wedgie:

Now this is just a guess from riding in your truck . Putter putter sputter sputter ..I NEED FUEL
 

Mopar1973Man

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ramhunter9

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What I said but in a more technical term ^:Wedgie:
 
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Montgomery Farms
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Then wouldnt it get worse in the higher RPM range instead of clearing up? that doesnt make sense...
 

ramhunter9

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With a load there is more need for fuel .

Your truck NEEDS more fuel in lower gears than top end . Taking off from a dead stop requires more fuel as the truck / motor needs to get going . At top end it already has the mass moving so less fuel is needed .
 

ramhunter9

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Greyish last time I seen it
 

Rogan68

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That's definitely a fuel starvation then. Mine smoked gray when the lift pump was going out, and stuttered like hell.

per Tapatalk on my EVO
 

ramhunter9

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And to think I have Raptor lift pump just sitting here ..LOL

Austin .. dam kid I am going to need your SS number so I can claim you on my taxes as a dependent .
 

rambob

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And to think I have Raptor lift pump just sitting here ..LOL

Austin .. dam kid I am going to need your SS number so I can claim you on my taxes as a dependent .

haha, nice.
 

ramhunter9

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**** I had to feed the kid the other night .. poor little guy
 
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**** I had to feed the kid the other night .. poor little guy

Whatever!!! I went to Casey's! You
Made me drive over there when your wife coulda brought me something! Haha

Anyways, I read that your not even supposed to shift into 5th until 50MPH... I don't know... I guess it's time to invest in a fuel pressure gauge...
 
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"""""The surging in the engine is caused by the small factory DV's in the 160 pumps, At light loads and low rpm the stock dv's can't give enough fuel to keep the larger injector open through the full cycle. Atleast this is how I have had it explained to me. I replaced mine with .022 and the surging stopped.""""" -Mr.Diesel

Just found this... I think this at least part of my problem, if not all of it. But it is time to get my fuel press. guage. This would explain why it does it in low RPM's AND at light loads. Like I said how if I get more into the pedal it powers through it.
 

Uncle Ugly

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Check your fuel pressure... P7100 pumps are known for having weak overflow valves and losing fuel pressure...

True....Depending on the mileage it would be very benefecial to make a change in the OFV.

Also remember stock lift pumps are not efficent pumps for high performance then tend to come up short at high RPM's...

ACtually this is not correct..The factory lift pump will support plenty of power.However,if the fuel system is compromised by air leaks(which is a very common problem) the factory lift pump will struggle to maintain even at low power levels.I have personally seen factory pumps run into the 800hp range.

IMO what you have is a fuel system that is allowing air into it somewhere that is causing a lean condition down low and when the RPM's rise the motor can overcome it.The injectors you installed are not large enough to cause this problem at all.I would start by pulling the rubber boot off the lift pump plunger and unplug the fuel heater wiring.IF you find that either are wet/damp with fuel they are allowing air into the fuel system which will be one problem.

The next place to look is the return line that runs behind the P7100 and off of the OFV.Follow the hard line and you will find a small section of rubber hose that gets hard and cracks and causes air leaks also.

Another place to look in the engine bay is where the factory fuel lines cross the bell housing.Mopar uses a line that is a braided outside/plastic lined center which are notorious for leaks as the plastic gets old.

Next place to look for leaks is by following the fuel lines along the frame rails.As the trucks get older the steel lines fail as they rust and will begin to weep or show wet spots.Also try and look on top of the fuel tank basket as you will also find that the hoses there will fail with age and leak or possibly break off a barb fitting and it will leak.

Until you troiuble shoot the fuel system I would not look elsewhere.DV's can cause what your experiencing BUT usually when the have issues the truck will miss from the bottom to the top and not smooth out.I have also seen what you experiencing due to dirty fuel filter and/or pre-filter screen(pre-filter is located down on the lift pump assembly).

Let me know how you make out and I hope this helps.I spent HOURS redoing the fuel system on my old 12v and have seen many guys miss one little leak and it killed them for power..........Andy

P.S.-Also make sure you have no wet injector lines at their mounting points and the small brass washer hoops on the return lines are not leaking.
 

Rogan68

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True....Depending on the mileage it would be very benefecial to make a change in the OFV.



ACtually this is not correct..The factory lift pump will support plenty of power.However,if the fuel system is compromised by air leaks(which is a very common problem) the factory lift pump will struggle to maintain even at low power levels.I have personally seen factory pumps run into the 800hp range.
I have, as well. My stock OE lift pump on the 12V supplies more than enough fuel for my 400+hp.
IMO what you have is a fuel system that is allowing air into it somewhere that is causing a lean condition down low and when the RPM's rise the motor can overcome it.The injectors you installed are not large enough to cause this problem at all.I would start by pulling the rubber boot off the lift pump plunger and unplug the fuel heater wiring.IF you find that either are wet/damp with fuel they are allowing air into the fuel system which will be one problem.

The next place to look is the return line that runs behind the P7100 and off of the OFV.Follow the hard line and you will find a small section of rubber hose that gets hard and cracks and causes air leaks also.

Another place to look in the engine bay is where the factory fuel lines cross the bell housing.Mopar uses a line that is a braided outside/plastic lined center which are notorious for leaks as the plastic gets old.

Next place to look for leaks is by following the fuel lines along the frame rails.As the trucks get older the steel lines fail as they rust and will begin to weep or show wet spots.Also try and look on top of the fuel tank basket as you will also find that the hoses there will fail with age and leak or possibly break off a barb fitting and it will leak.

Until you troiuble shoot the fuel system I would not look elsewhere.DV's can cause what your experiencing BUT usually when the have issues the truck will miss from the bottom to the top and not smooth out.I have also seen what you experiencing due to dirty fuel filter and/or pre-filter screen(pre-filter is located down on the lift pump assembly).

Let me know how you make out and I hope this helps.I spent HOURS redoing the fuel system on my old 12v and have seen many guys miss one little leak and it killed them for power..........Andy

P.S.-Also make sure you have no wet injector lines at their mounting points and the small brass washer hoops on the return lines are not leaking.

I forgot all about that. I had to fix a ton of small leaks on the 12V.. The one most hidden, or hardest for me to find was where the steel hardline on the framerail connects to the braided line over the bell housing. The retainer clip inside the lower-most end of the braided line was rusted to pieces (which is odd, as the rest of the hose was SS) and barely retaining the fuel line connection. It would suck air in there, and cause some crazy bucking.
 
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