Engine/Transmission (1994 - 1998) strange low power 95 3500

[TBurow]

my fathers 95 3500 has som strange problems, it will not start unless you press the accelerator, and sometimes will not start hot. new fuel lift pump,new fuel filter, pressure 20-30 psi, shutoff solenoid working properly.



also it is low on power, used to be able to fill the road with smoke, now just a light puff and pulls like its at 1/2 throttle. just replaced turbo(old one had frozen open wastegate), checked the function of afc it holds pressure and moves correctly, pulled cam plate and ground it to a #5 set full forward, no change. checked throttle movement, has full travel. no boost leaks, just no power. my 96 will smoke the tires and pulls like a scalded dog, his is just a dog. the t/c is not bad it is a low stall unit and works the same as when it had good power. i was going to replace the afc hose tomorrow but i dont think it will help.

 

[Missouri Mule]

Check your/his pre-filter screen at the fuel heater.



Did you do overflow valve test when you did fuel pressure test?



Using a little pedal with the p7100 is Ok when starting.



P7100 could be on it last days.

 

[bmoeller]

If cleaning the screen and replacing the overflow valve don't do it, you could be sucking air from somewhere as well. The rubber fuel lines are known for leaking air, but not fuel.

 

[TBurow]

how do you check the overflow valve? cleaned the screen last year, will check again. i also have had to turn the idle up 2 times in the last month it was dying at stops and had a low idle. idles good now just feels like it starts de fueling about 1500 rpms. could bad gov springs cause this? also his fuel filter was rusty, on the outer(unfiltered)part and clean on the middle threaded section where the filtered fuel comes out, but not much water in the filter about a tablespoon full. i doubt water got into the pump, but you never know. i was leaning toward bad injectors not popping where they should. i have another set of stockers i might try.

 

[Joe G.]

I think timing must have slipped. Just in case it's a fuel supply problem email me at -- email address removed -- for my 12 valve fuel supply system write up, how it works and how to fix it.

 

[TBurow]

ok, checked the pre filter and cleaned it, no effect. pulled the fuel plate to look at the gov springs and the nuts that hold them on were so loose that there was only 1 or 2 threads engaged in the nuts, tightened them so there was just a little tension on them just enough so they locked in place. runs better but sometimes stalls when put in gear but still not the same power as before. this makes no sense. i am starting to think he needs a new ip.

 

[Missouri Mule]

Overflow valve check; While doing fuel pressure test take a pair of pliers and squeeze the rubber return line if the pressure goes up your overflow valve is bad if doesn't go up or goes up slowly it is your lift pump.

 

[TBurow]

it isnt a fuel pressure problem fuel press is 20 at idle and 30+ at 2000 under load. we are draining the fuel tank as the fuel looked a little hazy and may have had some water in it. the old fuel filter was rusty so i figure draining and cleaning the tank is in order.

 

[TBurow]

ok, got it nailed down, fuel had water in it and the gov spring had backed off on one side causing all sorts of wierd things to happen. theese things have locks made into them, strange it would back off. but all is well with new turbo with working wastegate (no longer frozen open), clean fuel and clean filters. so DRAIN YOUR WATER SEPERATORS REGULARLY. my father needs to learn proper maintenance.

 

[TBurow]

well this problem has resurfaced, lately it will not start if it sits a while without a shot of starting fluid( i know its bad but it will not start without it) i have bled the system and am getting pressure from the lines at the dv's. the grid heaters work, i tested them. it runs smooth when it starts so its not air in the fuel. i also pressurized the tank to 10psi to check for leaks and it didnt drip in 3 days. so, i think the i/p is dying. it runs fine when i get it to start, just a little low on power. could loose gov springs or incorrectly adjusted ones cause this?

 

[GSRichards]

my truck is doing the same thing, its hard to start after sitting for even 10 minutes, but once it gets started it runs fine

 

[Hammer]

Its either timing related or air... . simple



Either your timing has retarded/slipped backwards,which they are known to do.



or



your sucking air into the fuel system in a place you have overlooked. 3 of the biggest problem areas for that... .

-The return line under the intake shelf AND the braided lines that go over the transmission bellhousing. Those braided lines are a known issue which can not bee seen when they leak. Follow the return line back to where it crosses the bell and you will find them. Inside the braided line is plastic which will fail as it gets older and will allow a leak or air into the line thus the engine does not stay primed.

-The fuel heater assembly and lift pump itself will cause the same issues your having. Unplug the heater and look to see if the plug is wet,if so then its leaking and allowing air intot he system. The lift pump will begin to leak after time also,look under the rubber primer boot(pull it off)and if its wet then its compromising the fuel system.

-The fuel lines and the lines at the tank module. The factory fuel lines are corroding inside the frames of our trucks and you can not see an issue until the leak actully gets bad enough it drips out of the frame rail. ma Mopar has discontinued them completely so unless you go to Classic line and oder a new set or use rubber like most do then your out of luck. Also note the line attach on the tank module are notorious for rusting and allowing air to leak and cause the same issue.



I will also say the Prime-Lok may be a canidate here also. Many people have removed them due to issues like this and gone back to the factory set up... ... ... Andy

 

[Matt42]

A problem peculiar to the 12 valve trucks is the throttle linkage. (Strictly speaking, there ain't a throttle. ) The linkage is the adjustable arm that connects the accelerator pedal to the P-7100 injector pump and has a ball and socket at each end. The socket is lined with nylon, which can wear out. The adjustment jam nut can come loose, which will cause the fuel delivery to be reduced. The effect is that when you press the accelerator pedal, you get way less fuel delivered than you should.



It's a quick adjustment if that's the problem. If the sockets are worn, it's a new part, should be under $30. In bad cases, one end or the whole thing falls off. That would be obvious, though. Note that this problem will only cause reduced power, and should not cause a non-start condition. There was a recall for this in circa 1999. I discovered the problem towing up the Black Canyon grade in 2002, and adjusted it on the roadside. I now carry a spare link.