Engine/Transmission (1994 - 1998) Low power on a 1995 12 v

[JPS]

Have a 95 12v , 70k for miles. As you can see, I don't drive it a lot. Had to make a 400 mile round trip the other day. Found I was lacking power. Changed fuel filter when back home. Helped some but not sure what truck should do as far as speed. 75-80 is about top. Even hard to get it to that speed. This truck is pretty much stock. While running that speed for a couple of miles it seemed to detune, so to speak. Start from a stop, push throttle wide open, runs that way for a couple miles and then slows done to about 60mph. Sure could use some help. Did a search, didn,t find much. TIA jps

 

[surfbeetle]

Check your boost, check the hose from the turbo to the injection pump, more boost gives it more fuel. Check your intercooler for loose hoses/clamps. Check your return fuel line, check your fuel delivery valve (I think that's what it's called) between the injection pump and the head at the front driver's side of the engine. Also check the fuel shut off solenoid, if it's not getting enough juice, it will not hold up all of the way and restrict the fuel flow. Also by the book with only 70,000 miles, you may have only adjusted the valves once or twice, I recommend just doing it once per year or sooner depending on mileage. The last few years, I have only averaged 7,000 miles per year and just do the valves once a year, it makes a difference.

I have 216,000 on my 95 so I have all of this happen on mine. Other then the automatic, I'm kind of jealous of your low mileage truck. Good luck on your troubleshooting.

 

[GAmes]

How old is the fuel in your tank and was the tank only partially full while it was sitting? Diesel absorbs water from the air, so keeping the tank full while being stored (or nearly empty requiring new fuel when you take it out) is a good idea. This is one time I would try a good additive like Stanadyne, plus fill the tank with new fuel preferably from a high turnover truck stop.

 

[JPS]

Fuel

Did use fuel from one of the busy truck stops in the area. Thought about fuel also. Added power service about 150 miles from home on 400 mi. trip. Plan on adding fuel from another stop, see if that helps. Will also add Stan dyne. Hoping for the best. Thanks for the replies, guys!! jps

 

[hsmith]

You also need to check the pre filter screen.

 

[FParisi]

Is it smoking when under full throttle? I second checking the hoses to + from the intercooler.

Have you checked the air filter?

 

[wrichards]

Mine is the same way. i just bought it 72k on clock but no poer 75-80 max. Maybe its normal. Teh one thing I noticed is that I do not hear the turbo spooling like on my other cummins. Also will have no turbo bark if floored than let off. I am also going to check the above items. If not than maybe this is normal.

 

[Bob4x4]

Always check fuel pressure with a low power . no smoke condition on a 12 valve

 

[JPS]

I have a fuel kit that puts the filter up on the fire wall. Not sure of the name. They were popular on this site a few years back. Was made for easier fuel filter change. Isn't there a tapped plug on those for a pressure gauge. TIA jps

 

[MLee]

Yes they have a pre and post plug. If you have the pressure kit you can test above the original filter mount and get a better reading for the pump. But for accuracy you should use a snubber to control the needle on the gage.

 

[Bob4x4]

A snubber is only needed for a permanent installation not for testing

 

[GAmes]

I installed a needle valve that is just barely cracked open to dampen the fuel pump pulses, so I guess you could call it a snubber. The cost was way less than $19.

 

[JPS]

THANKS FOR ALL THE REPLY'S,GUY. i REALLY APPRECIATE THEM. A LOT OF THIS I COMING BACK TO THIS OLD MIND... KEEP THEM COMING!! jps sorry didn't realize caps were on

 

[KBurgoyne]

a second vote for the prefilter. if its slowing down while holding steady on the go pedal its losing fuel. a boost leak is usually audible too. i believe its a 17mm socket to remove the prefilter, just dont be directly under it unless you like the flavor of diesel. easier if you drain the fuel filter first to depressurize the system. then just blow the nasty out of it with a compressor. if thats the problem it could take 10 minutes. you should get rid of that stupid fuel heater anyway.

 

[JPS]

Thanks KB. Fuel heater is already gone. jps

 

[crabman]

The engine is starving for fuel. If you have checked all the above advice and still have the problem, I would check to see if the fuel shutoff solenoid is fully opening, which if it isn't, would cause the problem you are having.
Please post whatever you find out that fixes the problem.

 

[JPS]

Will do!!! jps

 

[JPS]

What kind of fuel pressure should I have with this 95 12v? Going to try and check at the Prime Loc kit mounted on the fire wall. TIA jps

Mine is the same way. i just bought it 72k on clock but no poer 75-80 max. Maybe its normal. Teh one thing I noticed is that I do not hear the turbo spooling like on my other cummins. Also will have no turbo bark if floored than let off. I am also going to check the above items. If not than maybe this is normal.

 

[crabman]

Have you ever replaced the 2 small fuel lines that are located on the back of the engine? One is the supply line & the other is the return. They just bridge the hard lines (6-8" long) and are for damping the vibration. These hoses can look fine but suck air thru cracks which fuel will not leak out of and cause loss of power. Do NOT use regular fuel line from auto parts store or you will just be replacing them again. Buy USCG approved marine grade fuel line and you will never have to replace them again. The thickness of the hose wall is 3-4 times that of regular hose. Use all stainless steel clamps and have a good 1/4" drive ratchet set.
Note>be sure to have some bandages for your hands, arms & fingers as they are a PITA to change, hence the marine grade hose.

 

[JPS]

Yes, those two hoses have been replaced. Has anyone have info on the spring that was used in the injection pump? Something about upping the rpm when really stomping on it. I think later it was discovered the same thing could be done with washers. Talked to a guy at Geno's garage, said he had never heard of the spring. I have one, not installed, sure I bought it at Geno's. I remember the cost, $125, if I am correct.

What kind of fuel pressure should I have with this 95 12v? Going to try and check at the Prime Loc kit mounted on the fire wall. TIA jps