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I am new to this forum and I hope that it helps me out. I have a 97 Cummins that I am having some trouble with. It has 240,000 miles on it, and a few aftermarket parts on her. I have a stage 2 AFE air filter, 3K GSK from TST Products, a #4 Fuel Plate (the biggest one they make) also from TST Products, and 4" turbo back exhaust.
Recently I had my injectors tested and they were a little low on opening pressure, 220 bar, so I opted to purchase some new ones hoping that this would solve my lack of power/poor fuel economy problems. I got the 70-90 hp injectors and there was a tiny amount of power gain.
I know that the pickup is not making the power it is suppose to because TST said that with a #4 fuel plate alone, my transmission would be wrecked if it was not upgraded, and well it is not upgraded. And on top of that big fuel plate I have now installed the 70-90 hp injectors? I am at a loss.
I am maybe thinking that the low fuel pressure side of my injector pump is to low, suppsed to be 17-25 psi at idle and 25-35 psi at 2500rpm, or something like that.
what is your fuel pressure?.. your stats are right on pressure...did u try changing your filter and cleaning your prefilter? with out the right presuure you will fall on your face. also make sure your fuel shut off solenoid is in the full up position..
click> Fuel Pre-Filter Cleaning on Ram/Cummins
click> TSB 14-07-96 Rev. A
I replaced the prefilter about 4,000 miles ago. I also had the injector pump recalibrated about 20,000 miles ago. I clean/replace my filters every 6,000 miles. It is time to clean/replace them again but this problem has been pretty consistant. As for the fuel heater I have never heard of it.
Something I though was a little weird, if the truck idles for long periods of time while warm, like as if I was filling up the fuel tank, the truck has a bunch of power for a few moments then goes back to no power?
Thanks for the posts so fast, I will definately check the fuel shut off solenoid since I have never thought about it! As well as look into the fuel heater.
Oh, and as for what my fuel pressure is... I don't know. I am a college student and dont really have the funds to just go to a mechanics shop to get it tested. I am pretty mechanically inclined, going for a mechanical engineering degree, and I don't want to buy a tool to do it myself if that is not a possiblity. SO, I'm just looking to get some advice about what it could be. Knowing that the fuel pressure could be a cause I will buy the tools to get the job done.
I know this is an old thread but I thought I would update. I found what you were talking about ykdave. I purchased a new filter and replaced it however, the old one didn't look too dirty. I still have not found out what my fuel pressure is, however I have replaced the overflow valve, and that did give me an average of +2mpg in town.
The new thing is a bit of smoke out of the tailpipe. I cannot tell if it is white or blue, if it is blue it is a very light shade. I can easily tell the smoke coming out when it is night time and there is a car behind me. At idle, the smoke is clearly visible, and when I take off I can see a smoke trail behind me, not heavily, but noticible. Investigating this I decided to do a compression test on the truck. I know that the cummins usually uses a blow by test, but I found a compression tester for $10 and thought that I would try that.
In doing the compression test I found that every cylinder was around 300psi +/- 10psi or so. I heard that the most important thing is that the cylinders be close together which they were. However, compresson is what makes these things work and if there is not enough compression, all of the fuel will not be burned, which may be the reason for the smoke trail I am seeing.
So, sorry for the long post, my question is; are the numbers for the compression in the cylinder ok, or is that really low? Could this be the reason for the smoke that I am seeing? Low power?
as you already know, compression numbers (overall) dont really mean much, you are well within the cranking pressure for a good engine and the variance between cylinders is awesome if your only +/- 10psi
If its "hazing" or smoking, i would be looking at f'd injectors or slipped timing
2015 3500 laramie dually. 6.7, aisin, 4.10s, bone stock... (for now )
2014 forest river XLR 395amp, 42.5ft of truck killing, wind catching, toy and booze hauling, fun...
Hazing would be the correct word. The injectors are fairly new, a bit over a year now. Also I was a but concerned that the injectors I purchased wend bs so I pulled them about 3 months ago and got them tested. They tested what pressure they opened at and said they were within spec and they didn't leak. I didn't ask anymore questions about the injectors.
I have heard about the slipped timing quite a bit. I suppose that is where I will go next. There are many different write ups on how to check/add timing to the p7100. One of which is a proclaimed 40 minute procedure. Is there a certain one that you would prefer? I have heard that 16* is about the max advance with no head studs, is this correct?
I sure don't mean to be a leach on your brain but I Luke knowledge. Would slipped timing be the cause for these various topics;
1. Changing fuel plates from a #8 to a #4 to a stock plate don't have much affect.
2. When engine is first turned on, even when it is close to 90*, if the throttle is hammered with no load the engine will sputter. Goes away mostly when engine is warm.
3. Even with warm engine, while in gear and idling, if I tap the throttle as if to accelerate moderately and quickly let of of it (I mean on and off the throttle fast), the engine will
4. Changing the fuel plate from factory position to ff position seem to have little affect.
5. I can't really tell anymore that I have 3k gsk installed. I can still wrap the engine up to 3k however, it has no pulling power from about 2500 on up.
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